FOREWORD
FOREWORD
1. The first edition of the Manual of Aeronautical Meteorological Practice, published in response to recommendations made by the Meteorology and Operations Divisional Meeting1 (Paris, 1964), was intended as a guide for use by pilots and other aeronautical personnel on meteorological procedures, codes, symbols and abbreviations. It also contained a multilingual list of terms and phrases commonly used in meteorological briefings.
2. A second edition was prepared in 1977 to reflect, in particular, the many changes in procedures and terminology recommended by the Eighth Air Navigation Conference and the Meteorology Divisional Meeting2 (1974).
3. As demand for the manual continued to grow and because further important changes to meteorological procedures had taken place, particularly in connection with the recommendations for the establishment of a world area forecast system (WAFS) made by the Communications/Meteorology Divisional Meeting3 (Montréal, 1982), a third edition was prepared. This edition was rewritten aiming to meet the needs of operational aeronautical meteorologists, as well as the needs of pilots and other aeronautical personnel.
4. As a consequence of an extensive amendment proposal to Annex 3 developed by the Communications/Meteorology/Operations (COM/MET/OPS) Divisional Meeting4 (1990) including, in particular, provisions regarding the transition to the final phase of the WAFS, aerodrome observations, reports and forecasts, SIGMET information, etc., a fourth edition of the manual was published. In order to continue to meet users’ requirements, however, the structure of the manual was not changed.
5. The fifth edition is the direct result of Amendment 70 to Annex 3, applicable from 1 January 1996, which constituted a comprehensive update of the provisions, in particular, those related to air-reporting and the observation and reporting of wind shear. In addition, new provisions concerning information on weather phenomena hazardous to low-level flights (AIRMET and GAMET messages) were introduced. However, the basic structure of the manual was maintained.
6. The sixth edition reflects the substantial changes made to Annex 3 in Amendments 71 and 72.
7. The body of the manual is still based primarily on Annex 3, summarized and enlarged upon, where necessary. The appendices provide:
a) detailed information on aeronautical meteorological codes, model forms and charts used for documentation, etc., which are dispersed throughout various ICAO and World Meteorological Organization (WMO) documents, and whose consolidation in the manual provides users with a single reference document for most of their day-to-day needs in aeronautical meteorological practice;
b) information on other subjects such as location of instruments at aerodromes and use of meteorological information by flight operations officers.
8. Annex 3 is a constantly evolving document, as are all ICAO Annexes. Some procedures described in this manual are currently under review by the Air Navigation Commission and may have changed by the time it is printed and issued. However, the usual amendment service for ICAO documents will keep users of this manual up to date, on a timely basis, on changes of this kind.
9. In conclusion, it should be stressed that the material in this manual is intended for guidance only. It is not intended to replace relevant national instructions, or explanatory material, such as the explanations of codes and symbols, normally shown in flight documentation, nor is it intended to cover the many non-aeronautical uses of meteorological information. Nothing in this manual should be taken as contradicting or conflicting with Annex 3 provisions or any other Standards, Recommended Practices, procedures or guidance material published by ICAO or WMO. It should also be noted that in this manual the words “shall” or “should” are not used in a regulatory sense as in ICAO or WMO regulatory documents.
1. Held conjointly with the Third Session of the Commission for Aeronautical Meteorology (CAeM) of the WMO.
2. Held, in part, conjointly with the Extraordinary Session (1974) of the body mentioned in Note 1.
3. Held conjointly with the Seventh Session of the body mentioned in Note 1.
4. Held conjointly with the Ninth Session of the body mentioned in Note 1.
Chapter 1
METEOROLOGICAL SERVICES FOR AVIATION
1.1 GENERAL
1.1.1 Meteorological services for international aviation are provided by meteorological authorities designated by States. Details of the services to be provided for international aviation are determined by each State in accordance with the provisions of ICAO Annex 3 and with due regard for regional air navigation agreements, which apply to specific areas designated as air navigation regions by ICAO. Each State also establishes a suitable number of meteorological offices, i.e. aerodrome meteorological offices, meteorological watch offices, other offices and aeronautical meteorological stations. Meteorological offices and aeronautical meteorological stations provide information required for operational planning, flight operations, the protection of aeronautical equipment on the ground, and for various other aeronautical uses. The information provided includes observations and reports of actual weather conditions at aerodromes and forecasts dealt with in Chapter 3; it is made available at aerodrome meteorological offices and is disseminated as appropriate to aeronautical users, including operators, flight crew members, air traffic services (ATS) units, search and rescue (SAR) units, airport management and others concerned with the conduct or development of international air navigation.
1.1.2 Forecasts of en-route conditions, except forecasts for low-level flights issued by meteorological offices, are normally prepared by world area forecast centres (WAFCs) (see 1.5 below). This ensures the provision of high quality and uniform forecasts for flight planning and flight operations. It also permits meteorological watch offices to concentrate on keeping watch on weather conditions in their flight information regions (FIRs), and meteorological offices at aerodromes to concentrate on local aerodrome forecasting, to keep watch over local (aerodrome) conditions and to issue warnings of weather conditions that could adversely affect operations and facilities at the aerodrome (e.g. aerodrome and wind shear warnings).
1.1.3 SIGMET and AIRMET information concerning the occurrence of specified en-route phenomena which may affect the safety of aircraft operations are issued by meteorological watch offices (MWOs) (see 1.3). In the specific case of SIGMET information related to tropical cyclones and volcanic ash, specialized advisory information is required to support the preparation of these SIGMET information messages in meteorological watch offices. Tropical cyclone advisory centres (TCACs) and volcanic ash advisory centres (VAACs) (see 1.6 and 1.7) prepare and disseminate such advisory information.
1.1.4 The responsibility for the provision of meteorological service for international air navigation mentioned in 1.1.1 rests with the meteorological authority designated by each State. The meteorological authority may wish to provide the service or may arrange for the provision of the service by other providers on its behalf.
1.1.5 In order to meet the objectives of meteorological service for international air navigation and provide users with the assurance that the service, including the meteorological information provided, comply with the aeronautical requirements, the meteorological authority should establish and implement a properly organized quality system in accordance with the International Organization for Standardization (ISO) 9000:2000 Series quality assurance standards. The system should be certified by an approved organization.
Note.— Specific guidance on this subject is intended to be issued.
1.1.6 Properly educated and trained personnel should be employed in the provision of meteorological service for international air navigation. It is, therefore, an important responsibility of the meteorological authority to ensure that widely recognized standards are applied to the qualifications, education and training of all of the personnel involved in the provision of meteorological service for international air navigation. As far as the meteorological personnel are concerned, the requirements of the World Meteorological Organization (WMO) should be applied.
Note 1.— The requirements are given in the WMO Publication No. 49, Technical Regulations, Volume I — General Meteorological Standards and Recommended Practices, Education and Training.
Note 2.— It may be noted that education and training in aeronautical meteorology of aeronautical personnel (e.g. pilots, ATC personnel, flight dispatch officers, etc.), required by the aeronautical authorities concerned, should comply with the relevant ICAO documents (e.g. Training Manual, Part F-1 — Meteorology for Air Traffic Controllers and Pilots (Doc 7192).
1.2 METEOROLOGICAL OFFICES
Meteorological offices serving aviation are normally located at aerodromes, in which case they are called aerodrome meteorological offices. In addition to maintaining a continuous survey of meteorological conditions over the aerodrome(s) under their responsibility, preparing forecasts of local meteorological conditions, aerodrome warnings and wind shear warnings, these offices also provide briefing, consultation and flight documentation or other meteorological information, display weather charts, reports, forecasts, meteorological satellite images and information derived from ground-based weather radar (radar network). Much of the information is obtained from WAFCs or from other meteorological offices (which may be located in a different country). Furthermore, meteorological offices supply meteorological information to aeronautical users and exchange meteorological information with other meteorological offices. This also includes the exchange of operational meteorological (OPMET) data required by regional air navigation agreement. In addition, where necessary, meteorological offices supply the information regarding pre-eruption activity, volcanic ash eruptions or the presence of volcanic ash in the atmosphere to their associated air traffic services (ATS) units, the aeronautical information services (AIS) units and the meteorological watch offices (MWO) concerned, as agreed between the ATS, AIS and meteorological authorities concerned. However, not all aerodromes have a meteorological office and for such aerodromes the national aeronautical information publications (AIPs) indicate the name and location of the meteorological office designated to supply meteorological information concerning the aerodrome to operators, ATS units and others concerned.
1.3 METEOROLOGICAL WATCH OFFICES
1.3.1 States accepting responsibility for an FIR have to either designate a meteorological watch office (MWO) to serve that FIR or delegate the responsibility to another MWO. The MWOs so designated are listed in the relevant air navigation plans to indicate the overall integrity of the plan. They maintain a continuous watch over meteorological conditions affecting the flight operations within their areas of responsibility, issue information on the occurrence or expected occurrence of specified hazardous en-route weather conditions which may affect the safety of aircraft and low-level aircraft operations (SIGMET and AIRMET information, respectively) and supply this and other weather information to their associated ATS units, usually a flight information centre (FIC) or an area control centre (ACC). In addition, MWOs exchange SIGMET information issued by other MWOs as required by regional air navigation agreement. The AIRMET information issued is transmitted to MWOs and meteorological offices in adjacent FIRs (for details see Chapter 4). In preparing SIGMET and AIRMET information, MWOs normally make use of special air-reports, satellite and radar data and, to the extent decided by the meteorological authority, forecasts obtained from WAFCs.
1.3.2 MWOs also supply the information received on pre-eruption volcanic activity, volcanic eruptions and volcanic ash clouds, for which a SIGMET information has not already been issued, to their associated ACCs/FICs, and in accordance with regional air navigation agreement, to the VAACs concerned. It is also the responsibility of MWOs to supply information received concerning an accidental release of radioactive materials into the atmosphere within the area of their responsibility to their associated ACC(s)/FIC(s) and to the relevant AIS units, as agreed by the ATS, AIS and the meteorological authorities concerned. This information is usually obtained from the WMO regional specialized meteorological centre (RSMC) which specializes in the provision of computer generated transport model products for radiological environmental emergency response.
1.4 METEOROLOGICAL
STATIONS
1.4.1 The actual weather observations at aerodromes and offshore structures are made by aeronautical meteorological stations which are situated at most of those facilities. Aeronautical meteorological stations may also be established at other points of significance to international air navigation. The specific types of observations and related reports are disseminated either locally, or to other aerodromes, as required, in accordance with regional air navigation agreement.
1.4.2 In the areas prone to volcanic eruptions, aeronautical meteorological stations make observations regarding volcanic activity and volcanic eruptions. These observations form the basis for the issuance of volcanic activity reports. Details on the content and dissemination of such reports are given in 2.12.
1.5 WORLD AREA FORECAST
CENTRES (WAFCs)
1.5.1 World area forecast centres (WAFCs) are components of the world area forecast system (WAFS), which is designed to primarily supply meteorological offices with forecasts of en-route meteorological conditions (i.e. forecasts of upper-air data and significant weather forecasts) suitable, as far as practicable, for direct use by operators, flight crew members, ATS units and other aeronautical users. Forecasts of global upper winds, upper-air temperatures, tropopause heights, maximum winds and humidity data in the binary GRIB code form for direct input into meteorological and/or flight planning computers are also supplied by this system. In the near future, significant weather forecasts will be prepared by WAFCs in binary data format using WMO BUFR code form.
1.5.2 The WAFS consists of two WAFCs. The WAFCs issue global forecasts of upper winds, temperatures, tropopause heights, maximum winds and humidity, as well as forecasts of significant weather phenomena, in digital and/or pictorial form. WAFCs also issue amendments to these forecasts in abbreviated plain language in accordance with specified criteria.
Note.— Further information on the WAFS and its evolution is given in Appendix 1.
1.6 TROPICAL CYCLONE
ADVISORY CENTRES
(TCACs)
TCACs are meteorological centres designated by regional air navigation agreement on advice from WMO. They monitor the development of tropical cyclones in their areas of responsibility, using geostationary and polar-orbiting satellite data and other meteorological information. Based on these input data and information, TCACs provide MWOs, providers of international operational meteorological (OPMET) databanks established by regional agreement, providers of the (AFS) satellite distribution systems and, as necessary, other TCACs with advisory information regarding the position of a tropical cyclone centre, its forecast direction and speed of movement, central pressure and maximum surface wind near the cyclone centre. The advisory information is to be used by MWOs in support of the issuance of SIGMET information for tropical cyclones and an outlook, should be included in these SIGMET.
1.7 VOLCANIC ASH
ADVISORY CENTRES
(VAACs)
1.7.1 VAACs are meteorological centres designated by regional air navigation agreement on advice from WMO. They monitor relevant satellite data to detect volcanic ash in the atmosphere. Subsequently, VAACs run volcanic ash numerical trajectory dispersion models to forecast the movement of a volcanic ash cloud. As a result, the VAACs provide, as required, MWOs, ACCs, FICs, NOTAM offices, WAFCs, providers of international OPMET databanks established by regional air navigation agreement, providers of AFS satellite distribution systems, and other VAACs, with advisory information regarding the lateral and vertical extent and forecast movement of volcanic ash in the atmosphere following volcanic eruptions. The advisory information is to be used by MWOs in support of the issuance of SIGMET information on volcanic ash clouds and an outlook should be included in these SIGMET. The information is also made available, through the aeronautical fixed telecommunication network (AFTN), to aeronautical users.
1.7.2 VAACs form part of the ICAO International Airways Volcano Watch (IAVW). The international arrangements set up within the IAVW are aimed at monitoring volcanic ash in the atmosphere and providing warnings to aircraft of volcanic ash and associated volcanic activity.
Note.— Detailed information on the IAVW can be found in the Manual on Volcanic Ash, Radioactive Material and Toxic Chemical Clouds (Doc 9691) and in the Handbook on the International Airways Volcano Watch (IAVW) — Operational Procedures and Contact List (Doc 9766) and also on the ICAO website.
Chapter 2
METEOROLOGICAL OBSERVATIONS AND REPORTS
2.1 GENERAL
2.1.1 Observations of meteorological conditions are made by means of instruments and visual estimation and are used for landing and take-off, en-route navigation and flight performance, and as a basis for forecasting. Those observations used primarily for aircraft operations are called “operational meteorological (OPMET) data” while those used primarily for forecasting purposes are considered to be “basic meteorological data”. Some observations are used for both purposes. OPMET data include aerodrome observations, landing forecasts, aerodrome forecasts, SIGMET information and AIRMET information. Basic meteorological data include synoptic surface and upper air observations, satellite information, weather radar data and aircraft observations. OPMET data are described in detail below.
2.1.2 At many locations, observations are made by use of automatic observing equipment. The equipment normally forms part of an integrated automatic or semi-automatic system, with displays at local aeronautical meteorological station(s), meteorological office(s), briefing facilities and ATS units. This automatic observing equipment provides for the manual insertion of weather elements which the equipment is not capable of observing.
Note.— It should be noted that Human Factors principles should be observed in the design of these systems as well as of other systems and equipment used in the provision of meteorological service to international air navigation. Guidance material on the matter is given in the Human Factors Training Manual (Doc 9683).
2.2 AERODROME OBSERVATIONS
AND REPORTS
2.2.1 At aerodromes, routine observations are normally made and reported at hourly or half-hourly intervals depending on regional air navigation agreements. When required as a result of specified operationally significant changes in weather conditions, special observations and reports are made whenever such changes occur between routine observations (see 2.4 and 2.5).
2.2.2 Observational data are combined into a report for dissemination at the local aerodrome or beyond (see Examples 2-1 and 2-2). Depending on their use, the reports are presented in two forms, i.e. as local reports in abbreviated plain language intended for dissemination and use at the aerodrome of origin or as reports in the METAR and SPECI code forms (METARs and SPECIs), prescribed by WMO intended for the dissemination and use beyond the aerodrome of origin.
2.2.3 The need to provide aeronautical users with the two reports, one for local aerodrome use and one for the use beyond the aerodrome, is to meet operational requirements as follows:
— local reports for aircraft about to land or take off including requirements for ATIS broadcasts and DATIS transmissions; and
— METARs/SPECIs for flight planning and en-route flight information service purposes, including requirements for VOLMET broadcasts and DVOLMET transmissions.
The information in both reports, therefore, differs slightly to fully reflect the respective operational requirements. Technical specifications for local routine reports, local special reports and reports in the METAR and SPECI code forms are reproduced in Appendix 2, including an extensive set of detailed examples relating to individual portions and groups in the reports. The appendix also contains technical specifications concerning trend-type landing forecasts, which are often attached to local reports and reports in the METAR/SPECI code forms. These forecasts are dealt with in 3.6.
2.3 ROUTINE REPORTS
2.3.1 Paragraphs 2.3.3 to 2.3.14 deal with the content and format of routine reports; both those in abbreviated plain language disseminated locally (referred to below as local routine reports or MET REPORTs) and those disseminated beyond the aerodrome of origin (referred to as reports in the METAR code form or METARs). Local _special reports (referred to as SPECIALs) and special reports disseminated beyond the aerodrome of their origin (referred to as reports in the SPECI code form or SPECIs) are dealt with in 2.4 and 2.5, respectively. Practices relating to the transmission of local reports by local ATS units to aircraft taking off and landing are dealt with in 2.6.
2.3.2 The METAR and SPECI code forms were developed by WMO on the basis of aeronautical requirements established by ICAO. These codes were developed using the ICAO Procedures for Air Navigation Services — ICAO Abbreviations and Codes (PANS-ABC, Doc 8400). In view of this, the METARs and SPECIs are easily readable.
Note 1.— A tabulation developed by WMO to assist aeronautical personnel in the decoding of METAR and SPECI messages is reproduced in Appendix 3.
Note 2.— All details relating to the METAR and SPECI code forms are contained in WMO Publication No. 306 — Manual on Codes, Volume I, Part A — Alphanumerical Codes.
Note 3.— Units of measurement differ in some States depending on national practices. In this manual, all units used are those prescribed by ICAO Annex 5 — Units of Measurement to be Used in Air and Ground Operations as primary or alternative units. As regards elements for which either of these units is permitted, numerical criteria are given for both units, and examples of reports are given in one or the other unit.
Note 4.— The approved ICAO abbreviations which are to be used in “abbreviated plain language” are given in the Procedures for Air Navigation Services — ICAO Abbreviations and Codes (Doc 8400).
Note 5.— Details concerning regional differences in aerodrome reports and concerning requirements for the exchange of these reports between meteorological offices can be found in the ICAO air navigation plan publications for the various ICAO regions.
Note 6.— Selected criteria applicable to meteorological information referred to in 2.3.7 to 2.3.15 for inclusion in aerodrome reports are given in tabular form in Appendix 4.
2.3.4 Type of report
(MET REPORT) – MET REPORT
(METAR) – METAR
2.3.5 Aerodrome identification
(YUDO) in both reports
ICAO four-letter location indicator for the aerodrome for which the report is made. (The full name of the aerodrome is used in the transmission to aircraft.)
Note.— The indicators are prescribed in Doc 7910 — Location Indicators.
2.3.6 Time
(221630Z) in both reports
Date and time of observation: day of the month and time in hours and minutes, in Coordinated Universal Time (UTC).
2.3.7 Wind direction/speed
(WIND 240/18KMH) — MET REPORT
(24015KMH) — METAR
2.3.7.1 Direction (true) from which surface wind is blowing, in degrees rounded off to the nearest 10 degrees. The unit used for wind speed should be indicated both in local reports and METARs. In local reports, the term “CALM” is used when a wind speed of less than 2 km/h (1 kt) is observed. Wind speed of 200 km/h (100 kt) or more is to be indicated as ABV199KMH or ABV99KT.
Note 1.— Wind direction reported to aircraft for landing or take-off purposes must be converted into degrees magnetic. This conversion is normally carried out by the ATS unit concerned.
Note 2.— For wind speed, either kilometres per hour or knots may be used.
2.3.7.2 In reports disseminated locally at the aerodrome, surface wind should be based on an averaging period of 2 minutes.
2.3.7.3 In reports in the METAR code form, surface wind should be based on an averaging period of 10 minutes, except that when the 10-minute period includes a marked discontinuity in the wind direction and/or speed, only data occurring since the discontinuity should be used for obtaining mean values, and the time interval should be correspondingly reduced. A marked discontinuity occurs when there is an abrupt and sustained change in wind direction of 30° or more, with a wind speed of 20 km/h (10 kt) before or after the change, or a change in wind speed of 20 km/h (10 kt) or more, lasting at least 2 minutes. The provision in 2.3.7.1 requires that the wind direction be reported by three figures, e.g. 030 or 240. The wind speed is reported by two (or three) figures, e.g. 05 or 15, supplemented by the units used (KMH or KT). (For further details, see 2.3.8.3 and 2.3.8.5). Calm conditions are reported as 00000.
2.3.8 Variations of wind
(Table 2-1)
2.3.8.1 Variations of wind direction and speed given in meteorological reports always refer to the 10-minute period preceding the observation. When the wind is gusty, with variations from the mean wind speed (gusts) exceeding 20 km/h (10 kt), speed variations are indicated.
2.3.8.2 In local reports, when the wind direction varies by 60 degrees or more and when:
a) the mean speed exceeds 6 km/h (3 kt) and the wind direction varies by less than 180 degrees:
• report the two extreme directions between which the wind has varied in degrees, after indication of the mean wind direction and speed, for example “WIND 010/9KT VRB BTN 350/ AND 050/” (mean surface wind direction 10 degrees; wind speed 9 knots; wind direction variable between 350 degrees and 050 degrees);
b) the wind direction varies by 180 degrees or more or where it is not possible to report a mean wind direction (e.g. when a thunderstorm passes over the aerodrome):
• indicate the wind direction by the term “variable” (VRB) followed by the mean speed, with no indication of the mean wind direction, e.g. “WIND VRB 6KMH” or “VRB 3KT”.
2.3.8.3 In reports in the METAR code form disseminated beyond the aerodrome, the variations from the mean wind direction are reported when the total variation is 60 degrees or more but less than 180 degrees and mean speed is above 6 km/h (3 kt). In these conditions, mean wind direction and speed data (10-minute means) are followed by extreme direction values (reported clockwise) in a separate group. VRB is reported when the mean wind speed is 6 km/h (3 kt) and less. A variable wind at higher wind speeds is reported when the variation in wind direction is 180 degrees and more or when it is impossible to determine a mean wind direction (e.g. when a thunderstorm passes over the aerodrome).
2.3.8.4 In reports disseminated locally at the aerodrome, speed variations are given as the maximum and minimum values of the wind speed attained, after indication of the mean wind direction and speed, in the form “WIND 180/40KMH MAX 70 MNM 20” or “WIND 180/20KT MAX 35 MNM 10”. See Table 2-2.
2.3.8.5 In reports in the METAR code form, speed variations shall be given as the maximum value attained, after indication of the mean wind direction and speed and preceded by the letter indicator G (for gusts); the minimum wind speed is never included (see Table 2-2). For wind speed of 100 units or more, the exact number of wind speed units is reported (e.g. 120KMH). When a wind speed is 200 km/h (100 kt) or more, the wind speed is reported as P199KMH (P99KT).
2.3.8.6 Wind observations in local reports used for arriving or departing aircraft should be representative for the touchdown zone and the conditions along the runway, respectively. Positions of wind sensors along individual runways should be indicated together with the reported wind data by the sections of the runway for which the wind data are to be representative. When wind observations are available from more than one runway in use, the indication of the relevant runway should also be attached to the reported wind data. Surface wind observations included in the METARs should be representative of the whole runway complex at the aerodrome.
2.3.9 Visibility
(VIS 600M) — MET REPORT
(0600) — METAR
Note 1. — Visibility may be observed by a human observer or assessed by instrumented means. The following definition for visibility for aeronautical purposes applies:
Visibility for aeronautical purposes is the greater of:
a) the greatest distance at which a black object of suitable dimensions, situated near the ground, can be seen and recognized when observed against a bright background;
b) the greatest distance at which lights in the vicinity of 1 000 candelas can be seen and identified against an unlit background.
Note 2.— The two distances have different values in air of a given extinction coefficient, and the latter (b) varies with the background illumination. The former (a) is represented by the meteorological optical range (MOR).
Note 3.— Guidance on the conversion of instrumented readings into visibility is given in Annex 3, Attachment D.
Note 4.— Transmissometers and/or forward-scatters metres should be used as sensors in instrumented systems for the assessment of visibility.
2.3.9.1 Visibility is reported in steps of 50 m, e.g. VIS 350M, when visibility is less than 800 m; steps of 100 m, e.g. VIS 600M, when visibility is 800 m or more, but less than 5 km; in steps of one kilometre, e.g. VIS 6KM, when visibility is 5 km or more, but less than 10 km. When visibility is 10 km or more, it is given as VIS 10KM, except when the conditions for the use of CAVOK apply.
Note.— The conditions governing the use of CAVOK are summarized in the Note under 2.3.12.2 below.
2.3.9.2 In reports disseminated locally at the aerodrome:
a) in reports for departing aircraft, the visibility observations should be representative of the take-off and climb-out area; and
b) in reports for arriving aircraft, the visibility observations should be representative of the approach and landing area.
2.3.9.3 In local reports, when the visibility is observed for more than one runway in use and at more than one location along the runway, the identification of relevant runways and locations along the runways should be attached to the reported values of visibility.
2.3.9.4 In reports in the METAR code form, visibility observations should be representative of the aerodrome and its immediate vicinity. In such observations, special attention should be paid to significant directional variations in visibility. When the visibility is not the same in different directions, the rules given in Table 2-3 apply. The reporting steps given in 2.3.9.1 apply also to the visibility values included in these reports. Visibility observations in metres are reported by four figures, e.g. 0200, 1500, 4000. When visibility is 10 km and above and the conditions for the use of CAVOK do not apply, visibility is indicated as 9999.
Note.— For the definition of CAVOK, see the Note under 2.3.12.2.
2.3.10 Runway visual range
(RVR RWY 12 1000M) — MET REPORT
(R12/1000U) — METAR
2.3.10.1 RVR should be reported whenever visibility or runway visual range (RVR) is less than 1 500 m, particularly at aerodromes having precision approach runways or runways used for take-off with high-intensity edge lights and/or centre line lights, including the aerodromes with the runways intended for Category I approach and landing operations. RVR is reported at all runways intended for Category II or III instrument approach and landing operations. Steps of 25 m are used for RVR below 400 m, steps of 50 m for RVR between 400 m and 800 m and steps of 100 m for RVR above 800 m. RVR values which do not fit the reporting scale are rounded down to the next lower step in the scale.
2.3.10.2 In reports disseminated locally at the aerodrome, 1-minute mean values are reported. The RVR is reported in metres with an indication of the unit, and the runway(s) to which the values refer, e.g. RVR RWY 20 500M RVR RWY 26 800M (RVR runway 20: 500 m, RVR runway 26: 800 m). If RVR is observed for more than one position along a runway, the value representative of the touchdown zone is given first, followed by the locations representative of the mid-point and stop-end, e.g. RVR RWY 16 TDZ 600M MID 500M END: 400M (RVR runway 16 at the touchdown zone: 600 m, at the mid-point: 500 m and at the stop-end: 400 m). When RVR is above the maximum value that can be determined by the system in use, it is reported in the form RVR ABV 1200M where 1 200 m is the maximum value for that system. When RVR is below the minimum value that can be determined by the system in use, it is reported in the form RVR BLW 150M, where 150 m is the minimum value for that system. For assessment of RVR, 50 m is considered the lower limit and 1 500 m the upper limit. Outside these limits, reports merely indicate that the RVR is less than 50 m or more than 1 500 m, in the form RVR BLW 50M (RVR below 50 metres) or RVR ABV 1 500M (RVR above 1 500 metres), respectively.
2.3.10.3 The provisions given in 2.3.10.1 also apply to reports in the METAR code form. In these reports, RVR values in metres are reported by four figures preceded by the letter indicator R and the runway designator DRDR plus / (e.g. R12/0500, R26/1200). Additional reporting procedures are given in Table 2-4.
Note 1.— An RVR observation is the best possible assessment of the range over which the pilot of an aircraft on the centre line of a runway can see the runway surface markings or the lights delineating the runway or identifying its centre line. For this assessment, a height of approximately 5 m (15 ft) is regarded as corresponding to the average eye level of a pilot in an aircraft. This assessment may be based on readings of transmissometers or forward-scatter meters or may be determined by an observer counting markers, runway lights or, in some cases, specially installed lights on the side of the runway.
Note 2.— Detailed information on RVR observing and reporting is contained in the ICAO Manual of Runway Visual Range Observing and Reporting Practices (Doc 9328).
2.3.11 Present weather
(FG MOD DZ) — MET REPORT
(FZ DZ) — METAR
2.3.11.1 Present weather phenomena are reported in terms of type and characteristics and are qualified with respect to intensity or proximity to the aerodrome, as appropriate.
2.3.11.2 The types of present weather phenomena of significance to aviation, their respective abbreviations and relevant criteria for their reporting are given in Table 2-5.
2.3.11.3 The characteristics of the present weather phenomena that are reported, as necessary, and their respective abbreviations are given in Table 2-6.
2.3.11.4 The relevant intensity and, as appropriate, the proximity to the aerodrome of the reported present weather phenomena are indicated in Table 2-7.
2.3.11.5 One or more (up to a maximum of three) of the present weather abbreviations given in Tables 2-5 and 2-6 should be used, as necessary, together with an indication, where appropriate, of the characteristics and intensity or proximity to the aerodrome, so as to convey a complete description of the present weather at or near the aerodrome of significance to flight operations. The following general rules apply:
a) an indication of intensity or proximity, as appropriate, should be reported first;
b) this is followed by both the characteristics and the type of weather phenomena in the form “HVY TSRA” or “VC FG”;
c) where two different types of weather are observed, they should be reported in two separate groups, in the form “HVY DZ FG” or “FBL DZ VC FG”, where the intensity or proximity indicator refers to the weather phenomenon which follows the indicator; and
d) different types of precipitation occurring at the time of observation should be reported as one single group with the dominant type of precipitation reported first, preceded by only one intensity qualifier which refers to the intensity of the total precipitation, in the form “HVY TSRASN” or “FBL SNRA FG”.
2.3.11.6 When local reports are used for departing and arriving aircraft, the present weather observations should be representative of the take-off/climb-out areas or the approach/landing areas, respectively. Observations of present weather in the METAR reports should be representative of the aerodrome and its vicinity.
2.3.12 Cloud
(CLD SCT 300M OVC 600M) — MET REPORT
(SCT010 OVC020) — METAR
2.3.12.1 Cloud amount is given using the abbreviations FEW (1-2 oktas)1, SCT (3-4 oktas)1, BKN (5-7 oktas)1 or OVC (8 oktas)1. The type of cloud is identified only for cumulonimbus and towering cumulus clouds when observed at or near the aerodrome. Cloud amount, cloud type (CB and TCU only) and height of cloud base above aerodrome elevation are reported in that order and in the sequence shown:
— the lowest layer or mass, regardless of amount, reported as FEW, SCT, BKN or OVC, as appropriate;
— the next layer or mass, covering more than 2/81, reported as SCT, BKN or OVC, as appropriate;
— the next higher layer or mass, covering more than 4/81, reported as BKN or OVC as appropriate; and
— cumulonimbus (CB) and/or towering cumulus (TCU) clouds, whenever observed and not reported in previous parts of the report.
Note.— Towering cumulus (TCU) is used to indicate cumulus congestus clouds of great vertical extent.
2.3.12.2 When an individual layer (mass) of cloud is composed of cumulonimbus and towering cumulus clouds with a common cloud base, the type of cloud is reported as cumulonimbus only. If no clouds are present, and there is no restriction on vertical visibility and the term CAVOK (see the Note below) is not appropriate, the term SKC (sky clear) is used.
Note.— The term CAVOK2 is used when the following visibility/cloud/weather conditions occur simultaneously:
— Visibility: 10 km or more.
— Cloud: No cloud below 1 500 m (5 000 ft) or below the highest minimum sector altitude, whichever is greater, and no cumulonimbus.
— Weather: No weather of significance to aviation as given in Tables 2-5 and 2-6.
2.3.12.3 If no clouds of operational significance are present, i.e. below 1 500 m (5 000 ft) or below the highest minimum sector altitude, whichever is greater, no cumulonimbus occur and no restriction on vertical visibility exists and the abbreviation “CAVOK” and “SKC” cannot be used, the abbreviation “NSC” (i.e. nil significant clouds) should be used.
2.3.12.4 In local reports, the height of the base of cloud is reported in steps of 30 m (100 ft) up to 3 000 m (10 000 ft), together with the units used, in the form “300M” or “1000FT”, and in steps of 300 m (1 000 ft) above 3 000 m (10 000 ft). When the cloud base is diffuse or ragged or fluctuating rapidly, the minimum height of the cloud, or cloud fragments, is given, followed by the relevant abbreviation DIF (diffuse) or RAG (ragged) or FLUC (fluctuating).
Note 1.— In reports for arriving aircraft, where a precision approach runway has a touchdown elevation of 15 m (50 ft) or more below the aerodrome elevation, arrangements are normally made for cloud height to be given with reference to the touchdown elevation.
Note 2.— In reports from offshore structures, the height of the base of cloud is given above mean sea level.
2.3.12.5 The provisions given in 2.3.12.1 and 2.3.12.2 apply also to cloud observations reported in the METAR messages where relevant abbreviations for cloud amount (i.e. FEW, SCT, BKN or OVC) are followed by three figures indicating the reported cloud height in steps of 30 m (100 ft) (e.g. 005, 020) up to 3 000 m (10 000 ft) and in steps of 300 m (1 000 ft) above 3 000 m (10 000 ft). Up to three groups plus an additional group reporting CB and/or TCU could be included in one report. The note under 2.3.12.2 applies to the use of CAVOK.
2.3.12.6 When the sky is obscured and observations of vertical visibility are available at the aerodrome, the abbreviations VER VIS (vertical visibility) are used, followed by the value of the vertical visibility and the units used. The reporting steps for vertical visibility are the same as those used for reporting the height of the cloud base. In the METAR messages, the vertical visibility value is reported in the same manner as the cloud height described in 2.3.12.4, preceded by the letter indicator VV. VV/// indicates the absence of vertical visibility data.
2.3.12.7 Cloud observations included in local reports should be representative of the approach area or in the case of precision approach runways, of the middle marker site of the instrument landing system. Cloud observations in reports in the METAR code form should be representative of the aerodrome and its vicinity.
2.3.12.8 Where local reports include cloud base data from more than one runway in use, the runway indication should be attached to the reported cloud base data.
2.3.13 Air temperature/dew point
temperature
(T17 DP16) — MET REPORT
(17/16) — METAR
2.3.13.1 Reported in whole degrees Celsius, with observed values involving 0.5° rounded up to the next higher whole degree Celsius, for example, +2.5ûC is rounded off to +3ûC and –2.5ûC is rounded off to –2ûC. In local reports, the air temperature is identified by T and the dew point temperature by DP in the form T17 DP16 (temperature 17, dew point 16). For a temperature below 0 degrees Celsius, the value is preceded by MS (minus), e.g. TMS8.
2.3.13.2 Air temperature and dew point temperature values are reported in reports in the METAR code form in the form of T’T’/Td’Td’. Temperatures below 0ûC are preceded by M meaning minus. In addition, air temperatures and dew point temperatures of –9ûC to +9ûC are preceded by 0, e.g 02/M08.
2.3.13.3 Observations of air temperature and dew point temperature should be representative of the whole runway complex.
2.3.14 Pressure values
(QNH 1018 HPA) — MET REPORT
(Q1018) — METAR
2.3.14.1 In local reports, pressure values are given in hectopascals and are identified by QNH (altimeter showing aerodrome elevation when the aircraft is on the ground and QNH is set on the altimeter sub-scale) or QFE (altimeter showing zero elevation when the aircraft is on the ground and QFE is set on the altimeter sub-scale). QFE is normally used only at the aerodrome where it is provided on request or, by local agreement, on a regular basis, in addition to QNH. Pressure values are rounded down to the nearest lower whole hectopascal, e.g. QNH 1011.4 is reported as QNH 1011HPA and QFE 995.6 is reported as QFE 0995HPA or QFE RWY 18 0995HPA (where the number of the runway is indicated).
Note.— When a QFE altimeter setting is provided, it corresponds to the aerodrome elevation except for:
a) non-precision approach runways, if the threshold is 2 m (6.6 ft) or more below the aerodrome elevation; and
b) precision approach runways,
in which cases, the QFE corresponds to the relevant runway threshold elevation.
2.3.14.2 QNH values specified in 2.3.12.1 are presented in METAR messages by four figures (e.g. 0995 or 1011) following the letter indicator Q.
2.3.15 Supplementary information
2.3.15.1 Local reports may also include available supplementary information on significant meteorological conditions, particularly those in the approach or climb-out area and, specifically, the location of cumulonimbus, thunderstorms, presence of wind shear, moderate or severe turbulence, hail, severe squall line, moderate or severe icing, freezing precipitation, severe mountain waves, sandstorm, duststorm and blowing snow or funnel cloud (tornado or waterspout). The abbreviations in Table 2-8 a) should be used in reporting this supplementary information. Also included are any of the weather phenomena listed in Table 2-8 b) or combinations thereof, if observed at the aerodrome within the period since the last issued routine report or last hour, whichever is the shorter, but not at the time of observation (recent weather of significance). Up to a maximum of three groups of the recent weather should be reported.
Note.— Observations of supplementary information, in particular the conditions relating to the occurrence of icing, turbulence and, to a large extent, of wind shear, should be derived from aircraft observations during the approach and climb-out phases of flights. (For details concerning aircraft observations and air-reports, see Chapter 4.)
2.3.15.2 In reports in the METAR code form, supplementary information includes information on recent weather of operational significance, as given in 2.3.15.1, observed at the aerodrome within the period since the last issued routine report or last hour, whichever is the shorter, but not at the time of observation. Where local circumstances so warrant, wind shear should be included as necessary. Up to three groups of recent significant weather information selected from the following list may be included in a report using suitable abbreviations from Tables 2-5 and 2-6:
— freezing precipitation
— moderate or heavy precipitation (including showers thereof)
— moderate or heavy blowing snow (including snowstorm)
— duststorm or sandstorm
— thunderstorm
— funnel cloud (tornado or water spout)
— volcanic ash
Information on recent significant weather is to be added in the form, for example, “REFZRA”. Information on wind shear is added, if necessary, in the form “WS RWY 12” or “WS ALL RWY”. Information on sea-surface temperature and the state of the sea is included in reports from aeronautical meteorological stations established on offshore structures in support of helicopter operations, as determined by regional air navigation agreement. Information on the state of the runway(s) may also appear in these reports in accordance with regional air navigation agreement. The same applies to other information to be added to the METAR messages intended for international use .
Note 1.— The “local circumstances” referred to above include, but are not necessarily limited to, wind shear of a non-transitory nature such as might be associated with low-level temperature inversions or local topography.
Note 2.— Warnings of wind shear in the climb-out and approach paths are detailed in Chapter 4.
Note 3.— The state of the sea is specified in WMO Publication No. 306, Manual on Codes, Volume I, Code Table 3700.
2.3.16 Landing forecasts
A trend forecast is often attached to a local routine report as well as a routine report in the METAR code form; together they constitute a “trend-type” landing forecast, details of which are given in Chapter 3 and Appendix 2.
2.4 LOCAL SPECIAL REPORTS
2.4.1 Local special reports are issued in abbreviated plain language in addition to local routine reports (see 2.3 above) to provide information on significant deteriorations or improvements in aerodrome weather conditions at the aerodrome concerned. They are issued whenever one or more elements of a routine report change in accordance with criteria established by the meteorological authority in consultation with the ATS authority, the operators and others concerned. These criteria include:
a) those values which correspond with the operating minima of the operators using the aerodrome;
b) those values which satisfy other local requirements of ATS units and of the operators;
c) an increase in air temperature of 2ûC or more from that given in the latest report, or an alternative threshold value as agreed upon between the meteorological authority, the appropriate ATS authority and the operators concerned;
d) the available supplementary information concerning the occurrence of significant meteorological conditions in the approach and climb-out areas; and
e) the criteria given below (2.5.1 refers) for the issuance of special reports in the SPECI code form disseminated beyond the aerodrome (i.e. aviation selected special weather reports referred to in the WMO Publication No. 306, Manual on Codes, Volume I.1, Part A under FM 16-XII SPECI code form).
Local special reports in respect of RVR, surface wind or some other elements are not normally issued if the local ATS unit(s) has indicators for these elements corresponding to the indicators in the meteorological station, or if changes in RVR are continuously reported to the ATS unit by an observer at the aerodrome. Displays of automated aerodrome meteorological observing stations/systems located at the local ATS units are widely used to meet this requirement.
2.4.2 Local special reports carry the identifier SPECIAL and, as Example 2-2 shows, have the same content and sequence of elements as local routine reports (2.3.4 to 2.3.15 refer). As with local routine reports, a trend forecast is often appended to the special report (see 2.3.16 above).
2.5 SPECIAL REPORTS IN
THE SPECI CODE FORM
2.5.1 Special reports in the SPECI code form are issued in accordance with the following criteria:
a) when the mean surface wind direction has changed by 60 degrees or more from that given in the latest report, the mean speed before and/or after the change being 20 km/h (or 10 kt) or more;
b) when the mean surface wind speed has changed by 20 km/h (or 10 kt) or more from that given in the latest report;
c) when the variation from the mean surface wind speed (gusts) has increased by 20 km/h (or 10 kt) or more from that given in the latest report, the mean speed before and/or after the change being 30 km/h (or 15 kt) or more;
d) when the wind changes through values of operational significance. The threshold values should be established by the meteorological authority in consultation with the appropriate ATS authority and operators concerned, taking into account changes in the wind which would:
1) require a change in runway(s) in use; and
2) indicate that the runway tailwind and crosswind components have changed through values representing the main operating limits for typical aircraft operating at the aerodrome.
e) when the visibility is improving and changes to, or passes through, one or more of the values below; or when the visibility is deteriorating and passes through one or more of the values below:
1) 800 m, 1 500 m or 3 000 m
2) 5 000 m, in cases where significant numbers of flights are operated in accordance with visual flight rules;
f) when the RVR is improving and changes to, or passes through, one or more of the values below; or when the RVR is deteriorating and passes through one or more of the values below:
150 m, 350 m, 600 m or 800 m;
g) when the onset, cessation or change in intensity of any of the following weather phenomena or combinations thereof occurs:
— freezing precipitation
— freezing fog
— moderate or heavy precipitation (including showers thereof)
— low drifting dust, sand or snow
— blowing dust, sand or snow (including snowstorm)
— duststorm
— sandstorm
— thunderstorm (with or without precipitation)
— squall
— funnel cloud (tornado or waterspout).
h) when the height of the base of the lowest cloud layer of BKN or OVC extent is lifting and changes to, or passes through, one or more of the values below; or when the height of the base of the lowest cloud layer of BKN or OVC extent is lowering and passes through one or more of the values below:
1) 30 m, 60 m, 150 m or 300 m (100 ft, 200 ft, 500 ft or 1 000 ft);
2) 450 m (1 500 ft), in cases where significant numbers of flights are operated in accordance with visual flight rules;
i) when the amount of a cloud layer below 450 m (1 500 ft) changes:
1) from SKC, FEW or SCT to BKN or OVC; or
2) from BKN or OVC to SKC, FEW or SCT;
j) when the sky is obscured and the vertical visibility is improving and changes to, or passes through, one or more of the values below; or when the sky is obscured and the vertical visibility is deteriorating and passes through one or more of the values below:
— 30 m, 60 m, 150 m or 300 m (100 ft, 200 ft, 500 ft or 1 000 ft).
