Commission Implementing Regulation (EU) 2017/373 of 1 March 2017 laying down common requirements for providers of air traffic management/air navigation services and other air traffic management network functions and their oversight, repealing Regulation (EC) No 482/2008, Implementing Regulations (EU) No 1034/2011, (EU) No 1035/2011 and (EU) 2016/1377 and amending Regulation (EU) No 677/2011 (Text with EEA relevance. )

• (1) In local routine report, local special report, METAR and SPECI, the RVR shall be:
• (i) reported throughout periods when either the visibility or the runway visual range is less than 1 500 m;
• (ii) reported in steps of 25 m when it is less than 400 m, in steps of 50 m when it is between 400 and 800 m, and in steps of 100 m when it is more than 800 m.

• (2) Any observed value which does not fit the reporting scale in use shall be rounded down to the nearest lower step in the scale.

• (3) In local routine report, local special report, METAR and SPECI:
• (i) when the RVR is above the maximum value that can be determined by the system in use, it shall be reported using the abbreviation ‘ABV’ in local routine report and local special report, and the abbreviation ‘P’ in METAR and SPECI followed by the maximum value that can be determined by the system;
• (ii) when the RVR is below the minimum value that can be determined by the system in use, it shall be reported using the abbreviation ‘BLW’ in local routine report and local special report, and the abbreviation ‘M’ in METAR and SPECI, followed by the minimum value that can be determined by the system.

• (4) In local routine report and local special report:
• (i) the units of measurement used shall be included;
• (ii) if the RVR is observed from only one location along the runway, such as the touchdown zone, it shall be included without any indication of location;
• (iii) if the RVR is observed from more than one location along the runway, the value representative of the touchdown zone shall be reported first, followed by the values representative of the mid-point and stop-end, and the locations for which these values are representative shall be indicated;
• (iv) when there is more than one runway in use, the available RVR values for each runway shall be reported, and the runways to which the values refer shall be indicated.

(d) Present weather phenomena

• (1) In local routine report and local special report, observed present weather phenomena shall be reported in terms of type and characteristics and qualified with respect to intensity, as appropriate.

• (2) In METAR and SPECI, observed present weather phenomena shall be reported in terms of type and characteristics and qualified with respect to intensity or proximity to the aerodrome, as appropriate.

• (3) In local routine report, local special report, METAR and SPECI, the following characteristics of present weather phenomena, as necessary, shall be reported using their respective abbreviations and relevant criteria, as appropriate:
• (i) Thunderstorm (TS) Used to report a thunderstorm with precipitation. When thunder is heard or lightning is detected at the aerodrome during the 10-minute period preceding the time of observation but no precipitation is observed at the aerodrome, the abbreviation ‘TS’ shall be used without qualification.
• (ii) Freezing (FZ) Supercooled water droplets or precipitation, used with types of present weather phenomena in accordance with Appendix 1.

• (4) In local routine report, local special report, METAR and SPECI:
• (i) one or more, up to a maximum of three, of the present weather abbreviations shall 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 of significance to flight operations;
• (ii) the indication of intensity or proximity, as appropriate, shall be reported first followed respectively by the characteristics and the type of weather phenomena;
• (iii) where two different types of weather are observed, they shall be reported in two separate groups, where the intensity or proximity indicator refers to the weather phenomenon which follows the indicator. However, different types of precipitation occurring at the time of observation shall be reported as one single group with the dominant type of precipitation reported first and preceded by only one intensity qualifier which refers to the intensity of the total precipitation.

(e) Clouds

• (1) In local routine report, local special report, METAR and SPECI, the height of cloud base shall be reported in steps of 100 ft up to 10 000 ft and in steps of 1 000 ft above 10 000 ft.

• (2) Any observed value which does not fit the reporting scale in use shall be rounded down to the nearest lower step in the scale.

• (3) In local routine report and local special report:
• (i) the units of measurement used for the height of cloud base and vertical visibility shall be indicated;
• (ii) when there is more than one runway in use and the heights of cloud bases are observed by instruments for these runways, the available heights of cloud bases for each runway shall be reported, and the runways to which the values refer shall be indicated.