2.5.2 Special reports in the SPECI code form carry the identifier SPECI and, as Example 2-2 shows, have the same content and sequence of elements as routine reports in the METAR code form (2.3.4 to 2.3.15 refer). As with reports in the METAR code form, a trend forecast is often appended to these reports (2.3.14).
2.5.3 Special reports in the SPECI code form are disseminated beyond the aerodrome of origin to other aerodromes in accordance with the regional air navigation agreement which ensures, inter alia, that the special reports are available for VOLMET broadcasts, for D-VOLMET, and for individual transmissions to aircraft in flight through ATS units or operators .
Note.— Details on requirements for the exchanges between meteorological offices of special reports in the SPECI code form can be found in the ICAO air navigation plan publications for the various ICAO regions.
2.6 INFORMATION ON
METEOROLOGICAL CONDITIONS
FOR AIRCRAFT TAKING OFF
AND LANDING
Local routine and local special reports, as described in 2.3 and 2.4, are usually supplied to those ATS units which use them, together with any information obtained from their own duplicate displays (e.g. wind or RVR indicators), displays of automated aerodrome weather observing stations or supplementary visual observations taken by ATS personnel, in order to provide the required meteorological information to aircraft taking off or landing. These reports are supplied to aircraft by ATS units by air-ground data link, by directed transmissions and/or through broadcasts. Further details on coordination between meteorological offices/stations and ATS units in this and other respects are given in Chapter 8.
2.7 REPRESENTATIVENESS AND
ACCURACY AERODROME
REPORTS
To the extent practicable, aerodrome observations are made at locations considered to be suitable for representative measurements of elements affecting aircraft during take-off and landing operations. Details in respect of these locations and in respect of the aeronautical requirements for the operationally desirable accuracy of meteorological observations and the currently attainable accuracies are given in Appendix 5, Parts 1 and 2, respectively, to this manual.
2.8 WEATHER RADAR
OBSERVATIONS AND
REPORTS
2.8.1 Weather radar observations permit the locating and tracking of thunderstorms and tropical cyclones, and the evaluation of precipitation and cloud height. This information is used for early warnings of certain meteorological phenomena hazardous to aviation, particularly in the vicinity of aerodromes, and in the preparation of trend forecasts. Radar data are usually available only locally, but in many parts of the world, data from large radar networks are distributed to meteorological offices and other aeronautical users by means of various data processing systems and high-speed communication channels in coded or pictorial forms and, in particular, in digital form. The processed and integrated weather radar information is often displayed for ATS personnel through ATS systems.
2.8.2 Increasing use is being made of Doppler weather radar for both storm warning purposes and, specifically, to detect low-level wind shear. In the latter case, fully automated terminal Doppler weather radar is available, which can provide wind shear warnings to ATC and directly to aircraft equipped with an air-ground data link.
2.9 AIRCRAFT OBSERVATIONS
AND REPORTS (AIREP)
Weather reports from aircraft constitute an important source of upper-air data. They are especially useful in areas where ground-based observations are sparse or not available. In view of its importance, air-reporting is covered further in Chapter 7 of this manual.
2.10 BASIC SURFACE
AND UPPER-AIR OBSERVATIONS
2.10.1 Weather observations containing elements similar to those in aerodrome reports, but with additional details of cloud, weather, pressure, etc., are made at many aerodromes and other locations (including ships) for basic meteorological purposes. They are made at three-hourly or six-hourly intervals (0000 UTC, 0300 UTC, 0600 UTC, etc.), disseminated in a code form (SYNOP) established by WMO, and used for the preparation of surface weather charts.
2.10.2 Upper-air information is obtained principally from instruments carried aloft by balloons released from fixed ground observation sites or from ships. These balloon-borne instruments reach altitudes approaching 30 km (100 000 ft) and provide data on wind speed and direction, temperature, pressure and relative humidity to approximately 15 km (50 000 ft). Upper-air observations of this type are made at standard hours, 0000 UTC and 1200 UTC and additionally in some areas at 0600 UTC and 1800 UTC. Other upper-air information is obtained through specialized equipment carried on board certain aircraft. All these data are disseminated in code forms established by WMO, and are used for the preparation of upper-air charts.
2.11 METEOROLOGICAL
SATELLITE DATA
In addition to information on cloud type, amount and height of cloud tops, meteorological satellite data also provide information on vertical temperature and humidity distribution and on upper winds derived from cloud movement. The information provided by satellites is of particular importance in the areas where ground-based observations are sparse. It is received directly from geostationary or polar-orbiting satellites by ground-receiving equipment. The processed satellite data can be used to supplement the integrated weather radar data. Data from geostationary meteorological satellites are also used by volcanic ash advisory centres for the detection and tracking of volcanic ash clouds.
2.12 REPORTS OF
VOLCANIC ACTIVITY
As mentioned in 1.4.2, aeronautical meteorological stations (and other meteorological stations) located in the vicinity of active volcanoes are required to make observations of volcanic activity. The volcanic activity reports resulting from these observations should contain:
a) message type VOLCANIC ACTIVITY REPORT;
b) station identifier, location indicator or name of the station;
c) date/time of the message;
d) location of volcano, and name, if known; and
e) concise description of the event including, as appropriate, the level of intensity of the volcanic activity, occurrence of the eruption and its date and time, and the existence of a volcanic ash cloud in the area together with the direction of the ash cloud movement and height.
The reports should be issued in the form of abbreviated plain language and disseminated, as a matter of urgency, to the associated ATS units, meteorological watch offices, and aeronautical information services units. These reports are important for the operations of the International Airways Volcano Watch (IAVW).
Note.— Pre-eruption volcanic activity in this context means unusual and/or increasing volcanic activity which could presage a volcanic eruption.
Table 2-1. Reporting procedures related to directional variations of wind. ddd = mean wind direction,
ddd1 and ddd2 = extreme wind directions, = |ddd1 - ddd2|, VV = mean wind speed.
Averaging period applied indicated as a subscript.
V = indicators of variability.
|Type of report |Directional variations during past 10 minutes |
| |Δ < 60° |Δ > 60° |
| | |VV > 6 km/h (3 kt) |VV < 6 km/h (3 kt) |
| | | |[but VV > 2 km/h (1 kt)]1 |
| | |Δ < 180° |Δ > 180° |Δ < 180° |Δ > 180° |
|Report disseminated locally at |ddd/VV2 min |ddd/VV2 min |VRB/VV2 min2 | |VRB/VV2 min2 |
|the aerodrome | |VRB BTN | |ddd/VV2 min VRB BTN | |
| | |ddd1/ AND ddd2/ | |ddd1/ AND ddd2/VV2 | |
| | | | |min | |
| |dddVV10 min |dddVV10 min | VRBVV10 min |VRBVV10 min2 |VRBVV10 min2 |
|Report in the METAR code form | | | | | |
| | |ddd1Vddd23 | | | |
|1. In the reports disseminated locally, CALM should be indicated. |
|2. Or, where it is not possible to report a mean wind direction, e.g. when a thunderstorm is passing over the aerodrome. |
|3. ddd1 ddd2 in clockwise order. |
Table 2-2. Reporting procedures related to speed variations of wind. ddd = mean wind direction,
VVmnm and VVmax = minimum and maximum wind speed, VV = mean wind speed, = VVmax - VV.
Averaging period applied indicated as a subscript.
G = indicators for gusts.
|Type of report |Speed variations during past 10 minutes |
| |Δ < 20 km/h (10 kt) |Δ > 20 km/h (10 kt) |
|Report disseminated locally at the aerodrome |ddd/VV2 min |ddd/VV2 min MAX VVmax MNM VVmnm |
|Report in the METAR code form |dddVV10 min | |
| | |dddVV10 min G VV max |
Table 2-3. Reporting procedures related to visibility — to be applied in reports in the METAR code form
|Conditions |Action |
|VIS not the same in different directions, no marked directional |Report the lowest VIS |
|variations | |
|VIS in one or more directions is more than 50 per cent above the lowest |Report the lowest VIS together with its general direction from the |
|VIS and the minimum value 400 km; error in speed >20 per cent; error in core height >900 m (3 000 ft).
Other significant en-route weather phenomena and any new information concerning volcanic ash eruptions and accidental release of radioactive material into the atmosphere. Newly expected occurrence; no longer expected.
3.12.2 In order to assist WAFCs in keeping their forecasts under continuous review, it is an important responsibility of meteorological offices receiving WAFS products (both in the BUFR and GRIB code forms and in chart format) to notify the WAFCs concerned of significant discrepancies between forecast and observed conditions. The notification by meteorological offices should be based on the criteria given in 3.12.1. Abbreviated plain language should be used in preparing the notification in accordance with the guidance material given in Appendices 10 and 17. The aeronautical fixed telecommunication network (AFTN) should be used for transmission of the notifications to relevant WAFCs. The priority assigned to administrative messages should be applied to the notification. The WAFC, after receiving such a notification, should acknowledge receipt and make a brief comment including, if necessary, a proposal for follow-up action.
3.12.3 Amendments to the forecasts prepared by WAFCs in accordance with the criteria in 3.12.1 are also issued in the form of abbreviated plain language texts. Guidance on the format of such texts, together with relevant examples, is given in Appendix 10. Coding procedures for amendments to forecasts issued in the ROFOR code are given in WMO Publication No. 306 — Manual on Codes.
3.13 AREA FORECASTS FOR LOW-LEVEL
FLIGHTS EXCHANGED BETWEEN
METEOROLOGICAL OFFICES
IN SUPPORT OF THE ISSUANCE
OF AIRMET INFORMATION
3.13.1 When the density of traffic below FL 100 warrants the issuance of AIRMET information in accordance with 4.4.1 on the basis of a regional air navigation agreement, area forecasts for operations concerning en-route weather phenomena hazardous to low-level flights have to be exchanged between meteorological offices responsible for the issuance of flight documentation for low-level flights in the FIRs concerned and communicated to the meteorological watch offices responsible for the issuance of relevant AIRMET information. These area forecasts should cover the layer between the ground and FL 100 (or up to FL 150 in mountainous areas) and should be prepared in a format agreed upon between the meteorological authorities concerned, i.e. or in abbreviated plain language or in chart form.
3.13.2 When abbreviated plain language is used, the forecasts are prepared as a GAMET area forecast (see Example 3-3 and Table 3-5), using approved ICAO abbreviations and numerical values. The area forecasts contain the following information as necessary and, when prepared in GAMET format, in the order indicated:
a) location indicator of the air traffic services unit serving the flight information region(s) to which the area forecast for low-level flights refers; for example, “YUCC”;
b) message identification using the abbreviation “GAMET”;
c) date-time groups indicating the period of validity in UTC; for example, “VALID 220600/221200”;
d) location indicator of the meteorological office originating the message, followed by a hyphen to separate the preamble from the text; for example, “YUDO-”;
e) on the next line, name of the flight information region, or a sub-area thereof, for which the area forecast for low-level flights is issued; for example “AMSWELL FIR/2 BLW FL120”;
f) on the next line, indication of the beginning of the first section of the area forecast using the abbreviation “SECN I”;
g) widespread mean surface wind speed exceeding 60 km/h (30 kt); for example, “SFC WSPD: 10/12 65 KMH”;
h) widespread areas of surface visibility below 5 000 m including the weather phenomena causing the reduction of visibility; for example, “SFC VIS: 06/08 3000 M BR N OF 51 DEG N”;
i) significant weather conditions encompassing thunderstorms and heavy sandstorm and duststorm (except for phenomena for which a SIGMET message has already been issued); for example, “SIGWX: 11/12 ISOL TS”;
j) mountain obscuration; for example, “MT OBSC: MT PASSES S OF 48 DEG N”;
k) widespread areas of broken or overcast cloud with height of base less than 300 m (1 000 ft) above ground level (AGL) or above mean sea level (AMSL) and/or any occurrence of cumulonimbus (CB) or towering cumulus (TCU) clouds, giving height indications of their bases and tops; for example, “SIG CLD: 06/09 OVC 800/1100 FT AGL N OF N51 10/ 12 ISOL TCU 1200/8000 FT AGL”;
l) icing (except for that occurring in convective clouds and for severe icing for which a SIGMET message has already been issued); for example, “ICE: MOD FL050/080”;
m) turbulence (except for that occurring in convective clouds and for severe turbulence for which a SIGMET message has already been issued); for example, “TURB: MOD ABV FL090”;
n) mountain wave (except for a severe mountain wave for which a SIGMET message has already been issued); for example, “MTW: MOD ABV FL080 E OF 63 DEG N”;
o) SIGMET messages applicable to the FIR concerned or the sub-area thereof, for which the area forecast is valid; for example, “SIGMET APPLICABLE: 3,5”.
p) on the next line, indication of the beginning of the second section of the area forecast using the abbreviation “SECN II”;
q) pressure centres and fronts and their expected movements and developments; for example, “PSYS: 06 L 1004 HPA 51.5 DEG N 10.0 DEG E MOV NE 25 KT WKN”;
r) upper winds and upper-air temperatures for at least the following altitudes: 600 m, 1 500 m and 3 000 m (2 000 ft, 5 000 ft and 10 000 ft); for example, “WIND/T: 2000 FT 270/70 KMH PS03 5000 FT 250/80 KMH MS02 10000 FT 240/85 KMH MS11”;
s) cloud information not included under k), giving cloud amount, type and height indications of the bases and tops above ground level (AGL) or above mean sea level (AMSL); for example, “CLD: BKN SC 2500/8000 FT AGL”;
t) height indication of 0ûC level(s) above ground level (AGL) or above mean sea level (AMSL), if lower than the top of the airspace for which the forecast is supplied; for example, “FZLVL: 3000 FT AGL”;
u) forecast lowest QNH during the period of validity; for example, “MNM QNH: 1004 HPA”;
v) sea-surface temperature and state of the sea if required by regional air navigation agreement; for example, “SEA: T15 HGT 5 M”; and
w) location of volcanic eruptions which are producing ash clouds of significance to aircraft operations, the name of the volcano and the time of the first eruption, if known; for example, “VA: MT. HOKKAIDO KOMAGATAKE PSN N4292 E14040 ERUPTED VA CLD TOP 4900 FT MOV SE”.
3.13.3 AIRMET information is issued when specified en-route weather phenomena hazardous to low-level flights occur or are expected to occur, which have not been included in relevant area forecasts for low-level flights and consequently have also not been included in the flight documentation for low-level flights supplied to pilots. The complete information regarding the en-route weather phenomena hazardous to low-level flights is contained in the first part (i.e. Section I) of the GAMET area forecast given in 3.13.2. It is important that where the area forecasts for low-level flights are prepared in significant weather chart format, they cover the same type of information.
3.13.4 Area forecasts for low-level flights exchanged between meteorological offices in support of the issuance of AIRMET information are issued every 6 hours for a period of validity of 6 hours and transmitted to meteorological offices concerned not later than one hour prior to the beginning of their validity period.
Table 3-1. Types of aeronautical meteorological forecasts, including
SIGMET and AIRMET information, warnings,
volcanic ash advisories and tropical cyclone advisories
|Type of forecast |Area/airspace covered |Stage of flight planning |Responsibility for | |
| | | |preparing/issuing the forecast | |
| | | | | |
|Aerodrome forecast |Aerodrome |Pre-flight and in-flight |Aerodrome meteorological office | |
|Landing forecast |Aerodrome (especially approach|In-flight |Aerodrome meteorological office | |
| |and touchdown zone) | | | |
|Take-off forecast |Runway complex |Pre-flight |Aerodrome meteorological office | |
|Forecasts of en-route |Route, route system(s) or |Pre-flight and in-flight |World and/or regional | |
|conditions |area/conditions at levels | |area forecast centre | |
| |applicable to the operation | |(WAFC/RAFC); | |
| | | |Aerodrome meteorological office | |
|SIGMET information |Flight information region |Pre-flight and in-flight |Meteorological watch office (MWO)| |
| |(FIR) or control area/all | | | |
| |levels used for flight | | | |
| |operations, including, if | | | |
| |applicable, supersonic | | | |
| |operations | | | |
|AIRMET information |Flight information region |Pre-flight and in-flight |Meteorological watch office (MWO)| |
| |(FIR) or control area or a | | | |
| |sub-area thereof/all flight | | | |
| |levels up to FL 100 (FL 150 in| | | |
| |mountainous areas) | | | |
|Aerodrome warnings |Aerodrome/surface conditions |Parked aircraft, aerodrome |Aerodrome meteorological office | |
| | |installations | | |
|Wind shear warnings |Aerodrome and |In-flight and prior to and |Aerodrome meteorological office | |
| |approach/take-off paths |during take-off | | |
| |between runway level and 500 m| | | |
| |(1 600 ft), or higher, if | | | |
| |necessary | | | |
|Volcanic ash advisories |Area (FIRs) of volcanic ash |Pre-flight and in-flight |Volcanic ash advisory centre | |
| |cloud occurrence | |(VAAC) | |
|Tropical cyclone advisories |Area (FIRs) of tropical |Pre-flight and in-flight |Tropical cyclone advisory centre | |
| |cyclone occurrence | |(TCAC) | |
| |
|Note.— For details on SIGMET and AIRMET information and warnings, as well as volcanic ash and tropical cyclone advisories, see Chapter 4. |
Table 3-2. Formats of forecasts, including SIGMET and AIRMET information,
warnings, tropical cyclone advisories and volcanic ash advisories
|Type of forecast |Abbreviated plain |Code |Tabular (using |Charts |
| |language | |abbreviated plain | |
| | | |language) | |
| | | | | |
|Aerodrome forecasts | |X1 |X2 | |
|Trend-type landing forecasts |X |X1 | | |
|Take-off forecasts |X | | | |
|Forecasts of en-route conditions |X |X3 |X |X |
|SIGMET information |X4 | | | |
|AIRMET information |X4 | | | |
|Aerodrome warnings |X4 | | | |
|Wind shear warnings |X4 | | | |
|Volcanic ash advisories |X4 | | | |
|Tropical cyclone advisories |X4 | | | |
| |
|1. Alphanumeric and/or binary code forms. |
|2. Used mostly in flight documentation. |
|3. Alphanumerical and/or binary code forms. |
|4. See Chapter 4. |
Table 3-3. Validity of forecasts, including SIGMET and AIRMET information,
warnings, tropical cyclone advisories and volcanic ash advisories
|Forecast |Usual validity period or fixed time of validity |
| | |
|Aerodrome forecast |9, 12, 18 or 24 hours |
|Landing forecast |2 hours |
|Take-off forecast |For specified period (usually short) |
|Forecasts of en-route conditions |In chart form: fixed valid times, usually 0600,1200,1800 or exceptionally 2400 hours UTC |
| | |
| |In other forms: either fixed times as above or periods corresponding to the period of the |
| |flight |
|SIGMET information |Not more than 6 hours, and preferably not more than 4 hours1 |
|AIRMET information |Not more than 6 hours, and preferably not more than 4 hours |
|Aerodrome warnings |Usually not more than 24 hours |
|Wind shear warnings |For as long as wind shear is expected to last |
|Volcanic ash advisory |18 hours (to be updated at least every 6 hours) |
|Tropical cyclone advisory |24 hours (to be updated at least every 6 hours) |
| |
|1. See Chapter 4 in respect of the inclusion of an outlook in SIGMET information for tropical cyclones and for volcanic ash clouds. |
Table 3-4. Criteria for the indication of changes and/or
preparation of amendments to aerodrome forecasts in the TAF code form
|Meteorological element |Criteria for the inclusion of change groups or for the |Remarks |
| |amendment of aerodrome forecasts | |
| | | |
|Surface wind |Forecast changes through values of operational significance, for |Threshold values to be established |
| |example: |by the MET authority in consultation|
| | |with appropriate ATS authorities and|
| |1) changes that required changes in the runway(s) in use; and |operators. |
| | | |
| |2) changes in runway tailwind/crosswind component through values | |
| |representative of operating limits of typical aircraft using the | |
| |airport. | |
|Visibility |— When the visibility is improving, forecast changes to, or passes |At aerodromes with a significant |
| |through, one or more of the values below; or |number of VFR flights, the value of |
| | |5 000 m is also included in the |
| |— when the visibility is deteriorating, forecast changes through one or|criteria. |
| |more of the values below: | |
| | | |
| |150 m, 350 m, 600 m, 800 m, 1 500 m, or 3 000 m. | |
|Weather |Forecasts of beginning, end or change in intensity of the following | |
| |weather phenomena or combinations thereof: | |
| | | |
| |— freezing precipitation | |
| |— freezing fog | |
| |— moderate or heavy precipitation (including showers) | |
| |— low drifting dust, sand or snow | |
| |— blowing dust, sand or snow (including snowstorm) | |
| |— duststorm | |
| |— sandstorm | |
| |— thunderstorm (with or without precipitation) | |
| |— squall | |
| |— funnel cloud (tornado or waterspout) | |
| |— other weather phenomena given in Table 2-5, which are expected to | |
| |cause a significant change in visibility. | |
|Cloud |— When the height of the lowest layer or mass of cloud of BKN or OVC |At aerodromes with significant |
| |extent is forecast to lift, changes to, or passes through, one or more |number of VFR flights, the height of|
| |of the values below; or |cloud base of 450 m (1 500 ft) is |
| | |also included in the criteria. |
| |— when the height of the lowest layer or mass of cloud of BKN or OVC | |
| |extent is forecast to lower than, or changes through, one or more of | |
| |the values below: | |
| | | |
| |30 m, 60 m, 150 m or 300 m (100 ft, 200 ft, 500 ft, or 1 000 ft). | |
|Vertical visibility |— When the vertical visibility is forecast to improve, changes to, or | |
| |passes through, one or more of the values below; or | |
| | | |
| |— when the vertical visibility is forecast to deteriorate to, or | |
| |changes through, one or more of the values below: | |
| | | |
| |30 m, 60 m, 150 m or 300 m (100 ft, 200 ft, 500 ft, or 1 000 ft). | |
|Temperature |None |A regional air navigation agreement |
| | |may apply. |
|Other |Other criteria based on local aerodrome operating minima. |As agreed between the MET authority |
| | |and the operators concerned. |
Table 3-5. Additional provisions concerning the
issuance of GAMET area forecasts
|Condition | |Action |
| | | |
|Specific hazardous phenomenon not expected or expected but already | |Omit from the GAMET |
|covered by a SIGMET message (items g) to o) refer) | | |
|No hazardous phenomenon expected and no SIGMET messages applicable | |The term “HAZARDOUS WX NIL” replaces all the lines from the third |
| | |line onward in the GAMET |
|Specific hazardous phenomenon has been included in GAMET but does | |Issue GAMET AMD amending the element concerned |
|not occur or is no longer forecast to occur | | |
|Example 3-1. Aerodrome forecasts in abbreviated plain language |
|and in TAF code form |
| |
| |
|Abbreviated plain language: |
| |
|FCST YUDO 160000Z 16 06/24 130/18KMH VIS 9KM BKN 600M BECMG 06/08 SCT CB 450M BKN 600M TEMPO 08/12 170/25KMH MAX40 VIS 1000M MOD TSRA SCT CB |
|300M BKN 600M FM1230 150/15KMH 10KM BKN 600M BKN 3000M MAX T25 AT 1200Z MNM TMS2 AT 2300Z |
| |
|TAF code form: (same location and weather conditions): |
| |
|TAF YUDO 160000Z 160624 13018KMH 9000 BKN020 BECMG 0608 SCT015CB BKN020 TEMPO 0812 17025G40KMH 1000 TSRA SCT010CB BKN020 FM1230 15015KMH 9999 |
|BKN020 BKN100 T25/12Z TM02/23Z |
|Meaning of both forecasts: |
| |
|Aerodrome forecast for Donlon/International* issued on the 16th of the month at 0000UTC valid from 0600 UTC to 2400 UTC on the 16th of the |
|month; surface wind direction 130 degrees; wind speed 18 kilometres per hour; visibility 9 kilometres; broken cloud at 600 metres; becoming |
|between 0600 UTC and 0800 UTC, scattered cumulonimbus cloud at 450 metres and broken cloud at 600 metres; temporarily between 0800 UTC and |
|1200 UTC surface wind direction 170 degrees; wind speed 25 kilometres per hour gusting to 40 kilometres per hour; visibility 1 000 metres in a|
|moderate thunderstorm with rain, scattered cumulonimbus cloud at 300 metres and broken cloud at 600 metres; from 1230 UTC surface wind |
|direction 150 degrees; wind speed 15 kilometres per hour; visibility 10 kilometres or more; broken cloud at 600 metres and broken cloud at |
|3 000 metres; maximum air temperature 25 degrees Celsius at 1200 UTC**; minimum air temperature minus 2 degrees Celsius at 2400 UTC**. |
| |
|* Fictitious location |
| |
|** Inclusion of temperature forecasts (maximum and minimum expected to occur during the aerodrome forecast validity period and their |
|corresponding times of occurrence) is subject to regional air navigation agreement. |
| |
|Example 3-2. Trend-type landing forecasts in abbreviated plain language |
|and in the METAR and SPECI code forms |
|a) Routine reports with trend. |
| |
|Disseminated locally at the aerodrome in abbreviated plain language: |
| |
|MET REPORT YUDO* 221630Z WIND 240/18KMH VIS 600M RVR RWY 12 1000M FG MOD DZ CLD SCT 300M OVC 600M T17 DP16 QNH 1018HPA TREND BECMG TL1700 VIS |
|800M FG BECMG AT 1800 VIS 10KM NSW |
| Disseminated beyond the aerodrome in the METAR code form: |
| |
|METAR YUDO* 221630Z 24015KMH 0600 R12/1000U FG DZ SCT010 OVC020 17/16 Q1018 BECMG TL1700 0800 FG BECMG AT1800 9999 NSW |
|Meaning of both reports with trend: |
| |
|Local routine report or routine report in the METAR code form for Donlon/International* issued on the 22nd of the month at 1630 UTC; surface |
|wind direction 240 degrees; wind speed 18 or 15 kilometres per hour (averaged over 2 or 5 minutes, respectively); visibility 600 metres; |
|runway visual range representative of the touchdown zone for runway 12 is 1 000 metres (averaged over 1 or 10 minutes, respectively); (only |
|for reports disseminated beyond the aerodrome: the runway visual range values have shown a distinct upward tendency during previous 10 |
|minutes); fog and moderate drizzle; scattered cloud at 300 metres; overcast at 600 metres; air temperatures 17 degrees Celsius; dew point |
|temperature 16 degrees Celsius; QNH 1018 hectopascales; trend during next two hours; visibility becoming 800 metres in fog by 1700 UTC; |
|visibility becoming 10 kilometres or more and nil significant weather. |
|b) Special reports with trend. |
| |
|Disseminated locally at the aerodrome in abbreviated plain language: |
| |
|SPECIAL YUDO* 151115Z WIND 050/26KT MAX37 MNM10 VIS 1200M HVY TSRA CLD BKN CB 500FT T25 DP22 QNH 1008HPA TREND TEMPO TL1200 VIS 600M BECMG |
|AT1200 VIS 10KM NSW NSC |
| Disseminated beyond the aerodrome in the SPECI code form : |
| |
|SPECI YUDO* 151115Z 05025G37KT 1200NE 6000S +TSRA BKN005CB 25/22 Q1008 TEMPO TL1200 0600 BECMG AT1200 9999 NSW NSC |
| |
|Meaning of both reports with trend: |
| |
|Special report for Donlon/International* issued on the 15th of the month at 1115 UTC; surface wind direction 050 degrees; wind speed 26 and 25|
|knots (averaged over 2 and 10 minutes, respectively), gusting between 10 and 37 knots (for special reports disseminated beyond aerodrome: |
|“gusting to 37 knots”); visibility 1 200 metres (for reports disseminated beyond the aerodrome: “visibility lowest to north east at 1 200 |
|metres, visibility 6 000 metres to south); thunderstorm with heavy rain; broken cumulonimbus cloud at 500 feet; air temperature 25 degrees |
|Celsius; dew point temperature 22 degrees Celsius; QNH 1008 hectopascal; trend during next two hours; visibility temporarily 600 metres from |
|1115 to 1200 UTC; becoming at 1200 UTC visibility 10 kilometres or more, thunderstorm ceases and nil significant weather, and nil significant |
|cloud. |
|* Fictitious location |
|Example 3-3. GAMET area forecast |
| |
|YUCC GAMET VALID 220600/221200 YUDO |
|AMSWELL FIR/2 BLW FL100 |
|SECN I |
|SFC WSPD: 10/12 65 KMH |
|SFC VIS: 06/08 3000 M BR N OF N51 |
|SIGWX: 11/12 ISOL TS |
|SIG CLD: 06/09 OVC 800/1100 FT AGL N OF N51 10/12 ISOL TCU 1200/8000 FT AGL |
|ICE: MOD FL050/080 |
|TURB: MOD ABV FL090 |
|SIGMETS APPLICABLE: 3,5 |
|SECN II |
|PSYS: 06 L 1004 HPA N51.5 E10.0 MOV NE 25 KT WKN |
|WIND/T: 2000 FT 270/70 KMH PS03 5000 FT 250/80 KMH MS02 10000 FT 240/85 KMH MS11 |
|CLD: BKN SC 2500/8000 FT AGL |
|FZLVL: 3000 FT AGL |
|MNM QNH: 1004 HPA |
|SEA: T15 HGT 5M |
|VA: NIL |
|Meaning: |
|An area forecast for low-level flights (GAMET) issued for sub-area two of the Amswell* flight information region (identified by YUCC Amswell |
|area control centre) for below flight level 100 by the Donlon/International* meteorological office (YUDO); the message is valid from 0600 UTC |
|to 1200 UTC on the 22nd of the month. |
| |
|Section I: |
| |
|Surface wind speeds: between 1000 UTC and 1200 UTC 65 kilometres per hour; |
|Surface visibility: between 0600 UTC and 0800 UTC 3 000 metres north of 51 degrees north (due to mist); |
|Significant weather phenomena: between 1100 UTC and 1200 UTC isolated thunderstorms without hail; |
|Significant clouds: between 0600 UTC and 0900 UTC overcast base 800, top 1100 feet above ground level north of 51 degrees north; between 1000 |
|UTC and 1200 UTC isolated towering cumulus base 1200, top 8000 feet above ground level; |
|icing: moderate between flight level 050 and 080; |
|Turbulence: moderate above flight level 090 (at least up to flight level 100); |
|SIGMET messages: 3 and 5 applicable to the validity period and subarea concerned; |
|Section II: |
| |
|Pressure systems: at 0600 UTC low pressure of 1004 hectopascals at 51.5 degrees north 10.0degrees east, expected to move north-eastwards at 25|
|knots and to weaken; |
| |
|Winds and temperatures: at 2 000 feet above ground level wind direction 270 degrees; wind speed 70 kilometres per hour, temperature plus 3 |
|degrees Celsius; at 5000 feet above ground level wind direction 250 degrees; wind speed 80 kilometres per hour, temperature minus 2 degrees |
|Celsius; at 10000 feet above ground level wind direction 240 degrees; wind speed 85 kilometres per hour, temperature minus 11 degrees Celsius;|
| |
|Clouds: broken stratocumulus, base 2 500 feet, top 8 000 feet above ground level; |
|Freezing level: 3 000 feet above ground level; |
|Minimum QNH: 1004 hectopascals; |
|Sea: surface temperature 15 degrees Celsius; and state of sea 5 metres; |
|Volcanic ash: nil. |
| |
|* Fictitious locations |
Chapter 4
SIGMET INFORMATION, TROPICAL CYCLONE
AND VOLCANIC ASH ADVISORY INFORMATION,
AIRMET INFORMATION, AERODROME WARNINGS AND
WIND SHEAR WARNINGS
4.1 GENERAL
The preparation and issuance of information advising pilots and other aeronautical personnel of weather no conditions likely to affect the safety of international civil aviation are important functions of meteorological offices. In fact, the meteorological watch offices (MWOs) exist primarily to prepare and issue information on potentially hazardous en-route weather phenomena in their area of responsibility (see 1.3). This information is called “SIGMET and AIRMET information”. Tropical cyclone and volcanic ash advisories are products of tropical cyclone advisory centres (TCACs) and volcanic ash advisory centres (VAACs) (see 1.6 and 1.7). MWOs use these advisories in preparing SIGMET information for tropical cyclones and volcanic ash clouds. The issuance of warnings of hazardous weather conditions at or near aerodromes, including wind shear warnings, is usually the primary responsibility of aerodrome meteorological offices.
Note.— Data type designators to be used in abbreviated headings for messages including SIGMET and AIRMET information, tropical cyclone and volcanic ash advisories are given in Chapter 6, 6.2.2 and in the WMO Manual on the Global Telecommunications System (WMO-No. 386).
4.2 SIGMET INFORMATION
4.2.1 The purpose of SIGMET information is to advise pilots of the occurrence or expected occurrence of en-route weather phenomena which may affect the safety of aircraft operations. The list of phenomena calling for the issuance of SIGMET messages is given below, together with the abbreviations to be used:
a) at subsonic cruising levels:
thunderstorm
obscured OBSC TS
embedded EMBD TS
frequent FRQ TS
squall line SQL TS
obscured with hail OBSC TS GR
embedded with hail EMBD TS GR
frequent, with hail FRQ TS GR
squall line with hail SQL TS GR
tropical cyclone
tropical cyclone with 10-minute mean surface wind
speed of 63 km/h (34 kt)
or more TC (+ cyclone name)
turbulence
severe turbulence SEV TURB
icing
severe icing SEV ICE
severe icing due
to freezing rain SEV ICE (FZRA)
mountain wave
severe mountain wave SEV MTW
duststorm
heavy duststorm HVY DS
sandstorm
heavy sandstorm HVY SS
volcanic ash
volcanic ash VA (+ volcano name, if known)
b) at transonic and supersonic cruising levels:
turbulence
moderate turbulence MOD TURB
severe turbulence SEV TURB
cumulonimbus
isolated cumulonimbus ISOL CB
occasional cumulonimbus OCNL CB
frequent cumulonimbus FRQ CB
hail
hail GR
volcanic ash
volcanic ash VA (+ volcano name, if known)
Only one element from those listed in a) or b) may be used in a SIGMET message for subsonic, cruising levels or a SIGMET message for transonic, and supersonic cruising levels, respectively.
4.2.2 Messages concerning thunderstorms, tropical cyclones or severe squall lines should not include references to associated turbulence or icing. However, the occurrence of heavy hail (with no intensity indicated) with thunderstorms should be indicated.
4.2.3 SIGMET information is often based on aircraft reports, in particular, on special air-reports; it may also be based on weather satellite data and on ground-based observations, such as weather radar observations, or on forecasts.
4.2.4 SIGMET information messages are issued by MWOs and distributed to aircraft in flight through associated ATS units and to operators’ local representatives. Aircraft in flight should normally be given, on ground initiative, SIGMET information messages affecting their routes to a distance equivalent to 2 hours’ flying time ahead of the position of the aircraft. In addition, SIGMET information for volcanic ash and tropical cyclones should be supplied to aircraft in flight, as necessary (i.e. on ground initiative or on request by pilots), to cover the areas affected by these phenomena during the whole flight (see 4.2.5).
4.2.5 The SIGMET messages are disseminated to MWOs, WAFCs and to other meteorological offices as determined by regional air navigation agreement. Furthermore, SIGMET messages are transmitted to the ICAO international OPMET databanks and to the international centres responsible for operations of the aeronautical fixed service (AFS) satellite distribution systems. In addition, SIGMET messages for volcanic ash cloud are disseminated to VAACs. Operators are supplied with SIGMET information mainly from meteorological offices. They can also obtain this information through various automated meteorological information systems or through automated information systems for pre-flight planning. The period of validity of these messages is normally up to 4 hours and should not exceed 6 hours. In the special case of SIGMET messages for volcanic ash cloud and tropical cyclones, an outlook should be included giving information for up to 12 hours beyond the normal period of validity concerning the expected trajectory of the volcanic ash cloud and positions of the tropical cyclone centre (see 4.3). SIGMETs related to tropical cyclones and volcanic ash clouds are to be available at departure aerodromes for the whole route for non-stop flights intending to cross areas affected by these phenomena. SIGMET messages relating to the expected occurrence of weather phenomena, with the exception of volcanic ash cloud and tropical cyclones, should be issued not more than 6 hours, and preferably not more than 4 hours, before the expected time of occurrence of that phenomenon. SIGMET messages are cancelled by the issuing office when the phenomena are no longer occurring or are no longer expected to occur in the area.
4.2.6 It should be noted that information on volcanic ash cloud and associated volcanic activity events is promulgated to users, including ATS units, also by a NOTAM or preferably an ASHTAM. ACCs/FICs routinely receive volcanic ash advisories from the VAACs to which they are associated in accordance with regional air navigation agreement. In view of this, it is important that MWOs maintain close coordination with their associated ACCs/FICs (and relevant aeronautical information services centres or offices) to ensure that information on volcanic ash in SIGMETs and NOTAMs or ASHTAMs is consistent.
Note.— Information on procedures to be used for the dissemination of information on volcanic eruptions is given in the Manual on Volcanic Ash, Radioactive Material and Toxic Chemical Clouds (Doc 9691), the Handbook on the International Airways Volcano Watch (IAVW) — Operational Procedures and Contact List (Doc 9766) and on the ICAO website: under Air Navigation Bureau, Meteorology.
4.2.7 SIGMET information messages (see Example 4-1) are in abbreviated plain language using approved ICAO abbreviations. In order to facilitate computer processing of the information, strict adherence to the relevant specifications for AIRMET information messages contained in Appendix 11 is essential. To describe weather phenomena, no additional descriptive material is therefore permitted. The message contains the following:
— location indicator of the ATS unit serving the FIR or control area to which the SIGMET message refers — for example “YUCC”;
Note.— In cases where the airspace is divided into a flight information region (FIR) and an upper flight information region (UIR), the SIGMET is identified by the location indicator of the air traffic services unit serving the FIR; nevertheless, the SIGMET message applies to the whole airspace within the lateral limits of the FIR, i.e. to the FIR and to the UIR. The particular areas and/or flight levels affected by the meteorological phenomena causing the issuance of the SIGMET are given in the text of the message.
— identification of information and sequence number — for example “SIGMET 5” or “SIGMET SST 1”;
Note.— Messages containing SIGMET information for aircraft in transonic and supersonic flight are identified as SIGMET SST. The number following the identification of information (SIGMET or SIGMET SST) is a sequence number corresponding to the number of SIGMET information messages issued by the issuing office during 24 hours starting at 0001 UTC. Separate sequences of numbers are used for SIGMET and SIGMET SST messages.
— date-time groups indicating the period of validity in UTC — for example “VALID 221215/221600”;
Note.— It should be understood that the period of validity refers to the expected duration of the phenomenon, and therefore transmission of the information to aircraft in flight by ground initiative is to be carried out only for those SIGMET which are still valid.
— location indicator of the meteorological watch office originating the message followed by a hyphen to separate the preamble from the text — for example “YUDO -”;
— on the next line, name of the flight information region or control area for which the SIGMET is issued — for example “AMSWELL FIR”;
— phenomenon and its description, using only the abbreviations given in 4.2.1 — for example "SEV TURB" or “FRQ TS”;
— type of information: if observed and expected to continue, using the abbreviation “OBS” and, if appropriate, the time of observation in UTC; if forecast, using the abbreviation “FCST”; "OBS AND FCST" may also be used;
— location and level, referring, where possible, to latitude/longitude and/or locations or geographical features well known internationally — for example “S OF N54 FL390” or “SIBY/BISTOK FL250”;
— movement: observed or expected movement with reference to one of the eight points of the compass, given in kilometres per hour or knots, or stationary — for example “MOV E 40 KMH”;
— changes in intensity: using, as appropriate, the abbreviations “INTSF”, “WKN” or “NC”;
— on the next line, in SIGMET information messages concerning volcanic ash cloud or tropical cyclones, an outlook providing information beyond the period of validity specified above and covering up to 12 hours of the trajectory of the volcanic ash cloud or positions of the tropical cyclone centre — for example “OTLK TC CENTRE 260400 N2830 W0743 261000 N2912 W7530”.
Note 1.— In order to provide advance warning of the existence of volcanic ash clouds and tropical cyclones, the SIGMET message should be issued up to 12 hours before the commencement of the period of validity or as soon as practicable if such advance warning of the existence of these phenomena is not available. These SIGMETs need to be updated at least every 6 hours.
Note 2.— For further details on the preparation and dissemination of SIGMET information messages, see also the Guide for the Preparation and Dissemination of SIGMET Information, prepared by the ICAO Regional Offices for use in their respective regions. Information on the required exchanges of SIGMET information messages between meteorological offices is contained in the ICAO air navigation plan publications for the various ICAO regions. Additional useful information including arrangements for the distribution of SIGMET information messages at aerodromes and to FICs, etc., can be obtained from the ICAO Manual on Coordination between Air Traffic Services, Aeronautical Information Services and Aeronautical Meteorological Services (Doc 9377).
4.2.8 The issuance of SIGMET messages on volcanic ash cloud and/or tropical cyclones in the form of abbreviated plain language messages may be supplemented by the MWOs, which is in a position to do so by the issuance of these SIGMET messages in graphical format. If this is the case, the WMO BUFR code form should be used. A model has not yet been developed.
4.3 TROPICAL CYCLONE AND
VOLCANIC
ASH ADVISORY
INFORMATION
4.3.1 The preparation of SIGMET information, and particularly of outlooks (see 4.2.5) relating to tropical cyclones and volcanic ash clouds, should be based, where possible, on advisory information produced in TCACs and VAACs (1.6 and 1.7 refers). The supply of the advisory information from TCACs and VAACs to MWOs is defined by regional air navigation agreement whereby MWOs, which are required to prepare SIGMETs for tropical cyclones and volcanic ash, are associated with the individual designated TCACs and VAACs. In addition, the distribution for both advisories is as follows:
— for tropical cyclone advisory information — WAFCs, TCACs, whose area of responsibility may be affected, ICAO international OPMET databanks, and centres operating AFS satellite distribution systems;
— for volcanic ash advisory information — WAFCs, VAACs, whose area of responsibility may be affected, ACCs/FICs, whose area of responsibility may be affected, relevant NOTAM offices, ICAO international OPMET databanks, and centres responsible for operations of AFS satellite distribution systems. Airline operators can obtain the advisory information through the AFTN address1 established to serve this purpose.