(f) Air temperature and dew-point temperature

• (1) In local routine report, local special report, METAR and SPECI, the air temperature and the dew-point temperature shall be reported in steps of whole degrees Celsius.

• (2) Any observed value which does not fit the reporting scale in use shall be rounded to the nearest whole degree Celsius, with observed values involving 0,5° rounded up to the next higher whole degree Celsius.

• (3) In local routine report, local special report, METAR and SPECI, a temperature below 0 °C shall be identified.

(g) Atmospheric pressure

• (1) In local routine report, local special report, METAR and SPECI, the QNH and QFE shall be computed in tenths of hectopascals and reported therein in steps of whole hectopascals, using four digits.

• (2) Any observed value which does not fit the reporting scale in use shall be rounded down to the nearest lower whole hectopascal.

• (3) In local routine report and local special report:
• (i) QNH shall be included;
• (ii) QFE shall be included if required by users or, if so agreed locally between the provider of meteorological services, the ATS unit and the operators concerned, on a regular basis;
• (iii) the units of measurement used for QNH and QFE values shall be included;
• (iv) if QFE values are required for more than one runway, the required QFE values for each runway shall be reported, and the runway(s) to which the values refer shall be indicated.

• (4) In METAR and SPECI, only QNH values shall be included.

MET.TR.210 Observing meteorological elements

The following meteorological elements shall be observed and/or measured with specified accuracy and disseminated by automatic or semi-automatic meteorological observing system.

(a) Surface wind direction and speed

The mean direction and the mean speed of the surface wind shall be measured, as well as significant variations of the wind direction and speed (gusts), and reported in degrees true and knots, respectively.

(1) Siting

The meteorological instrument used to measure surface wind direction and speed shall be situated in such a way as to provide data which is representative of the area for which the measurements are required.

(2) Display

Surface wind displays relating to each sensor shall be located in the aeronautical meteorological station. The displays in the aeronautical meteorological station and in the air traffic services units shall relate to the same sensors, and where separate sensors are required, the displays shall be clearly marked to identify the runway and section of runway monitored by each sensor.

(3) Averaging

The averaging period for surface wind observations shall be:

• (i) 2 minutes for local routine report and local special report and for wind displays in ATS units;

• (ii) 10 minutes for METAR and SPECI, except that when the 10-minute period includes a marked discontinuity in the wind direction and/or speed; only data occurring after the discontinuity shall be used for obtaining mean values; hence, the time interval in these circumstances shall be correspondingly reduced.

(b) Visibility

• (1) The visibility shall be measured or observed, and reported in metres or kilometres.

• (2) Siting

The meteorological instrument used to measure visibility shall be situated in such a way as to supply data which is representative of the area for which the measurements are required.

• (3) Displays

When instrumented systems are used for the measurement of visibility, visibility displays relating to each sensor shall be located in the aeronautical meteorological station. The displays in the aeronautical meteorological station and in the air traffic services units shall relate to the same sensors, and where separate sensors are required, the displays shall be clearly marked to identify the area monitored by each sensor.

• (4) Averaging

The averaging period shall be 10 minutes for METAR, except that when the 10-minute period immediately preceding the observation includes a marked discontinuity in the visibility, only those values occurring after the discontinuity shall be used for obtaining mean values.

(c) Runway visual range (RVR)

(1) The RVR shall be reported in metres.

(2) Siting

The meteorological instrument used to assess the RVR shall be situated in such a way as to provide data which is representative of the area for which the observations are required.

(3) Instrumented systems

Instrumented systems based on transmissometers or forward-scatter meters shall be used to assess RVR on runways intended for Category II and III instrument approach and landing operations, and for Category I instrument approach and landing operations as determined by the competent authority.

(4) Display

Where the RVR is determined by instrumented systems, one display or more, if required, shall be located in the aeronautical meteorological station. The displays in the aeronautical meteorological station and in the ATS units shall relate to the same sensors, and where separate sensors are required, the displays shall be clearly marked to identify the runway and section of the runway monitored by each sensor.