To date, nine VAACs and seven TCACs have been designated by regional air navigation agreements (see Appendix 12).
4.3.2 The advisory information on tropical cyclones should comprise the following in the order indicated:
1) TC ADVISORY;
2) DTG: year month date (yyyymmdd)/time (in UTC) (using “Z”) of issue;
3) TCAC: name of TCAC (location indicator or full name);
4) TC: name of tropical cyclone;
5) NR: advisory number (starting with “01” for each cyclone);
6) PSN: position of the centre in degrees and minutes (“Nnnnn” or “Snnnn”, “Wnnnnn” or “Ennnnn”);
7) MOV: direction and speed of movement respectively to at least eight compass points (“N”, “NE”, “E”, “SE”, “S”, “SW”, “W”, “NW”) and in km/h (or kt);
8) C: central pressure (in hPa);
9) MAX WIND: maximum surface wind near the centre (mean over 10 minutes, in km/h (or kt));
10) FCST PSN + 12 HR: forecast of centre position for fixed valid time of …. UTC (12 hours after time of issuance of the advisory);
11) FCST MAX WIND + 12 HR: forecast of maximum surface wind for fixed valid time of …. UTC (12 hours after time of issuance of the advisory);
12) FCST PSN + 18 HR: forecast of centre position for fixed valid time of …. UTC (18 hours after time of issuance of the advisory);
13) FCST MAX WIND + 18 HR: forecast of maximum surface wind for fixed valid time of …. UTC (18 hours after time of issuance of the advisory);
14) FCST PSN + 24 HR: forecast of centre position for fixed valid time of …. UTC (24 hours after time of issuance of the advisory);
15) FCST MAX WIND + 24 HR: forecast of maximum surface wind for fixed valid time of …. UTC (24 hours after time of issuance of the advisory);
16) NXT MSG: expected year month date (yyyymmdd)/time (in UTC) (using “Z”) of issuance of next advisory (using “BFR”, if applicable) or “NO MSG EXP”.
4.3.3 The advisory information on volcanic ash issued in abbreviated plain language should comprise the following in the order indicated:
1) VOLCANIC ASH ADVISORY;
2) ISSUED: year month date (yyyymmdd)/time in UTC (using “Z”) or date month year (ddxxx2yyyy)/time in UTC (using “Z”);
3) VAAC: name of volcanic ash advisory centre;
4) VOLCANO: name and IAVCEI3 number (or “UNKNOWN” or “UNNAMED”);
5) LOCATION: degrees/minutes (“Nnnnn” or “Snnnn”, “Wnnnnn” or “Ennnnn” or “UNKNOWN” or “UNNAMED”);
6) AREA: State, or region if ash is not reported over a State;
7) SUMMIT ELEVATION: elevation in m or ft (including units);
8) ADVISORY NUMBER: year in full and message number (assuming separate sequence for each volcano);
9) INFORMATION SOURCE: free text;
10) AVIATION COLOUR CODE: colour code (“RED”, “ORANGE”, “YELLOW”, “GREEN”) or (“UNKNOWN”) or (“NOT GIVEN”) or (“NIL”);
11) ERUPTION DETAILS: free text description (including date/time of eruption(s)) or (“UNKNOWN”);
12) OBS ASH DATE/TIME: dd/time (UTC) (using “Z”);
13) OBS ASH CLOUD: “SFC” or “FLnnn/nnn, boundary coordinates/area, direction of movement in eight compass points (“N”, “NE”, “E”, “SE”, “S”, “SW”, “W”, “NW”) and speed of each cloud mass in km/h or kt (including units), (up to 4 layers)”; or if ash reported (e.g. AIREP) but not identifiable from satellite data, include “ASH NOT IDENTIFIABLE FROM SATELLITE DATA” and instead of forecast ash positions include “WINDS” followed by upper winds for up to four selected layers;
14) FCST ASH CLOUD + 6 HR: forecast height and position for each cloud mass for fixed valid time .... UTC (six hours from observed time of ash cloud given in Item 12), in flight levels, and degrees/minutes or km or NM;
15) FCST ASH CLOUD + 12 HR: forecast height and position for each cloud mass for fixed valid time .... UTC (twelve hours from observed time of ash cloud given in Item 12), in flight levels, and degrees/minutes or km or NM;
16) FCST ASH CLOUD + 18 HR: forecast height and position for each cloud mass for fixed valid time .... UTC (eighteen hours from observed time of ash cloud given in Item 12), in flight levels, and degrees/minutes or km or NM, or “ASH DISSIPATED”;
17) NEXT ADVISORY: year month date (yyyymmdd)/time in UTC (using “Z”) or date month year (ddxxx4yyyy)/time in UTC (using “Z”) or “NO LATER THAN year month date (yyyymmdd)/time (UTC)” (using “Z”) or date month year (ddxxx4yyyy)/time in UTC (using “Z”) or “NO FURTHER ADVISORIES” or “WILL BE ISSUED BY”;
18) REMARKS: free text or “NIL”.
Note.— PANS-ABC (Doc 8400) abbreviations may be used in the advisory information to present short free text.
4.3.4 As shown in 4.3.2 and 4.3.3, the advisories are issued in abbreviated plain language using approved ICAO abbreviations. The order of information presented in both advisories is to be strictly adhered to. Example 4-2 a) and b) show a tropical cyclone advisory message and a volcanic ash advisory message. Volcanic ash advisories may also be issued in graphical format as outlined in Appendix 9, Model VAG.
4.3.5 Updates to both types of advisory information are issued at least every six hours, or as necessary.
4.4 AIRMET INFORMATION
4.4.1 The purpose of AIRMET information is to advise pilots of the occurrence or expected occurrence of specified en-route weather phenomena, which may affect the safety of low-level aircraft operations and which were not already included in the forecast issued for low-level flights (see 3.13) in the FIR concerned or sub-area thereof. The list of phenomena calling for the issuance of AIRMET is given below, together with the abbreviations to be used in AIRMET messages:
At cruising levels below FL 100 (or below FL 150 in mountainous areas or higher, when necessary):
surface wind speed
widespread mean surface wind speed above
60 km/h (30 kt) SFC WSPD
(+ wind speed and units)
surface visibility
widespread areas affected by the reduction of
visibility to less than 5 000 m including the
weather
phenomenon causing the reduction
of visibility SFC VIS
(+ visibility)
(+ weather phenomena to be selected from
the list in Table 2-5)
thunderstorms
isolated thunderstorms without hail ISOL TS
occasional thunderstorms without hail OCNL TS
isolated thunderstorms with hail ISOL TSGR
occasional thunderstorms with hail OCNL TSGR
mountain obscuration
mountains obscured MT OBSC
cloud
widespread areas of broken or overcast cloud with height
of the base less than 300 m (1 000 ft) above ground level:
• broken BKN CLD
(+ height of the base and top and units)
• overcast OVC CLD
(+ height of the base and top and units)
cumulonimbus clouds which are:
• isolated ISOL CB
• occasional OCNL CB
• frequent FRQ CB
towering cumulus clouds which are:
• isolated ISOL TCU
• occasional OCNL TCU
• frequent FRQ TCU
icing
moderate icing (except for icing in
convective clouds) MOD ICE
turbulence
moderate turbulence (except for
turbulence in convective clouds) MOD TURB
mountain wave
moderate mountain wave MOD MTW
4.4.2 Messages concerning thunderstorms or cumulonimbus clouds should not include references to associated turbulence or icing. However, the occurrence of hail (no indication of intensity) with thunderstorms needs to be indicated.
Note.— The specifications for SIGMET information which are also relevant to low-level flights are given in 4.2.1.
4.4.3 AIRMET information is often based on weather satellite data and on ground-based observations, such as weather radar observations, or on forecasts.
4.4.4 AIRMET information messages are issued by MWOs in accordance with regional air navigation agreement, taking into account the density of air traffic operating below FL 100 (or FL 150 in mountainous areas). The technical specifications for SIGMET and AIRMET information messages and special air-reports are reproduced in Appendix 11. AIRMET messages are distributed to aircraft in flight through associated ATS units. Low-level aircraft in flight should normally be given, on ground initiative, AIRMET information messages affecting their routes. The AIRMET messages are disseminated to MWOs in adjacent flight information regions and to other meteorological offices as agreed by the meteorological authorities concerned. The period of validity of these messages is normally up to 4 hours and should not exceed 6 hours. AIRMET messages are cancelled by the issuing office when the phenomena are no longer occurring or are no longer expected to occur in the area.
4.4.5 AIRMET information messages (see Example 4-3) are in abbreviated plain language using approved ICAO abbreviations. In order to facilitate computer processing of the information, strict adherence to the technical specifications concerning AIRMET information messages, mentioned in 4.4.4 is essential. To describe weather phenomena, no additional descriptive material is therefore permitted. The message contains the following:
— location indicator of the ATS unit serving the FIR or control area to which the AIRMET message refers — for example “YUCC”;
— message identification and sequence number — for example “AIRMET 2”;
Note.— The number following the message identification (AIRMET) is a sequence number corresponding to the number of AIRMET information messages issued by the issuing office during 24 hours starting at 0001 UTC.
— date-time groups indicating the period of validity in UTC — for example “VALID 221215/221600”;
Note.— It should be understood that the period of validity refers to the expected duration of the phenomenon, and therefore transmission of the information to aircraft in flight by ground initiative is to be carried out only for those AIRMET messages which are still valid.
— location indicator of the MWO originating the message followed by a hyphen to separate the preamble from the text — for example “YUDO -”;
— on the next line, name of the FIR or sub-area thereof for which the AIRMET is issued — for example “AMSWELL FIR”;
— phenomenon and its description, causing the issuance of the AIRMET, using only the abbreviations given in 4.4.1 — for example “MOD MTW”;
— type of information: if observed and expected to continue, using the abbreviation “OBS” and, if appropriate, the time of observation in UTC; if forecast, using the abbreviation “FCST” — for example “OBS AT 1325”; “OBS AND FCST” may also be used;
— location and level, referring, where possible, to latitude/longitude and/or locations or geographical features well known internationally — for example “S OF N50 AT FL090”;
— movement: observed or expected movement with reference to one of the eight points of the compass, given in kilometres per hour or knots, or stationary — for example “STNR”;
— changes in intensity: using, as appropriate, the abbreviations “INTSF”, “WKN” or “NC”;
4.5 AERODROME WARNINGS
4.5.1 The purpose of aerodrome warnings is to give concise information, in plain language, of meteorological conditions which could adversely affect aircraft on the ground, including parked aircraft, and the aerodrome facilities and services.
4.5.2 Aerodrome warnings are issued in accordance with local arrangements to operators, aerodrome services and to others concerned, by the meteorological office designated to provide service for that aerodrome. They normally relate to the occurrence or expected occurrence of one or more of the following phenomena:
— tropical cyclone
— thunderstorm
— hail
— snow
— freezing precipitation
— hoar frost or rime
— sandstorm
— duststorm
— rising sand or dust
— strong surface wind and gusts
— squall
— frost.
4.5.3 Where quantitative criteria are required for the issue of aerodrome warnings, e.g. expected maximum wind or expected total snow fall, these are established by agreement between the meteorological office and the users of the warnings.
4.6 WIND SHEAR WARNINGS
4.6.1 Wind shear has been cited as a cause or a contributory factor in a number of major aircraft accidents. At aerodromes where wind shear is considered to be a factor, it is therefore necessary to make arrangements, in addition to the inclusion of wind shear in the supplementary information of local routine and special reports and reports in the METAR and SPECI code forms, to provide all concerned with specific wind shear warnings, which would alert ATS units and, through them, the pilots to the existence or expected existence of this hazardous phenomenon.
4.6.2 Evidence of the existence of wind shear should be derived from:
— ground-based wind shear remote-sensing equipment, e.g. Doppler radar;
— ground-based wind shear detection equipment, e.g. a system of surface wind and/or pressure sensors located in an array, monitoring a specific runway or runways and associated approach and departure paths;
— aircraft observations during the climb-out or approach phases of flight to be made in accordance with Chapter 7; or
— other meteorological information, e.g. from appropriate sensors located on existing masts or towers in the vicinity of the aerodrome or nearby areas of higher ground.
Note.— Wind shear conditions are normally associated with one or more of the following phenomena:
— thunderstorms, microbursts, funnel cloud (tornado or waterspout) and gust fronts;
— frontal surfaces;
— strong surface winds coupled with local topography;
— sea breeze fronts;
— mountain waves (including low-level rotors in the terminal area);
— low-level temperature inversions.
4.6.3 As an example of the use of masts for the observation of wind shear and of low-level temperature inversions, details of the system in use at Helsinki-Vantaa airport are given in Appendix 13.
4.6.4 The objective of wind shear warnings is to give concise information on the observed or expected existence of wind shear which could adversely affect:
a) aircraft on the approach path or take-off path or during circling approach between runway level and 500 m (1 600 ft) above that level or higher, where local topography produces operationally significant wind shears at greater heights; and
b) aircraft on the runway during the landing roll and take-off run.
The warnings shall be either prepared by the meteorological office designated to provide service for the aerodrome, and disseminated to aerodromes where wind shear is considered a factor, in accordance with local arrangements with the appropriate ATS authority and operators concerned, or disseminated directly from the automated ground-based wind shear remote-sensing or detection equipment referred to in 4.6.2.
4.6.5 Wind shear warnings are prepared in abbreviated plain language. Wind shear in the approach area is reported, for example, as “WS WRNG SURFACE WIND 320/20KMH WIND AT 60 M 360/50KMH IN APCH” (wind shear warning surface wind 320 degrees 20 km/h wind at 60 m 360 degrees 50 km/h in approach). Where microbursts are observed, reported by pilots or detected by ground-based wind shear detection or remote-sensing equipment, the wind shear warning must include a reference to microbursts, e.g. “WS WRNG MBST APCH RWY 26”. Where information from ground-based wind shear detection or remote-sensing equipment is used to prepare a wind shear warning, it should, if possible, relate to specific sections of the runway and distances along the approach or take-off path as agreed between the meteorological authority, the appropriate ATS authority and the operators concerned, e.g.“WS WRNG 60KMH AIRSPEED LOSS 4KM FINAL RWY 13”. When an aircraft report is used to prepare a wind shear warning or to confirm a warning previously issued, this report, including the aircraft type, is given unchanged in the warning, for example, “WS WRNG B747 REPORTED MOD WS IN APCH RWY 34 AT 1510” (wind shear warning B747 reported moderate wind shear in approach to runway 34 at 1510 hours UTC).
Note 1.— Following reported encounters by both arriving and departing aircraft two different wind shear warnings may exist, one for arriving aircraft and one for departing aircraft.
Note 2.— Specifications for reporting the intensity of wind shear are still undergoing development. It is recognized, however, that pilots, when reporting wind shear, may use the qualifying terms “moderate”, “strong” or “severe”, based to a large extent on their subjective assessment of the intensity of the wind shear encountered. Such reports are incorporated unchanged in wind shear warnings.
4.6.6 Wind shear warnings for arriving aircraft and/or departing aircraft are cancelled when aircraft reports indicate that wind shear no longer exists, or alternatively, after an agreed elapsed time. The criteria for the cancellation of a wind shear warning should be defined locally for each aerodrome, as agreed between the meteorological authority, the appropriate ATS authority and the operators concerned.
Note.— Guidance on the issuance of wind shear warnings is provided in ICAO Circular 186 — Wind Shear.
1. The AFTN address can be found in Table 4-1 of the Handbook on the International Airways Volcano Watch (IAVW) — Operational Procedures and Contact List (Doc 9766) and on the ICAO website: under Air Navigation Bureau, Meteorology.
2. Use abbreviations for months of the year from the PANSABC (Doc 8400), for example, “JAN”.
3. International Association of Volcanology and Chemistry of the Earth’s Interior (IAVCEI).
| |
|Example 4-1. SIGMET messages |
| |
|a) SIGMET for turbulence |
| |
|YUCC* SIGMET 5 VALID 221215/221600 YUDO*- |
|AMSWELL FIR SEV TURB OBS AT 1210Z YUSB FL250 MOV E 40KMH WKN |
|Meaning: |
| |
|The fifth SIGMET message issued for Amswell* flight information region (identified in abbreviated plain language and by YUCC area control |
|centre) by the Donlon/International* meteorological watch office (YUDO) since 0001 UTC; the message is valid from 1215 UTC to 1600 UTC on the |
|22nd of the month; severe turbulence was observed at 1210 UTC over Siby/Bistock* aerodrome (YUSB) at level 250; the turbulence is expected to |
|move eastwards at 40 kilometres per hour and to weaken in intensity. |
|b) SIGMET for tropical cyclone |
| |
|YUCC* SIGMET 3 VALID 251600/252200 YUDO*- |
|AMSWELL* FIR TC GLORIA OBS AT 1600Z N2706 W07306 CB TOP FL500 WI 150NM OF CENTRE MOV NW 10KT NC FCST 2200Z TC CENTRE N2740 W07345 |
|OTLK TC CENTRE 260400 N2830 W07430 261000 N2912 W07530 |
|Meaning: |
| |
|The third SIGMET message issued for the Amswell* flight information region (identified in abbreviated plain language and by YUCC area control |
|centre) by the Donlon/International* meteorological watch office (YUDO) since 0001 UTC, the message is valid from 1600 UTC to 2200 UTC on the |
|25th of the month; tropical cyclone "GLORIA" was observed at 1600 UTC 27 degrees 6 minutes north, 73 degrees 6 minutes west; cumulonimbus tops|
|reaching flight level 500 within 150 nautical miles of its centre; the centre of the tropical cyclone is moving northwest at 10 knots; no |
|change in intensity expected; forecast for 2200 UTC the tropical cyclone centre at 27 degrees 40 minutes north, 73 degrees 45 minutes west. |
| Outlook for the position of the tropical cyclone centre: at 0400 UTC on the 26th the centre is expected to be located at 28 degrees 30 |
|minutes north, 74 degrees 30 minutes west; at 1000 UTC on the 26th at 29 degrees 12 minutes north, 75 degrees 30 minutes west. |
|c) SIGMET for volcanic ash |
| |
|YUKK* SIGMET 2 VALID 211100/211700 YUGG*- |
|KENTAL* FIR/UIR VA ERUPTION MT ASHVAL LOC S1500 E07348 VA CLD OBS AT 1100Z FL310/450 APRX 220KM BY 35KM S1500 E07348 TO S1530 E07642 MOV ESE |
|65KMH FCST 1700Z VA CLD APRX S1506 E07500 TO S1518 E08112 TO S1712 E08330 TO S1824 E07836 |
|OTLK 212300Z VA CLD APRX S1600 E07806 TO S1642 E08412 TO S1824 E08900 TO S1906 E08100 220500Z VA CLD APRX S1700 E08100 TO S1812 E08636 TO |
|S2000 E09224 TO S2130 E08418 |
|Meaning: |
| |
|The second SIGMET message issued for the Kental* flight information region (identified in abbreviated plain language and by YUKK Kental area |
|control centre/upper information centre) by the Gales* meteorological watch office (YUGG) since 0001 UTC, the message is valid from 1100 UTC |
|to 1700 UTC on the 21st of the month; a volcanic ash eruption at the “Mount Ashval” volcano located at 15 degrees 0 minutes north, 73 degrees |
|48 minutes east; volcanic ash cloud observed at 1100 UTC between flight levels 310 and 350 extents approximately 220 km by 35 km, 15 degrees 0|
|minutes south, 73 degrees 48 minutes east to 15 degrees 30 minutes south, 76 degrees 42 minutes east; moving to east-south-east by 65 |
|kilometres per hour; forecast position of the cloud at 1700 UTC approximately 15 degrees 6 minutes south, 75 degrees 0 minutes east to 15 |
|degrees 18 minutes south, 81 degrees 12 minutes east to 17 degrees 12 minutes south, 83 degrees 30 minutes east to 18 degrees 24 minutes |
|south, 78 degrees 36 minutes east. |
| |
|Outlook: for 2300 UTC on the 21st of the month volcanic ash cloud extending approximately at 16 degrees 0 minutes south, 78 degrees 6 minutes |
|east to 16 degrees 42 minutes south, 84 degrees 12 minutes east to 18 degrees 24 minutes south, 89 degrees 0 minutes east to 19 degrees 6 |
|minutes south, 81 degrees 0 minutes east; for 0500 UTC on the 22nd of the month volcanic ash cloud extending approximately 17 degrees 0 |
|minutes south, 81 degrees 0 minutes east to 18 degrees 12 minutes south, 86 degrees 36 minutes east to 20 degrees 0 minutes south, 92 degrees |
|24 minutes east to 21 degrees 30 minutes south, 84 degrees 18 minutes east. |
|d) SIGMET information message to be cancelled |
| |
| |
|Note.— The content of the message below relates to the message in a). This type of message applies also to SIGMET information messages for |
|tropical cyclone and volcanic ash cloud shown in b) and c). |
| |
|YUCC* SIGMET 6 VALID 221400/1600 YUDO*- |
|AMSWELL* FIR CNL SIGMET 5 221215/1600 |
|Meaning: |
| |
|The sixth SIGMET message issued for the AMSWELL* flight information region (identified in abbreviated plain language and by YUCC Amswell area |
|control centre) by the Donlon /International* meteorological watch office (YUDO) since 0001 UTC; the message is valid from 1400 UTC to 1600 |
|UTC on the 22nd of the month. The fifth SIGMET information message of the day is cancelled. |
| |
|* Fictitious locations |
| |
|Example 4-2. Advisory messages for tropical cyclones and volcanic ash |
| |
|a) Tropical cyclone advisory |
| |
|TC ADVISORY |
|DTG: 19970925/1600Z |
|TCAC: YU FO |
|TC: GLORIA |
|NR: 01 |
|PSN: N2706 W07306 |
|MOV: NW 20KMH |
|C: 965HPA |
|MAX WIND: 90KMH |
| |
|FCST PSN + 12 HR: 260400 N2830 W07430 |
|FCST MAX WIND + 12 HR: 90KMH |
|FCST PSN + 18 HR: 261000 N2852 W07500 |
|FCST MAX WIND + 18 HR: 85KMH |
|FCST PSN + 24 HR: 261600 N2912 W07530 |
|FCST MAX WIND + 24 HR: 80KMH |
|NXT MSG: 19970925/2000Z |
| |
|Note.— For the decode see 4.3.2 above. |
| |
|b) Volcanic ash advisory |
| |
|VOLCANIC ASH ADVISORY |
|ISSUED: 20000402/0700Z |
|VAAC: TOKYO |
|VOLCANO: USUZAN 805-03 |
|LOCATION: N4230E14048 |
|AREA: JAPAN |
|SUMMIT ELEVATION: 732M |
|ADVISORY NUMBER: 2000/432 |
|INFORMATION SOURCE: GMS JMA |
|AVIATION COLOUR CODE: RED |
|ERUPTION DETAILS: ERUPTED 20000402/0614Z ERUPTION OBS ASH TO ABV FL300 |
|OBS ASH DATE/TIME: 02/0645Z |
|OBS ASH CLD: FL150/350 N4230E14048-N4300E14130-N4246E14230-N4232E14150- |
| |
|N4230E14048 SFC/FL150 MOV NE 25KT FL150/350 MOV E 30KT |
|FCST ASH CLD + 6 HR: 02/1245Z SFC/FL200 N4230E14048-N4232E14150-N4238E14300-N4246 |
| |
|E14230 FL200/350 N4230E14048-N4232E14150N4238E14300- |
| |
|N4246E14230 FL350/600 NO ASH EXP |
| |
|FCST ASH CLD + 12 HR: 02/1845Z SFC/FL300 N4230E14048-N4232E14150-N4238E14300- |
| |
|N4246E14230 FL300/600 NO ASH EXP |
| |
|FCST ASH CLD + 18 HR: 03/0045Z SFC/FL600 NO ASH EXP |
|NEXT ADVISORY: 20000402/1300Z |
|REMARKS: ASH CLD CAN NO LONGER BE DETECTED ON SATELLITE IMAGE |
| |
|Note.— For the decode see 4.3.3 above. |
|Example 4-3. AIRMET message |
| |
|YUCC AIRMET 2 VALID 221215/221600 YUDO- |
|AMSWELL FIR MOD MTW OBS AT 1205Z AND FCST N48 E10 FL080 STNR NC |
| |
|Meaning: |
| |
|The second AIRMET message issued for the AMSWELL* flight information region (identified in abbreviated plain language and by YUCC Amswell area|
|control centre) by the Donlon/International* meteorological watch office (YUDO) since 0001 UTC; the message is valid from 1215 UTC to 1600 UTC|
|on the 22nd of the month; moderate mountain wave was observed at 1205 UTC at 48 degrees north and 10 degrees east at flight level 080; the |
|mountain wave is expected to remain stationary and not to undergo any changes in intensity. |
| |
|* Fictitious locations |
Chapter 5
METEOROLOGICAL SERVICE FOR
OPERATORS AND FLIGHT CREW MEMBERS
5.1 GENERAL PROVISIONS
5.1.1 Meteorological service for operators and flight crew members consists of the following information:
a) pre-flight planning by operators;
b) in-flight replanning by operators using centralized operational control of flight operations;
c) use by flight crew members before departure;
d) aircraft in flight.
Note.— The provision of meteorological information to aircraft in flight is normally the responsibility of ATS units; details in this respect can be found in the Air Traffic Services Planning Manual (Doc 9426) and are therefore not reproduced in this manual. However, meteorological information supplied by aerodromes and other meteorological offices to ATS units is outlined in Chapter 8 of this manual.
5.1.2 The meteorological services required to be provided at or for aerodromes by aerodromes or other meteorological offices are determined by regional air navigation agreement and are listed in the various ICAO air navigation plan publications. Factual information on existing meteorological services is shown in the aeronautical information publications (AIPs) issued by individual States. These publications usually contain details of the type of meteorological offices provided at aerodromes and the services provided by them, together with the address of the meteorological authority to which aeronautical users may apply for meteorological data. For aerodromes without meteorological offices, the AIPs give the address and the telephone number of the office responsible for the supply of the necessary meteorological information. (See Chapter 9 for information on the preparation and contents of the meteorology sections of AIPs.)
5.1.3 The meteorological services provided may include briefing/consultation and flight documentation. When such services are desired, the operator or a flight crew member must notify the aerodrome or other meteorological office concerned in sufficient time to allow that office to prepare the information required and, as necessary, to obtain information from world area forecast centres and other meteorological offices. The notice should include such details as:
a) aerodrome of departure and estimated time of departure;
b) destination and estimated time of arrival;
c) route to be flown and estimated times of arrival at, and departure from, any intermediate aerodrome(s);
d) alternate aerodromes needed to complete the operational flight plan, taken from a list of alternates contained in Table AOP 1 of the air navigation plan publication concerned;
e) cruising level(s);
f) for supersonic flights, the alternative subsonic cruising level(s) and the locations of the transonic acceleration and deceleration areas and of the climb and descent paths;
g) type of flight, whether under the visual or the instrument flight rules;
h) type of meteorological information requested, i.e. whether flight documentation and/or briefing or consultation;
i) time(s) at which briefing, consultation and/or flight documentation are required.
Note.— In the case of scheduled flights, the requirement for some or all of this information may be waived by agreement between the meteorological office and the operator. In those cases, operators or flight crew members must keep the meteorological authority, or the aerodrome or other meteorological office concerned, informed of any changes in schedules, or plans for non-scheduled flights.
5.2 PRE-FLIGHT INFORMATION
5.2.1 Operators or their representatives, such as flight operations officers or flight crew members, require meteorological information for pre-flight planning. Meteorological information for in-flight replanning under centralized operation control may also be required. This information, i.e. for pre-flight planning and in-flight replanning, includes the following information, as required:
a) current and forecast upper winds, upper-air temperatures, tropopause heights and maximum wind information and amendments thereto;
b) existing and expected significant en-route weather phenomena and jet stream information and amendments thereto;
c) a forecast for take-off;
d) aerodrome reports (METARs and SPECIs, including TREND forecasts) for the aerodrome of departure, the aerodrome of intended landing, the take-off, and the en-route and destination alternate aerodromes as determined by regional air navigation agreement;
e) aerodrome forecasts (TAF) and amendments thereto for the aerodromes of departure and intended landing and for take-off, and the en-route and destination alternate aerodromes as determined by regional air navigation agreement; and
f) SIGMET information and appropriate special air-reports relevant to the entire route concerned as determined by regional air navigation agreement.
Note 1. — Appropriate special air-reports will be those not already used in preparation of SIGMET messages.
Note 2. — It may be noted that the application of advanced communication technologies and the use of modern communication systems/equipment have provided for the exchange/collection/dissemination of OPMET data on a nearly global basis. In view of this, certain limitations, applied in the past for supplying operators and flight crew members with, in particular, SIGMET messages (except those for tropical cyclones and volcanic ash) and METAR and SPECI messages including trend type forecasts, could have been relaxed. Nevertheless, it is important that the desired high efficiency of this global exchange and collection of these data within the aeronautical fixed telecommunication network (AFTN) be maintained through the application of regional air navigation agreement (d), e) and f) above refer). The quasi-global set of OPMET data is disseminated by the AFS satellite distribution system. Individual messages or bulletins of the messages can also be obtained on request via the AFTN from the international OPMET databanks established by regional air navigation agreement (for details see 6.4).
5.2.2 The information listed in 5.2.1 should cover the flight in respect of time, altitude and geographical extent up to the aerodrome of intended landing. When there is doubt as to the practicability of landing at that aerodrome, additional information should be included covering the meteorological conditions expected between the aerodrome of intended landing and one or more suitable en-route and destination alternate aerodromes as required by the operator to complete the operational flight plan.
5.2.3 The meteorological office that prepares the pre-flight information or the information for in-flight replanning will, in cases of significant changes (e.g. when new information is received), advise the operator of changes in the pre-flight information and/or bring the flight documentation issued in accordance with 5.4 up to date, in writing or orally, before it is supplied to flight crew members. The flight documentation itself should normally be supplied as close to the departure time as practicable. Should a need for amendment arise after the flight documentation has been supplied and before the aircraft has taken off, arrangements normally exist by which the meteorological office issues the updated information to the operator or to the local ATS unit for transmission to the aircraft. In case of unusual delays, completely new flight documentation may be requested by the flight crew from the meteorological office concerned.
5.2.4 For pre-flight planning and in-flight replanning by operators for supersonic aircraft, the information should include data covering the levels used for transonic and supersonic flights, together with the levels that may be used for subsonic flights. Particular mention should be made of occurrence and expected occurrence, location and vertical extent of cumulonimbus clouds, turbulence and precipitation.
5.2.5 For helicopter operations to offshore structures, pre-flight and in-flight planning information should include data from sea level to FL 100. The data will need to cover surface visibility, amount, type, when available, base and tops of cloud below FL 100, sea state and sea surface temperature, mean sea level pressure, turbulence and icing. Details of the requirements in this regard vary from region to region, and are therefore determined by regional air navigation agreement. Where available, AIRMET information and the area forecasts issued for these types of operations should also be provided to operators for flight planning purposes.
5.2.6 For low-level operations, including those in accordance with the visual flight rules, the pre-flight and in-flight planning information on en-route conditions should cover the layer from ground to FL 100 or up to FL 150 or more in mountainous areas. The information should include en-route weather phenomena given in 3.13. In view of this, AIRMET information is of particular importance in planning low-level flights.
5.2.7 The upper wind and upper-air temperature information and the significant en-route weather information requested for pre-flight and in-flight planning by the operator is usually supplied in chart form as soon as it becomes available, but not later than three hours before departure.
5.2.8 Where operators carry out computer flight planning, the necessary upper wind and upper-air temperature information is supplied at times and in formats agreed between the meteorological authority and the operator concerned. Digital grid-point forecasts, prepared by WAFCs, are widely used by the users. These forecast data are disseminated through the AFS satellite distribution systems to authorized users. Alternatively, and if arrangements have been made to that effect between the meteorological authority and such operators, this information may be obtained by the operators through direct reception of the data from the WAFC concerned (see 3.9).
Note.— Further details on the use of meteorological data in computer as well as in manual flight planning by flight operations officers are given in Appendix 14 to this manual.
5.3 BRIEFING, CONSULTATION
AND DISPLAY
5.3.1 A briefing or consultation is provided on request to flight crew members or other flight operations personnel. A briefing consists of an oral commentary, either directly by a person at the departure aerodrome or by telephone or other suitable telecommunication means from the meteorological office who was notified of the flight and who issued the flight documentation, or through self-briefing computer terminals. A consultation consists of a personal discussion, including questions and answers. The purpose of the briefing or consultation is to supply the latest available information of the type outlined in 5.2.1 and 5.2.3 on existing and expected meteorological conditions along the route to be flown, at the aerodrome of intended landing and at any necessary alternate aerodromes. Such information may be given either to explain and amplify the contents of the flight documentation or, if so agreed between the meteorological authority and the operator, it may serve in lieu of flight documentation.
5.3.2 For supersonic flights and for low-level flights, a briefing or consultation should include information covering the levels of particular interest to these operations. In addition to weather phenomena that affects all flight operations, specific mention should be made of phenomena likely to affect supersonic operations, such as location and vertical extent of cumulonimbus clouds, turbulence and precipitation; in the case of low-level flights, including those in accordance with the visual flight rules, any phenomena causing a widespread reduction of visibility to below 5 000 m and clouds which may affect the flight, should be mentioned.
5.3.3 To assist the flight crew members and others concerned with the preparation of a flight, and for use in a briefing or consultation, aerodrome meteorological offices also display aerodrome reports and forecasts, SIGMET and AIRMET information and special air-reports not covered by a SIGMET, as well as meteorological charts, including meteorological satellite images and ground-based weather radar information. This information can also be displayed for users by means of various self-briefing or meteorological information systems (see 5.7).
Note.— A multilingual list of abbreviations and their decodes, which should be used in phraseologies in a briefing or consultation, is given in Appendix 15.
5.4 FLIGHT DOCUMENTATION —
METHODS OF PRESENTATION
5.4.1 Flight documentation is written or printed information that is provided to flight crew members before take-off and which they take with them on the flight. It should comprise:
a) upper wind and upper-air temperatures;
b) expected significant en-route weather phenomena and, if relevant, tropopause heights and jet streams;
c) aerodrome forecasts;
d) reports in the METAR code form and special reports in the SPECI code form for destination aerodromes and take-off, en-route and destination alternate aerodromes;
e) SIGMET information and appropriate special air reports for a distance related to the whole route; and
f) AIRMET information for low-level flights.
However, in accordance with regional air navigation agreements or, in the absence thereof, when agreed between the meteorological authority and the operator concerned, flight documentation for flights of two hours duration or less, after a short stop or turnaround, may be limited to only the operational information; in all cases, however, the flight documentation should comprise information on at least c), d), e) and, if appropriate, f).
5.4.2 The information on upper winds and upper-air temperatures, expected significant en-route weather phenomena, tropopause heights, maximum winds and jet streams should be received by meteorological offices from within the framework of the WAFS or based on information obtained from that system. (This does not apply to the information relating to the layer from ground to FL 100 or FL 150 which is prepared by the meteorological offices concerned.)
5.4.3 The flight documentation is presented in one or more of the following forms:
a) en-route information:
1) chart form;
2) tabular form;
3) abbreviated plain-language text;
b) aerodrome information:
1) METAR, SPECI and TAF codes;
2) abbreviated plain language (usually in tabular form).
5.4.4 Wherever possible, the charts included in flight documentation should be direct copies of charts received within the framework of the WAFS, as discussed in Chapter 3. The forms included in flight documentation are printed in English, French, Russian or Spanish; they should, wherever practicable, be completed in the language requested by the operator, preferably using one of those languages. The dimensional units used in flight documentation are normally those employed by the meteorological authority concerned, which are in compliance with Annex 5 — Units of Measurement to be Used in Air and Ground Operations and are indicated for each element. Copies of flight documentation should be retained, either as printed copies or as computer files, by the issuing meteorological authority for at least 30 days.
5.4.5 The height indications used in aerodrome forecasts are always given as height above official aerodrome elevation. On charts and forms giving en-route meteorological conditions, height indications in terms of flight levels are preferred, but pressure-altitude, pressure or altitude (for low-level flights, height above ground level) may also be used; on such charts and forms, the height indication used is always indicated.
Note.— Detailed characteristics of charts included in flight documentation, such as size, depiction of geographical features and grids, labels, etc., are given in Annex 3, 9.4. Examples of charts and forms included in flight documentation are shown in Appendix 9 to this manual. The appendix also includes MODEL SN containing a comprehensive set of important explanatory material relating to charts, symbols, units of measurement, and abbreviations contained in flight documentation. This model should, therefore, be supplied, or be made available to flight crew members and/or operators together with flight documentation.
5.5 FLIGHT DOCUMENTATION —
FORECASTS OF EN-ROUTE CONDITIONS
5.5.1 The various types of forecasts of upper winds, upper-air temperatures and significant weather conditions en route are discussed in Chapter 3. The charts issued as flight documentation for flights between FL 250 and FL 450 include a high-level significant weather chart — an SWH chart (FL 250 to FL 450) and a forecast chart of upper winds and temperature for the level of 250 hPa. The medium-level significant weather chart — an SWM chart, issued in accordance with regional air navigation agreement for limited geographical areas, is included in flight documentation for flights between FL 100 and FL 250. Upper wind and upper-air temperature charts and significant weather charts to be included in flight documentation are determined on the basis of agreements between meteorological authorities, users, and the WAFCs concerned.
5.5.2 Where upper wind and upper-air temperature information is supplied in tabular form, it includes data for the same flight levels as the corresponding upper-air charts. This information should be given for spot locations on a regular grid. Forecasts of en-route conditions for low-level flights in tabular form include, in addition to upper wind and upper-air temperature forecasts, significant weather forecasts containing the information given in 3.10.4. The upper wind and upper-air temperature forecasts include data representative for individual, separated portions of the route concerned. These should not exceed a distance of 500 km. The following altitudes should be covered: 600 m, 1 500 m and 3 000 m (2 000 ft, 5 000 ft and 10 000 ft).
5.5.3 Where flight documentation is supplied in the form of an abbreviated plain-language text, it should cover the whole route to be flown. If such documentation covers more than one route, it should permit ready identification by the user of the information concerning the route to be flown. Forecasts of en-route conditions for low-level flights in abbreviated plain language include the information in 3.10.4, as well as upper wind and upper-air temperature forecasts for the altitudes specified in 3.10.3. The lowest forecast QNH datum (for the whole route) or data (relating to individual portions of the route) should also be given. Where forecasts of en-route conditions are issued in the form of a GAMET area forecast, as described in 3.13.2, this forecast message should be the principal part of the flight documentation for low-level flights.
Note.— The en-route forecasts for low-level flights referred to in 5.5.1 to 5.5.3 are prepared by meteorological offices as agreed locally or in accordance with regional air navigation agreement. This applies particularly for the regions where AIRMET information is to be issued by regional air navigation agreement. In these regions, the GAMET forecasts are normally prepared in support of the issuance of AIRMET information and SIGMET and AIRMET information relevant to the flight concerned is to be included in flight documentation for low-level flights.
5.6 FLIGHT DOCUMENTATION —
AERODROME FORECASTS
5.6.1 The various types of aerodrome forecasts are discussed in Chapter 3. Flight documentation always includes aerodrome forecasts for the aerodrome of departure, and for the aerodrome of intended landing. In addition, flight documentation includes aerodrome forecasts for one or more suitable alternate aerodromes, as needed, to complete the operational flight plan and as selected by agreement between the meteorological authority and the operator. By agreement between the meteorological authority and the operator, flight documentation may also include forecasts for a limited number of alternate aerodromes en route and for aerodromes where intermediate stops are planned. In such cases, use is normally made of available forecasts for regular aerodromes.
5.6.2 Aerodrome forecasts received from other meteorological offices should be included in flight documentation without any change in the substance. When an aerodrome forecast is not received in time, the meteorological office issuing the flight documentation should, if possible, prepare a provisional forecast. The meteorological office should inform the flight crew member that the forecast is provisional and record its origin in the flight documentation.
5.6.3 Similarly, if during a briefing or consultation an opinion is expressed on developments in the meteorological situation at an aerodrome, which is appreciably different from the aerodrome forecast included in the flight documentation, the attention of all concerned needs to be drawn to this divergence and a record of the divergence supplied to the operator.
5.6.4 Aerodrome forecasts are normally presented in the TAF code form; they may also be presented in tabular form or in abbreviated plain-language text. Where presentation in the TAF code form is used, the location indicators and the abbreviations used are explained in the flight documentation and the presentation is in a form permitting ready identification of the beginning and end of each forecast.
5.7 AUTOMATED PRE-FLIGHT
INFORMATION SYSTEMS
5.7.1 Centralization and automation on the part of meteorological authorities prompted the development and implementation of automated pre-flight information systems. Pre-flight information, self-briefing, consultation and flight documentation can be obtained by flight crew members, operators and other flight operations personnel through an automated pre-flight information system. The meteorological information to be displayed in meteorological offices can also be made available to the users through these systems. Some of these systems serve the above purposes exclusively while others allow for the provision of an integrated information system, which may not be confined to the meteorological part of pre-flight planning. Several systems already in place, or being developed, enable users a harmonized, common-point access to AIS and MET pre-flight information. Automated pre-flight information systems may form part of a multi-purpose aeronautical or public information system.
5.7.2 Meteorological information and services supplied through an automated pre-flight information system to users should comply with Annex 3 provisions, primarily those in Chapters 3 and 5 of this manual.
5.7.3 The principal features and capabilities of automated pre-flight information systems should:
a) provide for continuous updating of the system database and the monitoring of the validity and integrity of the meteorological information stored;
b) permit access to the system by operators, flight crew members and other aeronautical users concerned through suitable telecommunications means (including public communications, such as telephone, fax, telex and data networks); and
c) use access and interrogation procedures based on abbreviated plain-language, ICAO location indicators, WMO aeronautical meteorological code data designators or based on a menu-driven interface or other mechanisms, as agreed between the meteorological authority and the operators concerned; and
d) provide for rapid response to user requests for information.
5.7.4 Where the AIS/MET automated pre-flight information systems are established and used, the full responsibility for the MET data processed and supplied rests with the meteorological authority(ies) concerned, through all levels of processing up to the supply of the data to users. The same applies to the AIS authority(ies) designated by a State(s) for the AIS data processed and supplied by such systems. The information to be supplied through such systems to the personnel involved in the pre-flight planning, i.e. its quality, geographical and spacial coverage, format, content, validity, time and the frequency of supply etc., should be in conformity with the relevant provisions of Annex 3 and Annex 15.
Chapter 6
DISSEMINATION OF AERONAUTICAL
METEOROLOGICAL INFORMATION
6.1 GENERAL
6.1.1 Efficient telecommunications are essential for the speedy dissemination of aeronautical meteorological information to all users. Suitable telecommunication facilities must therefore be available at aerodromes to ensure rapid communications between meteorological offices and stations, and to allow these offices and stations to supply the necessary meteorological information to ATS units (control towers, approach control, etc.), operators and other aeronautical users at the aerodrome. Automatic telecommunication and information systems, telephones, and teletypewriters are used for this purpose; if used between meteorological offices and ATS units, telephones should allow contact with the required points within 15 seconds (even if switchboards are used), and printed communications within 5 minutes, including any necessary retransmission.
6.1.2 For the dissemination of operational meteorological (OPMET) information beyond the aerodrome, the aeronautical fixed telecommunication network (AFTN) and the aeronautical fixed service (AFS) satellite distribution broadcast systems (see 6.3 and Appendix 1) are the primary communication means. Both the network and the broadcast are part of the AFS, which embraces all telecommunication systems used for international air navigation, except ground-to-air transmissions. Four ICAO international OPMET databanks, which can be accessed primarily through the AFTN, support inter-regional and regional exchanges and dissemination of OPMET information. These OPMET databanks were established by regional air navigation agreement in Brasilia, Brussels, Vienna and Washington. AFS circuits, other than those within the AFTN, may also be used, if necessary, for exchanges, collection and dissemination of OPMET information.
6.2 DISSEMINATION OF OPMET
INFORMATION ON THE AFTN
6.2.1 OPMET information in alphanumeric form is transmitted on the AFTN (and on most other networks) in the form of “bulletins”, each bulletin containing one or more reports, forecasts or other types of information (but always only one type per bulletin) and the appropriate bulletin heading. The heading is essential to permit recognition by users and handlers, including computers, of type, time and origin of the data contained in the bulletin. It should not be confused with the “AFTN message heading” which determines priority, routing and other telecommunication aspects of the message. All meteorological bulletins transmitted via the AFTN have to be “encapsulated” into the text part of the AFTN message format.
Note.— Details concerning the AFTN message format are given in Annex 10 — Aeronautical Telecommunications, Volume II — Communication Procedures including those with PANS status.
6.2.2 The meteorological bulletin abbreviated heading consists of a single line, precedes the OPMET data contained in the bulletin, and normally comprises three groups as follows:
a) an identifier;
b) an ICAO location indicator;
c) a date-time group; and
d) if necessary, a fourth group can be added as an identifier for a delayed, corrected or amended bulletin.
The meaning of these four groups is as follows:
— The identifier comprises four letters and two figures: the first and second letters are the data type designators, the third and fourth letters are the geographical designators, and the figures are added to identify two or more bulletins originated by the same centre. The data designators are:
SA Routine report (in the METAR code form), including trend-type forecast, if provided
SP Special report (in the SPECI code form), including trend-type forecasts, if provided
FT Aerodrome forecast valid for 12 to 24 hours (in the TAF code form)
FC Aerodrome forecast valid for 9 to 12 hours (in the TAF code form)
WA AIRMET information
WS SIGMET information
WC SIGMET information for tropical cyclones
WV SIGMET information for volcanic ash
FK Tropical cyclone advisory message
FV Volcanic ash advisory message
UA Air-report (AIREP)
FA Area forecasts (GAMET forecasts)
FR Route forecast (in the ROFOR code form)
|Example.— SAZB02 = Second of two bulletins containing routine |
|reports in the METAR code form (SA) from Zambia (ZB). |
Note.— A complete list of geographical designators is given in WMO Publication No. 386 — Manual of the Global Telecommunication System; the data designators listed above are taken from the same WMO publication.
— The ICAO location indicator consists of four letters (e.g. YUDO [fictitious location]) and identifies the meteorological office that compiled the bulletin. The complete list of location indicators is published in Location Indicators (Doc 7910).
— The date-time group consists of six figures, the first two figures indicating the day of the month and the next four figures indicating:
a) for routine and special reports (METARs and SPECIs), the time of observation in UTC;
b) for aerodrome, route and area forecasts, the full hour in UTC (of which the last two figures are always 00) preceding the transmission time; for other forecasts, the standard time of observation in UTC on which the forecast is based;
c) for other meteorological bulletins, such as SIGMET information, the time of origin in UTC of the text of the bulletin(s).
|Example.— 151200 = The routine reports are based on observations |
|made on the 15th of the month at 1200 UTC. |
Note.— In the case of bulletins, the time of observation of each report needs to be clearly identified.
— If necessary, the abbreviated heading may include a fourth group consisting of three letters to identify delayed (RRA), corrected (CCA) or amended (AAA) bulletins. If additional delayed, corrected or amended bulletins are necessary, they should be identified by RRB, RRC, etc.; CCB, CCC, etc.; and AAB, AAC, etc.
|Example.— A complete heading will be as follows: |
| |
|SAZB02 YUDO 151200 RRA = Delayed second of two bulletins of routine|
|reports in the METAR code form for 1200 UTC on the 15th from |
|Zambia, compiled by YUDO*. |
| |
|* Fictitious location |
6.2.3 Bulletins containing OPMET information and disseminated on the AFTN are given priorities depending on their urgency; warnings (SIGMET information), amendments to forecasts, and other meteorological information of immediate concern to aircraft in flight or about to depart are given a relatively high priority; next are meteorological forecasts, reports, and other messages exchanged between meteorological offices.
Note.— Details concerning message priorities on the AFTN are given in Annex 10 — Aeronautical Telecommunications, Volume II — Communication Procedures including those with PANS status.
6.2.4 Messages containing meteorological data should be filed promptly for transmission on the AFTN, METARs and SPECIs are normally filed within 5 minutes of the time of the observation, and aerodrome forecasts at least one hour before the commencement of their validity (unless otherwise determined by regional air navigation agreement).
6.2.5 The time interval between the time of filing to the time of receipt of a message is called the “transit” time. Messages containing OPMET data transmitted on the AFTN should normally have transit times of less than 5 minutes, except for METARs and SPECIs and aerodrome forecasts (TAFs) exchanged over distances exceeding 900 km which may have transit times of up to 10 minutes.
6.3 DISSEMINATION OF AERONAUTICAL
METEOROLOGICAL INFORMATION
ON CIRCUITS/SYSTEMS
OTHER THAN THE AFTN
6.3.1 OPMET data are also disseminated on AFS circuits (including AFS satellite distribution systems) or networks other than the AFTN. In some cases, use is made of special circuits dedicated only to the dissemination of OPMET data, while in other cases, whole networks may be used for entering and extracting information. In some regions, special collection and dissemination systems have been designed for the more efficient handling of OPMET information exchanged on AFTN circuits as, for example, the Regional Operational Meteorological Bulletin Exchange (ROBEX) in the MID/ASIA/PAC regions, and the Africa-Indian Ocean Meteorological Bulletin Exchange (AMBEX) in the AFI region. Non-aeronautical circuits or broadcasts, for example those of the WMO, are also sometimes used for the transmission of OPMET information; similarly, aeronautical circuits may be occasionally used for the collection and exchange of basic data (i.e. WMO-type).
6.3.2 WAFS data are disseminated through three satellite broadcasts, directly from WAFCs to the meteorological offices. Other OPMET data also become an important portion of the WAFS satellite broadcasts. Where the necessary arrangements have been made, the broadcasts may also be received by other users, such as ATS units and operators. The transmission of WAFS data through satellite broadcasts have two formats:
a) digital data, comprising upper wind and upper-air temperature forecasts in the GRIB code form (these data are tailored for direct use by computers), as well as significant weather forecasts in the BUFR code form; and
b) digital facsimile charts, comprising both upper wind and upper-air temperature forecasts, as well as significant weather forecasts.
6.3.3 The dissemination of WAFS data through satellite broadcasts is the most efficient method, as it combines excellent quality with relatively low-cost, user-friendly receiving equipment. States are therefore encouraged to arrange for the reception of the broadcasts which now provide global coverage. The procedures and conditions concerning the authorized access to the WAFS satellite broadcasts are given in Appendix 1, paragraph 4.
Note.— For details on the methods to be used in the various ICAO regions for the exchange of OPMET information, see the ICAO air navigation plan publications. Details on regional networks or systems for the exchange of OPMET information are published by ICAO regional offices on a regular basis.
6.4 INTERROGATION PROCEDURES
FOR INTERNATIONAL OPMET DATABANKS
6.4.1 In addition to the dissemination means described in 6.2 and 6.3, OPMET data can also be obtained by interrogation of one of the ICAO international OPMET databanks. This is effected by means of a standardized message which triggers the automatic retrieval of the requested information and its immediate transmission to the originator. Except in special cases, the information given to the user is always the most recent available.
6.4.2 In order to be accepted by the databank, the interrogation message must be in agreement with the following principles:
a) it must contain the proper AFTN address used for interrogation (e.g. SBBRYZYX for Brasilia, EBBRYZYX for Brussels, LOWMYZYX for Vienna, KWBCYZYX for Washington); and
b) only one line of interrogation (69 characters of text) is allowed.
6.4.3 The standard interrogation for one message shall include the elements listed below in the following order:
a) “RQM/” indicating the start of a data request line;
b) data type identifier;
c) a 4-letter ICAO location indicator; and
d) the equal sign (=) indicating the end of the interrogation line, e.g. RQM/SAMTSJ=.
Note.— MTSJ is a fictitious location indicator.
6.4.4 The accepted data type designators are as given in 6.2.2. Some of the data types listed in that paragraph may not be available in all the international OPMET databanks.
6.4.5 The following special interrogation procedures are available if more than one message is needed:
a) the same data type may be requested for a number of stations without repeating the data type identifier. The location indicators have to be separated by commas (,) which indicate the continuation of the request for the same type of data, e.g. RQM/SAEHAM,EHRD=;
b) various data types may be interrogated in the same message using the oblique (/) as a separator, e.g. RQM/SAKMIA/FTKMIA=.
6.4.6 There are additional features used for interrogation that are not available in all the international OPMET databanks. These are described in detail in the “catalogues of OPMET data available at the OPMET databanks”, prepared and updated on regular basis by the ICAO regional offices concerned. It should be noted that some international OPMET databanks restrict access to one authorized user per State, and the computer will not respond to an unauthorized interrogation.
6.5 DISSEMINATION OF
AERONAUTICAL METEOROLOGICAL
INFORMATION TO AIRCRAFT
IN FLIGHT
6.5.1 The transmission of aeronautical meteorological information to aircraft in flight is the responsibility of the ATS units. Details on the meteorological information provided to aircraft in flight can be found in the Manual on Coordination between Air Traffic Services, Aeronautical Information Services and Aeronautical Meteorological Services (Doc 9377).
6.5.2 VOLMET broadcasts by VHF or HF voice communications and D-VOLMET by data links1 are parts of aeronautical mobile service communications. Both communication systems are established and operated in States, usually by the ATS authorities, in accordance with regional air navigation agreement. Depending on these agreements, METARs, SPECIs (including trend forecasts, where required), TAFs, and SIGMET information messages are supplied through these telecommunications systems to aircraft in flight. Details relating to the cooperation of the meteorological and ATS authorities in the provision of the services are dealt with in the Manual on Coordination between Air Traffic Services, Aeronautical Information Services and Aeronautical Meteorological Services (Doc 9377). The standard meteorological phraseologies to be used in VOLMET broadcasts by voice communication are given in Appendix 1 to this manual.
1. The following data link services of the data link flight information service (D-FIS) application should be used for the supply of OPMET data, referred to above, to aircraft in flight: D-METAR service, D-TAF service, D-SIGMET service. For details on these data link services, see the Manual of Air Traffic Services Data Link Applications (Doc 9694)
Chapter 7
AIRCRAFT OBSERVATIONS AND REPORTS
7.1 GENERAL
7.1.1 There are two kinds of aircraft observations as listed below and discussed in detail in the following paragraphs:
a) routine aircraft observations during en-route and climb-out phases of the flight; and
b) special and other non-routine aircraft observations during any phase of the flight.
7.2 REPORTING OF AIRCRAFT
OBSERVATIONS DURING FLIGHT
7.2.1 Aircraft observations are to be reported using the following means:
a) air-ground data link. This is the preferred mode of reporting; and
b) voice communication. This is to be used only if the air-ground data link is not available or appropriate.
7.2.2 Aircraft observations are to be reported during flight at the time the observation is made or as soon thereafter as is practicable.
7.3 ROUTINE
AIRCRAFT OBSERVATIONS
7.3.1 Frequency of reporting
When air-ground data link is used and automatic dependent surveillance (ADS) is being applied, automated routine observations are made every 15 minutes during the en-route phase and every 30 seconds during the climb-out phase for the first 10 minutes of the flight. When voice communications are used, routine meteorological observations by aircraft are made only during the en-route phase of the flight at ATS reporting points or intervals:
a) at which the applicable ATS procedures require routine position reports; and
b) which correspond most closely to intervals of one hour of flying time.
For helicopter operations to and from aerodromes on offshore structures, routine observations are to be made from helicopters at points and times as agreed between the meteorological authorities and the helicopter operators concerned.
Note 1.— In most ICAO regions, specific ATS/MET reporting points have been designated. Lists of these points are available from the ICAO regional offices.
Note 2.— On aeronautical charts, the ATS/MET reporting points are indicated by the following symbols:
[pic]
7.3.2 Exemptions from reporting
Where voice communications are used, an aircraft is exempted from making routine observations when:
a) the aircraft is not equipped with RNAV equipment; or
b) the flight duration is 2 hours or less; or
c) the aircraft is at a distance equivalent to less than one hour of flying time from the next intended point of landing; or
d) the altitude of the flight path is below 1 500 m (5 000 ft).
In some regions, with high-density air traffic and/or with adequate ground-based observing networks, additional exemptions are prescribed by regional air navigation agreement for all aircraft.
Note.— When air-ground data link is used, no exemptions are to be applied.
7.3.3 Designation procedures
In the case of air-routes with high-density air traffic (e.g. organized tracks), an aircraft from among the aircraft operating at each flight level shall be designated, at approximately hourly intervals, to make routine observations in accordance with the frequency specified in 7.3.1, as appropriate. These designation procedures for the en-route phase of the flight are prescribed by regional air navigation agreement. In the case of the requirement to report during the climb-out phase, an aircraft is to be designated, at approximately hourly intervals, at each aerodrome to make routine observations in accordance with 7.3.1. The details concerning the required frequency to make routine aircraft observations and the associated designation procedures are shown in Table 7-1.
Note.— Details on exemption and designation procedures for the en-route phase of the flight are contained in the Regional Supplementary Procedures (Doc 7030), Part 3 — Meteorology.
7.4 SPECIAL AND OTHER
NON-ROUTINE
AIRCRAFT OBSERVATIONS
7.4.1 Special aircraft observations
Special observations are required to be made by all aircraft operating on international air routes whenever the following conditions are encountered or observed:
a) severe turbulence; or
b) severe icing; or
c) severe mountain wave; or
d) thunderstorms, without hail, that are:
• obscured; or
• embedded; or
• widespread; or
• in squall lines; or
e) thunderstorms, with hail, that are:
• obscured; or
• embedded; or
• widespread; or
• in squall lines; or
f) heavy duststorms or heavy sandstorms; or
g) volcanic ash cloud; or
h) pre-eruption volcanic activity or volcanic eruption.
Note 1.— The exemptions from routine observations, mentioned in 7.3.2 above, do not apply to special observations which are required to be made by all aircraft during any phase of the flight and in all regions.
Note 2.— Pre-eruption volcanic activity in this context means unusual and/or increasing volcanic activity which could presage a volcanic eruption.
In addition, in the case of transonic and supersonic flights:
i) moderate turbulence; or
j) hail; or
k) cumulonimbus clouds.
Note 1.— When air-ground data link is used, special air-reports constitute a data link application mentioned in 7.5.6, Note 1. To facilitate the issuance of special air-reports by the pilot in the data link environment, a future data link application with a menu-driven system for the cockpit is being developed. An example of this type of user-friendly system, not requiring any additions of free text, is shown in Table 7-2.
Note 2.— Reports of turbulence and icing during climb-out and approach are especially important, since no satisfactory method of observing these hazards from the ground is available at this time.
7.4.2 Other non-routine observations
Other non-routine aircraft observations are made when meteorological conditions are encountered which are different from those listed under 7.4.1 (e.g. wind shear) and which, in the opinion of the pilot-in-command, may affect the safety or markedly affect the efficiency of other aircraft operations. These observations are to be made through voice communications by advising the appropriate ATS unit as soon as practicable. In the case of wind shear reports:
a) the aircraft type must be included; and
b) pilots must inform appropriate ATS units as soon as practicable if forecast wind shear conditions are not encountered.
7.5 CONTENT OF AIR-REPORTS
7.5.1 A report consisting of a position report and of meteorological information is called a “routine air-report”. (It may also contain operational information.) Reports containing special aircraft observations are called “special air-reports” and, in most cases, constitute a basis for the issuance of SIGMETs.
7.5.2 When voice communications are used, the elements contained in routine and special air-reports are as follows:
|Routine air-reports |Special air-reports |
| |Message type designator |
|Message type designator | |
| | |
|Section 1 (position information) |Section 1 (position information) |
|Aircraft identification |Aircraft identification |
|Position or latitude and |Position or latitude or longitude|
|longitude | |
|Time |Time |
|Flight level or altitude |Flight level or altitude |
|Next position and time over | |
|Ensuing significant point |Section 3 (meteorological |
| |information) |
| |Condition prompting the issuance |
| |of a special air-report1 |
|Section 2 (operational | |
|information) | |
|Estimated time of arrival | |
|Endurance | |
| | |
|Section 3 (meteorological | |
|information) | |
|Temperature | |
|Wind direction | |
|Wind speed | |
|Turbulence | |
|Aircraft icing | |
|Humidity (if available) | |
| |
|1. One condition to be selected from the list presented under |
|7.4.1. |
7.5.3 When air-ground data link is used and ADS is being applied, the elements contained in routine air-reports are as follows:
Message type designator
Aircraft identification
Data block 1
Latitude
Longitude
Level
Time
Data block 2
Wind direction
Wind speed
Wind quality flag
Temperature
Turbulence (if available)
Humidity (if available)
Note.— When ADS is being applied, the requirements of routine air-reports may be the combination of the basic ADS data block (data block 1) and the meteorological information data block (data block 2), available from ADS reports. The ADS message format is specified in the Procedures for Air Navigation Services — Air Traffic Management (PANS-ATM, Doc 4444), Chapter 13 and in Annex 10 — Aeronautical Telecommunications, Volume III — Part I — Digital Data Communication Systems.
7.5.4 When air-ground data link is used and ADS is not being applied, the elements contained in routine air-reports are as in routine air-reports by voice communications, i.e. as indicated in 7.5.2.
Note.— The controller-pilot data link communications (CPDLC) application entitled “Position report” may be used for these air-reports. The details of the data link application are specified in the Manual of Air Traffic Services Data Link Applications (Doc 9694) and Annex 10 — Aeronautical Telecommunications, Volume III — Part I — Digital Data Communication Systems.
7.5.5 The meteorological content of routine reports using voice communications and air-ground data link, respectively, is summarized in Table 7-3.
7.5.6 When air-ground data link is used, the elements contained in special air-reports are as follows:
Message designator
Aircraft identification
Data block 1
Latitude
Longitude
Level
Time
Data block 2
Wind direction
Wind speed
Wind quality flag
Temperature
Turbulence (if available)
Humidity (if available)
Data block 3
Condition prompting the issuance of a special air-report (one condition to be selected from the list in 7.4.1).
Table 7-3. Meteorological content of
routine air-reports
(All the reports include information on the position
of the aircraft in four dimensions)
|Reports transmitted via |
|voice communications and |air-ground data link ADS applied |
|air-ground data link, ADS not | |
|applied | |
|Temperature |Wind direction |
|Wind direction |Wind speed |
|Wind speed |Wind quality flag |
|Turbulence |Temperature |
|Aircraft icing |Turbulence (if available) |
|Humidity (if available) |Humidity (if available) |
Note 1.—The data link flight information service (D-FIS) application entitled “Special air-report service” may be used for these air-reports. The details of this data link application are specified in the Manual of Air Traffic Services Data Link Applications (Doc 9694) and Annex 10 — Aeronautical Telecommunications, Volume III — Part I — Digital Data Communication Systems.
Note 2.—In the case of the transmission of a special air-report of pre-eruption volcanic activity, a volcanic eruption or volcanic ash cloud, there are additional requirements (see 7.8).
7.6 CRITERIA FOR REPORTING
METEOROLOGICAL AND RELATED
PARAMETERS IN AUTOMATED AIR-REPORTS
When air-ground data link is used, the wind direction and speed, wind quality flag, temperature, turbulence and humidity, to be included in automated air-reports, are reported in accordance with the criteria shown in Appendix 16.
7.7 EXCHANGE OF AIR-REPORTS
7.7.1 Basic principles
Air traffic services and meteorological authorities should establish appropriate arrangements to ensure that routine and special air-reports reported by aircraft in flight to ATS units are transmitted without delay to the world area forecast centres (WAFCs). In the case of all special air-reports and those routine reports which are received by voice communications, these are also to be transmitted to the associated meteorological watch office (MWO).
7.7.2 Additional exchange of
air-reports beyond MWOs
The MWO assembles the routine reports received by voice communications and transmits these to other meteorological offices in accordance with regional air navigation agreement.
Special air-reports are not normally exchanged regionally beyond the MWO. However, further dissemination is required in the following circumstances:
a) When a special air-report is received but the forecaster considers that the phenomenon causing the report is not expected to persist and, therefore, does not warrant issuance of a SIGMET, the special air-report should nevertheless be disseminated in the same way that SIGMET messages are disseminated, i.e. to MWOs and other meteorological offices in accordance with regional air navigation agreement; and
b) Special air-reports of pre-eruption volcanic activity, volcanic eruption or volcanic ash cloud are to be transmitted to the regional volcanic ash advisory centre(s) (VAACs).
7.7.3 Additional exchange of air-reports
beyond WAFCs
Air-reports exchanged beyond WAFCs are considered as basic meteorological data and therefore their further dissemination is subject to WMO provisions.
Note 1.— The exchange requirements of routine air-reports received by voice communications between meteorological offices are usually shown in the ICAO air navigation plan publications.
Note 2.— An example of a dissemination pattern of air-reports is shown in Table 7-4.
7.8 RECORDING AND POST-FLIGHT
REPORTING OF AIRCRAFT OBSERVATIONS
OF VOLCANIC ACTIVITY
Special aircraft observations of pre-eruption volcanic activity, volcanic eruption or volcanic ash cloud are the only type of air-report that requires a post-flight report, which should be recorded using the special air-report of volcanic activity form (MODEL VAR). A copy of the form shown in Figure 7-1 is included with the flight documentation provided to flight crews operating on routes which could be affected by volcanic ash clouds.
7.9 DETAILED INSTRUCTIONS
CONCERNING THE RETRANSMISSION
OF AIR-REPORTS RECEIVED BY MWOs
7.9.1 The following paragraphs provide details on the content of routine and special air-reports received by voice communications (see also Example 7-1). It is essential that air-reports be retransmitted by the MWO concerned in the correct order and format to permit their use in meteorological and other computers. Of special importance is the application of the indicator (ARS) for a special air-report.
Note.— MWOs do not need to retransmit information concerning “next position and time over”, “estimated time of arrival” or “endurance”.
7.9.2 Message type designator
(ARS)
Air-reports are routine by default. A message type designator is, therefore, required only for special air-reports, i.e. “ARS”.
Note.— Where air-reports are handled by automatic data processing equipment that cannot accept this message type designator, the use of a different message type designator is permitted by regional air navigation agreement, provided that:
i) the data transmitted is in accordance with that specified in the special air-report format; and
ii) measures are taken to ensure that special air-report messages are forwarded to the appropriate meteorological unit and to other aircraft likely to be affected.
7.9.3 Aircraft identification
(BAGABCD or VA812)
Aircraft identification consists of either the operator’s designator (BA) and aircraft registration (GABCD), or flight number (VA812), reported as one unit without any spaces.
7.9.4 Position
(49N050W, 2020N07005W)
Position is given in degrees latitude and longitude in whole degrees (two figures for latitude, followed without a space by N or S, three figures for longitude, followed without a space by E or W); degrees and minutes may also be used (four figures for latitude and five for longitude). If a coded indicator (two to five characters) for a significant point (e.g. LN, MAY, HADDY), or a significant point followed by the magnetic bearing (degrees in three figures) and distance (three figures and KM or NM) of that point (e.g. DUB180040NM) has been used in the message received, the MWO concerned should convert this information into a position expressed as latitude and longitude.
7.9.5 Time
(1317, 1215)
The time of aircraft, at the position indicated, is shown in hours and minutes UTC (4 numerics).
7.9.6 Flight level or altitude
(F310, F180)
The flight level is shown by an “F” followed by the actual level; the altitude is shown by an “F” followed by 3 numerics and “M” or “FT”, as appropriate. This is followed by “ASC” (level) or “DES” (level) when ascending or descending to a new level after passing the significant point.
7.9.7 Air temperature
(MS47)
Temperature (corrected for instrument error and air speed) is shown in degrees Celsius (two figures) preceded, without a space, by “PS” (plus) or “MS” (minus), as appropriate.
7.9.8 Wind direction and wind speed
(255/65KMH)
The wind report refers to a “spot” wind at the position given for the report. Direction is in degrees true (three figures) and wind speed in kilometres per hour or knots (two or three figures) separated by a “/”, indicating the unit used. Record calm as “00000”.
7.9.9 Turbulence
(TURB MOD, MTW SEV)
Turbulence is reported using the abbreviation TURB followed by FBL, MOD or SEV (light, moderate or severe), as appropriate.
Note.— Severe turbulence in subsonic flight and moderate or severe turbulence in transonic or supersonic flight are reported as soon as possible by means of an AIREP SPECIAL.
7.9.10 Aircraft icing
(ICE FBL)
Icing is recorded in the same way as turbulence, using the abbreviation ICE followed by FBL, MOD or SEV, as appropriate.
Note.— Severe icing requires an AIREP SPECIAL.
7.9.11 Humidity
(RH075)
If reported, humidity is shown by “RH” followed, without a space, by the humidity in per cent (3 figures).
Note.— The reporting of humidity is optional and shall be included only when available.
7.9.12 Phenomenon prompting
a special air-report
(MTW SEV)
Record the phenomenon reported as follows:
• severe turbulence as “TURB SEV”
• severe icing as “ICE SEV”
• severe mountain wave as “MTW SEV”
• thunderstorm without hail1 as “TS”
• thunderstorm with hail1 as “TSGR”
• heavy duststorm or sandstorm as “HVY SS”
• volcanic ash cloud as “VA CLD”
• pre-eruption volcanic activity or a volcanic eruption as “VA”
• moderate turbulence2 as “TURB MOD”
• hail2 as “GR”
• cumulonimbus clouds2 as “CB”.
Note.— Detailed instructions for making and transmitting air-reports, together with examples of air-reports, are contained in the Procedures for Air Navigation Services — Air Traffic Management (PANS-ATM) (Doc 4444).
1. The thunderstorms to be reported should be confined to those which are:
• obscured in haze; or
• embedded in cloud; or
• widespread; or
• forming a squall line.
2. Applies only to supersonic transport at transonic levels and supersonic cruising levels.
Table 7-1. Frequency and associated
designation procedures of routine air-reports
| |Voice communications |Air-ground data link |
| |En-route phase |En-route phase |Climb-out phase |
| | | |(Terminal area) |
| |low-density |high-density |low-density |high-density | |
| |traffic |traffic |traffic |traffic | |
|Frequency |All aircraft |Designated |All aircraft |Designated |Designated |
| | |aircraft | |aircraft |aircraft |
| |1 every ATS/MET reporting point |1 every 15 min |1 every 30 s for |
| |(simultaneously with position | |the first 10 min of |
| |reports) or 1 every hour | |the flight |
|Designation |none |An aircraft at |none |An aircraft at |An aircraft at |
|procedures | |hourly | |hourly |hourly intervals at |
| | |intervals1 | |intervals1 |each international |
| | | | | |aerodrome |
| |
|1. Subject to regional air navigation agreement included in the Regional Supplementary Procedures (Doc 7030), Part 3 — Meteorology. |
Table 7-2. Downlink message menu incorporating conditions
prompting the issuance of special air-reports
|SEVERE TURBULENCE |
|SEVERE ICING |
|SEVERE MOUNTAIN WAVE |
|THUNDERSTORMS WITHOUT HAIL1 |
|THUNDERSTORMS WITH HAIL1 |
|HEAVY DUSTSTORM/SANDSTORM |
|VOLCANIC ASH CLOUD |
|PRE-ERUPTION VOLCANIC ACTIVITY/VOLCANIC ERUPTION |
| |
|SST2: MODERATE TURBULENCE |
|SST: HAIL |
|SST: CB CLOUDS |
|1. Only report thunderstorms if they are a) forming a squall line or b) over a widespread|
|area or c) obscured or d) embedded. |
|2. SST = supersonic transport (transonic levels and supersonic cruising levels). |
Table 7-4. Dissemination pattern of air-reports
(“→” indicates the centre(s)/office(s) to which the air-report is to be transmitted)
| |Type of air-report received at the ATS unit |
| |Routine by |Special by |Routine |Special |
| |air-ground |air-ground |by voice |by voice |
| |data link |data link |communications |communications |
|Dissemination |initially by |→ WAFCs |→ MWO |→ MWO |→ MWO |
| |ATS unit | |→ WAFCs | | |
| |subsequently | — |→ VAACs1 |→ WAFCs |→ WAFCs |
| |by MWO | | |→ MET offices1 |→ VAACs2 |
| | | | | |→ MET offices3 |
| | | | | |→ MWOs3 |
|1. In accordance with regional air navigation agreement. |
|2. Only special air-reports of pre-eruption volcanic activity, volcanic eruption or volcanic ash cloud. |
|3. To be disseminated in the same way as SIGMET messages (i.e. to MWOs and other MET offices in accordance with regional air |
|navigation agreement) only if the special air-report does not warrant issuance of a SIGMET. |
|Example 7-1. AIREP and AIREP SPECIAL messages as recorded on the ground |
|by the MWO concerned |
| |
|a) AIREP message |
| |
|BAGABCD 49N050W 1317 F310 MS47 255/65KMH TURB MOD ICE FBL RH075 |
| |
|Meaning: |
| |
|Routine air-report from British Airways aircraft GABCD. Report refers to position 49 degrees north and 50 degrees west at 1317 UTC, at flight |
|level 310. The outside temperature is –47 degrees Celsius, the (spot) wind measured at the position is 255 degrees 65 kilometres per hour. |
|Moderate turbulence and light aircraft icing are experienced at the time of the observation. Relative humidity is 75 per cent. |
| |
|b) SPECIAL AIREP message |
| |
|ARS VA812 2020NO7005W 1215 F180 MTW SEV |
| |
| |
|Meaning: |
| |
|Special air-report from VIASA flight number 812. Report refers to position 20 degrees 20 minutes north and 70 degrees 5 minutes west at 1215 |
|UTC, at flight level 180. Severe mountain wave has been encountered. |
Figure 7-1. Special air-report of volcanic activity
(MODEL VAR)
Chapter 8
COORDINATION BETWEEN AERONAUTICAL
METEOROLOGICAL SERVICES AND
ATS AND SAR UNITS
8.1 GENERAL
8.1.1 ATS units require a considerable amount of actual and forecast meteorological information to assist them in:
a) providing control of air traffic in flight and at the aerodrome; and/or
b) providing information to aircraft en route as well as prior to take-off and landing.
8.1.2 The same applies to rescue coordination centres, which are designated by regional air navigation agreement and which can be regarded as having requirements for meteorological information similar to those of ATS units, with the addition of certain specific data, such as information on forecasts provided to the missing aircraft, and on meteorological conditions that existed at the last known position of a missing aircraft and along the intended route of that aircraft, with particular reference to:
a) significant en-route weather phenomena;
b) cloud amount and type, particularly cumulonimbus; height indications of bases and tops;
c) visibility and phenomena reducing visibility;
d) surface wind and upper wind;
e) state of the ground, in particular, any snow cover or flooding;
f) sea-surface temperature, state of the sea, ice cover if any and ocean currents, if relevant to the search area;
g) sea level pressure data.
8.1.3 In order to ensure orderly and timely provision of the meteorological information required by ATS units, each ATS unit usually has an associated meteorological office. The designation of associated meteorological offices to the ATS units shown below is a responsibility of the meteorological authority in each State.
|ATS unit |Associated |
| |meteorological office1 |
|Aerodrome control tower |Aerodrome meteorological |
|(TWR) |office |
|Approach control office (APP) |Aerodrome meteorological office |
|Area control centre (ACC) |Meteorological watch office (MWO)|
|Flight information centre (FIC) |Meteorological watch office (MWO)|
|Rescue coordination |As designated by regional |
|centre (RCC) |air navigation agreement (usually|
| |an MWO) |
| |
|1. One aerodrome meteorological office may be associated to more |
|than one aerodrome and to the TWRs and/or APPs established at these|
|aerodromes. Similarly, one MWO may be associated to more than one |
|FIC/UIC/ACC. |
8.2 METEOROLOGICAL
INFORMATION REQUIRED
BY ATS UNITS
8.2.1 The meteorological information required by ATS units and provided by their associated meteorological offices includes nearly all types of aeronautical meteorological information. Detailed listings of this information are given in the Manual on Coordination between Air Traffic Services, Aeronautical Information Services and Aeronautical Meteorological Services (Doc 9377). A summary of the types of information most frequently supplied to ATS units and to air-ground control radio stations (if established to serve associated FICs/ACCs), the meteorological units responsible for providing the information, the frequency with which it is usually provided, and the communications means normally used for this purpose, is given in Table 8-1.
8.2.2 In view of the importance of the meteorological information supplied to ATS units for the safety and efficiency of aviation, it is essential that the information is always up to date, accurate, and provided in a timely manner. Of particular importance in this connection is information on significant changes in meteorological conditions. Such changes include not only changes requiring special reports but may also include, as agreed, changes in wind, temperatures, pressure and other elements that may require ATS units to take action (e.g. change of runway-in-use).
8.2.3 ATS units, in particular aerodrome control towers and approach control offices, need to have duplicate displays of meteorological elements such as surface wind, pressure and RVR, which are related to the same sensors as those providing information to meteorological offices or stations. In those cases, it is usually arranged that ATS units need not be provided with local special reports (SPECIALs) indicating significant changes in those elements.
8.2.4 In the case of area control centres and air traffic flow management centres (units established in some States which deal with large amounts of traffic), States sometimes have found it expedient to station meteorologists in the unit. Apart from ensuring that the unit is supplied with all the necessary meteorological information, the duty of the meteorologist is mainly to advise controllers on weather conditions that could influence the progress of traffic in their areas of responsibility, such as widespread thunderstorms, changes in jet stream configuration or heavy snow falls over large areas. This advice is of particular importance where quick decisions are needed in the face of rapid weather developments or in cases of in-flight emergencies.
8.3 METEOROLOGICAL INFORMATION
PROVIDED BY ATS UNITS
8.3.1 As ATS units may have to provide information to aircraft at very short notice, and as even the best observation methods and the fastest communication means between meteorological offices and ATS units cause some time lag between the occurrence of a change in weather conditions and the transmission of relevant information to aircraft, arrangements often exist whereby ATS personnel are given sufficient training to allow them to update routine observations provided by meteorological stations so as to reflect changed conditions. Such arrangements of course require close coordination between the ATS unit and the meteorological office or station, and are subject to specific agreements between MET and ATS authorities.
8.3.2 In view of their location on high towers, aerodrome controllers can often observe certain weather features better than meteorological personnel. Such observations, which may include, for example, weather conditions in approach and climb-out directions, would not only be used by controllers to modify or amplify observations provided by the meteorological station (where such actions are agreed), but would also normally be provided to the meteorological station or office. Adequate basic training in meteorological observations is to be provided to the ATS personnel concerned.
8.3.3 ATS units are also required to transmit promptly to the WAFCs and meteorological watch offices, as appropriate, in accordance with 7.7 and Table 7-4, any air-reports they receive which contain meteorological information. This important responsibility of ATS units should be included in the Agreement on Coordination between the ATS and Meteorological Authorities to be developed in States.
8.4 COORDINATION BETWEEN
ATS UNITS AND METEOROLOGICAL
OFFICES AND STATIONS
8.4.1 To ensure that the cooperation between ATS units and aeronautical meteorological services functions efficiently, coordination arrangements are usually in written agreements between the national and/or local ATS and meteorological authorities. Such agreements are especially necessary where the provision of ATS and aeronautical meteorological services are not the responsibility of the same government department.
8.4.2 The aforementioned Manual on Coordination between Air Traffic Services, Aeronautical Information Services and Aeronautical Meteorological Services (Doc 9377) provides detailed information on such agreements, together with a sample letter of agreement. It also contains information on the ICAO Standards, Recommended Practices and procedures in the meteorological and ATS fields governing this subject, up-to-date information on available methods and means for the effective provision of meteorological information to ATS units, as well as procedures already in use in a number of States.
Table 8-1. Aeronautical meteorological information supplied to ATS units
|Information | |Distributor | |Destination | |Frequency | |Communications means |
| |
|Aerodrome reports METAR [with TREND1] | |Aeronautical MET station [TREND | |TWR | |Hourly2 | |See Note 1 |
| | |prepared by MET office] | |APP | | | |See Note 1 |
| | | | |ACC | | | |See Note 1 |
| | | | |FIC | | | |See Note 1 |
| | | | |COM station | | | |See Note 2 |
| |
|Note 1.— Communications by closed-circuit TV, video display unit, or similar. If none of these are available, or during unserviceability |
|periods, communications by phone, followed if possible by confirmation by other means. |
| |
|Note 2.— Communications by teleprinter. |
|_________________ |
|1. Trends to be added to METAR/SPECI for those stations so identified in the air navigation plan. |
|2. Or half-hourly if so decided by regional air navigation agreement. |
Chapter 9
INFORMATION ON AERONAUTICAL
METEOROLOGICAL SERVICES IN
AERONAUTICAL INFORMATION PUBLICATIONS
9.1 NATURE OF AERONAUTICAL
INFORMATION PUBLICATIONS
9.1.1 Aeronautical information publications (AIPs) are issued by States in accordance with ICAO Standards and Recommended Practices contained in Annex 15 — Aeronautical Information Services. These AIPs contain current information on aerodromes, communications facilities, navigation aids, meteorological services, air traffic services and other essential air navigation services. The information contained in AIPs is of a permanent nature, i.e. not expected to change frequently or at short notice, and is kept up to date by an amendment service. Information on sudden or temporary changes is promulgated in the form of NOTAM, i.e. (Class I NOTAM), or (Class II NOTAM), depending on their nature and urgency. Changes to facilities, services or procedures which can be foreseen well in advance and which require corresponding changes in airline manuals, etc., are issued as NOTAM on predetermined dates each month under the so-called AIRAC system. In addition to the foregoing, long-term changes to procedures or facilities, providing information such as the effect of certain weather phenomena on aircraft operations, are issued as aeronautical information circulars.
9.1.2 In order to assist users, who are mainly operators and pilots, to obtain the necessary information from AIPs quickly and without risk of misunderstanding, AIPs must be constructed uniformly and according to the pattern prescribed by ICAO. The information contained in the AIP must be accurate and up to date and follow the prescribed layout and order.
9.2 INFORMATION CONCERNING MET
SERVICES IN AERONAUTICAL
INFORMATION PUBLICATIONS
9.2.1 Details of the contents of AIPs may be found in Annex 15 and in the Aeronautical Information Services Manual (Doc 8126). The information concerning meteorological services provided is summarized below in order to provide aeronautical meteorological personnel with the necessary background information so that essential information and data can be provided to the aeronautical information services (AIS) for inclusion in the AIP. Normally, the meteorological authority submits the necessary information to the AIS office concerned.
a) General (GEN). This section includes information about the meteorological authority under GEN 1.1, indicating:
1) designated authority (inclusion of this information in the AIP is required (Annex 3, 2.1.4));
2) name of the authority;
3) postal address;
4) telephone number;
5) facsimile number;
6) telex number; and
7) aeronautical fixed service (AFS) address.
This section also includes a detailed description of meteorological services provided in the State concerned, including the following items:
1) Responsible service (GEN 3.5.1);
2) Area of responsibility (GEN 3.5.2);
3) Meteorological observations and reports
(GEN 3.5.3);
4) Types of services (GEN 3.5.4);
5) Notification required from operators
(GEN 3.5.5);
6) Aircraft reports (GEN 3.5.6);
7) VOLMET service (GEN 3.5.7);
8) SIGMET and AIRMET services
(GEN 3.5.8); and
9) Other automated meteorological services
(GEN 3.5.9).
b) Aerodromes (AD 2). This section describes, under AD 2.11, meteorological information provided at each international aerodrome and an indication of the meteorological office responsible for the provision of the information, as follows:
1) name of the associated meteorological office;
2) hours of service and, where applicable, the designation of the responsible meteorological office outside these hours;
3) office responsible for preparation of TAFs and periods of validity and interval of issuance of the forecasts;
4) availability of the trend forecasts for the aerodrome, and interval of issuance;
5) information on how briefing and/or consultation is provided;
6) types of flight documentation supplied and language(s) used in flight documentation;
7) charts and other information displayed or available for briefing or consultation;
8) supplementary equipment and receiver for satellite images available for providing information on meteorological conditions (e.g. weather radar);
9) the air traffic services unit(s) provided with meteorological information; and
10) additional information (e.g. concerning any limitation of service, etc.).
c) Heliports (AD 3). Meteorological information provided at each international heliport and an indication of the meteorological office responsible for the provision of the information. The relevant items to be published given in AD 3.11 are identical to those listed in AD 2.11 above.
9.2.2 The location of the sites of runway visual range transmissometers is included in aerodrome charts using the approved symbols in the Aerodromes (AD) section of the AIP.
9.2.3 Detailed examples of AIPs and other pertinent information and guidance for the preparation and updating of these publications are provided in the Aeronautical Information Services Manual (Doc 8126).
Note.— Detailed guidance concerning requirements for the submissions by the Meteorological Authority (or by designated meteorological offices or aerodrome meteorological stations on its behalf) to the AIS of the necessary information and data for the preparation and issuance of NOTAMs, ASHTAMs, SNOWTAMs and aeronautical information circulars (AICs) is given in the Manual on Coordination between Air Traffic Services, Aeronautical Information Services and Aeronautical Meteorological Services (Doc 9377, Chapter 6).