(5) Averaging

• (i) Where instrumented systems are used for the assessment of the RVR, their output shall be updated at least every 60 seconds to permit the provision of current, representative values.

• (ii) The averaging period for RVR values shall be:
• (A) 1 minute for local routine report and local special report and for RVR displays in ATS units;
• (B) 10 minutes for METAR and SPECI, except that when the 10-minute period immediately preceding the observation includes a marked discontinuity in RVR values; then only those values occurring after the discontinuity shall be used for obtaining mean values.

(d) Present weather phenomena

• (1) The following present weather phenomena shall be reported, as a minimum: rain, drizzle, snow and freezing precipitation, including intensity thereof, haze, mist, fog, freezing fog and thunderstorms, including thunderstorms in the vicinity.

• (2) Siting

The meteorological instrument used to measure present weather at the aerodrome and its vicinity shall be situated in such a way as to provide data which is representative of the area for which the measurements are required.

(e) Clouds

• (1) Cloud amount, cloud type and height of cloud base shall be observed and reported as necessary to describe the clouds of operational significance. When the sky is obscured, vertical visibility shall be observed and reported, where measured, instead of cloud amount, cloud type and height of cloud base. The height of cloud base and vertical visibility shall be reported in feet.

• (2) Siting

The meteorological instrument used to measure clouds amount and height shall be situated in such a way as to provide data which is representative of the area for which the measurements are required.

• (3) Display

When automated equipment is used for the measurement of the height of cloud base, at least one display shall be located in the aeronautical meteorological station. The displays in the aeronautical meteorological station and in the air traffic services units shall relate to the same sensors, and where separate sensors are required, the displays shall be clearly marked to identify the area monitored by each sensor.

• (4) Reference level

• (i) The height of cloud base shall be reported above aerodrome elevation.

• (ii) When a precision approach runway in use has a threshold elevation of 50 ft (15 m) or more below the aerodrome elevation, local arrangements shall be made in order that the height of cloud bases reported to arriving aircraft shall refer to the threshold elevation.

• (iii) In the case of reports from offshore structures, the height of cloud base shall be given above mean sea level.

(f) Air temperature and dew-point temperature

• (1) The air temperature and dew-point temperature shall be measured, displayed and reported in degrees Celsius.

• (2) When automated equipment is used for the measurement of air temperature and dew-point temperature, the displays shall be located in the aeronautical meteorological station. The displays in the aeronautical meteorological station and in the air traffic services units shall relate to the same sensors.

(g) Atmospheric pressure

• (1) The atmospheric pressure shall be measured, and QNH and QFE values shall be computed and reported in hectopascals.

• (2) Display

• (i) When automated equipment is used for the measurement of atmospheric pressure, QNH and, if required in accordance with point MET.TR.205(g)(3)(ii), QFE displays relating to the barometer shall be located in the aeronautical meteorological station with corresponding displays in the appropriate air traffic services units.

• (ii) When QFE values are displayed for more than one runway, the displays shall be clearly marked to identify the runway to which the QFE value displayed refers.

• (3) Reference level

A reference level for the computation of QFE shall be used.

Chapter 2 — Technical requirements for aerodrome meteorological offices

MET.TR.215 Forecasts and other information

• (a) Meteorological information for operators and flight crew members shall:
• (1) cover the flight in respect of time, altitude and geographical extent;
• (2) relate to appropriate fixed times or periods of time;
• (3) extend to the aerodrome of intended landing, also covering the meteorological conditions expected between the aerodrome of intended landing and alternate aerodromes designated by the operator;
• (4) be up to date.

• (b) Meteorological information provided to rescue coordination centres shall include the meteorological conditions that existed in the last known position of a missing aircraft and along the intended route of that aircraft with particular reference to elements which are not being distributed routinely.

• (c) Meteorological information provided to aeronautical information services units shall include:
• (1) information on meteorological service intended for inclusion in the aeronautical information publication(s) concerned;
• (2) information necessary for the preparation of NOTAM or ASHTAM;
• (3) information necessary for the preparation of aeronautical information circulars.

• (d) Meteorological information included in flight documentation shall be represented as follows:
• (1) winds on charts shall be depicted by arrows with feathers and shaded pennants on a sufficiently dense grid;
• (2) temperatures shall be depicted by figures on a sufficiently dense grid;
• (3) wind and temperature data selected from the data sets received from a world area forecast centre shall be depicted in a sufficiently dense latitude/longitude grid;
• (4) wind arrows shall take precedence over temperatures and chart background;
• (5) height indications referring to en-route meteorological conditions shall be expressed as determined to be appropriate for the situation, for instance in flight levels, pressure, altitude or height above ground level, whilst all references referring to aerodrome meteorological conditions shall be expressed in height above the aerodrome elevation.

• (e) Flight documentation shall comprise:
• (1) forecasts of upper-wind and upper-air temperature;
• (2) SIGWX phenomena;
• (3) METAR or, when issued, SPECI for the aerodromes of departure and intended landing, and for take-off, en-route and destination alternate aerodromes;
• (4) TAF or amended TAF for the aerodromes of departure and intended landing, and for take-off, en-route and destination alternate aerodromes;
• (5) SIGMET, and, when issued, AIRMET and appropriate special air-reports relevant to the whole route;
• (6) volcanic ash, tropical cyclone and space weather advisory information relevant to the whole route. However, when agreed between the aerodrome meteorological office and the operators concerned, flight documentation for flights of two hours' duration or less, after a short stop or turnaround, may be limited to the information operationally needed, but in all cases the flight documentation shall at least comprise the meteorological information listed in points (3), (4), (5) and (6).

• (f) Charts generated from digital forecasts shall be made available, as required by operators, for fixed areas of coverage as shown in Appendix 2.

• (g) When forecasts of upper-wind and upper-air temperature listed under point MET.OR.275(a)(1) are supplied in chart form, they shall be fixed-time prognostic charts for flight levels as specified in point MET.TR.275(b)(3). When forecasts of SIGWX phenomena listed under point MET.OR.275(a)(2) are supplied in chart form, they shall be fixed-time prognostic charts for an atmospheric layer limited by flight levels as specified in points MET.TR.275(c) and MET.TR.275(d).

• (h) The forecasts of upper-wind and upper-air temperature and of SIGWX phenomena above flight level 100 shall be supplied as soon as they become available, but not later than 3 hours before departure.

• (i) Aeronautical climatological information shall be prepared in the form of aerodrome climatological tables and aerodrome climatological summaries.

MET.TR.220 Aerodrome forecasts

• (a) Aerodrome forecasts and amendments thereto shall be issued as a TAF and shall include, in the order indicated, the:
• (1) identification of the type of forecast;
• (2) location indicator;
• (3) time of issue of forecast;
• (4) identification of a missing forecast, when applicable;
• (5) date and period of validity of forecast;
• (6) identification of a cancelled forecast, when applicable;
• (7) surface wind;
• (8) visibility;
• (9) weather;
• (10) cloud;
• (11) expected significant changes to one or more of these elements during the period of validity.

• (b) TAF shall be issued in accordance with the template shown in Appendix 3.

• (c) The period of validity of a routine TAF shall be either 9 or 24 or 30 hours, unless otherwise prescribed by the competent authority taking into account the traffic requirements for aerodromes which operate for less than 9 hours.

• (d) TAF shall be filed for transmission not earlier than 1 hour before the commencement of their period of validity.