Chapter 10
RELEVANT DOCUMENTS
10.1 ICAO DOCUMENTS
OF A SPECIFICALLY
METEOROLOGICAL NATURE
The following ICAO documents give additional or more detailed information on meteorological subjects that may be found useful. These documents contain:
a) Standards, Recommended Practices and guidance material dealing with aeronautical meteorology, parts of which are summarized or reproduced in extract form in this manual (Annex 3 to the Convention on International Civil Aviation);
b) specific regional meteorological procedures, facilities, services, etc. (Regional Supplementary Procedures, Air Navigation Plan Publications, regional guides); and
c) detailed guidance on specific subjects connected with aeronautical meteorology (runway visual range, air traffic services and meteorological coordination, etc.).
Annex 3 — Meteorological Service for International
Air Navigation (International Standards and
Recommended Practices)
This Annex contains international regulatory material covering principles and objectives, Standards and Recommended Practices (SARPs) and guidance material which have worldwide applicability. It establishes the specific responsibilities of States for providing meteorological services and the responsibility of operators using these services. The Appendices, which form part of the SARPs, comprise the model charts and forms used in flight documentation, technical specifications for aerodrome reports, aerodrome forecasts, SIGMET and AIRMET information, special air-reports and criteria for reporting meteorological and related parameters in automated air-reports. The attachments (green pages) comprise material supplementary to the SARPs or included as a guide to their application.
Regional Supplementary Procedures (Doc 7030)
Regional Supplementary Procedures (SUPPS), are approved by the Council of ICAO for application in the respective regions. Currently, the document contains specific procedures for the regional application of Annex 3, Chapter 5 (Aircraft Observations and Reports) as well as various specific regional procedures related to communications, air traffic services, etc.
Air Navigation Plan Publications (ANPP)
These documents detail the requirements for facilities and services (including meteorology) in the various ICAO regions and the status of implementation of these recommended facilities and services. Each ANPP includes a meteorology section, both in the part containing the basic regional air navigation plan (ANP) and in the part containing the facilities and services implementation document (FASID). The former part introduces basic planning principles, operational requirements and planning criteria relating to the meteorological service to be provided to international air navigation in the ICAO region concerned. These principles, requirements and criteria stem from relevant provisions of Annex 3 and, in particular, those calling for regional air navigation agreement. This service is to be considered as the minimum for planning of meteorological facilities and/or services by States in the region. A detailed description and the list of the meteorological facilities and services to be provided by States in order to fulfill the requirements of the Basic ANP is contained in the latter part of the ANPP, i.e. in the FASID. The meteorology parts of the Basic ANP and the FASID cover, as necessary, all or some of the following topics: meteorological service required at aerodromes, meteorological watch offices, meteorological observations and reports, aircraft observation and reports, forecasts, regional aspects of the world area forecast system (WAFS), tropical cyclone advisory information, volcanic ash advisory information, including regional aspects of the International Airways Volcano Watch (IAVW). Current air navigation plan publications include:
Africa-Indian Ocean Region (Doc 7474)
Asia and Pacific Regions (Doc 9673)
Caribbean and South American Regions (Doc 8733)
European Region (Doc 7754)
Middle East Region (Doc 9708)
North Atlantic, North American and Pacific Regions (Doc 8755)
North Atlantic Region (Doc 9634)
Facilities and Services Implementation Document (FASID) — North Atlantic Region (Doc 9635)
Manuals:
In addition to this manual, the following manuals provide detailed guidance or information on specific aspects connected with meteorological services to international air navigation:
Manual of Runway Visual Range Observing and Reporting Practices (Doc 9328)
Manual on Coordination between Air Traffic Services, Aeronautical Information Services and Aeronautical Meteorological Services (Doc 9377)
Manual on the ICAO Standard Atmosphere (Doc 7488)
Manual on Volcanic Ash, Radioactive Material and Toxic Chemical Clouds (Doc 9691)
Manual on the Provision of Meteorological Service for International Helicopter Operations (Doc 9680; a joint ICAO/WMO Manual/Guide)
Circulars:
Wind Shear (Cir 186)
Regional guides:
Most ICAO Regional Offices have prepared and make available regional guides on various subjects, including: preparation and dissemination of SIGMET information messages; the ROBEX system; the AMBEX system; catalogue of information available in international OPMET databanks; ATS/MET reporting points; facsimile broadcasts, etc. For details, Regional Offices should be approached directly.
World area forecast system (WAFS)
publications:1
Gridded Binary (GRIB code) Data on a “Thinned” Grid from World Area Forecast Centres London and Washington
PCGRIDDS User’s Guide
SADIS User Guide
International Airways Volcano Watch documents:
Handbook on the International Airways Volcano Watch (IAVW) — Operational Procedures and Contact List (Doc 9766)
10.2 WMO DOCUMENTS
Apart from issuing documents of a general meteorological character, WMO also publishes documents which deal with aeronautical meteorology. The following documents are relevant:
WMO Technical Regulations, Volume II (WMO No. 49) (equivalent in status to ICAO Standards and Recommended Practices and Procedures for Air Navigation Services).
Part C.3.1 — Standards and Recommended Practices: identical, except for a few minor editorial differences, to Annex 3.
Part C.3.2 — Aeronautical Climatology: enlarges on Annex 3, Chapter 8, and gives model forms for aerodrome climatological summaries.
Part C.3.3 — Format and Preparation of Flight Documentation: enlarges on Annex 3, Chapter 9, and gives model charts and forms. The latter are included in Appendix 9 to the present manual.
Manuals (these often have a higher status than ICAO manuals):
Manual on Codes (WMO No. 306): contains details of all meteorological codes, including those relevant to aviation.
Manual on the Global Telecommunication System (WMO No. 386): contains practices and procedures to be used in the collection, exchange and distribution of observational and processed information on a worldwide scale.
Manual on the Global Data-Processing System (WMO No. 485): contains practices and procedures to be used in the processing, storage and retrieval of meteorological information. The manual, among others, includes regulations relating to the provision of service by WMO regional specialized meteorological centres (RSMCs) in response to a nuclear emergency.
Manual on the Global Observing System (WMO No. 544): contains practices and procedures for methods, techniques, and facilities to be used for making observations on a worldwide scale.
Guides
Guide to Qualifications and Training of Meteorological Personnel employed in the provision of Meteorological Services for International Air Navigation (WMO No. 114)
Guide to Meteorological Instruments and Methods of Observation (WMO No. 8): outlines basic standards of instrument and observing practices.
Guidelines for the Education and Training of Personnel in Meteorology and Operational Hydrology (WMO No. 258, Volume II)
Guide on the Global Observing System (WMO No. 488).
Guide on the Global Data-Processing System (WMO No. 305).
Guide on Meteorological Observation and Information Distribution Systems at Aerodromes (WMO No. 731)
Guide to Practices for Meteorological Offices Serving Aviation (WMO No. 732)
Aerodrome Reports and Forecasts — A User’s Handbook to the Codes (WMO No. 782)
Documentation on Regional Specialized Meteorological Centres (RSMC) Support for Environmental Emergency Response: target for meteorologists at NMSs (WMO — TD No. 778)
10.3 OTHER ICAO DOCUMENTS
10.3.1 In addition to the above-mentioned documents dealing with aeronautical meteorological subjects, meteorological offices serving international civil aviation also require other ICAO documents. A detailed list of these as well as of the ICAO meteorological documents needed is given below. The list is divided into two parts:
Part 1 — ICAO publications required at both the administrative and the operational levels of meteorological services.
Part 2 — ICAO publications required mainly at the administrative level of meteorological services.
10.3.2 ICAO Regional Offices issue updated lists, based on the following list, providing details on the numbers and dates of current editions, loose-leaf amendments, corrigenda, and the prices of the documents.
ICAO PUBLICATIONS REQUIRED
BY METEOROLOGICAL SERVICES
PART 1 — ICAO publications required
at the administrative and operational levels
of meteorological services
Annex 3 — Meteorological Service for International Air Navigation
Annex 5 — Units of Measurement to be Used in Air and Ground Operations
Doc 8400, Procedures for Air Navigation Services — ICAO Abbreviations and Codes
Doc 7030, Regional Supplementary Procedures
Doc 7910, Location Indicators
Doc 8585, Designators for Aircraft Operating Agencies, Aeronautical Authorities and Services
ANPPs2 Air navigation plans and associated facilities and services implementation document (FASID) see 10.1.
Doc 7488, Manual of the ICAO Standard Atmosphere (extended to 80 kilometres (262 500 feet))
Doc 8896, Manual of Aeronautical Meteorological Practice
Doc 9713, International Civil Aviation Vocabulary
Doc 9328, Manual of Runway Visual Range Observing and Reporting Practices
Doc 9377, Manual on Coordination between Air Traffic Services, Aeronautical Information Services and Aeronautical Meteorological Services
Doc 9680, Manual on the Provision of Meteorological Service for International Helicopter Operations
Doc 9691, Manual on Volcanic Ash, Radioactive Material and Toxic Chemical Clouds
Doc 9766, Handbook on the International Airways Volcano Watch (IAVW) — Operational Procedures and Contact List
Cir 186, Wind Shear
ICAO Journal (official ICAO magazine issued ten times per year)
PART 2 — ICAO publications required mainly
at the administrative level of
meteorological services
Annex 2 — Rules of the Air
Annex 4 — Aeronautical Charts
Annex 6 — Operation of Aircraft, Part I — International Commercial Air Transport — Aeroplanes, Part II — International General Aviation — Aeroplanes, and Part III — International Operations — Helicopters
Annex 8 — Airworthiness of Aircraft
Annex 10 — Aeronautical Telecommunications, Volume I — Radio Navigation Aids, Volume II — Communication Procedures including those with PANS status, Volume III — Part I — Digital Data Communication Systems, Part II — Voice Communication Systems, Volume IV — Surveillance Radar and Collision Avoidance Systems and Volume V — Aeronautical Radio Frequency Spectrum Utilization
Annex 11 — Air Traffic Services
Annex 12 — Search and Rescue
Annex 13 — Aircraft Accident and Incident Investigation
Annex 14 — Aerodromes, Volume I — Aerodrome Design and Operations and Volume II — Heliports
Annex 15 — Aeronautical Information Services
Doc 4444, Procedures for Air Navigation Services — Air Traffic Management (PANS-ATM)
Doc 6920, Manual of Aircraft Accident Investigation
Doc 7100, Tariffs for Airports and Air Navigation Services
Doc 9731, International Aeronautical and Maritime Search and Rescue (IAMSAR) Manual
Doc 7475, Working Arrangements between the International Civil Aviation Organization and the World Meteorological Organization
Doc 8126, Aeronautical Information Services Manual
Doc 8259, Manual on the Planning and Engineering of the Aeronautical Fixed Telecommunication Network
Doc 8168, Procedures for Air Navigation Services — Aircraft Operations, Volume I — Flight Procedures and Volume II — Construction of Visual and Instrument Flight Procedures
Doc 9082, ICAO’s Policies on Charges for Airports and Air Navigation Services
Doc 9137, Airport Services Manual
Part 1 — Rescue and Fire Fighting
Part 2 — Pavement Surface Conditions
Part 3 — Bird Control and Reduction
Part 5 — Removal of Disabled Aircraft
Part 6 — Control of Obstacles
Part 7 — Airport Emergency Planning
Part 8 — Airport Operational Services
Part 9 — Airport Maintenance Practices
Doc 9150, Stolport Manual
Doc 9157, Aerodrome Design Manual
Part 1 — Runways
Part 2 — Taxiways, Aprons and Holding Bays
Part 3 — Pavements
Part 4 — Visual Aids
Part 5 — Electrical Systems
Doc 9161, Manual on Air Navigation Services Economics
Doc 9184, Airport Planning Manual
Part 1 — Master Planning
Part 2 — Land Use and Environmental Control
Part 3 — Guidelines for Consultant/Construction Services
Doc 9261, Heliport Manual
Doc 9683, Human Factors Training Manual
Catalogue of ICAO Publications and Audio-visual Training Aids
1. Available in the ICAO Secretariat, Air Navigation Bureau, Meteorology Section.
2. States need to have available the ANPP for the region in which they are situated as well as ANPPs for adjacent regions to and from which they have flight operations.
Appendix 1
INFORMATION ON THE WORLD AREA
FORECAST SYSTEM (WAFS)
1. GENERAL DESCRIPTION
OF THE WAFS
1.1 The world area forecast system (WAFS) brings to meteorological forecasting the concept of centralization, in designated centres, of forecasting activities for the pre-flight planning and the en-route phases of flights. Its general aspects were developed by the Communications/Meteorology Divisional Meeting (1982), held conjointly with the Seventh Session of the World Meteorological Organization (WMO) Commission for Aeronautical Meteorology, and later by the Communications/Meteorology/Operations Divisional Meeting (1990), held conjointly with the Ninth Session of the same WMO Commission. After approval by the governing bodies of ICAO and WMO, the WAFS provisions resulting from these two meetings were embodied in ICAO’s Annex 3 and in the WMO Technical Regulations, and became applicable in November 1984 and November 1992, respectively.
1.2 The main objectives of the system are to provide meteorological services, pilots and aeronautical operators with uniform grid-point upper wind and upper-air temperature forecasts, as well as significant weather forecasts, with worldwide coverage, in a format suitable for direct use in computer flight planning. In addition, the system is designed to provide data to be used for meteorological briefing and for direct copying as flight documentation, as well as for other aeronautical uses such as air traffic services (ATS) computer-assisted control of air traffic.
2. EVOLUTION OF THE SYSTEM
2.1 The concept of centralization of global forecasting was initially considered impossible to achieve due primarily to two constraints. Firstly, computers with the capability of preparing forecasts on a global basis were not available. Secondly, there were no communications systems capable of transmitting large amounts of data to a large number of centres in an economical and efficient manner.
2.2 The first constraint was resolved with the introduction of powerful mainframe computers, through which forecasting of upper winds and upper-air temperatures became possible. However, fully objective forecasting of significant weather on a global scale remains an objective to be achieved.
2.3 The second constraint was eliminated with the advent of the broadcast capabilities of communications satellites, when satellite broadcast of data in digital bitstream or facsimile formats became possible. Such systems allow for reception of the broadcast through small dish antennas coupled with inexpensive receiving systems. In fact, three so-called WAFS satellite broadcasts (i.e. the aeronautical fixed service (AFS) satellite distribution systems) were implemented by two provider States (United Kingdom and United States). They provide for the global coverage by means of three International Telecommunications Satellite Organization (INTELSAT) satellites. Diagrams of the coverage of these satellites are reproduced in Figures A1-1, A1-2 and A1-3. In addition to WAFS data and charts, a global set of alphanumeric OPMET messages is disseminated through the satellite distribution systems.
3. PLANNING OF THE WAFS
3.1 Planning of the WAFS has been based on the concept of a three-tiered system comprising:
a) two World Area Forecast Centres (WAFCs), London and Washington — these centres produce global forecasts of upper winds and upper-air temperatures;
b) a number of Regional Area Forecast Centres (RAFCs) — these centres prepare significant weather (SIGWX) forecasts for selected “areas of coverage” with the assistance of upper-air data received from the WAFCs and, where applicable, SIGWX forecasts received from other RAFCs. They are also responsible for the transmission of those SIGWX forecasts, as well as upper-air forecasts to users within their “service areas”; and
c) the “users”, consisting essentially of meteorological services, operators and other aeronautical users. The users receive WAFS data from the WAFCs and/or RAFCs concerned.
Note.— The definitions of “areas of coverage”, “areas of responsibility” and “service areas” are given in 6.1.1 below.
3.2 Work has been proceeding at a fast pace in a few States, aimed at the development of computer methods for the preparation of significant weather forecasts. Complete automatic production of significant weather forecasts in the format familiar to the aviation community is still a complex task to achieve, but this was resolved by the use of computer graphics systems. With these computer systems, meteorologists in WAFCs prepare the forecasts with the direct support of computer-prepared upper-air forecasts and other data that can be superimposed on computer screens, thereby permitting fast handling of large amounts of data. With these computer systems, significant weather charts covering large areas of the globe are being produced operationally and disseminated to users. In the near future, the WMO Binary Universal Form for the Representation of Meteorological Data (BUFR) code will be used for the transmission of significant weather forecasts from WAFCs to users via the WAFS satellite distribution systems.
3.3 Since the WAFCs are producing significant weather forecasts on a global basis by computer systems, the requirement for the RAFCs has disappeared and all the RAFCs have been phased out.
3.4 The current phase of the implementation of the WAFS, is known as the final phase. In this phase, the two WAFCs prepare all the required significant weather and upper-air forecasts and disseminate these to all users through satellite broadcasts (see Figure A1-4).
3.5 Within the context of the regional planning, the ICAO regions have completed solutions appropriate for the transition to the final phase of the WAFS in each region, and relevant details can be found in the air navigation plans for the regions concerned.
Note.— The 0° elevation angle contour is the theoretical extent of coverage, while the 5 elevation angle is considered to be the practical extent of coverage according to nominal design criteria.
4. AUTHORIZED ACCESS
TO THE
WAFS SATELLITE
BROADCAST
4.1 As was mentioned in section 2, an international telecommunication service via satellite was developed and implemented in compliance with Annex 10, Volume III, 10.1 and 10.2, for the dissemination of WAFS data and products. This service, called the WAFS satellite broadcast, provides for global coverage by means of three satellite broadcasts, as follows:
a) International Satellite Communications System 1 (ISCS1) from WAFC Washington covering the CAR, NAM, NAT and SAM Regions;
b) International Satellite Communications System 2 (ISCS2) from WAFC Washington covering the Asia (eastern part) and PAC Regions; and
c) Satellite Distribution System for Information Relating to Air Navigation (SADIS) from WAFC London covering the AFI, Asia (western part), EUR and MID Regions.
4.2 The OPMET information (broadcast by means of these services) currently includes:
a) WAFS global grid-point upper wind, temperature, height of tropopause, maximum wind and humidity forecasts in the GRIB code;
b) WAFS SIGWX and upper wind and temperature charts; and
c) alphanumeric messages (e.g. METARs, TAFs and SIGMETs).
Note.— SIGWX forecasts in the BUFR code will soon be introduced in the broadcast.
4.3 The information broadcast is not encrypted; however, a mechanism exists to allow the control management centre of the service provider, on the advice from the provider State, to control which very small aperture terminal (VSAT) receives the information broadcast.
4.4 The guidelines for authorized access to the WAFS satellite broadcast were developed to assist States in arranging for access to the WAFS satellite broadcast. The guidelines are reproduced below:
“4.4.1 General
4.4.1.1 The satellite broadcast constitutes a sub-system of the ICAO aeronautical fixed service (AFS), providing an international point-to-multipoint telecommunication service via satellite for the dissemination of aeronautical information to ICAO Contracting States.
4.4.1.2 The aeronautical information disseminated by the satellite broadcast includes primarily operational meteorological (OPMET) information consisting of the WAFS upper wind, upper-air temperature and significant weather forecasts in digital grid-point and graphical formats, and alphanumeric messages.
4.4.1.3 Through the use of the satellite broadcast, Contracting States may wish to meet their obligation under Article 28 of the Convention on International Civil Aviation (Doc 7300) regarding the supply to users of meteorological information for the provision of meteorological service for international air navigation.
4.4.1.4 Recovery by Contracting States of associated costs through charges on international civil aviation should be based on the principles contained in Article 15 of the Convention on International Civil Aviation and the Statements by the Council to Contracting States on Charges for Airports and Air Navigation Services (Doc 9082).
4.4.2 Authorized access to the
satellite broadcast
4.4.2.1 It is the prerogative of each Contracting State to determine the distribution of the OPMET information to users, in the State concerned, as well as means, links and information flow to be used for this purpose. In view of this, it is for each Contracting State to determine the users in the State concerned to be provided with the authorized access to the satellite broadcast.
4.4.2.2 Where the meteorological service for international air navigation is provided by or through arrangements made by the Meteorological Authority in compliance with the Standard contained in 2.1.4 of Annex 3 — Meteorological Service for International Air Navigation to the Convention on International Civil Aviation, the Meteorological Authorities, World Area Forecast Centres and aerodrome and other meteorological offices should fully enjoy the benefits of the satellite broadcast to receive the OPMET information broadcast. Furthermore, it is at the discretion of each Contracting State to determine, on advice from its Meteorological Authority, whether any of the following users will be provided with authorized access to the satellite broadcast: operators; air traffic services units; search and rescue services units; aeronautical information services units; volcanic ash and tropical cyclone advisory centres; and other aeronautical users.
4.4.2.3 Each Contracting State will notify ICAO and, for the purpose of efficiency, also the provider State responsible for the satellite broadcast concerned, regarding the users in that State it has authorized to access the satellite broadcast.
Note 1.— Where the satellite broadcast also comprises a sub-system of the World Meteorological Organization Global Telecommunication System (WMO GTS), in accordance with the action by the ICAO Council on Recommendation 4.2/5 — Relationship of satellite communication system to the WMO’s GTS of the Communications/Meteorology Divisional Meeting (1982), the WMO Member State concerned determines the users authorized to receive basic synoptic data and analyses via the satellite broadcast and notifies ICAO through WMO, accordingly.
Note 2.— The United States is the provider State for ISCS1 and ISCS2; the United Kingdom is the provider State for SADIS.”
5. DUTIES OF METEOROLOGICAL OFFICES
IN THE CONTEXT OF THE WAFS
It should be noted that while the WAFS provides en-route weather forecasts, the preparation of meteorological observations and aerodrome forecasts remains the responsibility of individual meteorological offices. With the full implementation of the WAFS, they can dedicate much more of their resources to these essential tasks.
Figure A1-1. Footprint of the International Satellite Communications System 1 (ISCS1)
by WAFC Washington. The INTELSAT satellite over 34.5ûW
(an Atlantic Ocean satellite) is used for the broadcast.
Note.— The 0° elevation angle contour is the theoretical extent of coverage, while the 5° elevation angle is considered to be the practical extent of coverage according to nominal design criteria.
Figure A1-2. Footprint of the International Satellite Communications System 2 (ISCS2)
by WAFC Washington. The INTELSAT satellite over 177ûW
(a Pacific Ocean satellite) is used for the broadcast.
Note.— The 0° elevation angle contour is the theoretical extent of coverage, while the 5° elevation angle is considered to be the practical extent of coverage according to nominal design criteria.
Figure A1-3. Footprint of the Satellite Distribution System for Information Relating
to Air Navigation (SADIS) by WAFC London. The INTELSAT satellite over 63ûE
(an Indian Ocean satellite) is used for the broadcast.
Note.— The 0° elevation angle contour is the theoretical extent of coverage, while the 5° elevation angle is considered to be the practical extent of coverage according to nominal design criteria.
Figure A1-4. Concept for satellite broadcast of WAFS products — the final phase of the WAFS
Appendix 2
TECHNICAL SPECIFICATIONS FOR
LOCAL ROUTINE REPORTS, LOCAL SPECIAL REPORTS AND
REPORTS IN THE METAR/SPECI CODE FORMS
(See Chapter 4 of Annex 3.)
Table A2-1. Template for the local routine (MET REPORT) and local special (SPECIAL) reports
Key: M = inclusion mandatory, part of every message
C = inclusion conditional, dependent on meteorological conditions
O = inclusion optional
Note. — The ranges and resolutions for the numerical elements included in the local routine and special reports are shown in Table A2-4 of this appendix.
|Element as |Detailed content |Template(s) |Examples |
|specified in | | | |
|Annex 3, | | | |
|Chapter 4 | | | |
| | | | |
|Identification of |Type of report |MET REPORT or SPECIAL |MET REPORT |
|the type of report | | |SPECIAL |
|(M) | | | |
|Location indicator |ICAO location indicator |nnnn |YUDO1 |
|(M) |(M) | | |
|Time of the |Date and time of the |nnnnnnZ |221630Z |
|observation (M) |observation in UTC | | |
|Surface wind (M) |Name of the element (M) |WIND |WIND 240/15KMH |
| | | |(WIND 240/8KT) |
| |Runway (O)2 |[RWY nnn] |WIND RWY 18 TDZ 190/22KMH |
| | | |(WIND RWY 18 TDZ 190/11KT) |
| |Runway section (O)3 |[TDZ] | |
| |Wind direction (M) |nnn/ |VRB BTN nnn/ AND nnn/ | CALM |WIND VRB6KMH WIND CALM |
| | | |or | |(WIND VRB3KT) |
| | | |VRB | |WIND VRB BTN 350/ AND 050/6KMH |
| | | | | |(WIND VRB BTN 350/ AND 050/3KT) |
| |Wind speed (M) |[ABV]nn[n]KMH or [ABV]nnKT | |WIND 270/ABV 199KMH |
| | | | |(WIND 270/ABV 99KT) |
| |Significant speed |MAX[ABV]nn[n] MNMnn | |WIND 120/12KMH MAX35 MNM8 |
| |variations (C)4 | | |(WIND 120/6KT MAX18 MNM4) |
| |Significant directional |VRB BTN nnn/|— | |WIND 020/20KMH VRB BTN 350/ AND 070/ |
| |variations (C)5 |AND nnn/ | | |(WIND 020/10KT VRB BTN 350/ AND 070/) |
| |Runway section (O)3 |[MID] |WIND RWY 14R MID 140/22KMH |
| | | |(WIND RWY 14R MID 140/11KT) |
| |Wind direction (M) |nnn/ |VRB BTN nnn/ AND nnn/ | CALM | |
| | | |or | | |
| | | |VRB | | |
| |Wind speed (M) |[ABV]nn[n]KMH or [ABV]nnKT | | |
| |Significant speed |MAX[ABV]nn[n] MNMnn | | |
| |variations (C)4 | | | |
| |Significant directional |VRB BTN nnn/|— | | |
| |variations (C)5 |AND nnn/ | | | |
| |Runway section (O)3 |[END] |WIND RWY 27 TDZ 240/32KMH MAX54 MNM20 END |
| | | |250/28KMH |
| | | |(WIND RWY 27 TDZ 240/16KT MAX27 MNM10 END |
| | | |250/14KT) |
| |Wind direction (M) |nnn/ |VRB BTN nnn/ AND nnn/ | CALM | |
| | | |or | | |
| | | |VRB | | |
| |Wind speed (M) |[ABV]nn[n]KMH or [ABV]nnKT | | |
| |Significant speed |MAX[ABV]nn[n] MNMnn | | |
| |variations (C)4 | | | |
| |Significant directional |VRB BTN nnn/|— | | |
| |variations (C)5 |AND nnn/ | | | |
|Visibility (M) |Name of the element (M) |VIS |CAVOK |VIS 350M CAVOK |
| | | | |VIS 7KM |
| | | | |VIS 10KM |
| |Runway (O)2 |[RWY nnn] | |VIS RWY 09 TDZ 800M END 1200M |
| |Runway section (O)3 |[TDZ] | | |
| |Visibility (M) |nnnnM or nnKM | | |
| |Runway section (O)3 |[END] | |VIS RWY 18 TDZ 6KM RWY 27 TDZ 4000M |
| |Visibility (M) |nnnnM or nnKM | | |
|RVR (C)5 |Name of the element (M) |RVR | |RVR RWY 32 400M |
| | | | |RVR RWY 20 500M |
| |Runway (C)7 |RWY nnn | | |
| |Runway section (C)8 |TDZ | | |
| |RVR (M) |[ABV or BLW] nnnnM | |RVR RWY 10 BLW 50M |
| | | | |RVR RWY 14 ABV 1500M |
| | | | |RVR RWY 10 BLW 150M |
| | | | |RVR RWY 12 ABV 1200M |
| |Runway section (C)8 |MID | |RVR RWY 12 TDZ 1100M MID ABV 1400M |
| |RVR (M) |[ABV or BLW] nnnnM | | |
| |Runway section (C)8 |END | |RVR RWY 16 TDZ 600M MID 500M END 400M |
| | | | |RVR RWY 26 500M RWY 20 800M |
| |RVR (M) |[ABV or BLW] nnnnM | | |
|Present weather |Intensity or proximity of|FBL or |— |VC | | |
|(C)9, 10 |present weather (C)11 |MOD or | | | | |
| | |HVY | | | | |
| |Characteristics and type |DZ or RA or |FG or BR |FG or PO or | |MOD RA HZ VCFG |
| |of present weather (M)12 |SN or SG or |or SA or |FC or | |HVY TSRA FG VCSH |
| | |PL or IC or |DU or HZ |DS or | |HVY DZ VA VCTS |
| | |GR or GS or |or FU or |SS or | |FBL SN MIFG VCBLSA |
| | |DS or SS or |VA or SQ |TS or | | |
| | |TS or TSRA |or FZFG |SH or | |HVY TSRASN |
| | |or TSSN or |or DRSN |BLSN or | |FBL SNRA |
| | |TSPL or TSGR|or DRSA |BLSA | | |
| | |or TSGS or |or DRDU |or | |FBL DZ FG |
| | |SHRA or SHSN|or MIFG |BLDU | |HVY SHSN MOD BLSN |
| | |or SHPL or |or BCFG | | | |
| | |SHGR or SHGS|or PRFG | | | |
| | |or FZRA or | | | | |
| | |FZDZ or BLSN| | | | |
| | |or BLSA or | | | | |
| | |BLDU or PO | | | | |
| | |or FC | | | | |
|Cloud (M)13 |Name of the element (M) |CLD | | |
| |Runway (O)2 |[RWY nnn] | | |
| |Cloud amount (M) or |FEW or |OBSC |SKC or NSC| | |CLD SCT 300M OVC 600M |
| |vertical visibility (O)9 |SCT or | | | | |(CLD SCT 1000FT OVC 2000FT) |
| | |BKN or | | | | | |
| | |OVC | | | | |CLD OBSC VER VIS 150M CLD SKC |
| | | | | | | |(CLD OBSC VER VIS 500FT) CLD NSC |
| |Cloud type (C)9 |CB or TCU |— | | | |CLD BKN TCU 270M |
| | | | | | | |(CLD BKN TCU 900FT) |
| |Height of base or the |nnnnM [DIF |[VER VIS | | | |CLD RWY 08 BKN 60M RWY 26 BKN 90M |
| |value of vertical |or RAG or |nnnM or | | | |(CLD RWY 08 BKN 200FT RWY 26 BKN 300FT) |
| |visibility (C)9 |FLUC] |VER VIS | | | | |
| | |or nnnnFT |nnnnFT] | | | | |
| | |[DIF or RAG | | | | | |
| | |or FLUC] | | | | | |
|Air temperature (M)|Name of the element (M) |T |T17 |
| | | |TMS8 |
| |Air temperature (M) |[MS]nn | |
|Dew-point |Name of the element (M) |DP |DP15 |
|temperature (M) | | |DPMS18 |
| |Dew-point temperature (M)|[MS]nn | |
|Pressure values (M)|Name of the element (M) |QNH |QNH 0995HPA |
| | | |QNH 1009HPA |
| |QNH (M) |nnnnHPA | |
| |Name of the element (O)14|QFE |QNH 1022HPA QFE 1001HPA |
| | | |QNH 0987HPA QFE RWY 18 0956HPA |
| | | |RWY 24 0955HPA |
| |QFE (O)1 |[RWY nnn] nnnnHPA [RWY nnn nnnnHPA] | |
|Supplementary |Significant |CB or TS or MOD TURB or SEV TURB or WS or GR or SEV|FC IN APCH |
|information (C)9 |meteorological phenomena |SQL or MOD ICE or SEV ICE or FZDZ or FZRA or SEV |WS IN APCH WIND AT 60M 360/50KMH |
| |(C)9 |MTW or SS or DS or BLSN or FC15 |WS RWY 12 |
| |Location of the |IN APCH or IN CLIMB-OUT or RWYnnn | |
| |phenomenon (C)9 | | |
| |Recent weather (C)9 |REFZDZ or REFZRA or REDZ or RE[SH]RA or RE[SH]SN or|REFZRA |
| | |RE[SH]SG or RE[SH]PL or REIC or RE[SH]GR or |CB IN CLIMB-OUT RETS |
| | |RE[SH]GS or REBLSN or RESS or REDS or RETS or REFC | |
| | |or REVA | |
|Trend forecast |Name of the element (M) |TREND | |
|(O)16 | | | |
| |Change indicator (M) |NOSIG |BECMG or TEMPO |TREND NOSIG TREND BECMG FEW 600M |
| | | | |(TREND BECMG FEW 2000FT) |
| |Period of change (C)9 | |FMnnnn and/or TLnnnn | |
| | | |or | |
| | | |ATnnnn | |
| |Wind (C)9 | |nnn/[ABV]nn[n]KMH [MAX[ABV]nn[n]] or |TREND TEMPO 250/70KMH MAX 100 |
| | | |nnn/[ABV]nnKT [MAX[ABV]nn] |(TREND TEMPO 250/35KT MAX 50) |
| |Visibility (C)9 | |VIS nnnnM or |CAVOK |TREND BECMG AT1800 VIS 10KM NSW |
| | | |VIS nnKM | |TREND BECMG TL1700 VIS 800M FG |
| | | | | |TREND BECMG FM1030 TL1130 CAVOK |
| |Weather phenomenon: | |FBL or |— |NSW | |TREND TEMPO TL1200 VIS 600M BECMG AT1200 |
| |intensity (C)11 | |MOD or | | | |VIS 8KM NSW NSC |
| | | |HVY | | | | |
| |Cloud amount and vertical| |FEW or |OBSC |SKC or | |TREND BECMG AT1130 OVC 300M |
| |visibility (C)9 | |SCT or | |NSC | |(TREND BECMG AT1130 OVC 1000FT) |
| | | |BKN or | | | | |
| | | |OVC | | | | |
| |Height of base or the | |nnnnM or |[VER VIS | | | |
| |value of vertical | |nnnnFT |nnnM or | | | |
| |visibility (C)9 | | |VER VIS | | | |
| | | | |nnnnFT] | | | |
| |
|1. Fictitious location. |
|2. Optional values for one or more runways. |
|3. Optional values for one or more sections of the runway. |
|4. To be included if the maximum is exceeding the mean speed by 20 km/h (10 kt). |
|5. To be included if the directional variations > 60° but < 180° and the wind speed > 6 km/h (3 kt). |
|6. To be included if visibility or RVR < 1 500 m. |
|7. To be included if more than one runway in use. |
|8. To be included if RVR is observed from more than one location along the runway. |
|9. To be included whenever applicable. |
|10. One or more, up to a maximum of three groups. |
|11. To be included whenever applicable; only qualifiers MOD and HVY (i.e. well-developed) to be used with PO and FC. |
|12. Precipitation types DZ, RA, SN, SG, PL, IC, GR and GS may be combined, where appropriate. Only moderate or heavy precipitation to be |
|indicated in trend forecasts. |
|13. Up to four cloud layers. |
|14. Optional element. |
|15. Any of the phenomena, or combinations thereof. Abbreviated plain language to be used to amplify the phenomena, as necessary. |
|16. To be included subject to regional air navigation agreement. |
Table A2-2. Template for reports in the METAR/SPECI code forms
Key: M = inclusion mandatory, part of every message
C = inclusion conditional, dependent on meteorological conditions or method of observation
O = inclusion optional
Note. — The ranges and resolutions for the numerical elements included in reports in the METAR/SPECI code forms are shown in Table A2-5 of this appendix.