• (e) The meteorological elements included in TAF shall be: (1) Surface wind
• (i) In forecasting surface wind, the expected prevailing direction shall be given.
• (ii) When it is not possible to forecast a prevailing surface wind direction due to its expected variability, the forecasted wind direction shall be indicated as variable using ‘VRB’.
• (iii) When the wind is forecasted to be less than 1 kt, the forecasted wind speed shall be indicated as calm.
• (iv) When the forecast maximum speed exceeds the forecasted mean wind speed by 10 kt or more, the forecasted maximum wind speed shall be indicated.
• (v) When a wind speed of 100 kt or more is forecasted, it shall be indicated to be more than 99 kt. (2) Visibility
• (i) When the visibility is forecasted to be less than 800 m, it shall be expressed in steps of 50 m; when it is forecasted to be 800 m or more, but less than 5 km, in steps of 100 m; when it is forecasted to be 5 km or more, but less than 10 km, in kilometre steps; and when it is forecasted to be 10 km or more, it shall be expressed as 10 km, except when conditions of CAVOK are forecasted to apply. The prevailing visibility shall be forecasted.
• (ii) When visibility is forecasted to vary in different directions and the prevailing visibility cannot be forecasted, the lowest forecasted visibility shall be given. (3) Weather phenomena
• (i) One or more, up to a maximum of three, of the following weather phenomena or combinations thereof, together with their characteristics and, where appropriate, intensity, shall be forecasted if they are expected to occur at the aerodrome:
• (A) freezing precipitation;
• (B) freezing fog;
• (C) moderate or heavy precipitation (including showers thereof);
• (D) low drifting dust, sand or snow;
• (E) blowing dust, sand or snow;
• (F) dust storm;
• (G) sandstorm;
• (H) thunderstorm (with or without precipitation);
• (I) squall;
• (J) funnel cloud (tornado or waterspout);
• (K) other weather phenomena, as agreed by the aerodrome meteorological office with the ATS units and operators concerned.
• (ii) The expected end of occurrence of those phenomena shall be indicated by the abbreviation ‘NSW’. (4) Cloud
• (i) The cloud amount shall be forecast using the abbreviations ‘FEW’, ‘SCT’, ‘BKN’ or ‘OVC’, as necessary. When it is expected that the sky will remain or become obscured and clouds cannot be forecasted and information on vertical visibility is available at the aerodrome, the vertical visibility shall be forecasted in the form ‘VV’ followed by the forecasted value of the vertical visibility.
• (ii) When several layers or masses of cloud are forecasted, their amount and height of base shall be included in the following order:
• (A) the lowest layer or mass regardless of amount, to be forecasted as FEW, SCT, BKN or OVC as appropriate;
• (B) the next layer or mass covering more than 2/8, to be forecast as SCT, BKN or OVC as appropriate;
• (C) the next higher layer or mass covering more than 4/8, to be forecast as BKN or OVC as appropriate;
• (D) cumulonimbus clouds and/or towering cumulus clouds, whenever forecasted and not already included under points (A) to (C).
• (iii) Cloud information shall be limited to cloud of operational significance; when no cloud of operational significance is forecasted and ‘CAVOK’ is not appropriate, the abbreviation ‘NSC’ shall be used.

• (f) Use of change groups
• (1) The criteria used for the inclusion of change groups in TAF or for the amendment of TAF shall be based on any of the following weather phenomena, or combinations thereof, being forecasted to begin or end or change in intensity:
• (i) freezing fog;
• (ii) freezing precipitation;
• (iii) moderate or heavy precipitation (including showers thereof);
• (iv) thunderstorm;
• (v) dust storm;
• (vi) sandstorm.
• (2) When a change in any of the elements given in point (a) is required to be indicated, the change indicators ‘BECMG’ or ‘TEMPO’ shall be used followed by the time period during which the change is expected to occur. The time period shall be indicated as the beginning and end of the period in whole hours UTC. Only those elements for which a significant change is expected shall be included following a change indicator. However, in the case of significant changes in respect of cloud, all cloud groups, including layers or masses not expected to change, shall be indicated.
• (3) The change indicator ‘BECMG’ and the associated time group shall be used to describe changes where the meteorological conditions are expected to reach or pass through specified threshold values at a regular or irregular rate and at an unspecified time during the time period. The time period shall not exceed 4 hours.
• (4) The change indicator ‘TEMPO’ and the associated time group shall be used to describe expected frequent or infrequent temporary fluctuations in the meteorological conditions which reach or pass specified threshold values and last for a period of less than 1 hour in each instance and, in the aggregate, cover less than one half of the forecast period during which the fluctuations are expected to occur. If the temporary fluctuation is expected to last 1 hour or longer, the change group ‘BECMG’ shall be used in accordance with point (3), or the validity period should be subdivided in accordance with point (5).
• (5) Where one set of prevailing weather conditions is expected to change significantly and more or less completely to a different set of conditions, the period of validity shall be subdivided into self-contained periods using the abbreviation ‘FM’ followed immediately by a six-figure time group in days, hours and minutes UTC indicating the time the change is expected to occur. The subdivided period following the abbreviation ‘FM’ shall be self-contained and all forecasted conditions given before the abbreviation shall be superseded by those following the abbreviation.