|Element as specified|Detailed content |Template(s) |Examples |
|in Annex 3, | | | |
|Chapter 4 | | | |
| | | | |
|Identification of |Type of report (M) |METAR or SPECI |METAR |
|the type of report | | |SPECI |
|(M) | | | |
|Location indicator |ICAO location indicator (M) |nnnn |YUDO1 |
|(M) | | | |
|Time of the |Date and time of the |nnnnnnZ |221630Z |
|observation (M) |observation in UTC (M) | | |
|Surface wind (M) |Wind direction (M) |nnn |VRB |24015KMH VRB06KMH |
| | | | |(24008KT) (VRB03KT) |
| | | | |19022KMH |
| | | | |(19011KT) |
| | | | |00000KMH |
| | | | |(00000KT) |
| | | | |140P199KMH |
| | | | |(140P99KT) |
| |Wind speed (M) |[P]nn[n] | |
| |Significant speed variations|G[P]nn[n] |12012G35KMH |
| |(C)2 | |(12006G18KT) |
| | | |24032G54KMH |
| | | |(24016G27KT) |
| |Units of measurement (M) |KMH or KT | |
| |Significant directional |nnnVnnn |— |02020KMH 350V070 |
| |variations (C)3 | | |(02010KT 350V070) |
|Visibility (M) |Minimum visibility (M) |nnnn |C | |0350 CAVOK |
| | | |A | |7000 |
| | | |V | |9999 |
| | | |O | | |
| | | |K | | |
| |Direction of the minimum |N or NE or E or SE or S or SW or W or NW | | |0800E |
| |visibility (C)4 | | | | |
| |Maximum visibility (C)5 |nnnn | | |1100SE 7000NW |
| | | | | |1200S 6000W |
| |Direction of the maximum |N or NE or E or SE or S or SW or W or NW | | | |
| |visibility (C)5 | | | | |
|RVR (C)6 |Name of the element (M) |R | | |R32/0400 |
| | | | | | |
| | | | | |R10/M0050 |
| | | | | |R14L/P1500 |
| |Runway (M) |nn[n]/ | | | |
| |RVR (M) |[P or M]nnnn | | |R16L/0650 R16C/0500 |
| | | | | |R16R/0450 R17L/0450 |
| |RVR variations (C)7 |V[P or M]nnnn | | |R20/0700V1200 |
| | | | | |R19/0350VP1200 |
| |RVR past tendency (C)8 |U, D or N | | |R12/1100U |
| | | | | |R26/0550N R20/0800D |
| | | | | | |
| | | | | |R09/0375V0600U |
| | | | | |R10/M0150V0500D |
|Present weather |Intensity or proximity of |– or + |— |VC | | | |
|(C)9, 10 |present weather (C)11 | | | | | | |
| |Characteristics and type of |DZ or RA or SN|FG or BR or |FG or PO or | | |RA HZ VCFG |
| |present weather (M)12 |or SG or PL or|SA or DU or |FC or | | |+TSRA FG VCSH |
| | |IC or GR or GS|HZ or FU or |DS or | | |+DZ VA VCTS |
| | |or DS or SS or|VA or SQ or |SS or | | |–SN MIFG VCBLSA |
| | |TS or TSRA or |FZFG or DRSN|TS or | | | |
| | |TSSN or TSPL |or DRSA or |SH or | | |+TSRASN |
| | |or TSGR or |DRDU or MIFG|BLSN or | | |–SNRA |
| | |TSGS or SHRA |or BCFG or |BLSA | | | |
| | |or SHSN or |PRFG |or | | |–DZ FG |
| | |SHPL or SHGR | |BLDU | | |+SHSN BLSN |
| | |or SHGS or | | | | | |
| | |FZRA or FZDZ | | | | | |
| | |or BLSN or | | | | | |
| | |BLSA or BLDU | | | | | |
| | |or | | | | | |
| | |PO or FC | | | | | |
|Cloud (M)13 |Cloud amount and |FEWnnn or |VVnnn or |SKC | | |FEW015 VV005 SKC |
| |height of base or |SCTnnn |VV/// |or | | |OVC030 VV/// NSC |
| |vertical visibility (M) |or | |NSC | | | |
| | |BKNnnn or | | | | |SCT010 OVC020 |
| | |OVCnnn | | | | | |
| |Cloud type (C)9 |CB or |— | | | |BKN009TCU |
| | |TCU | | | | | |
| | | | | | | |SCT008 BKN025CB |
|Air and dew-point |Air and dew-point |[M]nn/[M]nn |17/10 |
|temperature (M) |temperatures (M) | |02/M08 |
| | | |M01/M10 |
|Pressure values (M) |Name of the element (M) |Q |Q0995 |
| | | |Q1009 |
| | | |Q1022 |
| | | |Q0987 |
| |QNH (M) |nnnn | |
|Supplementary |Recent weather (C)9, 10 |REFZDZ or REFZRA or REDZ or RE[SH]RA or RE[SH]SN or |REFZRA |
|information (C)9 | |RE[SH]SG or RE[SH]PL or REIC or RE[SH]GR or RE[SH]GS|RETS |
| | |or REBLSN or RESS or REDS or RETS or REFC or REVA | |
| |Wind shear (C)9 |WS RWYnn[n] or WS ALL RWY |WS RWY03 |
| | | |WS ALL RWY |
| |Sea-surface temperature and |W[M]nn/Sn |W15/S2 |
| |state of the sea (C)14 | | |
| |State |Runway designator |nn |SNOCLO |99421594 |
| |of the |(M) | | |SNOCLO |
| |runway | | | | |
| |(C)14 | | | | |
| | |Runway deposits (M)|n or / | | |
| | |Extent of runway |n or / | | |
| | |contamination (M) | | | |
| | |Depth of deposit |nn or // | | |
| | |(M) | | | |
| | |Friction |nn or // | | |
| | |coefficient or | | | |
| | |braking action (M) | | | |
|Trend forecast (O)14|Change indicator (M)15 |NOSIG |BECMG or TEMPO |NOSIG BECMG FEW020 |
| |Period of change (C)9 | |FMnnnn and/or | |
| | | |TLnnnn | |
| | | |or | |
| | | |ATnnnn | |
| |Wind (C)9 | |nnn[P]nn[n][G[P]nn[n]]KMH |TEMPO 25070G100KMH |
| | | |or |(TEMPO 25035G50KT) |
| | | |nnn[P]nn[G[P]nn]KT | |
| |Visibility (C)9 | |nnnn |C |BECMG FM1030 TL1130 CAVOK |
| | | | |A | |
| | | | |V |BECMG TL1700 0800 FG |
| | | | |O | |
| | | | |K |BECMG AT1800 9000 NSW |
| | | | | | |
| | | | | |BECMG FM1900 0500 +SNRA |
| | | | | | |
| | | | | |BECMG FM1100 SN TEMPO FM1130 BLSN |
| | | | | | |
| | | | | |TEMPO FM0330 TL0430 FZRA |
| |Weather phenomenon: | |– or + |— |N | | |
| |intensity (C)11 | | | |S | | |
| | | | | |W | | |
| |Weather phenomenon: | |DZ or RA or |FG or BR or | | | |
| |characteristics and type | |SN or SG or |SA or DU or | | | |
| |(C)9,10,12 | |PL or IC or |HZ or FU or | | | |
| | | |GR or GS or |VA or SQ or | | | |
| | | |DS or SS or |FZFG or DRSN| | | |
| | | |TS or TSRA |or DRSA or | | | |
| | | |or TSSN or |DRDU or MIFG| | | |
| | | |TSPL or TSGR|or BCFG or | | | |
| | | |or TSGS or |PRFG | | | |
| | | |SHRA or SHSN| | | | |
| | | |or SHPL or | | | | |
| | | |SHGR or SHGS| | | | |
| | | |or FZRA or | | | | |
| | | |FZDZ or BLSN| | | | |
| | | |or BLSA or | | | | |
| | | |BLDU or | | | | |
| | | |PO or FC | | | | |
| |Cloud amount and height of | |FEWnnn or |VVnnn or |S | |TEMPO TL1200 0600 BECMG AT1200 8000 |
| |base or vertical visibility | |SCTnnn |VV/// |K | |NSW NSC |
| |(C)9 | |or | |C | | |
| | | |BKNnnn | | | |BECMG AT1130 OVC010 |
| | | |or | |or | | |
| | | |OVCnnn | | | | |
| | | | | |N | | |
| | | | | |S | | |
| | | | | |C | | |
| |Cloud type (C)9 | |CB or TCU |— | | |TEMPO TL1530 +SHRA BKN012CB |
| |
|1. Fictitious location. |
|2. To be included if the maximum is exceeding the mean speed by 20 km/h (10 kt). |
|3. To be included if the directional variations > 60° but < 180° and the wind speed > 6 km/h (3 kt). |
|4. To be included if the visibility in one or more directions is more than 50 per cent above the minimum visibility. |
|5. To be included if the minimum visibility is less than 1 500 m and the visibility in another direction is more than 5 000 m. |
|6. To be included if visibility or RVR < 1 500 m; for up to a maximum of four runways. |
|7. To be included if the 1-minute RVR values during the 10-minute period immediately preceding the observation vary from the mean value more |
|than 50 m or more than 20 per cent, whichever is greater; the 1-minute mean minimum and the 1-minute mean maximum values are reported |
|(instead of the 10minute mean value). |
|8. To be included if the RVR values during the 10-minute period preceding the observation have shown a distinct tendency such that the mean |
|RVR during the first 5 minutes varies by 100 m or more from the mean during the second 5 minutes of the period. No tendency indication where |
|not available. |
|9. To be included whenever applicable. |
|10. One or more, up to a maximum of three groups. |
|11. To be included whenever applicable. No qualifier for moderate intensity; only qualifier “+” (i.e. well-developed) to be used with PO and |
|FC. |
|12. Precipitation types DZ, RA, SN, SG, PL, IC, GR and GS may be combined, where appropriate. Only moderate or heavy precipitation to be |
|indicated in trend forecasts. |
|13. Up to four cloud layers. |
|14. To be included subject to regional air navigation agreement. |
|15. Number of change indicators to be kept to a minimum; normally not exceeding three groups. |
Table A2-3. Use of change indicators in trend forecasts
|Change indicator |Time indicator and period |Meaning |
|NOSIG |— |no significant changes are forecast |
|BECMG |FMn1n1n1n1 TLn2n2n2n2 |the change is |commence at n1n1n1n1 UTC and be completed by n2n2n2n2 UTC |
| | |forecast to | |
| |TLnnnn | |commence at the beginning of the trend forecast period and be |
| | | |completed by nnnn UTC |
| |FMnnnn | |commence at nnnn UTC and be completed by the end of the trend |
| | | |forecast period |
| |ATnnnn | |occur at nnnn UTC (specified time) |
| |— | |a) commence at the beginning of the trend forecast period and be |
| | | |completed by the end of the trend forecast period; or |
| | | |b) the time is uncertain |
|TEMPO |FMn1n1n1n1 TLn2n2n2n2 |temporary |commence at n1n1n1n1 UTC and cease by n2n2n2n2 UTC |
| | |fluctuations are | |
| | |forecast to | |
| |TLnnnn | |commence at the beginning of the trend forecast period and cease by |
| | | |nnnn UTC |
| |FMnnnn | |commence at nnnn UTC and cease by the end of the trend forecast |
| | | |period |
| |— | |commence at the beginning of the trend forecast period and cease by |
| | | |the end of the trend forecast period |
Table A2-4. Ranges and resolutions for the numerical elements
included in the local meteorological message
|Element as specified in Annex 3, Chapter 4 |Range |Resolution |
|Runway | |01 – 36 |1 |
|Wind direction: |°true |010 – 360 |10 |
|Wind speed: |KMH |1 – 3991 |1 |
| |KT |1 – 1991 |1 |
|Visibility: |M |0 – 800 |50 |
| |M |800 – 5 000 |100 |
| |KM |5 – 10 |1 |
|RVR: |M |0 – 400 |25 |
| |M |400 – 800 |50 |
| |M |800 – 1 500 |100 |
|Vertical visibility: |M |0 – 600 |30 |
| |FT |0 – 2 000 |100 |
|Cloud: height of base: |M |0 – 3 000 |30 |
| |M |3 000 – 20 000 |300 |
| |FT |0 – 10 000 |100 |
| |FT |10 000 – 60 000 |1 000 |
|Air temperature; |°ûC |–80 – +60 |1 |
|Dew-point temperature: | | | |
|QNH; QFE: |hPa |0500 – 1 100 |1 |
| |
|1. There is no aeronautical requirement to report surface wind speeds of 200 km/h (100 kt) or more; however, provision has been made for |
|reporting wind speeds up to 399 km/h (199 kt) for non-aeronautical purposes, as necessary. |
Table A2-5. Ranges and resolutions for the numerical elements
included in meteorological message in the METAR/SPECI code forms
|Element as specified in Annex 3, Chapter 4 |Range |Resolution |
|Runway: | |(no units) |01 – 36 |1 |
|Wind direction: | |° true |000 – 360 |10 |
|Wind speed: | |KMH |00 – 3991 |1 |
| | |KT |00 – 1991 |1 |
|Visibility: | |M |0000 – 0800 |50 |
| | |M |0800 – 5 000 |100 |
| | |M |5 000 – 9 000 |1 000 |
| | |M |9 000 – 9 999 |999 |
|RVR: | |M |0000 – 0400 |25 |
| | |M |0400 – 0800 |50 |
| | |M |0800 – 1 500 |100 |
|Vertical visibility: | |30’s M (100’s FT) |000 – 020 |1 |
|Cloud: height of base: | |30’s M (100’s FT) |000 – 100 |1 |
| | |30’s M (100’s FT) | 100 – 6002 |10 |
|Air temperature; | | | | |
|Dew-point temperature: | |°C |–80 – +60 |1 |
|QNH: | |hPa |0850 – 1 100 |1 |
|Sea-surface temperature: | |°ûC |–10 – +40 |1 |
|State of the sea: | |(no units) |0 – 9 |1 |
|State of the runway |Runway designator: |(no units) |01 – 36; 51 – 86; 88; 99 |1 |
| |Runway deposits: |(no units) |0 – 9 |1 |
| |Extent of runway |(no units) |1; 2; 5; 9 |— |
| |contamination: | | | |
| |Depth of deposit: |(no units) |00 – 90; 92 – 99 |1 |
| |Friction coefficient/braking |(no units) |00 – 95; 99 |1 |
| |action: | | | |
| |
|1. There is no aeronautical requirement to report surface wind speeds of 200 km/h (100 kt) or more; however, provision has been made for |
|reporting wind speeds up to 399 km/h (199 kt) for non-aeronautical purposes, as necessary. |
| |
|2. 100 – 200 in trend forecasts. |
EXAMPLES OF REPORTS
|Example 1.— Routine report |
| |
|a) METAR for YUDO (Donlon/International)*: |
| |
|METAR YUDO 221630Z 24015KMH 0600 R12/1000U FG DZ SCT010 OVC020 17/16 Q1018 BECMG TL1700 0800 FG BECMG AT1800 9999 NSW |
| |
|b) Local routine report (same location and weather conditions as METAR): |
| |
|MET REPORT YUDO 221630Z WIND 240/15KMH VIS 600M RVR RWY 12 TDZ 1000M FG MOD DZ CLD SCT 300M OVC 600M T17 DP16 QNH 1018 TREND BECMG TL1700 VIS |
|800M FG BECMG AT1800 VIS 10KM NSW |
| |
|c) Meaning of both reports: |
| |
|Routine report for Donlon/International* issued on the 22nd of the month at 1630 UTC; surface wind direction 240 degrees; wind speed 15 |
|kilometres per hour; visibility 600 metres; runway visual range representative of the touchdown zone for runway 12 is 1 000 metres and the |
|runway visual range values have shown an upward tendency during previous 10 minutes (RVR tendency to be included in METAR only); fog and |
|moderate drizzle; scattered cloud at 300 metres; overcast at 600 metres; air temperature 17 degrees Celsius; dew-point temperature 16 degrees |
|Celsius; QNH 1018 hectopascals; trend during next two hours visibility becoming 800 metres in fog by 1700 UTC; at 1800 UTC visibility becoming|
|10 kilometres or more and nil significant weather. |
| |
|* Fictitious location |
| |
|Note.— In this example, the primary units “kilometre per hour” and “metre” were used for wind speed and height of cloud base respectively. |
|However, in accordance with Annex 5, the corresponding non-SI alternative units “knot” and “foot” may be used instead. |
|Example 2.— Special report |
| |
|a) SPECI for YUDO (Donlon/International)* |
| |
|SPECI YUDO 151115Z 05025G37KT NE1200 S6000 + TSRA BKN005CB 25/22 Q1008 TEMPO TL1200 0600 BECMG AT1200 8000 NSW NSC |
| |
|b) Local special report (same location and weather conditions as SPECI): |
| |
|SPECIAL YUDO 151115Z WIND 050/25KT MAX37 MNM10 VIS 1200M HVY TSRA CLD BKN CB 500FT T25 DP22 QNH 1008 TREND TEMPO TL1200 VIS 600M BECMG AT1200 |
|VIS 8KM NSW NSC |
| |
|c) Meaning of both reports: |
| |
|Selected special report for Donlon/International* issued on the 15th of the month at 1115 UTC; surface wind direction 050 degrees; wind speed |
|25 knots gusting between 10 and 37 knots (minimum wind speed not to be included in SPECI); visibility lowest to north east at 1 200 metres, |
|visibility 6 000 metres to south (directional variations to be included in SPECI only; visibility representative of the runway included in the|
|local special report); heavy thunderstorm with rain; broken cumulonimbus cloud at 500 feet; air temperature 25 degrees Celsius; dew-point |
|temperature 22 degrees Celsius; QNH 1008 hectopascals; trend during next two hours, visibility temporarily 600 metres from 1115 to 1200, |
|becoming at 1200 UTC visibility 8 km, thunderstorm ceases and nil significant weather and nil significant cloud. |
| |
|* Fictitious location |
| |
|Note.— In this example, the non-SI alternative units “knot” and “foot” were used for wind speed and height of cloud base respectively. |
|However, in accordance with Annex 5, the corresponding primary units “kilometre per hour” and “metre” may be used instead. |
|Example 3.— Volcanic activity report |
| |
|VOLCANIC ACTIVITY REPORT YUSB* 231500 MT TROJEEN* VOLCANO N5605 W12652 ERUPTED 231445 LARGE ASH CLOUD EXTENDING TO APPROX 30000 FEET MOVING SW|
| |
|Meaning: Volcanic activity report issued by Siby/Bistock meteorological station at 1500 UTC on the 23rd of the month. Mt Trojeen volcano 56 |
|degrees 5 minutes north 126 degrees 52 minutes west erupted at 1445 UTC on the 23rd; a large ash cloud was observed extending to approximately|
|30 000 feet and moving in a south-westerly direction. |
| |
|* Fictitious locations |
Appendix 3
ABBREVIATED DECODE OF METAR AND SPECI MESSAGES
Appendix 4
SELECTED CRITERIA APPLICABLE TO AERODROME REPORTS
(The guidance in this table relates to Annex 3, Chapter 4 — Meteorological observations and reports, 4.5 to 4.12 inclusive.)
| |Surface wind |Visibility (VIS) |
| | | |
|Mean surface wind |Direction: 10° |Direction: ±5° |
| |Speed: ±2 km/h (1 kt) up to 19 km/h (10 kt) |Speed: ±2 km/h (1 kt) up to 37 km/h (20 kt) |
| |±10% above 19 km/h (10 kt) |±5% above 37 km/h (20 kt) |
|Variations from the |±4 km/h (2 kt), in terms of longitudinal |As above |
|mean surface wind |and lateral components | |
|Visibility |±50 m up to 600 m |±50 m up to 500 m |
| |±10% between 600 m and 1 500 m |±10% between 500 m and 2 000 m |
| |±20% above 1 500 m |±20% above 2 000 m up to 10 km |
|Runway visual range |±10 m up to 400 m |±25 m up to 150 m |
| |±25 m between 400 m and 800 m |±50 m between 150 m and 500 m |
| |±10% above 800 m |±10% above 500 m up to 2 000 m |
|Cloud amount |±1 okta |In daylight, an observer can attain an accuracy of ± 1 |
| | |okta at the point of observation. In darkness, and when |
| | |atmospheric phenomena limit the viewing of low cloud, |
| | |there will be difficulty in attaining that accuracy. |
|Cloud height |±10 m (33 ft) up to 100 m (330 ft) |±10 m (33 ft) up to 1 000 m (3 300 ft) |
| |±10% above 100 m (330 ft) |±30 m (100 ft) above 1 000 m (3 300 ft) up to |
| | |3 000 m (10 000 ft) |
|Air temperature and dew point |±1ûC |±0.2ûC |
|temperature | | |
|Pressure value (QNH, QFE) |±0.5 hPa |±0.3 hPa |
| |
|1. The operationally desirable accuracy is not intended as an operational requirement; it is to be understood as a goal that has been |
|expressed by the operators. |
|2. The accuracy stated refers to assessment by instruments (except for cloud amount); it is not normally attainable in observations made |
|without the aid of instruments. |
1. The term “instrument” is used in both senses.
2. Annex 3, 4.1.5, calls for meteorological instruments at aeronautical meteorological stations to be exposed, operated and maintained in accordance with the practices, procedures and specifications promulgated by the World Meteorological Organization (WMO). Detailed guidance in this respect can be found in the WMO Guide to Meteorological Instruments and Methods of Observation (WMO-No. 8).
3. WMO requirements for synoptic observations refer to a height of 10 m, and not 6 m to 10 m as the aeronautical requirements.
Table A5-1. Aerodrome reference code
(extract from Annex 14, Volume I)
| |Code element 1 | | |Code element 2 | |
|Code |Aeroplane reference | |Code |Wing span |Outer main gear |
|number |field length | |letter |(4) |wheel span1 |
|(1) |(2) | |(3) | |(5) |
|1 |Less than 800 m | |A |Up to but not |Up to but not |
| | | | |including 15 m |including 4.5 m |
|2 |800 m up to but not | |B |15 m up to but not |4.5 m up to but not |
| |including 1 200 m | | |including 24 m |including 6 m |
|3 |1 200 m up to but not | |C |24 m up to but not |6 m up to but not |
| |including 1 800 m | | |including 36 m |including 9 m |
|4 |1 800 m and over | |D |36 m up to but not |9 m up to but not |
| | | | |including 52 m |including 14 m |
| | | |E |52 m up to but not |9 m up to but not |
| | | | |including 65 m |including 14 m |
| | | |F |65 m up to but not |14 m up to but not |
| | | | |including 80 m |including 16 m |
| |
|Note.— Guidance on planning for aeroplanes with wing spans greater than 80 m is given in the Aerodrome Design Manual (Doc |
|9157), Parts 1 and 2. |
| |
|1. Distance between the outside edges of the main gear wheels. |
Table A5-2. Minimum dimensions of runways and slopes of associated transitional surfaces
(based on information contained in Chapters 3 and 4 of Annex 14, Volume I)
| |Aerodrome reference code number |Minimum |
| | |distance of |
| | |object from |
| | |taxiway centre line |
| |1 |2 |3 |4 | | |
| | | | | | | |
|Width of runway (metres) for aerodrome | | | | | | |
|reference code letter: | | | | | | |
|A |18 |23 |30 |— |16.25 | |
|B |18 |23 |30 |— |21.5 | |
|C |23 |30 |30 |45 |26.0 | |
|D |— |— |45 |45 |40.5 | |
|E |— |— |— |45 |47.5 | |
| | | | | | | |
|Semi-width of runway strips (metres) | | | | | | |
|Instrument runway: | | | | | | |
|Precision approach |75 |75 |150 |150 | | |
|Non-precision approach |75 |75 |150 |150 | | |
|Non-instrument runway |30 |40 |75 |75 | | |
| | | | | | | |
|Transitional surface (slope) | | | | | | |
|Instrument runway: | | | | | | |
|Precision approach |14.3% |14.3% |14.3% |14.3% | | |
|Non-precision approach |20% |20% |14.3% |14.3% | | |
|Non-instrument runway |20% |20% |14.3% |14.3% | | |
| | | | | | | |
|Inner transitional surface (minimum, | | | | | | |
|semi-width on the ground, metres) | | | | | | |
|Instrument runway: | | | | | | |
|Precision approach |CAT I: 45 |CAT I: 45 |CAT I, II |CAT I, II | | |
| | | |or III: 60 |or III: 60 | | |
|Non-precision approach |— |— |— |— | | |
|Non-instrument runway |— |— |— |— | | |
| | | | | | | |
|Inner transitional surface (slope) | | | | | | |
|Instrument runway: | | | | | | |
|Precision approach |40% |40% |33.3% |33.3% | | |
|Non-precision approach |— |— |— |— | | |
|Non-instrument runway |— |— |— |— | | |
Table A5-3. Location of meteorological instruments at aerodromes
(Meteorological instruments which may constitute obstacles are given in Doc 9137, Airport Services Manual, Part 6 —
Control of Obstacles, Chapter 5. Minimum distances from runways are illustrated in Figure A5-2.)
|Meteorological |Typical |Typical |Operational |Siting |Remarks |
|element |equipment |dimensions |area for which |provision in | |
|observed | |of equipment |element is to |Annex 3 | |
|or measured | | |be representative | | |
|Surface wind |Anemometer and |Usually mounted on |Take-off areas and |No specific provisions |Siting will be governed by |
|speed and |wind vane |tubular or lattice |touchdown zone. Where |so long as observations |obstacle limitation surfaces and|
|direction | |mast 6 m to 10 m (20|prevailing wind varies |are representative of |local prevailing surface wind |
| | |ft to 30 ft) high. |significantly at different|relevant operational |regime. Generally speaking, if |
| | |Single tube mast |sections of the runway, |areas. |the wind field over the |
| | |for both instruments|multiple anemometers may | |aerodrome is homogeneous, one |
| | |appropriate in |be required. | |strategically sited anemometer |
| | |proximity to | | |may suffice, preferably sited so|
| | |runways. | | |as not to infringe transitional |
| | | | | |surfaces. However, depending on |
| | | | | |local conditions, it may be |
| | | | | |necessary to locate a frangible |
| | | | | |and lighted mast within the |
| | | | | |runway strip. Only in |
| | | | | |exceptional circumstances should|
| | | | | |the mast infringe the |
| | | | | |obstacle-free zone (i.e. inner |
| | | | | |transitional surface) for |
| | | | | |precision approach runways. In |
| | | | | |the latter case, the mast must |
| | | | | |be frangible, lighted and |
| | | | | |preferably shielded by an |
| | | | | |existing essential navigation |
| | | | | |aid. The site must not be |
| | | | | |affected by buildings, etc., or |
| | | | | |by aircraft operations (e.g. jet|
| | | | | |efflux during taxiing). |
|Runway visual |Transmissometer |Usually two units, |Up to three |Not more than 120 m |Should be sited within 120 m |
|range | |transmitter and |transmissometers per |laterally from runway |laterally from runway centre |
| | |receiver separated |runway (i.e. runways for |centre line. For |line but not infringing obstacle|
| | |over baseline |which RVR is required). |touchdown zone, units |free zone (i.e. inner |
| | |varying from 10 m to|For touchdown zone at both|should be 300 m along |transitional surface) for |
| | |200 m depending on |ends and at the mid-point.|runway from threshold. |precision approach runways. |
| | |range of | | |Should be frangible structure, |
| | |visibilities to be | | |e.g. tubular supports and |
| | |assessed. Height of | | |shearing bolts at foundation. |
| | |units less than 2 m | | | |
| | |(6.5 ft). Solid | | | |
| | |foundation plinths | | | |
| | |required. | | | |
|Height of cloud |Ceilometer |Usually less than |Generally representative |No specific provisions |May be located at the middle |
|base | |1.5 m (5 ft) high |of the approach area, but |so long as observations |marker site or within the runway|
| | |but rather solid |for precision approach |representative of |strip but preferably not |
| | |structure including |runways, representative |relevant operational |infringing the obstacle free |
| | |foundation plinth. |for the middle marker site|areas. |zone (i.e. inner transitional |
| | | |(where pilot on approach | |surface) for precision approach |
| | | |has to decide whether to | |runways. |
| | | |continue the approach or | | |
| | | |execute a missed approach | | |
| | | |procedure (decision | | |
| | | |height)). | | |
Figure A5-1. Schematic representation of an aerodrome
and its most important features
Figure A5-2. Obstacle limitation surfaces
Figure A5-3. Typical layout plan of meteorological instruments at an aerodrome
Appendix 6
OPERATIONALLY DESIRABLE ACCURACY OF FORECASTS
Note 1.— The guidance contained in this table relates to Annex 3, Chapter 6 — Forecasts, in particular to 6.1.1.
Note 2.— If the accuracy of the forecasts remains within the operationally desirable range shown in the second column, for the percentage of cases indicated in the third column, the effect of forecast errors is not considered serious in comparison with the effects of navigational errors and of other operational uncertainties.
|Element to |Operationally desirable |Minimum percentage of |
|be forecast |accuracy of forecasts |cases within range |
| | | |
|AERODROME FORECAST |
|Wind direction |± 30° |80% of cases |
|Wind speed |± 9 km/h (5 kt) up to 46 km/h (25 kt) |80% of cases |
| |± 20% above 46 km/h (25 kt) | |
|Visibility |± 200 m up to 700 m |80% of cases |
| |± 30% between 700 m and 10 km | |
|Precipitation |Occurrence or non-occurrence |80% of cases |
|Cloud amount |± 2 oktas |70% of cases |
|Cloud height |± 30 m (100 ft) up to 120 m (400 ft) |70% of cases |
| |± 30% between 120 m (400 ft) and 3 000 m (10 000 ft) | |
|Air temperature |± 1ûC |70% of cases |
| |
|LANDING FORECAST |
|Wind direction |± 30° |90% of cases |
|Wind speed |± 9 km/h (5 kt) up to 46 km/h (25 kt) |90% of cases |
| |± 20% above 46 km/h (25 kt) | |
|Visibility |± 200 m up to 700 m |90% of cases |
| |± 30% between 700 m and 10 km | |
|Precipitation |Occurrence or non-occurrence |90% of cases |
|Cloud amount |± 2 oktas |90% of cases |
| |± 30% between 700 m and 10 km | |
|Cloud height |± 30 m (100 ft) up to 120 m (400 ft) |90% of cases |
| |± 30% between 120 m (400 ft) and 3 000 m (10 000 ft) | |
| | |
|FORECAST FOR TAKE-OFF | |
|Wind direction |± 30° |90% of cases |
|Wind speed |± 9 km/h (5 kt) up to 46 km/h (25 kt) |90% of cases |
| |± 20% above 46 km/h (25 kt) | |
|Temperature |± 1ûC |90% of cases |
|Pressure value (QNH) |± 1 hPa |90% of cases |
|AREA, FLIGHT AND ROUTE FORECASTS |
|Upper-air temperature |± 3ûC (Mean for 900 km/500 NM) |90% of cases |
|Upper wind |± 28 km/h (15 kt) up to flight level 250 |90% of cases |
| |± 37 km/h (20 kt) above flight level 250 | |
| |(Modulus of vector difference for 900 km/500 NM) | |
|Significant en-route |Occurrence or non-occurrence |80% of cases |
|weather phenomena and cloud | | |
| |Location: ± 100 km/60 NM |70% of cases |
| | | |
| |Vertical extent: ± 600 m/2 000 ft |70% of cases |
Appendix 7
TECHNICAL SPECIFICATIONS FOR AERODROME FORECASTS
IN THE TAF CODE FORM
(See Chapter 6 of Annex 3.)
Table A7-1. Template for aerodrome forecasts in the TAF code form
Key: M = inclusion mandatory, part of every message
C = inclusion conditional, dependent on meteorological conditions or method of observation
O = inclusion optional
Note.— The ranges and resolutions for the numerical elements included in aerodrome forecasts in the TAF code form are shown in Table A7-3 of this appendix.
|Element as specified |Detailed content |Template(s) |Examples |
|in Annex 3, Chapter 6| | | |
|Identification of the|Type of report (M) |TAF or |TAF |
|type of report (M) | |TAF AMD |TAF AMD |
|Location indicator |ICAO location indicator (M) |nnnn |YUDO1 |
|(M) | | | |
|Date and time of |Date and time of the origin of|nnnnnnZ |160000Z |
|origin of forecast |the forecast in UTC (M) | | |
|(M) | | | |
|Date and period of |Date and period of the |nnnnnn |160624 |
|validity of forecast |validity of the forecast in | |080918 |
|(M) |UTC (M) | | |
|Surface wind (M) |Wind direction (M) |nnn or VRB3 |24015KMH; VRB06KMH |
| | | |(24008KT); (VRB03KT) |
| | | |19022KMH |
| | | |(19011KT) |
| |Wind speed (M) |[P]nn[n] | | | |00000KMH |
| | | | | | |(00000KT) |
| | | | | | |140P199KMH |
| | | | | | |(140P99KT) |
| |Significant speed variations |G[P]nn[n] |12012G35KMH |
| |(C)2 | |(12006G18KT) |
| | | |24032G54KMH |
| | | |(24016G27KT) |
| |Units of measurement (M) |KMH or KT | |
|Visibility (M) |Minimum visibility (M) |nnnn |C |0350 CAVOK |
| | | |A |7000 |
| | | |V |9000 |
| | | |O |9999 |
| | | |K | |
|Weather (C)4, 5 |Intensity of weather |– or + |— | | |
| |phenomena (C)6 | | | | |
| |Characteristics and type of |DZ or RA or SN or SG or PL or|FG or BR or | |RA HZ |
| |weather phenomena (M)7 |IC or GR or GS or DS or SS or|SA or DU or | |+TSRA FG |
| | |TS or TSRA or TSSN or TSPL or|HZ or FU or | |–FZDZ PRFG |
| | |TSGR or TSGS or SHRA or SHSN |VA or SQ or | | |
| | |or SHPL or SHGR or SHGS or |FZFG or DRSN| |+TSRASN |
| | |FZRA or FZDZ or BLSN or BLSA |or DRSA or | | |
| | |or BLDU or PO or FC |DRDU or MIFG| |SNRA FG |
| | | |or BCFG or | | |
| | | |PRFG | | |
|Cloud (M)8 |Cloud amount and |FEWnnn |VVnnn or |SKC or | |FEW010 VV005 SKC |
| |height of base or |or |VV /// |NSC | |OVC020 VV/// NSC |
| |vertical visibility (M) |SCTnnn or | | | | |
| | |BKNnnn or | | | |SCT005 BKN012 |
| | |OVCnnn | | | | |
| |Cloud type (C)4 |CB |— | | |SCT008 BKN025CB |
|Temperature (O)9 |Name of the element (M) |TX |TX25/13Z TN09/05Z |
| |Maximum temperature (M) |nn/ | |
| |Time of occurrence of the |nnZ | |
| |maximum temperature (M) | | |
| |Name of the element (M) |TN | |
| |Minimum temperature (M) |nn/ | |
| |Time of occurrence of the |nnZ | |
| |minimum temperature (M) | | |
|Expected significant |Change or probability |PROB30 [TEMPO] or |BECMG |FM | |
|changes to one or |indicator (M)11 |PROB40 [TEMPO] |or TEMPO | | |
|more of the above | | | | | |
|elements during the | | | | | |
|period of validity | | | | | |
|(C)4, 10 | | | | | |
| |Period of occurrence |nnnn | |
| |or change (C)4 | | |
| |Wind (C)4 |nnn[P]nn[n][G[P]nn[n]]KMH |TEMPO 1518 25070G100KMH |
| | |or |(TEMPO 1518 25035G50KT) |
| | |VRBnnKMH | |
| | |or |TEMPO 1214 17025G050KMH 1000 |
| | |nnn[P]nn[G[P]nn]KT |TSRA SCT010CB BKN020 |
| | |or |(TEMPO 1214 17012G025KT 1000 |
| | |VRBnnKT |TSRA SCT010CB BKN020) |
| |Visibility (C)4 |nnnn |C |BECMG 1011 00000KMH 2400 OVC010 |
| | | |A |(BECMG 1011 00000KT 2400 OVC010) |
| | | |V | |
| | | |O |PROB30 1214 0800 FG |
| | | |K | |
| |Weather phenomenon: |– or + |— |NSW | |BECMG 1214 RA |
| |intensity (C)6 | | | | |TEMPO 0304 FZRA |
| | | | | | | |
| | | | | | |FM1030 SN TEMPO 1215 BLSN |
| | | | | | | |
| | | | | | |PROB40 TEMPO 0608 0500 FG |
| |Weather phenomenon: |DZ or RA or SN |FG or BR or SA| | | |
| |characteristics and type |or SG or PL or |or DU or HZ or| | | |
| |(C)4, 7, 10 |IC or GR or GS |FU or VA or SQ| | | |
| | |or DS or SS or |or FZFG or | | | |
| | |TS or TSRA or |DRSN or DRSA | | | |
| | |TSSN or TSPL or|or DRDU or | | | |
| | |TSGR or TSGS or|MIFG or BCFG | | | |
| | |SHRA or SHSN or|or PRFG | | | |
| | |SHPL or SHGR or| | | | |
| | |SHGS or FZRA or| | | | |
| | |FZDZ or BLSN or| | | | |
| | |BLSA or BLDU or| | | | |
| | | | | | | |
| | |PO or FC | | | | |
| |Cloud amount and height of |FEWnnn or |VVnnn or |SKC or NSC | |FM1230 15015KMH 9999 BKN020 BKN100 |
| |base or vertical visibility |SCTnnn or |VV/// | | |(FM1230 15008KT 9999 BKN020 BKN100) |
| |(C)4 |BKNnnn or | | | | |
| | |OVCnnn | | | |BECMG 1820 8000 NSW NSC |
| |Cloud type (C)4 |CB |— | | |BECMG 0608 SCT015CB BKN020 |
| |
|1. Fictitious location. |
|2. To be included if the maximum is exceeding the mean speed by 20 km/h (10 kt). |
|3. To be used only if the wind speed < 6 km/h (3 kt). |
|4. To be included whenever applicable. |
|5. One or more, up to a maximum of three groups. |
|6. To be included whenever applicable. No qualifier for moderate intensity; only qualifier “+” (i.e. well-developed) to be used with PO and |
|FC. |
|7. Precipitation types DZ, RA, SN, SG, PL, IC, GR and GS may be combined, where appropriate. Only moderate or heavy precipitation should be |
|indicated. |
|8. Up to four cloud layers. |
|9. To be included subject to regional air navigation agreement. |
|10. To be included when a change in some or all of the elements forecast is expected to occur; may be placed after any element forecast, as |
|appropriate. |
|11. Number of change indicators to be kept to a minimum; normally not exceeding five groups. |
Table A7-2. Use of change and time indicators in aerodrome forecasts in the TAF code form
|Change or time |Time period |Meaning |
|indicator | | |
|FM |nhnhnmnm |used to indicate a significant change in most weather elements occurring at nhnh hours |
| | |and nmnm minutes (UTC); |
| | |all the elements given before “FM” are to be included following “FM” (i.e. they are all|
| | |superseded by those following the abbreviation) |
|BECMG |n1n1n2n2 |the change is forecast to commence at n1n1 hours (UTC) and be completed by n2n2 hours |
| | |(UTC); |
| | |only those elements for which a change is forecast are to be given following “BECMG”; |
| | |the time period n1n1n2n2 should normally be less than 2 hours and in any case should |
| | |not exceed 4 hours |
|TEMPO |n1n1n2n2 |temporary fluctuations are forecast to commence at n1n1 hours (UTC) and cease by n2n2 |
| | |hours (UTC); |
| | |only those elements for which fluctuations are forecast are to be given following |
| | |“TEMPO”; |
| | |temporary fluctuations should not last more than one hour in each instance, and in the |
| | |aggregate, cover less than half of the period n1n1n2n2 |
|PROBnn |— |n1n1n2n2 |probability of occurrence (in %) of an |— |
| | | |alternative value of a forecast element or | |
| | | |elements; | |
| | | |nn = 30 or nn = 40 only; | |
| | | |to be placed after the element(s) concerned| |
| |TEMPO |n1n1n2n2 | |probability of occurrence of temporary |
| | | | |fluctuations |
EXAMPLE OF AN AERODROME FORECAST
|TAF for YUDO (Donlon/International)*: |
| |
|TAF YUDO 160000Z 160624 13018KMH 9000 BKN020 BECMG 0608 SCT015CB BKN020 TEMPO 0812 17025G40KMH 1000 TSRA SCT010CB BKN020 FM1230 15015KMH 9999 |
|BKN020 BKN100 |
| |
|Meaning of the forecast: |
| |
|Aerodrome forecast for Donlon/International* issued on the 16th of the month at 0000 UTC valid from 0600 UTC to 2400 UTC on the 16th of the |
|month; surface wind direction 130 degrees; wind speed 18 kilometres per hour; visibility 9 kilometres, broken cloud at 600 metres; becoming |
|between 0600 UTC and 0800 UTC, scattered cumulonimbus cloud at 450 metres and broken cloud at 600 metres; temporarily between 0800 UTC and |
|1200 UTC surface wind direction 170 degrees; wind speed 25 kilometres per hour gusting to 40 kilometres per hour; visibility 1 000 metres in a|
|moderate thunderstorm with rain, scattered cumulonimbus cloud at 300 metres and broken cloud at 600 metres; from 1230 UTC surface wind |
|direction 150 degrees; wind speed 15 kilometres per hour; visibility 10 km or more; broken cloud at 600 metres and broken cloud at 3 000 |
|metres. |
| |
|Note.— In this example, the primary units “kilometre per hour” and “metre” were used for wind speed and height of cloud base respectively. |
|However, in accordance with Annex 5, the corresponding non-SI alternative units “knot” and “foot” may be used instead. |
| |
|* Fictitious location |
Table A7-3. Ranges and resolutions for the numerical elements
included in meteorological messages in the TAF code form
|Element as specified in Annex 3, Chapter 6 |Range |Resolution |
|Wind direction: |° true |000 – 360 |10 |
|Wind speed: |KMH |00 – 3991 |1 |
| |KT |00 – 1991 |1 |
|Visibility: |M |0000 – 0800 |50 |
| |M |0800 – 5000 |100 |
| |M |5000 – 9000 |1000 |
| |M |9000 – 9999 |999 |
|Vertical visibility: |30’s M (100’s FT) |000 – 020 |1 |
|Cloud: height of base: |30’s M (100’s FT) |000 – 100 |1 |
| |30’s M (100’s FT) |100 – 200 |10 |
|Air temperature (maximum and minimum): |ûC |–80 – +60 |1 |
| |
|1. There is no aeronautical requirement to report surface wind speeds of 200 km/h (100 kt) or more; however, provision has been made |
|for reporting wind speeds up to 399 km/h (199 kt) for non-aeronautical purposes, as necessary. |
Appendix 8
CRITERIA FOR TREND-TYPE LANDING FORECASTS
|Element |Observed value |Trend-type landing forecasts to be issued when |
| |(given in report) |one or more of the following changes are expected |
|1. Surface wind | |Mean speed |Change in direction |Mean speed after the |
| | | | |change in direction |
|1.1 |Less than 20 km/h (10 kt) |60° or more |20 km/h (10 kt) or more | |
|1.2 |20 km/h (10 kt) or more |60° or more |Any speed | |
|1.3 |Any speed |Changes through values of | | |
| | |operational significance1 | | |
| | |Change in mean speed | | |
|1.4 |Any speed |20 km/h (10 kt) or more | | |
|2. Visibility | |Visibility reaching or passing | | |
| | |any one of the following values: | | |
| | |150 m | | |
| | |350 m | | |
| | |600 m | | |
| | |800 m | | |
| | |1 600 m | | |
| | |3 000 m | | |
| | |5 000 m2 | | |
|3. Weather |— freezing precipitation |Onset, cessation or change | | |
| |— freezing fog |in intensity | | |
| |— moderate or heavy | | | |
| |precipitation (including showers| | | |
| |thereof) | | | |
| |— low drifting dust, sand or | | | |
| |snow | | | |
| |— blowing dust, sand or snow | | | |
| |(including snowstorm) | | | |
| |— duststorm or sandstorm | | | |
| |— thunderstorm (with or without | | | |
| |precipitation) | | | |
| |— squall | | | |
| |— funnel cloud (tornado or water| | | |
| |spout) | | | |
| |— other weather phenomena given | | | |
| |in 4.8.4 of Annex 3 only if they| | | |
| |are expected to cause a | | | |
| |significant change in visibility| | | |
|4. Cloud |Amount |Height of base |Amount |Height of base |
|4.1 |BKN or OVC |Below 450 m |BKN or OVC |Changing to or passing |
| | |(1 500 ft) | |(either upwards or |
| | | | |downwards) any one of |
| | | | |the following values: |
| | | | |30 m (100 ft) |
| | | | |60 m (200 ft) |
| | | | |150 m (500 ft) |
| | | | |300 m (1 000 ft) |
| | | | |450 m (1 500 ft) |
|4.2 |BKN or OVC |At or above |BIKINI or OVC |Below 450 m |
| | |450 m (1 500 ft) | |(1 500 ft) |
|4.3 |SKC, FEW or SCT |Below 450 m |BKN or OVC | |
| | |(1 500 ft) | | |
|4.4 |BKN or OVC |Below 450 m |SKC, FEW or SCT | |
| | |(1 500 ft) | | |
|4.5 |SKC, FEW or SCT |At or above |BKN or OVC |Below 450 m |
| | |450 m (1 500 ft) | |(1 500 ft) |
|4.6 |BKN or OVC |At or above |SKC, FEW or |Below 450 m |
| | |450 m (1 500 ft) |SCT |(1 500 ft) |
|5. Vertical |Sky expected to become or remain| | |Vertical visibility |
|visibility (at |obscured | | |passing any one of the |
|aerodromes where such| | | |following values: |
|observations are | | | |30 m (100 ft) |
|available) | | | |60 m (200 ft) |
| | | | |150 m (500 ft) |
| | | | |300 m (1 000 ft) |
|1. The threshold values considered to be of operational significance are to be established by the meteorological authority in consultation |
|with the appropriate ATS authority and the operators concerned, taking into account changes in the wind which would require a change in the |
|runway(s) in use, and/or which would indicate that the runway tailwind or crosswind component will change through values representing the |
|main operating limits for typical aircraft operating at the airport. |
|2. 5 000 m is also used as a criterion when significant numbers of flights are conducted in accordance with the visual flight rules. |
Appendix 9
MODEL CHARTS AND FORMS
(See 9.4 to 9.8 of Annex 3.)
MODEL A — Aerodrome forecasts
Example 1 — Tabular form
Example 2 — TAF code form
MODEL TA — Tabular forecast of en-route conditions
Example 1 — Low level
Example 2 — Medium/high level
MODEL TB — Tabular forecast of upper winds and upper-air temperatures
Example 1 — Spot locations
Example 2 — Grid mesh
MODEL IS — Upper wind and temperature chart for standard isobaric surface
Example 1 — Arrows and feathers (Mercator projection)
Example 2 — Arrows and feathers (Polar stereographic projection)
MODEL SWH — Significant weather chart (high level)
Example 1 — Mercator projection
Example 2 — Polar stereographic projection
MODEL SWM — Significant weather chart (medium level)
MODEL SWL — Significant weather chart (low level)
Example 1
Example 2
MODEL VAG — Volcanic ash advisory information in graphical format
MODEL SN — Sheet of notations used in flight documentation
Model A. Aerodrome forecasts
Example 1 — Tabular form
|ISSUED BY METEOROLOGICAL OFFICE DATE TIME (UTC) |
|HEIGHTS ABOVE AERODROME ELEVATION |
|Aerodrome |Period of |Type and |Surface wind mean |Surface |Significant |Cloud |Forecast |Remarks |
| |validity |time of |direction |visibility |weather | |temperature | |
| |(UTC) |change |(degrees true) |(minimum) | | |(degrees Celsius) | |
| | | |mean wind speed | | | | | |
| | | |maximum wind speed | | | | | |
| | | | | | |Lowest layer |Higher layers | | |
| | | | | | |amount, height of |amount, height of | | |
| | | | | | |base (feet) and |base (feet) and | | |
| | | | | | |type (if CB) |type (if CB) | | |
|MOMBASA |06–06 | |150/15 KT |10 KM | |FEW 1500 |
| | |TEMPO 09–12 |VRB/20 KT |200 M |HVY SHRA |SCT 1000 CB |
| | | |MAX 30 KT | | | |
|ROME |
| |
| |
|INTENSITY |
| |
|“–” (light); no indicator (moderate); “+” (heavy, or well-developed in the case of dust/sand whirls (dust devils) and funnel |
|clouds) are used to indicate the forecast intensity of certain phenomena |
| | |
| | | | | | | | | | |
| |DZ |— |drizzle |BR |— |mist |PO |— |dust/sand whirls (dust devils) |
| |RA |— |rain |FG |— |fog |SQ |— |squall |
| |SN |— |snow |FU |— |smoke |FC |— |funnel cloud(s) (tornado or waterspout) |
| |SG |— |snow grains |VA |— |volcanic ash |SS |— |sandstorm |
| |IC |— |ice crystals (diamond dust) |DU |— |widespread dust |DS |— |duststorm |
| |PL |— |ice pellets |SA |— |sand | | | |
| |GR |— |hail |HZ |— |haze | | | |
| |GS |— |small hail and/or snow pellets | | | | | | |
| | | | | | | |
| |EXAMPLES | | | |
| | | | | | | |
| |+SHRA |— |heavy shower of rain |TSSN |— |moderate thunderstorm with snow |
| |+FZDZ |— |moderate freezing drizzle |SNRA |— |moderate snow and rain |
| |+TSSNGR |— |heavy thunderstorm with snow and hail | | | |
| | | | | | | |
| | | | |
| |SELECTED ICAO LOCATION INDICATORS | | |
| | | | | | | |
| |CYUL |Montreal Intl/Dorval |KJFK |New York/John F. Kennedy Intl |RJTT |Tokyo Intl |
| |EDDF |Frankfurt/Main |LFPG |Paris/Charles de Gaulle |SBGL |Rio de Janeiro Intl/Gale‹o |
| |EGLL |London/Heathrow |NZAA |Auckland Intl |YSSY |Sydney/Kingsford Smith Intl |
| |HKNA |Nairobi/Jomo Kenyatta Intl |OBBI |Bahrain Intl |ZBAA |Beijing/Capital |
| | | | | | | |
| | | | | | | |
| |RJTT |122130Z |130024 VRB03KT 4000 SCT025 BECMG 0305 9999 T30/12Z T20/06Z = |
| |EGLL |090845Z |091212 27010KT 9999 SCT020 BKN080 FM2100 30015KT |
| | | |3000 FZDZ BKN006 OVC060 FM0000 30015KT 0800 +RASN |
| | | |BKN004 OVC060 BECMG 0305 33020KT 5000 NSW SCT020 |
| | | |BKN100 BECMG 0709 9999 = |
| |LFPG |160910Z |161212 10008KT CAVOK FM2000 VRB03KT 8000 |
| | | |SCT012 FM0400 VRB03KT 0800 FG FM0900 10008KT CAVOK = |
| |OBBI |030300Z |030624 03010KT 9999 SCT010 PROB30 TEMPO |
| | | |0915 03030KT 0500 BLSA FM1800 VRB02KT 8000 SCT020 = |
| |HKNA |280215Z |280624 06010KT 9999 SCT025 TEMPO 1216 |
| | | |3000 SHRA BKN015 PROB40 TEMPO 1416 VRB20G30KT |
| | | |+TSRA SCT010CB BKN015 = |
Model TA. Tabular forecast of en-route conditions
Example 1 — Low level
|DATE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
|HEIGHTS IN FEET ABOVE MSL |
|ROUTE FROM . . . . . . . . . . . . . . . . . . . TO . . . . . . . . . . . . . . . . . . . VIA . . . . . . . . . . . . . . . |
|. . . . . |
|VALID FOR DEPARTURE BETWEEN . . . . . . . . . . . . . . . . . UTC AND . . . . . . . . . . . . . UTC AND |
|FOR ARRIVAL BETWEEN . . . . . . . . . . . . . . . . . . . . . . . . UTC AND . . . . . . . . . . . . . UTC |
|SPECIAL FEATURES OF THE METEOROLOGICAL SITUATION: |
| |
|ACTIVE COLD FRONT FROM HUMBER TO CHANNEL ISLES AT 1000 UTC MOVING EAST AT 20 KNOTS TO LIE NORTH/SOUTH ACROSS TRACK ABOUT 40 |
|NM WEST OF AMSTERDAM BY 1900 UTC. |
|ZONE |LONDON 02°E AMSTERDAM |
|UPPER WINDS | | |
|(DEGREES TRUE AND KNOTS) 10 000 ft |280/30 MS 12 |250/45 MS 09 |
|TEMPERATURES 5 000 ft |290/25 MS 03 |240/35 00 |
|(DEGREES CELSIUS) 2 000 ft |290/20 PS 03 |230/30 PS 06 |
|CLOUD | SCT CU XXX | ISOL EMBD CB XXX |
| |1500 |1000 |
| | BKN SC 10 000 | BKN ST 800 |
| |2500 |500 |
| | BKN AC LYR XXX | OVC SC XXX |
| |12 000 |AS LYR 2000 |
|SURFACE VISIBILITY |1 500 M IN SHOWERS |4000 M IN MODERATE RAIN AND |
| | |1000 M IN THUNDERSTORMS |
|SIGNIFICANT WEATHER | | ISOL THUNDERSTORMS |
| |MODERATE OCNL 10 000 | |
| |SEVERE ICING 3500 |MODERATE OCNL XXX |
| | |SEVERE ICING 5000 |
| | | |
| | |MODERATE OCNL SEVERE |
| | |TURBULENCE IN XXX |
| | |FRONTAL ZONE 1000 |
|HEIGHT OF 0°C ISOTHERM |3500 |5000 |
|FORECAST LOWEST QNH (hPa) |1008 |1004 |
|Issued by . . . . . . . . . . at . . . . . . . . . . . UTC on . . . . . . . . . . . . . . 20 . . . . by . . . . . . . . . |
|. Forecaster. |
| |
|Notes: 1. Positive and negative values are indicated by the prefix “PS” (plus) and “MS” (minus) respectively. |
|2. When a single numerical value of an element is given in a forecast it is to be interpreted as representing the most |
|probable mean of a range of values which the element may assume during the period of the forecast. |
| |
|Abbreviations: SKC — 0 oktas, FEW — 1 to 2 oktas, SCT — 3 to 4 oktas, BKN — 5 to 7 oktas, OVC — 8 oktas, LYR — Layered, LOC |
|— Locally, ISOL — Isolated, OCNL — Occasional, FRQ — Frequent, EMBD — Embedded. |
Model TA. Tabular forecast of en-route conditions
Example 2 — Medium/high level
|DATE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . HEIGHTS IN PRESSURE ALTITUDE IN HUNDREDS OF FEET |
|ROUTE FROM . . . . . . . . . . . . . . . . . . . TO . . . . . . . . . . . . . . . . . . . VIA . . . . . . . . . . . . . . . . . . |
|VALID FOR DEPARTURE BETWEEN . . . . . . . . . . . . . . . . . UTC AND . . . . . . . . . . . . . UTC AND |
|FOR ARRIVAL BETWEEN . . . . . . . . . . . . . . . . . . . . . . . . UTC AND . . . . . . . . . . . . . UTC |
|SPECIAL FEATURES OF THE METEOROLOGICAL SITUATION (SURFACE CENTRES AND FRONTS): |
| |
|ACTIVE COLD FRONT FROM HUMBER TO CHANNEL ISLES AT 1000 UTC MOVING EAST AT 20 KNOTS TO |
|LIE NORTH/SOUTH ACROSS TRACK ABOUT 40 NM WEST OF AMSTERDAM BY 1900 UTC. |
|ZONE |LONDON 02°E AMSTERDAM |
|UPPER WINDS FL 300 |250/50 MS 52 |230/65 MS 50 |
|(DEGREES TRUE AND KNOTS) FL 240 |260/40 MS 40 |240/60 MS 36 |
|TEMPERATURES FL 180 |270/35 MS 26 |240/50 MS 24 |
|(DEGREES CELSIUS) FL 100 |280/30 MS 12 |250/45 MS 09 |
|SIGNIFICANT WEATHER | MODERATE TURBULENCE 180 | ISOL THUNDERSTORMS |
|AND ASSOCIATED CLOUD |XXX |300 |
| | |MODERATE TO SEVERE XXX |
| | |ICING AND TURBULENCE |
|* TROPOPAUSE HEIGHT |—————— |—————— |
|* JET STREAM |—————— |—————— |
|* Above planned cruise level if not specified. | | |
| |
| |
| |
| |
|Issued by . . . . . . . . . . at . . . . . . . . . . UTC on . . . . . . . . . . . . 20 . . . . by . . . . . . . . . . Forecaster. |
| |
| |
| |
| |
|Notes: 1. Pressure altitude is the height in feet of a level in the standard atmosphere above the datum level corresponding to a pressure |
|of 1013.2 hPa. |
| |
|2. Positive and negative values are indicated by the prefix “PS” (plus) and “MS” (minus) respectively. |
| |
|3. Only cloud associated with significant weather is shown. Low stratus and fog, when expected, will be shown for terminal areas in |
|appropriate aerodrome forecasts. |
| |
|4. When a single numerical value of an element is given in a forecast, it is to be interpreted as representing the most probable mean of a |
|range of values which the element may assume during the period of the forecast. |
| |
|Abbreviations: SKC — 0 oktas, FEW — 1 to 2 oktas, SCT — 3 to 4 oktas, BKN — 5 to 7 oktas, OVC — 8 oktas, LYR — Layered, LOC — Locally, ISOL|
|— Isolated, OCNL — Occasional, FRQ — Frequent, EMBD — Embedded. |
Model TB. Tabular forecast of upper winds and upper-air temperatures
Example 1 – Spot locations
Example 2 – Grid mesh (from WINTEM)
Model IS. Upper wind and temperature chart for standard isobaric surface
Example 1 – Arrows and feathers (Mercator projection)
Example 2 – Arrows and feathers (Polar stereographic projection)
Model SWH. Significant weather chart (high level)
Example 1 – Mercator projection
Example 2 – Polar stereographic projection
Model SWM. Significant weather chart (medium level)
Model SWL. Significant weather chart (low level)
Example 1
Example 2
Model VAG. Volcanic ash advisory information in graphical format
Model SN. Sheet of notifications used in flight documentation
Appendix 10
GUIDANCE ON AREA FORECASTS IN
ABBREVIATED PLAIN LANGUAGE
(See 3.2.14, 3.2.15, 3.3.1 and 3.3.9 of Annex 3.)
PART 1 — FORMAT FOR ABBREVIATED PLAIN-LANGUAGE SIGNIFICANT WEATHER FORECAST
MESSAGES AND AMENDMENTS THERETO TO SERVE INTERNATIONAL CIVIL AVIATION
IN OPERATIONS ABOVE FLIGHT LEVEL 250
1. Specifications
1.1 For the purpose of these instructions, “abbreviated plain language” refers to a language conveying to aeronautical personnel a directly intelligible meaning through the use of abbreviations (except signals of the Q code) approved by ICAO and numerical values of self-explanatory nature supplemented, if suitable ICAO-approved abbreviations are not available, by other words taken with their usual meaning in aviation.
Note.— ICAO-approved abbreviations are published in the PANS-ABC (Doc 8400). Signals of the Q code should not be used in abbreviated plain-language significant weather area forecast messages.
1.2 In abbreviated plain-language significant weather forecast messages, the term “CB” should be understood to include pertinent weather phenomena normally associated with cumulonimbus, namely thunderstorms, moderate or severe turbulence, moderate or severe icing, and hail.
1.3 An abbreviated plain-language significant weather forecast message should be consistent with the significant weather forecast chart from which it was derived.
1.4 The format should be as follows:
a) World Meteorological Organization abbreviated heading.
b) Type of message; applicable vertical range; valid time; area to which the forecast message relates. Describe the forecast area by reference to latitude, to longitude, to latitude/longitude coordinates, to major geographical features, or to any combination thereof. Describe, in the same manner, any part of the area for which a significant weather forecast cannot be given because of lack of data.
c) Synopsis. Include descriptions of significant weather features, such as tropical cyclones, surface positions of frontal systems and well-defined convergence zones; their forecast positions; their speed and direction of movement; and intensification or weakening, if considered significant. Give forecast positions as in b). Describe direction of movement in terms of eight points of the compass related to true north; give speed of movement in kilometres per hour or knots.
d) Significant weather phenomena. Describe areas as in b). Describe the amount of cumulonimbus as ISOL EMBD CB (individual embedded cumulonimbus with a maximum spatial coverage of cumulonimbus less than 50 per cent of the area affected, or forecast to be affected, by the phenomenon) or ISOL CB IN HAZE (individual cumulonimbus concealed in haze with a maximum spatial coverage less than 50 per cent of the area affected, or forecast to be affected, by the phenomenon); OCNL EMBD CB (well-separated embedded cumulonimbus with a maximum spatial coverage of cumulonimbus between 50 and 75 per cent of the area affected, or forecast to be affected, by the phenomenon) or OCNL CB IN HAZE (well-separated cumulonimbus concealed in haze with a maximum spatial coverage between 50 and 75 per cent of the area affected, or forecast to be affected, by the phenomenon); or FRQ CB (cumulonimbus clouds with little or no separation with a maximum spatial coverage greater than 75 per cent of the area affected, or forecast to be affected, by the phenomenon). Describe cumulonimbus clouds contained in layers of other clouds as EMBD. Give bases and tops of significant weather phenomena as flight level (FL). If no significant weather is forecast, enter the term “SIGWX NIL”.
Note.— Give bases of significant weather phenomena only if expected to be at or above the lowest level of the atmosphere for which the forecast is prepared. Similarly, give the tops of significant weather phenomena only if expected to be at or below the highest level of the atmosphere for which the forecast is prepared.
e) Turbulence. This should include turbulence, other than that associated with cumulonimbus, if expected to be moderate or severe, and the intensity thereof. Describe areas as in b). Give bases and tops of phenomenon as FL. If no turbulence in this category is forecast, no entry for turbulence should be given.
Note.— See Note under 1.4 d) for similar application.
f) Volcanic eruptions. Include information on the location of volcanic eruptions which are producing ash clouds of significance to aircraft operations, including those producing only steam, comprising: the name of the volcano, its international number, latitude/longitude, the date and time of first eruption, if known, together with a reminder to users that reference should be made to SIGMETs and NOTAM or ASHTAM issued for the area concerned.
g) Radioactive materials in the atmosphere. Information on the location of an accidental release of radioactive materials into the atmosphere, of significance to aircraft operations, comprising: latitude/longitude of the site of the accident, date and time of accident and a reminder to users to check NOTAM for the area concerned.
2. Examples
Examples of abbreviated plain-language significant weather messages are given below.
|Example 1 |
| |
|FAPN13 KWBC 101200 |
|AREA FCST FL250 TO FL450 VALID 110000 FOR AREA N37E135 N48W108 N28W130 N28E158 N37E135. |
| |
|SYNOPSIS. COLD FRONT N45W179 N33W179 MOV E 20 KT. COLD FRONT N43W152 N44W140 N35W131 |
|N29W134 MOV NE 15 KT INTSF. |
| |
|SIGWX NIL |
| |
|TURB. MOD CAT FL260 TO FL340 N36E140 N36E150 N34E141 N36E140. MOD CAT FL280 TO FL380 N41W133 |
|N45W125 N42W117 N40W120 N41W133. |
|Example 2 |
| |
|FAEWI EJJJ 101300 |
|AREA FCST FL250 TO FL450 VALID 110000 FOR AREA N50W20 N50E20 N30E20 N30W20 N50W20. |
| |
|SYNOPSIS. NO MAJOR WX SYSTEM. |
| |
|SIGWX NIL. |
|Example 3 |
| |
|FANT10 KWBC 101200 |
|AREA FCST FL250 TO FL600 VALID 110000 FOR AREA N55W88 N50E42 N33E13 N27W59 N55W88. |
| |
|SYNOPSIS. WARM FRONT N42W84 N43W79 N39W62 MOV NE 30 KT. OCCLUDED FRONT N63W40 N60W25 |
|N50W29 MOV E 35 KT. COLD FRONT N50W29 N40W43 N31W60 MOV SE 10 KT INTSF. |
| |
|SIGWX AND ASSOCIATED CLD. ISOL EMBD CB TOPS FL340 N55E20 N55E30 N46E34 N44E24 N55E20. |
| |
|TURB. MOD CAT FL250 TO FL340 N46W41 N53W40 N56W28 N50W32 N46W41. MOD CAT FL250 TO FL350 |
|N62W30 N67W13 N63W08 N61W20 N62W30. |
|Example 4 |
| |
|FANT10 KWBC 101400 AMD |
|AMD AREA FCST FL250 TO FL600 VALID 110000 FOR AREA N55W88 N50E42 N33E13 N27W59 N55W88. |
| |
|SYNOPSIS. NO MAJOR WX SYSTEM. |
| |
|SIGWX AND ASSOCIATED CLD. FRQ CB TOPS FL480 N48W80 N46W65 N41W65 N45W79 N48W80. |
| |
|OTHER AMD NIL. |
|Example 5 |
| |
|FAXT1 KWBC 101200 |
|AREA FCST FL250 TO FL600 VALID 110000 FOR AREA N50W160 N50W43 S20W43 S20W160 N50W160. FCST NIL |
|FOR AREA SOUTH OF EQUATOR DUE LACK OF DATA. |
| |
|SYNOPSIS. WARM FRONT N41W85 N43W80 N39W70 N39W61 MOV NE 30 KT. COLD FRONT N41W85 N29W94 |
|MOV SE 25 KT. STNR FRONT N40W43 N30W63. COLD FRONT N49W132 N45W130 N40W133 N30W144 MOV NE |
|15 KT INTSF. |
| |
|SIGWX NIL. |
| |
|TURB. MOD CAT FL280 TO FL380 N41W116 N44W120 N45W125 N43W130 N42W133 N41W130 N39W116 |
|N41W116. MOD CAT FL280 TO FL380 N44W105 N41W109 N39W105 N44W105. MOD CAT FL240 TO FL350 |
|N50W70 N50W81 N44W87 N42W85 N45W75 N48W70 N50W70. |
PART 2 — FORMAT FOR ABBREVIATED PLAIN-LANGUAGE SIGNIFICANT WEATHER FORECAST
MESSAGES AND AMENDMENTS THERETO TO SERVE INTERNATIONAL CIVIL AVIATION
IN OPERATIONS BETWEEN FLIGHT LEVELS 100 AND 250
1. Specifications
1.1 For the purpose of these instructions, “abbreviated plain language” refers to a language conveying to aeronautical personnel a directly intelligible meaning through the use of abbreviations (except signals of the Q code) approved by ICAO and numerical values of self-explanatory nature supplemented, if suitable ICAO-approved abbreviations are not available, by other words taken with their usual meaning in aviation.
Note.— ICAO-approved abbreviations are published in the PANS-ABC (Doc 8400). Signals of the Q code should not be used in abbreviated plain-language significant weather area forecast messages.
1.2 In abbreviated plain-language significant weather forecast messages, the term “CB” should be understood to include pertinent weather phenomena normally associated with cumulonimbus, namely thunderstorms, moderate or severe turbulence, moderate or severe icing, and hail.
1.3 An abbreviated plain-language significant weather forecast message should be consistent with the significant weather forecast chart from which it was derived.
1.4 The format should be as follows:
a) World Meteorological Organization abbreviated heading.
b) Type of message; applicable vertical range; valid time; area to which the forecast message relates. Describe the forecast area by reference to latitude, to longitude, to latitude/longitude coordinates, to major geographical features, or to any combination thereof. Describe, in the same manner, any part of the area for which a significant weather forecast cannot be given because of lack of data.
c) Synopsis. Include descriptions of significant weather features, such as tropical cyclones, surface positions of frontal systems and well-defined convergence zones; their forecast positions; their speed and direction of movement; and intensification or weakening, if considered significant. Give forecast positions as in b). Describe direction of movement in terms of eight points of the compass related to true north; give speed of movement in kilometres per hour or knots.
d) Significant weather phenomena and associated clouds. Describe areas as in b). Give cloud amounts, except for cumulonimbus clouds, in terms of FEW (1 to 2 oktas), SCT (3 to 4 oktas), BKN (5 to 7 oktas), or OVC (8 oktas). Describe the amount of cumulonimbus as ISOL EMBD CB (individual embedded cumulonimbus with a maximum spatial coverage of cumulonimbus less than 50 per cent of the area affected, or forecast to be affected, by the phenomenon) or ISOL CB IN HAZE (individual cumulonimbus concealed in haze with a maximum spatial coverage less than 50 per cent of the area affected, or forecast to be affected, by the phenomenon); OCNL EMBD CB (well separated embedded cumulonimbus with a maximum spatial coverage of cumulonimbus between 50 and 75 per cent of the area affected, or forecast to be affected, by the phenomenon) or OCNL CB IN HAZE (well-separated cumulonimbus concealed in haze with a maximum spatial coverage between 50 and 75 per cent of the area affected, or forecast to be affected, by the phenomenon); or FRQ CB (cumulonimbus clouds with little or no separation with a maximum spatial coverage greater than 75 per cent of the area affected, or forecast to be affected, by the phenomenon). Describe cumulonimbus clouds contained in layers of other clouds as EMBD. Give bases and tops of significant weather phenomena and associated clouds as flight level (FL). If no significant weather is forecast, enter the term “SIGWX NIL”.
e) Turbulence. This should include turbulence, other than that associated with cumulonimbus, if expected to be moderate or severe, and the intensity thereof. Describe areas as in b). Give bases and tops of phenomenon as FL. If no turbulence in this category is forecast, no entry for turbulence should be given.
f) Icing. This should include icing, other than that associated with cumulonimbus, if expected to be moderate or severe, and the intensity thereof. Should also include icing in area(s) of forecast, freezing precipitation. Describe areas as in b). Give bases and tops of phenomenon as FL. If aircraft icing, other than that associated with cumulonimbus, is not forecast, no entry for icing should be given.
g) Volcanic eruptions. Include information on the location of volcanic eruptions which are producing ash clouds of significance to aircraft operations, including those producing only steam, comprising: the name of the volcano, its international number, latitude/longitude, the date and time of first eruption, if known, together with a reminder to users that reference should be made to SIGMETs and NOTAM or ASHTAM issued for the area concerned.
Note.— Give bases of significant weather phenomena (and associated clouds, if any) only if expected to be at or above the lowest level of the atmosphere for which the forecast is prepared. Similarly, give the tops of significant weather phenomena (and associated clouds, if any) only if expected to be at or below the highest level of the atmosphere for which the forecast is prepared.
h) Radioactive materials in the atmosphere. Information on the location of an accidental release of radioactive materials into the atmosphere, of significance to aircraft operations, comprising: latitude/longitude of the site of the accident, date and time of accident and a reminder to users to check NOTAM for the area concerned.
2. Examples
Examples of abbreviated plain-language significant weather messages are given below.
|Example 1 |
| |
|FAPN16 KWBC 101200 |
|AREA FCST FL100 TO FL250 VALID 110000 FOR AREA N37E135 N48W108 N28W130 N28E158 N37E135. |
| |
|SYNOPSIS. COLD FRONT N45W179 N33W179 MOV E 20 KT. COLD FRONT N43W152 N44W140 N35W131 N29W134 MOV NE 15 KT INTSF. |
| |
|SIGWX NIL. |
| |
|ICE. MOD ICE INC FL100 TO FL180 N42W140 N46W145 N47W138 N42W140. |
|Example 2 |
| |
|FANT14 KWBC 101200 |
|AREA FCST FL100 TO FL250 VALID 110000 FOR AREA N55W88 N50E42 N33E13 N27W59 N55W88. |
| |
|SYNOPSIS. WARM FRONT N42W84 N43W79 N39W62 MOV NE 30 KT. OCCLUDED FRONT N63W40 N60W25 N50W29 MOV E 35 KT. COLD FRONT N40W29 N40W43 N31W60 MOV |
|SE 10 KT INTSF. |
| |
|SIGWX AND ASSOCIATED CLD. ISOL EMBD CB N44E20 N55E30 N46E34 N44E24 N44E20. |
| |
|TURB. MOD CAT BASE FL240 N47W41 N53W40 N56W28 N50W32 N47W41. MOD CAT BASE FL250 N62W30 N67W13 N63W08 N61W20 N62W30. |
| |
|ICE. MOD ICE INC FL100 TO FL130 N55W03 N49W08 N43W00 N44E10 N50E14 N55E03. |
|Example 3 |
| |
|FANT14 KWBC 101400 AMD |
|AMD AREA FCST FL100 TO FL250 VALID 110000 FOR AREA N55W88 N40E42 N33E13 N27W59 N55W88. |
| |
|SYNOPSIS. WARM FRONT N42W84 N43W79 N39W62 MOV NE 10 KT INTSF. |
| |
|SIGWX AND ASSOCIATED CLD. FRQ CB N48W80 N46W65 N41W65 N45W79 N48W80 INTSF. |
| |
|OTHER AMD NIL. |
PART 3 — FORMAT FOR MESSAGES CONTAINING ABBREVIATED PLAIN-LANGUAGE
AMENDMENTS TO UPPER-AIR FORECASTS
1. Specifications
1.1 For the purpose of these instructions, “abbreviated plain language” refers to a language conveying to aeronautical personnel a directly intelligible meaning through the use of abbreviations (except signals of the Q code) approved by ICAO and numerical values of self-explanatory nature supplemented, if suitable ICAO-approved abbreviations are not available, by other words taken with their usual meaning in aviation.
Note.— ICAO-approved abbreviations are published in the PANS-ABC (Doc 8400). Signals of the Q code should not be used in abbreviated plain-language messages issued as amendments to relevant upper-air wind and temperature forecasts.
1.2 Abbreviated plain-language amendments to upper-air forecasts should be understood to apply to all relevant forecasts prepared by world and regional area forecast centres for any specified area, level and valid time(s). Such forecasts could include meteorological charts, grid-point data in numerical form and grid-point data in digital form.
1.3 The area and levels for which amendments to upper-air forecasts are to be issued should be described with regard to horizontal dimensions by applicable latitude/longitude coordinates and with regard to vertical dimensions by applicable ICAO flight levels related to standard constant pressure surfaces.
1.4 To minimize the possibility of misinterpretation of the amendments, the procedures given below should be followed:
a) amendments should be issued in abbreviated plain language as an amended area forecast under a World Meteorological Organization abbreviated heading, using as date time group the standard time of observation in UTC on which the original forecast was based;
b) the amendment criteria given by Annex 3, 3.2.12 should be followed;
c) the valid time(s) to which an amendment is intended to apply should be given in terms of 12, 18, 24 and/or 30 hours following the standard time in UTC on which the original forecast was based;
d) the area to which an amendment to be issued is intended to apply should be described as a four-sided polygon in terms of latitude/longitude intersections giving corner coordinates of the polygon. To minimize the risk of misinterpretation, the corner coordinates should be given in a clockwise or counter-clockwise sequence. Latitude should be given in whole degrees (two digits) followed by N (north) or S (south). Longitude should be given in whole degrees (three digits) followed by E (east) or W (west);
e) the ICAO flight levels to which an amendment is intended to apply should be given in the text of the amendment messages;
f) amendments to forecasts of wind speed should be given in terms of percentage increase, using three digits (010, 020, 030, 120 and so forth) preceded by PS (plus) or of percentage decrease (010, 020, 030 and so forth up to a maximum decrease of 099) preceded by MS (minus);
g) amendments to forecasts of wind direction should be given in terms of clockwise or counter-clockwise rotation from the forecast being amended, using three digits (010, 020 and so forth up to 180) preceded by CW (for clockwise) or CC (for counter-clockwise); and
h) amendments to upper-air temperature forecasts should be given in three digits as absolute increases or decreases, in degrees Celsius, preceded by PS (plus) or MS (minus).
Note.— No entry should be made for any feature for which an amendment is not being issued.
2. Examples
Examples of messages containing amendments to upper-air forecasts are given below.
|Example 1 |
| |
|FXPA1 KWBC 241200 AMD. |
|AMD AREA FCST. |
| |
|SPEED CHANGE PER CENT INCR (PS) OR DECR (MS). |
|DIRECTION CHANGE CLOCKWISE (CW) OR COUNTER-CLOCKWISE (CC). |
|TEMPERATURE CHANGE ABSOLUTE INCR (PS) OR DECR (MS). |
| |
|AMEND WIND AND TEMPERATURE FORECAST IN AREA N38E160 N46E160 N47W178 N35W178. |
|AMENDMENT VALID 18 HR 24 HR AND 30 HR AFTER 241200. |
|AMENDMENT FORFL250FL300FL340FL390. |
|WIND SPEED/PER CENTPS035PS035PS035PS035. |
|WIND DIRECTION/DEGCC020CC020CC020CC020. |
|TEMPERATURE/DEG CPS005PS005PS005PS005. |
| |
|AMEND WIND AND TEMPERATURE FORECAST IN AREA N47W177 N40W161 N30W161 N35W177. |
|AMENDMENT VALID 18 HR 24 HR AND 30 HR AFTER 241200. |
|AMENDMENT FORFL250FL300FL340FL390. |
|WIND SPEED/PER CENTMS025MS040MS050MS040. |
|Example 2 |
| |
|FXPA2 KWBC 241200 AMD. |
|AMD AREA FCST. |
| |
|SPEED CHANGE PER CENT INCR (PS) OR DECR (MS). |
|DIRECTION CHANGE CLOCKWISE (CW) OR COUNTER-CLOCKWISE (CC). |
|TEMPERATURE CHANGE ABSOLUTE INCR (PS) OR DECR (MS). |
| |
|AMEND WIND AND TEMPERATURE FORECAST IN AREA N33E143 N43E147 N45E159 N33E159. |
|AMENDMENT VALID 18 HR AND 24 HR AFTER 241200. |
|AMENDMENT FORFL250FL300FL340FL390. |
|WIND SPEED/PER CENTPS040PS050PS070PS050. |
|WIND DIRECTION/DEGCW020CW020CW020CW020. |
|TEMPERATURE/DEG CMS005MS008MS010MS008. |
Appendix 11
TECHNICAL SPECIFICATIONS FOR SIGMET AND
AIRMET MESSAGES AND SPECIAL AIR-REPORTS
(See Chapter 7 of Annex 3.)
Table A11-1. Template for SIGMET and AIRMET messages and special air-reports
Key: M = inclusion mandatory, part of every message
C = inclusion conditional, included whenever applicable
= = a double line indicates that the text following it should be placed on the subsequent line
Note.— The ranges and resolutions for the numerical elements included in SIGMET/AIRMET messages and in special air-reports are shown in Table A11-2 of this appendix.
|Element as |Detailed content |Template(s) |Examples |
|specified in | | | |
|Annex 3, | | | |
|Chapters 5 and 7 | | | |
| | |SIGMET |SIGMET SST1 |AIRMET |SPECIAL AIR-REPORT2 | |
|Location |ICAO location |nnnn |— |YUCC4 |
|indicator of |indicator of the | | |YUDD4 |
|FIR/CTA (M)3 |ATS unit serving | | | |
| |the FIR or CTA to| | | |
| |which the | | | |
| |SIGMET/AIRMET | | | |
| |refers (M) | | | |
|Identification |Message |SIGMET [nn]n |SIGMET SST [nn]n |AIRMET [nn]n |ARS |SIGMET 5 |
|(M) |identification | | | | |SIGMET A3 |
| |and sequence | | | | |SIGMET SST 1 |
| |number5 (M) | | | | |AIRMET 2 |
| | | | | | |ARS |
|Validity period |Date-time groups |VALID nnnnnn/nnnnnn |—6 |VALID 221215/221600 |
|(M) |indicating the | | |VALID 101520/101800 |
| |period of | | |VALID 251600/252200 |
| |validity in UTC | | | |
| |(M) | | | |
|Location |Location |nnnn— | |YUDO—4 |
|indicator of MWO |indicator of MWO | | |YUSO—4 |
|(M) |originating the | | | |
| |message with a | | | |
| |separating hyphen| | | |
| |(M) | | | |
|Name of the |Name of the |nnnnnnnnnn FIR[/UIR] or |nnnnnnnnnn FIR[/n] |nnnnnn |AMSWELL FIR4 |
|FIR/CTA or |FIR/CTA7 for |nnnnnnnnnn CTA | | |SHANLON FIR/UIR4 |
|aircraft |which the | | | | |
|identification |SIGMET/AIRMET is | | | |AMSWELL FIR/24 |
|(M) |issued or | | | |SHANLON FIR4 |
| |aircraft | | | | |
| |radiotelephony | | | |VA812 |
| |call sign (M) | | | | |
|IF THE SIGMET IS TO BE CANCELLED, SEE DETAILS AT THE END OF THIS TEMPLATE. |
|Phenomenon (M)8 |Description of |OBSC9 TS [GR10] |MOD TURB11 |SFC WSPD nn[n]KMH |TS |SEV TURB |
| |phenomenon |EMBD12 TS [GR] |SEV TURB |(SFC WSPD nn[n]KT) |TSGR |FRQ TS |
| |causing the |FRQ13 TS [GR] | | | |OBSC TS GR |
| |issuance of |SQL14 TS [GR] |ISOL15 CB16 |SFC VIS nnnnM (nn)17 |SEV TURB |EMD TS GR |
| |SIGMET/AIRMET (C)| |OCNL18 CB | |SEV ICE |TC GLORIA |
| | |TC nnnnnnnnnn |FRQ13 CB |ISOL15 TS[GR]10 | |VA ERUPTION MT |
| | | | |OCNL18 TS[GR] |SEV MTW |ASHVAL LOC S15 |
| | |SEV TURB11 |GR | | |E073 VA CLD |
| | |SEV ICE19 | |MT OBSC |HVY SS | |
| | |SEV ICE (FZRA)20 |VA[ERUPTION] [MT | | |MOD TURB |
| | |SEV MTW21 |nnnnnnnnnn] [LOC |BKN CLD |VA CLD [FL nnn/nnn] | |
| | | |Nnn[nn] or Snn[nn] |nnn/[ABV]nnnnM |VA [MT nnnnnnnnnn] |MOD MTW |
| | |HVY DS |Ennn[nn] or |(BKN CLD | |ISOL CB |
| | |HVY SS |Wnnn[nn]] VA CLD |nnn/[ABV]nnnnFT) | |BKN CLD 120/900M |
| | | | | | |(BKN CLD |
| | |VA[ERUPTION] [MT | |OVC CLD | |400/3000FT) |
| | |nnnnnnnnnn] [LOC | |nnn/[ABV]nnnnM | |OVC CLD |
| | |Nnn[nn] or Snn[nn] | |(OVC CLD | |270/ABV3000M |
| | |Ennn[nn] or | |nnn/[ABV]nnnnFT) |MOD TURB11 |(OVC CLD |
| | |Wnnn[nn]] VA CLD | | |GR10 |900/ABV10000FT) |
| | | | |ISOL15 CB16 |CB16 | |
| | | | |OCNL18 CB | |SEV ICE |
| | | | |FRQ13 CB | | |
| | | | | | | |
| | | | |ISOL15 TCU16 | | |
| | | | |OCNL18 TCU16 | | |
| | | | |FRQ13 TCU | | |
| | | | | | | |
| | | | |MOD TURB11 | | |
| | | | |MOD ICE19 | | |
| | | | |MOD MTW21 | | |
|Observed or |Indication |OBS [AT nnnnZ] |OBS AT nnnnZ |OBS AT 1210Z |
|forecast |whether the |FCST | |OBS |
|phenomenon (M) |information is |OBS [AT nnnnZ] AND FCST | |OBS AND FCST |
| |observed and | | | |
| |expected to | | |OBS AT 2245Z |
| |continue, or | | | |
| |forecast (M) | | | |
| | | |— | |
|Location (C) |Location |[N OF, NE OF, E OF, SE OF, S OF, SW OF, W OF, NW OF] |NnnnnWnnnnn or |S OF N54 |
| |(referring to |[Nnn[nn]][Wnnn[nn]] or |NnnnnWnnnnn or |N OF N50 |
| |latitude and |[N OF, NE OF, E OF, SE OF, S OF, SW OF, W OF, NW OF] |SnnnnWnnnnn or |N2020 W07005 |
| |longitude (in |[Nnn[nn]][Ennn[nn]] or |SnnnnEnnnnn |YUSB4 |
| |degrees and |[N OF, NE OF, E OF, SE OF, S OF, SW OF, W OF, NW OF] | |N2706 W07306 |
| |minutes) or |[Snn[nn]][Wnnn[nn]] or | | |
| |locations or |[N OF, NE OF, E OF, SE OF, S OF, SW OF, W OF, NW OF] | |N48 E010 |
| |geographic |[Snn[nn]][Ennn[nn]] or | | |
| |features well |[N OF, NE OF, E OF, SE OF, S OF, SW OF, W OF, NW OF] | | |
| |known |nnnnnnnnnnnn | | |
| |internationally) | | | |
|Level (C) |Flight level |FLnnn or FLnnn/nnn or TOP FLnnn or [TOP] ABV FLnnn or [TOP] |FLnnn |FL180 |
| |and |BLW FLnnn | |FL050/080 |
| |extent22(C) |or23 | |TOP FL390 |
| | |CB TOP [ABV] FLnnn WI nnnKM OF CENTRE | |BLW FL200 |
| | |(CB TOP [ABV] FLnnn WI nnnNM OF CENTRE) or | |TOP ABV FL100 |
| | |CB TOP [BLW] FLnnn WI nnnKM OF CENTRE | |FL310/450 |
| | |(CB TOP [BLW] FLnnn WI nnnNM OF CENTRE) | | |
| | | | |CB TOP FL500 WI |
| | |or24 | |270KM OF CENTRE |
| | | | |(CB TOP FL500 WI |
| | |FLnnn/nnn [APRX nnnKM BY nnnKM] | |150NM OF CENTRE) |
| | |[Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn] | | |
| | |TO Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn] | |FL310/350 APRX 220KM|
| | |[TO Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn]] | |BY 35KM |
| | |[TO Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn]] | | |
| | | | |FL390 |
| | |(FLnnn/nnn [APRX nnnNM BY nnnNM] | | |
| | |[Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn] | | |
| | |TO Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn] | | |
| | |[TO Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn]] | | |
| | |[TO Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn]]) | | |
|Movement or |Movement or |MOV N [nnKMH] or MOV NE [nnKMH] or MOV E [nnKMH] or | — |MOV E 40KMH |
|expected |expected movement|MOV SE [nnKMH] or MOV S [nnKMH] or MOV SW [nnKMH] or | |(MOV E 20KT) |
|movement (C) |with reference to|MOV W [nnKMH] or MOV NW [nnKMH] or | |MOV SE |
| |one of the eight |(MOV N [nnKT] or MOV NE [nnKT] or MOV E [nnKT] or MOV SE | |STNR |
| |points of |[nnKT] or MOV S [nnKT] or MOV SW [nnKT] or MOV W [nnKT] or MOV| | |
| |compass, or |NW [nnKT]) or | | |
| |stationary (C) |STNR | | |
|Changes in |Expected changes |INTSF or WKN or NC |— |WKN |
|intensity (C) |in intensity (C) | | | |
|Forecast position|Forecast position|FCST nnnnZ TC CENTRE |— |— |FCST 2200Z TC CENTRE|
|(C)22 |of volcanic ash |Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn] | | |N2740 W07345 |
| |cloud or the |or | | | |
| |centre of the TC |FCST nnnnZ VA CLD | | |FCST 1700Z VA CLD |
| |at the end of the|Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn] | | |S15 E075 TO S15 E081|
| |validity period |TO Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn]| | |TO S17 E083 TO S18 |
| |of the SIGMET | | | |E079 TO S15 E75 |
| |message (C) |[TO Nnn[nn] or Snn[nn]Wnnn[nn] or | | | |
| | |Ennn[nn]] | | | |
| | |[TO Nnn[nn] or Snn[nn]Wnnn[nn] or | | | |
| | |Ennn[nn]] | | | |
|Outlook22 (C) |Outlook providing|OTLK nnnnnn TC CENTRE |— | |OTLK 260400 TC |
| |information |Nnnnn or SnnnnWnnnnn or Ennnnn | | |CENTRE N28030 W07430|
| |beyond the period|nnnnnn TC CENTRE | | |261000 TC CENTRE |
| |of validity of |Nnnnn or SnnnnWnnnnn or Ennnnn | | |N3100 W07600 |
| |the trajectory of|or | | | |
| |the volcanic ash |OTLK nnnnn VA CLD APRX | | |OTLK 212300 VA CLD |
| |cloud and |[Flnnn/nnn]25 Nnn[nn] or Snn[nn] Wnnn[nn]| | |APRX S16 E078 TO S17|
| |positions of the |or Ennn[nn] | | |E084 TO S18 E089 TO |
| |tropical cyclone |TO Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn]| | |S19 E081 TO S16 E078|
| |centre (C) | | | |220300 VA CLD APRX |
| | |TO Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn]| | |S17 E81 TO S18 E86 |
| | | | | |TO S20 E92 TO S21 |
| | |[TO Nnn[nn] or Snn[nn]Wnnn[nn] or | | |E84 TO S17 E81 |
| | |Ennn[nn]] | | | |
| | |[TO Nnn[nn] or Snn[nn]Wnnn[nn] or | | | |
| | |Ennn[nn]] | | | |
| | |nnnnnn VA CLD APRX | | | |
| | |Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn] | | | |
| | |TO Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn]| | | |
| | | | | | |
| | |TO Nnn[nn] or Snn[nn]Wnnn[nn] or Ennn[nn]| | | |
| | | | | | |
| | |[TO Nnn[nn] or Snn[nn]Wnnn[nn] or | | | |
| | |Ennn[nn]] | | | |
| | |[TO Nnn[nn] or Snn[nn]Wnnn[nn] or | | | |
| | |Ennn[nn]] | | | |
|OR | | | | | | |
|Cancellation of |Cancellation of |CNL SIGMET [nn]n |CNL SIGMET SST |CNL AIRMET [nn]n |— |CNL SIGMET 2 |
|SIGMET/ |SIGMET/AIRMET |nnnnnn/nnnnnn |[nn]n nnnnnn/nnnnnn|nnnnnn/nnnnnn | |101200/10160026 |
|AIRMET26 (C) |referring to its | | | | | |
| |identification | | | | |CNL SIGMET SST 1 |
| | | | | | |212330/22013026 |
| | | | | | | |
| | | | | | |CNL AIRMET |
| | | | | | |151520/15180026 |
| |
|1. Only for transonic and supersonic flights. |
|2. Automated special air-reports also include information on wind and temperature which does not need to be uplinked to other aircraft in |
|flight. |
|3. In cases where the airspace is divided into a flight information region (FIR) and an upper flight information region (UIR), the SIGMET is |
|identified by the location indicator of the air traffic services unit serving the FIR; nevertheless, the SIGMET message applies to the whole |
|airspace within the lateral limits of the FIR, i.e. to the FIR and to the UIR. The particular areas and/or flight levels affected by the |
|meteorological phenomena causing the issuance of the SIGMET are given in the text of the message. |
|4. Fictitious location. |
|5. Corresponding with the number of SIGMET/AIRMET messages issued for the FIR/CTA since 0001 UTC on the day concerned. |
|6. Special air-reports are to be uplinked for 60 minutes after their issuance. |
|7. Or a sub-area thereof in the case of AIRMET messages. |
|8. Only one of the weather phenomena listed should be selected and included in each SIGMET. |
|9. Obscured (OBSC) indicates that the thunderstorm (including, if necessary, cumulonimbus cloud which is not accompanied by a thunderstorm) is|
|obscured by haze or smoke or cannot be readily seen due to darkness. |
|10. Hail (GR) may be used as a further description of the thunderstorm as necessary. |
|11. Severe and moderate turbulence (TURB) refers only to: low-level turbulence associated with strong surface winds; rotor streaming; or |
|turbulence whether in cloud or not in cloud (CAT) near to jet streams. Turbulence is not required to be used in connection with convective |
|clouds. Turbulence is considered: |
|a) severe whenever the turbulence index is between 15 and 27 (i.e. the peak value of the eddy dissipation rate (EDR) exceeds 0.5); and |
|b) moderate whenever the turbulence index is between 6 and 14 (i.e. the peak value of the eddy dissipation rate (EDR) exceeds 0.3 while not |
|exceeding 0.5). |
|12. Embedded (EMBD) indicates that the thunderstorm (including cumulonimbus cloud which is not accompanied by a thunderstorm) is embedded |
|within cloud layers and cannot be readily recognized. |
|13. Frequent (FRQ) indicates an area of thunderstorms within which there is little or no separation between adjacent thunderstorms with a |
|maximum spatial coverage greater than 75 per cent of the area affected, or forecast to be affected, by the phenomenon (at a fixed time or |
|during the period of validity). |
|14. Squall line (SQL) indicates thunderstorm along a line with little or no space between individual clouds. |
|15. Isolated (ISOL) indicates an area of individual cumulonimbus and/or thunderstorms with a maximum spatial coverage less than 50 per cent of|
|the area affected, or forecast to be affected, by the phenomenon (at a fixed time or during the period of validity). |
|16. The use of cumulonimbus, CB, is restricted to AIRMETs and SIGMETs related to SST flight during transonic and supersonic cruise; the use of|
|towering cumulus, TCU, is restricted to AIRMETs. |
|17. The weather phenomenon causing the reduction in visibility in brackets; choose one from the following list: DZ, RA, SN, SG, PL, IC, GR, |
|GS, FG, BR, SA, DU, HZ, FU, VA, PO, SQ, FC, DS or SS. |
|18. Occasional (OCNL) indicates an area of well-separated cumulonimbus and/or thunderstorms with a maximum spatial coverage between 50 and 75 |
|per cent of the area affected, or forecast to be affected, by the phenomenon (at a fixed time or during the period of validity). |
|19. Severe and moderate icing (ICE) refers to severe icing in other than convective clouds. |
|20. Freezing rain (FZRA) refers to severe icing conditions caused by freezing rain. |
|21. A mountain wave (MTW) is considered: |
|a) severe whenever an accompanying downdraft of 3.0 m/s (600 ft/min) or more and/or severe turbulence is observed or forecast; |
|b) moderate whenever an accompanying downdraft of 1.75–3.0 m/s (350–600 ft/min) and/or moderate turbulence is observed or forecast. |
|22. Only for SIGMET messages for volcanic ash cloud and tropical cyclones. |
|23. Only for SIGMET messages for tropical cyclones. |
|24. Only for SIGMET messages for volcanic ash. |
|25. Up to four layers (or levels) to be included in the SIGMET outlook for volcanic ash. |
|26. End of the message (as the SIGMET/AIRMET message is being cancelled). |
| |
|General Note.— Severe or moderate icing and severe or moderate turbulence (SEV ICE, MOD ICE, SEV TURB, MOD TURB) associated with |
|thunderstorms, cumulonimbus clouds or tropical cyclones should not be included |
EXAMPLES
|SIGMET |Cancellation of SIGMET |
|YUDD SIGMET 2 VALID 101200/101600 YUSO- |YUDD SIGMET 3 VALID 101345/101600 YUSO- |
|SHANLON FIR/UIR OBSC TS FCST TOP FL390 |SHANLON FIR/UIR CNL SIGMET 2 101200/101600 |
|S OF N54 MOV E WKN | |
|AIRMET |Cancellation of AIRMET |
|YUDD AIRMET 1 VALID 151520/151800 YUSO- |YUDD AIRMET 2 VALID 151650/151800 YUSO- |
|SHANLON FIR ISOL TS OBS TOP ABV FL100 |SHANLON FIR CNL AIRMET 1 151520/151800 |
|N OF S50 STNR WKN | |
EXAMPLES
|ADVISORY MESSAGE FOR TC |
| |
|TC ADVISORY |
|DTG: 19970925/1600Z |
|TCAC: YUFO |
|TC: GLORIA |
|NR: 01 |
|PSN: N2706 W07306 |
|MOV: NW 20KMH |
|C: 965HPA |
|MAX WIND: 90KMH |
|FCST PSN + 12 HR: 260400 N2830 W07430 |
|FCST MAX WIND + 12 HR: 90KMH |
|FCST PSN + 18 HR: 261000 N2852 W07500 |
|FCST MAX WIND + 18 HR: 85KMH |
|FCST PSN + 24 HR: 261600 N2912 W07530 |
|FCST MAX WIND + 24 HR: 80KMH |
|NXT MSG: 19970925/2000Z |
| |
|ADVISORY MESSAGE FOR VA |
| |
|VOLCANIC ASH ADVISORY |
|ISSUED: 20000402/0700Z |
|VAAC: TOKYO |
|VOLCANO: USUZAN 805-03 |
|LOCATION: N4230E14048 |
|AREA: JAPAN |
|SUMMIT ELEVATION: 732M |
|ADVISORY NUMBER: 2000/432 |
|INFORMATION SOURCE: GMS — JMA |
|AVIATION COLOUR CODE: RED |
|ERUPTION DETAILS: ERUPTED 20000402/0614Z ERUPTION OBS ASH TO ABV FL300 |
|OBS ASH DATE/TIME: 02/0645Z |
|OBS ASH CLD: FL150/350 N4230E14048-N4300E14130-N4246E14230-N4232E14150-N4230E14048 SFC/FL150 MOV NE 25KT FL150/350 MOV E 30KT |
|FCST ASH CLD + 6 HR: 02/1245Z SFC/FL200 N4230E14048-N4232E14150-N4238E14300-N4246 E14230 FL200/350 |
|N4230E14048-N4232E14150N4238E14300-N4246E14230 FL350/600 NO ASH EXP |
|FCST ASH CLD + 12 HR: 02/1845Z SFC/FL300 N4230E14048-N4232E14150-N4238E14300-N4246E14230 FL300/600 NO ASH EXP |
|FCST ASH CLD + 18 HR: 03/0045Z SFC/FL600 NO ASH EXP |
|NEXT ADVISORY: 20000402/1300Z |
|REMARKS: ASH CLD CAN NO LONGER BE DETECTED ON SATELLITE IMAGE |
| |
|SIGMET FOR TC |
| |
|YUCC SIGMET 3 VALID 251600/252200 YUDO |
|AMSWELL FIR TC GLORIA OBSN2706 W07306 AT 1600Z CB TOP FL500 WI 150NM OF CENTRE MOV NW 10KT NC FCST 2200Z TC CENTRE N2740 W07345 |
|OTLK TC CENTRE 260400 N2830 W07430 261000N2912 W07530 |
|SIGMET FOR VA |
| |
|YUDD SIGMET 2 VALID 211100/211700 YUSO- |
|SHANLON FIR/UIR VA ERUPTION MT ASHVAL LOC E S1500 E07348 VA CLD OBS AT 1100Z FL310/450 APRX 220KM BY 35KM S1500 E07348E TO S1530 E07642 MOV |
|ESE 65KMH FCST 1700Z VA CLD APRX S1506 E07500 TO S1518 E08112 TO S1712 E08330 TO S1824 E07836 |
|OTLK 212300Z VA CLD APRX S1600 E07806 TO S1642 E08412 TO S1824 E08900 TO S1906 E08100 220500Z VA CLD APRX S1700 E08100 TO S1812 E08636 TO |
|S2000 E09224 TO S2130 E08418 |
EXAMPLE OF SIGMET MESSAGE
|YUCC SIGMET 5 VALID 221215/221600 YUDO- |
|AMSWELL FIR SEV TURB OBS AT 1210Z YUSB FL250 MOV E 40KMH WKN |
| |
|Meaning: The fifth SIGMET message issued for the AMSWELL* flight information region (identified in abbreviated plain language and by YUCC |
|Amswell area control centre) by the Donlon/International* meteorological watch office (YUDO) since 0001 UTC; the message is valid from 1215 |
|UTC to 1600 UTC on the 22nd of the month; severe turbulence was observed at 1210 UTC over Siby/Bistock* aerodrome (YUSB) at flight level 250; |
|the turbulence is expected to move eastwards at 40 kilometres per hour and to weaken in intensity. |
| |
|* Fictitious locations |
EXAMPLE OF AIRMET MESSAGE
|YUCC AIRMET 2 VALID 221215/221600 YUDO- |
|AMSWELL FIR MOD MTW OBS AT 1205Z AND FCST N48 E10 FL080 STNR NC |
| |
|Meaning: The second AIRMET message issued for the AMSWELL* flight information region (identified in abbreviated plain language and by YUCC |
|Amswell area control centre) by the Donlon/International* meteorological watch office (YUDO) since 0001 UTC; the message is valid from 1215 |
|UTC to 1600 UTC on the 22nd of the month; moderate mountain wave was observed at 1205 UTC at 48 degrees north and 10 degrees east at flight |
|level 080; the mountain wave is expected to remain stationary and not to undergo any changes in intensity. |
| |
|* Fictitious locations |
Table A11-2. Ranges and resolutions for the numerical elements
included in SIGMET/AIRMET messages
|Element as specified in Annex 3, Chapter 7 |Range |Resolution |
|Surface wind speed: | KMH |60 – 199 |1 |
| |KT |30 – 99 |1 |
|Surface visibility: |M |0000 – 0800 |50 |
| |M |0800 – 5 000 |100 |
|Cloud: height of base: |M |000 – 300 |30 |
| |FT |000 – 1 000 |100 |
|Cloud: height of top: |M |000 – 3 000 |30 |
| |M |3 000 – 20 000 |300 |
| |FT |000 – 10 000 |100 |
| |FT |10 000 – 60 000 |1 000 |
|Latitudes: |° (degrees) |00 – 90 |1 |
| |' (minutes) |00 – 60 |1 |
|Longitudes: |° (degrees) |000 – 180 |1 |
| |' (minutes) |00 – 60 |1 |
|Flight levels: | |000 – 650 |10 |
|Movement: |KMH |0 – 100 |10 |
| |KT |0 – 50 |5 |
Appendix 12
LIST OF TROPICAL CYCLONE ADVISORY CENTRES AND
VOLCANIC ASH ADVISORY CENTRES
1. The following tropical cyclone advisory centres (TCACs) were designated by regional air navigation agreements:
TCAC Darwin (Australia)
TCAC Honolulu (United States)
TCAC Miami (United States)
TCAC Nadi (Fiji)
TCAC New Delhi (India)
TCAC Reunion (France)
TCAC Tokyo (Japan)
Note.— Complete information on areas of responsibilities assigned to the TCACs and lists of MWOs associated to the TCACs are given in the regional air navigation plan publications (ANPPs) under Meteorology, and in the related Facilities and Services Implementation Documents (FASID) under Meteorology.
2. The following volcanic ash advisory centres (VAACs) were designated by regional air navigation agreements:
VAAC Anchorage (United States)
VAAC Buenos Aires (Argentina)
VAAC Darwin (Australia)
VAAC London (United Kingdom)
VAAC Montréal (Canada)
VAAC Tokyo (Japan)
VAAC Toulouse (France)
VAAC Washington (United States)
VAAC Wellington (New Zealand)
Note.— Complete information on areas of responsibilities assigned to the VAACs and lists of MWOs associated to the VAACs are given in the regional air navigation plan publications (ANPPs) under Meteorology, and in the related Facilities and Services Implementation Documents (FASID) under Meteorology.
Appendix 13
AN OPERATIONAL WIND SHEAR AND INVERSION WARNING
SYSTEM FOR HELSINKI-VANTAA AIRPORT
1. THE MEASURING SITE AND AIRPORT
1.1 A 300 m high (1 000 ft) mast was installed 20 km southwest of the airport. Its elevation is 50 metres, the same as that of the airport. The terrain around the mast station is sparse forest. This kind of terrain covers most of the final approaches to Helsinki-Vantaa airport. The mast station is 7 km from the seashore while the airport itself is 15 km from the seashore, thus allowing for timely sea fog observations.
1.2 The effect of distance of the mast station from the airport was studied by comparing aircraft-measured INS-winds with mast-measured 2-minute mean winds. Results show a correlation of 0.83–0.85 for speed and 0.98–0.99 for direction at measuring levels of 90 m to 300 m (300 ft to 1 000 ft) INS-winds with mast-measured 2-minute mean winds. The INS-winds are on average 4 km/h (2 kt) higher than mast winds.
1.3 During strong inversions, the surface temperatures at the airport and at the mast station coincide within ±1ûC and surface inversions measured at the mast station also represent conditions at the airport.
2. SYSTEM CONFIGURATION
2.1 The system is a modified automatic weather station, which has several additional wind, temperature and humidity sensors compared to the usual surface weather station. Figure A13-1 represents the system near Kuopio airport. In this system, the data collection is performed via a cassette count.
2.2 Because of freezing conditions during the winter, wind is measured with modified Vaisala anemometers, equipped with Lambrecht cups. These cups give more torque and also absorb IR-radiation more easily, because their aluminium surface is painted black. Besides normal axial heating, the anemometers have IR-radiators situated above them. These radiators have a maximum output of 1.5 kw. Temperature is measured with Pt-100 thermo-elements and humidity with linearized Lambrecht hair hygrometers. Temperature and humidity sensors are shielded against radiation and rain and all sensors are also shielded against falling ice blocks.
3. WEATHER-WATCH
3.1 Vertical wind shear is calculated between measuring levels using 2-minute mean winds. Levels 90 m to 210 m (300 ft to 700 ft) and 210 m to 300 m (700 ft to 1 000 ft) are used in routine warning services; measurements from levels 30 m to 90 m (100 ft to 300 ft) are affected by local terrain. Calculation of wind shear magnitude is done by the formula
V ws = V 21 + V 22 – 2V1V2 cos µ
where V1 and V2 are wind speeds at the levels in question and µ the angle between winds. This shear magnitude is then scaled to the unit kt/100 ft. If a predetermined value is exceeded, the system reports it by a bell signal and shows the shear values. The shear alarm limit at the mast station is set at 42 km/h/100 m (7 kt/100 ft), and this means about 0.1 per cent of the cases or about 10 shear cases of this strength or more per year. The number of aircraft reports concerning wind shear has been about 9 cases per year at Helsinki-Vantaa airport.
3.2 A watch is also kept for temperature inversions by comparing temperatures at higher levels with the surface temperature. Adjacent levels are also compared, which means a total of 13 comparisons in this subroutine. If a predetermined value is exceeded, the system reports it by a bell signal and gives temperature values. The inversion alarm limit at the mast station is set to correspond to an inversion of 10ûC in the lowest 300 m (1 000 ft) layer.
4. ROUTINE WARNING SERVICES
AND USE OF MAST DATA
4.1 The mast system is a part of the unified warning service (see flow diagram in Figure A13-2).
4.2 On receiving an alarm signal from the mast system, the meteorologist on duty makes the final decision as to whether a warning should be given. The warning message is immediately reported in the ATIS broadcast. The warning message is also shown on the airport internal video network.
4.3 Besides wind shear and inversions, the strength of low-level turbulence can be estimated by the mast system. The system reports wind speed and direction variations over the averaging interval. If the speed variations exceed 40 km/h (20 kt) at levels 90 m to 300 m (300 ft to 1 000 ft), a turbulence warning is given.
4.4 Besides its use for warning purposes, the mast data is also used for routine forecasting. The uppermost level gives a fairly good estimate of wind for approach and holding purposes. Continuous temperature profiles provide important information when estimating the passage of a front. For example, the temperature rise associated with warm fronts (especially in winter) is seen clearly starting from the top of the mast. Humidity profiles have been used successfully when making TREND forecasts, especially in case of advective fog or low cloud from the sea sector. The humidity rise is always very rapid and starts from the lowest levels in the case of a dense sea fog. Fog associated with a frontal warm advection causes the humidity to rise first at upper levels.
Figure A13-1. System configuration
Figure A13-2. Warning service
Appendix 14
USE OF METEOROLOGICAL INFORMATION FOR
PRE-FLIGHT PLANNING
BY OPERATORS AND FLIGHT CREW
1. INTRODUCTION
1.1 The meteorological information to be supplied to operators and flight crew is covered in Chapter 9 of Annex 3 and in Chapter 5 of this manual. The purpose of this Appendix is to describe the type of information used in pre-flight planning, which provides aviation meteorologists and assistants with a basic understanding of the significance each item of information has in the preparation for a flight. Although some re-planning is often carried out in flight (e.g. when considering the acceptance of a different flight level, an alternative airway routing offered by air traffic control or a change of destination), the use made of the meteorological information required for such re-planning is similar to that in pre-flight planning.
1.2 Flight preparation has three phases: the take-off and climb to cruise altitude; the cruise to top of descent; and the approach and landing. These phases are not treated separately as they are interdependent, but for explanatory purposes, it is convenient to consider the specific use made of meteorological information in each of the three phases.
2. TAKE-OFF AND CLIMB-OUT
2.1 General
2.1.1 It is the pilot’s duty to optimize the performance of the aircraft, in order to maximize the economics of the operation while at the same time complying with all the requirements for take-off (including take-off minima) specified by the operator and approved by the State of the Operator and by the authority responsible for the aerodrome. The planning for the take-off and climb-out phases include calculating, by the pilot, the maximum permissible take-off mass (standard operating mass + passengers + cargo + fuel, etc.) given the constraints at a particular aerodrome. These constraints include runway length, runway slope, climb-out gradients (which ensure clearance of obstacles with one engine failed), aerodrome elevation, and current meteorological conditions, i.e. surface wind (specifically headwind component and limiting tailwind and crosswind components), temperature and pressure. Humidity, although theoretically also affecting aircraft performance, can be neglected as its effect is minimal. Runway contamination (snow or slush covered, wet, icy, etc.) also plays an important role, but is not usually regarded as “meteorological information”. Where aircraft take-off mass is not limited by aircraft performance considerations in the prevailing meteorological conditions, temperature has an effect on take-off speeds and on engine power settings and on the possible need to initiate engine and airframe anti-ice procedures.
2.1.2 The list of items that have to be considered in take-off calculations is rendered more manageable by the use of graphs, charts, nomograms and tables, etc., produced by the operator to assist the pilot or flight operations officer. In many operations, flight planning, particularly for the en-route stage, is carried out by computer. The pilot is able to control at least some of the many variables affecting the take-off performance of the aircraft; one example would be the choice of flap setting, another would be the cargo mass and/or fuel to be uplifted, although clearly the desire is to maximize the payload consistent with take-off requirements. Any of the various requirements may limit the operation, resulting in a lower payload or fuel uplift than desired, which may result in the need to land en route in order to refuel or, in extreme circumstances, preclude take-off (at a given mass) altogether.
2.2 Surface wind
2.2.1 The magnitude of the effects of meteorological parameters on take-off performance varies with different aircraft types, although the sense of the effect (positive or negative) is the same. Headwinds permit a greater mass to be lifted on take-off, as the presence of a headwind permits a higher airspeed to be achieved on the runway and therefore more lift to be generated by the aerodynamic surfaces. In contrast, a tailwind results in the reduction of the maximum permissible take-off mass as a lower airspeed is achieved. Otherwise expressed, headwinds permit more weight to be lifted on take-off, while tailwinds decrease the maximum permissible take-off weight.
2.2.2 The following are some figures to indicate the magnitudes of the above effects. For example, in the case of a DC-8 aircraft, a 10 kt tailwind component increases the runway length requirement for take-off by about 500 m over still air conditions, while a 10 kt headwind component decreases this requirement by about 100 m (assuming all other factors are equal). Another example expressed in terms of mass would be that for each knot increase in headwind component, an Airbus A300 can lift some 400 kg more mass on take-off. In addition to the headwind/tailwind component, consideration must also be given to the crosswind component. Each aircraft has crosswind limits (for large jet transports, typically between 15 kt and 35 kt for different runway conditions, e.g. wet or icy, or dry), beyond which it is very difficult for the pilot to maintain aircraft alignment along the runway, particularly in the case of an engine failure.
2.3 Temperature
2.3.1 Temperature affects air density; higher temperatures cause a decrease in density which reduces lift and hence maximum permissible take-off mass and also has detrimental effects on engine efficiency and hence attainable speeds. Lower temperatures have the opposite effect.
2.3.2 A temperature rise of 10ûC can, for a B737, reduce the permissible take-off mass by 600 kg. A decrease in temperature allows an increase in permissible take-off mass. In the case of the A310, for each degree that the temperature is below reference, the mass can be increased by 210 kg, all other factors being equal. Temperature also has an effect on the relationship between true airspeed and the airspeed indicated in the cockpit (indicated airspeed). Therefore, high ambient temperatures mean that for a given indicated airspeed the true airspeed is higher and the kinetic energy to be absorbed by the brakes and tires after landing or an abandoned take-off is also greater. Landing an aircraft on a short runway or abandoning take-off from high speed requires the aircraft brakes to absorb extremely large amounts of kinetic energy which, in turn, results in the brake assembly being heated to such high temperatures that brake cooling times as long as one hour could be necessary. The cooling time depends on, among other things, the outside air temperature. Flight crew are provided with nomograms to calculate this effect.
2.4 Pressure
2.4.1 Pressure also affects air density; the lower the surface pressure, the lower the air density and the lower the lift and the poorer the engine performance (and vice versa).
2.4.2 For a DC-8, a 10 hPa pressure change at a sea level aerodrome has about the same effect as a 3ûC temperature change. Similarly, for each hectopascal that the pressure rises above 1 013.2 hPa, an additional 150 kg can be carried by an Airbus A300.
2.5 Combined effects of surface wind,
temperature and pressure
Figure A14-1 illustrates the combined effects of the above-mentioned parameters on take-off performance, and Figure A14-2 gives a sample illustration of an actual take-off mass versus runway length calculation.
3. CRUISE TO TOP OF DESCENT
3.1 General
The meteorological parameters of importance in the preparation of flight plans for the cruise phase of flights consist in the first instance of upper-air temperatures and upper winds. Weather conditions en route and meteorological conditions at destination and at destination alternate and en-route alternate aerodromes also play an important role.
3.2 Temperature
As in the case of take-off performance, temperature is an important element in flight planning because, by affecting air density, it influences engine performance, fuel efficiency, true airspeed, and aircraft operating ceilings and optimum cruising levels, irrespective of aircraft type (piston, jet, etc.). For early types of jet engines, the fuel consumption increased by about 1 per cent for each degree Celsius rise in temperature above standard. For modern wide-bodied aircraft, the engines of which are more powerful and fuel efficient, fuel consumption increases only by about 3 per cent for each 10ûC temperature increase. However, as fuel constitutes about 30 per cent of the total take-off mass of modern jets which can exceed 200 tonnes, this means that some 2 tonnes of additional fuel may be required for a 10ûC temperature rise. For a given aircraft mass, temperature together with wind determines the flight level at which fuel efficiency and range (with a given cruise speed) will be at an optimum. Figure A14-3 illustrates the effects of various temperature deviations from standard temperature on optimum flight levels for a B737 aircraft.
3.3 Upper winds
Upper winds have an even more obvious effect on aircraft efficiency, decreasing or increasing flight time and consequently decreasing or increasing fuel consumption (if same ground speed is to be maintained). With modern wide-bodied jet aircraft, a 50 kt headwind decreases the range of the aircraft by about 11 per cent at best cruise speed; a tailwind has the reverse effect. For flight planning, the effects of wind components are usually calculated in terms of “equivalent still air distance” which is as follows:
|equivalent still-air distance = |TAS |
| |TAS ± wind component |
An example of a graph used for this calculation is given in Figure A14-4. This figure illustrates the effects of wind components, sometimes called “equivalent headwinds”, on aircraft performance. In this connection, it should be noted that the wind component used in the still-air distance equation does not take into account only headwind or tailwind components but also the effect of crosswinds. The equivalent still-air distance is then used to calculate the fuel required for the flight, including necessary reserves.
3.4 Meteorological conditions
3.4.1 Meteorological conditions en route and meteorological conditions at destination and alternate aerodromes are elements that are superimposed on the initial flight plan based on temperature and wind. Adverse en-route weather conditions may force the choice of a flight level or route segment not conforming with the optimum one given by the flight plan, although such changes are rare with modern high-flying jet aircraft. Unfavourable conditions expected at a destination may force a delay in take-off, or the preparation of additional flight plan segments to alternate aerodromes.
3.4.2 During flight, pilots may wish to optimize the aircraft performance by taking advantage of more favourable winds at another flight level. This situation may arise because initially the aircraft was unable to climb to this level due to air traffic control constraints, or it was too heavy to climb to the level with the most favourable tailwinds. As the aircraft mass progressively decreases as fuel is burned off, the pilot may request reclearance to a higher level. The information available to the pilot in considering these matters is greatly enhanced by the increased use of an on-board inertial reference system (IRS), which has the capability of giving instantaneous wind readouts. Many systems also give information on the increased headwind that can be tolerated by going to a higher level so as to take advantage of the decreased fuel consumption normally found at higher flight levels. This is usually referred to as a “wind/altitude trade”.
4. LANDING CALCULATIONS
4.1 For landing there are two basic considerations: the length of the runway and missed-approach capability. The speed flown by the aircraft on approach is a function of the stall speed which is determined by the aircraft mass, all other things being equal. The speed on touchdown will be the indicated airspeed flown plus or minus the headwind/tailwind. The presence of a headwind means that the aircraft will land at a lower ground speed and will therefore use less distance to stop. The opposite effect is felt with a tailwind. The stopping distance on the runway is also affected by the runway being wet, as brakes are less effective in these conditions. In addition, aircraft have tailwind and crosswind limits, and again these are lower in wet conditions than in dry; typical limits are shown in Figure A14-5.
4.2 For the missed approach possibility the same factors as runway length must be considered, e.g. temperature and pressure-altitude. Also, when icing conditions are present, ice formation on the wing and fuselage will adversely affect performance. A chart illustrating the effect of relevant meteorological factors on landing performance including climb capability for a missed approach procedure is given in Figure A14-6.
Figure A14-1. Effects of meteorological parameters on take-off performance
Figure A14-2. Sample of an actual take-off mass calculation
Figure A14-3. Optimum flight level (for B737) as a function of take-off mass and
temperature deviation from standard
Figure A14-4. The effects of wind on aircraft performance
Figure A14-5. Typical wind limit diagram
Figure A14-6. Landing performance calculations
Appendix 15
COMMONLY USED ABBREVIATIONS IN
METEOROLOGICAL MESSAGES
(extract from the Procedures for Air Navigation Services —
ICAO Abbreviations and Codes (PANS-ABC, Doc 8400))
Note.—Decodes of the abbreviations should be applied in phraseologies used in meteorological briefings and consultations.
A
AAA (or AAB, AAC . . . etc., in sequence) Amended meteorological message (message type designator)
ABV Above
AC Altocumulus
ADS Automatic dependent surveillance
AFTN‡ Aeronautical fixed telecommunication network
AIREP† Air-report
AIRMET† Information concerning en-route weather phenomena which may affect the safety of low-level aircraft operations
ALT Altitude
AMD Amend or amended (used to indicate amended meteorological message; message type designator)
APCH Approach
AS Altostratus
ASHTAM* A special series NOTAM notifying a pre-eruption or post-eruption change in activity of a volcano, a volcanic eruption and/or volcanic ash cloud of operational significance
AT . . . At (followed by time at which weather change is forecast to occur)
ATS Air traffic services
B
BC . . .* Patches (followed by FG = fog, fog patches randomly covering the aerodrome)
BCFG Fog patches
BECMG Becoming
BKN Broken
BL . . . Blowing (followed by DU = dust, SA = sand or SN = snow)
BLW Below . . .
BR Mist
BTN Between
BUFR* Binary Universal Form for the Representation of Meteorological Data (a WMO code form)
C
C Centre (runway identification)
C Degrees Celsius (Centigrade)
CALM* Calm
CAT Clear air turbulence
CAVOK† (to be pronounced “KAV-OH-KAY”) Visibility, cloud and present weather better than prescribed values or conditions
CB‡ (to be pronounced “CEE BEE”) Cumulonimbus
CC Cirrocumulus
CCA (or CCB, CCC . . . etc., in sequence) Corrected meteorological message (message type designator)
CI Cirrus
CLD Cloud
COR Correct or correction or corrected (used to indicate corrected meteorological message; message type designator)
CPDLC‡ Controller-pilot data link communication
CS Cirrostratus
CTA Control area
CU Cumulus
D
D Downward (tendency in RVR during previous 10 minutes)
DEG Degrees
DIF Diffuse
DP Dew point temperature
DR . . . Low drifting (followed by DU = dust, SA = sand or SN = snow)
DS Duststorm
DU Dust
D-VOLMET Data link VOLMET
DZ Drizzle
E
EMBD Embedded in a layer (to indicate cumulonimbus embedded in layers of other clouds)
END Stop-end (related to RVR)
F
FBL Light (used to indicate the intensity of weather phenomena, interference or static reports, e.g. FBL RA = light rain)
FC Funnel cloud (tornado or water spout)
FCST Forecast
FEW Few
FG Fog
FIR‡ Flight information region
FL Flight level
FLUC Fluctuating or fluctuation or fluctuated
FM . . . From (followed by time weather change is forecast to begin)
FRONT† Front (relating to weather)
FT Feet (dimensional unit)
FU Smoke
FZ Freezing
FZDZ Freezing drizzle
FZFG Freezing fog
FZRA Freezing rain
G
G* Indicator for variations from the mean wind speed (gusts) (used in the METAR, SPECI and TAF code forms)
GAMET Area forecast for low-level flights
GR Hail
GRIB Processed meteorological data in the form of grid point values expressed in binary form (aeronautical meteorological code)
GS Small hail and/or snow pellets
H
H* High pressure area or the centre of high pressure
HPA Hectopascal
HR Hours
HURCN Hurricane
HVY Heavy (used to indicate the intensity of weather phenomena, e.g. HVY RA = heavy rain)
HZ Haze
I
I.* Island (IS. Islands)
IAVW* International airways volcano watch
IC Ice crystals (very small ice crystals in suspension, also known as diamond dust)
ICE Icing
INC In cloud
INTSF Intensify or intensifying
ISOL Isolated
K
KM Kilometres
KMH Kilometres per hour
KT Knots
L
L* Low pressure area or the centre of low pressure
LAT Latitude
LOC Local or locally or location or located
LONG Longitude
LTD Limited
LVL Level
LYR Layer or layered
M
M* Indicator for minimum value of runway visual range (used in the METAR and SPECI code forms)
M Metres (preceded by figures)
MAX Maximum
MBST Microburst
MET† Meteorological or meteorology
METAR† Aviation routine weather report (in aeronautical meteorological code)
MET
REPORT* Local routine meteorological report (in abbreviated plain language)
MI . . .* Shallow (followed by FG = fog, less than 2 m (6 ft) above ground level)
MID Mid-point (related to RVR)
MIFG Shallow fog
MNM Minimum
MOD Moderate (used to indicate the intensity of weather phenomena, interference or static reports, e.g. MOD RA = moderate rain)
MOV Move or moving or movement
MS Minus
MSL Mean sea level
MT Mountain
MTW Mountain waves
MWO Meteorological watch office
N
N No distinct tendency (in RVR during previous 10 minutes)
N North or northern latitude
NC No change
NE North-east
NIL**† None or I have nothing to send to you
NM Nautical miles
NOSIG† No significant change (used in trend-type landing forecasts)
NOTAM† A notice containing information concerning the establishment, condition or change in any aeronautical facility, service, procedure or hazard, the timely knowledge of which is essential to personnel concerned with flight operations
NS Nimbostratus
NSC Nil significant cloud
NSW Nil significant weather
NW North-west
O
OBS Observe or observed or observation
OBSC Obscure or obscured or obscuring
OCNL Occasional or occasionally
OPMET† Operational meteorological (information)
OTLK Outlook (used in SIGMET messages for volcanic ash and tropical cyclones)
OVC Overcast
P
P* Indicator for maximum value of wind speed or runway visual range (used in the METAR, SPECI and TAF code forms)
PL Ice pellets
PO Dust/sand whirls (dust devils)
PR Partial (followed by FG = fog, a substantial part of the aerodrome covered by fog while the remainder is clear)
PRFG Aerodrome partially covered by fog
PROB† Probability
PS Plus
PSYS Pressure system(s)
Q
QFE‡ Atmospheric pressure at aerodrome elevation (or at runway threshold)
QNH‡ Altimeter sub-scale setting to obtain elevation when on the ground
R
R* Indicator for runway visual range (used in the METAR and SPECI code forms)
RA Rain
RAG Ragged
RE . . . Recent (used to qualify weather phenomena, e.g. RERA = recent rain)
RNAV† (to be pronounced “AR-NAV”) Area navigation
ROBEX† Regional OPMET bulletin exchange (scheme)
ROFOR Route forecast (in aeronautical meteorological code)
RRA (or RRB, RRC . . . etc., in sequence) Delayed meteorological message (message type designator)
RTD Delayed (used to indicate delayed meteorological message; message type designator)
RVR‡ Runway visual range
RWY Runway
S
S* Indicator for state of the sea (used in the METAR and SPECI code forms)
S South or southern latitude
SA Sand
SARPS Standards and Recommended Practices (ICAO)
SC Stratocumulus
SCT Scattered
SEA Sea (used in connection with sea-surface temperature and state of the sea)
SECN Section
SEV Severe (used e.g. to qualify icing and turbulence reports)
SFC Surface
SG Snow grains
SH . . . Showers (followed by RA = rain, SN = snow, PE = ice pellets, GR = hail, GS = small hail and/or snow pellets or combinations thereof, e.g. SHRASN = showers of rain and snow)
SIG Significant
SIGMET† Information concerning en-route weather phenomena which may affect the safety of aircraft operations
SKC Sky clear
SN Snow
SNOCLO* Indicator for aerodrome being closed due to snow on the runway (used in the METAR and SPECI code forms)
SPECI† Aviation selected special weather report (in aeronautical meteorological code)
SPECIAL† Special meteorological report (in abbreviated plain language)
SQ Squall
SQL Squall line
SS Sandstorm
SST Supersonic transport
STNR Stationary
STS Stratus
SW South-west
SYNOP* Report of surface observation from a fixed land station
T
T Temperature
TAF† Aerodrome forecast
TC Tropical cyclone
TCAC* Tropical cyclone advisory centre
TCU Towering cumulus
TDO Tornado
TEMPO† Temporary or temporarily
TL . . . Till (followed by time by which weather change is forecast to end)
TN* Indicator for minimum temperature (used in the TAF code form)
TO To . . . (place)
TOP† Cloud top
TREND†* Trend forecast
TS . . . Thunderstorm (followed by RA = RAIN, SN = snow, PE = ice pellets, GR = hail, GS = small hail and/or snow pellets or combinations thereof, e.g. TSRASN = thunderstorm with rain and snow)
TS Thunderstorm (in aerodrome reports and forecasts, TS used alone means thunder heard but no precipitation at the aerodrome)
TURB Turbulence
TX* Indicator for maximum temperature (used in TAF code form)
U
U Upward (tendency in RVR during previous 10 minutes)
UIR‡ Upper flight information region
UTC‡ Co-ordinated Universal Time
V
V* Indicator for variations from the mean wind direction (used in the METAR and SPECI code forms)
VA Volcanic ash
VAAC* Volcanic ash advisory centre
VC Vicinity of the aerodrome (followed by FG = fog, FC = funnel cloud, SH = showers, PO = dust/sand whirls, BLDU = blowing dust, BLSA = blowing sand or BLSN = blowing snow, e.g. VC FG = vicinity fog)
VER Vertical
VHF‡ Very high frequency [30 MHz to 300 MHz]
VIS Visibility
VOLMET† Meteorological information for aircraft in flight
VRB Variable
VV* Vertical visibility (used in the METAR and SPECI code forms)
W
W* Indicator for sea surface temperature (used in the METAR and SPECI code forms)
W West or western longitude
WAFC World area forecast centre
WAFS* World area forecast system
WI Within
WIND Wind
WINTEM Forecast upper wind and temperature for aviation
WKN Weaken or weakening
WRNG Warning
WS Wind shear
WSPD Wind speed
WX Weather
Z
Z Co-ordinated Universal Time (in meteorological messages)
† When radiotelephony is used, the abbreviations and terms are transmitted as spoken words.
‡ When radiotelephony is used, the abbreviations and terms are transmitted using the individual letters in non-phonetic form.
** Abbreviation not included in the PANS-ABC (Doc 8400).
** Abbreviation is also available for use in communicating with stations of the maritime mobile service.
Appendix 16
CRITERIA FOR REPORTING METEOROLOGICAL AND
RELATED PARAMETERS IN AUTOMATED AIR-REPORTS
(See Chapter 5 of Annex 3.)
1. WIND DIRECTION
The wind direction shall be reported in terms of degrees true, rounded to the nearest whole degree.
2. WIND SPEED
The wind speed shall be reported in kilometres per hour or knots, rounded to the nearest 2 km/h (1 knot). The units used shall be indicated.
3. WIND QUALITY FLAG
The wind quality flag shall be reported as 0 when the roll angle is less than 5 degrees and as 1 when the roll angle is 5 degrees or more.
4. TEMPERATURE
The temperature shall be reported to the nearest tenth of a degree Celsius.
5. TURBULENCE
The turbulence shall be observed in terms of the eddy dissipation rate (EDR).
Routine air-reports
The turbulence shall be reported during the en-route phase of the flight and shall refer to the 15-minute period immediately preceding the observation. Both the average and peak value of turbulence, together with the time of occurrence of the peak value to the nearest minute, shall be observed. The average and peak values shall be reported in terms of a turbulence index comprising seven intensity levels of EDR as indicated in Table A16-1. The time of occurrence of the peak value shall be reported as indicated in Table A16-2.
Interpretation of the turbulence index
Turbulence shall be considered:
a) severe when the turbulence index is between 15 and 27 (i.e. the peak value of the EDR is exceeding 0.5);
b) moderate when the turbulence index is between 6 and 14 (i.e. the peak value of the EDR is exceeding 0.3 while not exceeding 0.5);
c) light when the turbulence index is between 1 and 5 (i.e. the peak value of the EDR is between 0.1 and 0.3); and
d) nil when the turbulence index is 0 (i.e. the peak value of the EDR is less than 0.1).
Note.— The EDR is an aircraft-independent measure of turbulence. However, the relationship between the EDR index and the perception of turbulence is a function of aircraft type, and the mass, altitude, configuration and airspeed of the aircraft.
Special air-reports
Special air-reports on turbulence shall be made during any phase of the flight whenever the peak value exceeds the EDR value of 0.5. The special air-report on turbulence shall be made with reference to the 1-minute period immediately preceding the observation. Both the average and peak value of turbulence shall be observed. The average and peak values shall be reported in terms of a turbulence index as indicated in the shaded part of Table A16-1. Special air-reports shall be issued every minute until such time that the peak values of turbulence fall below the EDR value of 0.5.
6. HUMIDITY
The humidity shall be reported as the relative humidity, rounded to the nearest whole per cent.
Note.— The ranges and resolutions for the meteorological elements included in air-reports are shown in Table A16-3.
Table A16-1. Turbulence index to be reported as a function of the average and peak value of turbulence
(Classes corresponding to severe turbulence are shaded)
| |Peak value of turbulence |
|Average value |EDR (m2/3 s–1) |Nil report |
|of turbulence | | |
|EDR (m2/3 s–1) |< 0.1 |
|0 – 1 |0 |
|1 – 2 |1 |
|2 – 3 |2 |
|. . . |. . . |
|13 – 14 |13 |
|14 – 15 |14 |
|No timing information available |15 |
Table A16-3. Ranges and resolutions for the meteorological elements included in air-reports
|Element as specified in Annex 3, Chapter 5 |Range |Resolution |
|Wind direction: |true |000 – 360 |1 |
|Wind speed: |KMH |00 – 500 |2 |
| |KT |00 – 250 |1 |
|Wind quality flag: |(index)1 |0 – 1 |1 |
|Temperature: |°° |–80 – +60 |0.1 |
|Turbulence: routine air-report: |(index)1 |0 – 28 |1 |
| |(time of occurrence)1 |0 – 15 |1 |
|Turbulence: special air-report: |(index)1 |15 – 27 |1 |
|Humidity: |% |0 – 100 |1 |
| |
|1. Non-dimensional |
Appendix 17
NOTIFICATION OF WAFC CONCERNING
SIGNIFICANT DISCREPANCIES
1. PURPOSE OF THE REPORT
a) To permit the meteorological offices to inform the WAFCs about significant discrepancies on significant weather (SIGWX) forecasts issued by WAFCs, in accordance with Annex 3 criteria (3.2.13 of Annex 3 refers); and
b) to report significant discrepancies efficiently and unambiguously, and only when an amendment to the SIGWX forecast is required.
Note.— If a meteorological office finds a discrepancy, or a recurrent discrepancy, that does not necessitate an amendment to the SIGWX according to Annex 3, it has the option to inform the WAFC concerned by using route forecast (ROFOR) messages.
2. USEFULNESS OF THE
REPORT FOR THE WAFCs
WAFC benefits from the notification by:
a) being informed of possible discrepancies;
b) analysing the proposal coming from a meteorological office;
c) re-initiating the forecasts model, if appropriate, taking into account the proposal; or
d) sending an amendment for the SIGWX forecast concerned.
3. STEPS TO BE FOLLOWED BY
A METEOROLOGICAL OFFICE
a) WAFS SIGWX forecast is received by a meteorological office;
b) a meteorological office detects a significant discrepancy, in accordance with the criteria for the amendment of SIGWX forecasts in Annex 3 (3.2.13 of Annex 3 refers) (see also the attachment to this Appendix); no other differences should be reported;
c) the meteorological office describes the significant discrepancy using the following rules:
1) a notification of significant discrepancy concerning a forecast shall be elaborated and sent between six and nine hours before the commencement of the validity period of the forecast;
2) the notification is to be sent only to the WAFC concerned;
3) the notification is to be sent via e-mail or fax using the following e-mail addresses or fax numbers:
|Centre |Fax Number |E-Mail Address |
|WAFC |+1 816 880 0652 |jhenderson@awc.kc. |
|Washington | | |
|WAFC |+44 1344 854919 |floorman@ |
|London | | |
4) the notification of significant discrepancies shall be prepared using the form in the attachment to this Appendix;
5) the notification is to be written in English.
4. STEPS TO BE FOLLOWED BY A WAFC
a) The WAFC concerned acknowledges the receipt of the notification of the significant discrepancy to the meteorological office that originated it, together with a brief comment thereon and any action taken, using the same means of communication employed by the meteorological office; and
b) if necessary, the WAFC issues an amendment for the SIGWX forecast concerned.
ATTACHMENT TO APPENDIX 17
FORM TO BE USED FOR THE NOTIFICATION OF A SIGNIFICANT
DISCREPANCY
ON SIGNIFICANT WEATHER FORECASTS
FORECAST INVOLVED
|Originating WAFC | |
|ICAO Area | |
|Flight Level | |
|Validity Time | |
|Validity Date | |
DESCRIPTION OF THE DISCREPANCY(IES)
(Error in expected position or intensity of phenomena; new expected phenomena.)
| |WAFC Forecast |Proposal |
|Phenomena |FL |Position |Intensity |FL |Position |Intensity |Reference |
|Turbulence | | | | | | | |
|Icing | | | | | | | |
|Cumulonimbus | | | | | | | |
|Sandstorms | | | | | | | |
|Duststorms | | | | | | | |
|Volcanic activity | | | | | | | |
|Radioactive material into | | | | | | | |
|the atmosphere | | | | | | | |
Note.— The column “Reference” is to specify, for example, the observation, aircraft report or the forecast model field that directed the meteorological office to inform of a significant discrepancy. A copy of this information may be added to the form, if necessary.
— END —
................
................
In order to avoid copyright disputes, this page is only a partial summary.
To fulfill the demand for quickly locating and searching documents.
It is intelligent file search solution for home and business.