• (g) The probability of occurrence of an alternative value of a forecast element or elements shall be included when:
• (1) a 30 % or 40 % probability of alternative meteorological conditions exists during a specific forecast time period; or
• (2) a 30 % or 40 % probability of temporary fluctuations in meteorological conditions exists during a specific forecast time period. This shall be indicated in the TAF by using the abbreviation ‘PROB’ followed by the probability in tens of per cent and, in the case referred to in point (1), the time period during which the values are expected to apply, or in the case referred to in point (2), by using the abbreviation ‘PROB’ followed by the probability in tens of per cent, the change indicator ‘TEMPO’ and associated time group.

MET.TR.225 Forecasts for landing

• (a) TREND forecasts shall be issued in accordance with Appendix 1.

• (b) The units and scales used in the TREND forecast shall be the same as those used in the report to which it is appended.

• (c) The TREND forecast shall indicate significant changes in respect of one or more of the elements: surface wind, visibility, weather phenomena and clouds. Only those elements for which a significant change is expected shall be included. However, in the case of significant changes in respect of cloud, all cloud groups, including layers or masses not expected to change, shall be indicated. In the case of a significant change in visibility, the phenomenon causing the reduction of visibility shall also be indicated. When no change is expected to occur, this shall be indicated by the term ‘NOSIG’. (1) Surface wind The TREND forecast shall indicate changes in the surface wind which involve:
• (i) a change in the mean wind direction of 60° or more, the mean speed before and/or after the change being 10 kt or more;
• (ii) a change in mean wind speed of 10 kt or more;
• (iii) changes in the wind through values of operational significance. (2) Visibility
• (i) When the visibility is expected to improve and change to or pass through one or more of the following values, or when the visibility is expected to deteriorate and pass through one or more of the following values: 150, 350, 600, 800, 1 500 or 3 000 m, the TREND forecast shall indicate the change.
• (ii) When significant numbers of flights are conducted in accordance with the visual flight rules, the forecast shall additionally indicate changes to or passing through 5 000  m.
• (iii) In TREND forecasts appended to METAR and SPECI, visibility shall refer to the forecast prevailing visibility. (3) Weather phenomena
• (i) The TREND forecast shall indicate the expected onset, cessation or change in intensity of any of the following weather phenomena or combinations thereof:
• (A) freezing precipitation;
• (B) moderate or heavy precipitation, including showers thereof;
• (C) thunderstorm, with precipitation;
• (D) dust storm;
• (E) sandstorm;
• (F) other weather phenomena as agreed by the aerodrome meteorological office with the ATS units and operators concerned.
• (ii) The TREND forecast shall indicate the expected onset or cessation of any of the following weather phenomena or combinations thereof:
• (A) freezing fog;
• (B) low drifting dust, sand or snow;
• (C) blowing dust, sand or snow;
• (D) thunderstorm (without precipitation);
• (E) squall;
• (F) funnel cloud (tornado or waterspout).
• (iii) The total number of phenomena reported in points (i) and (ii) shall not exceed three.
• (iv) The expected end of occurrence of the weather phenomena shall be indicated by the abbreviation ‘NSW’. (4) Clouds
• (i) When the height of base of a cloud layer of BKN or OVC extent is expected to lift and change to or pass through one or more of the following values, or when the height of base of a cloud layer of BKN or OVC extent is expected to lower and pass through one or more of the following values: 100, 200, 500, 1 000 and 1 500  ft (30, 60, 150, 300 and 450 m), the TREND forecast shall indicate the change.
• (ii) When the height of base of a cloud layer is below or is expected to fall below or rise above 1 500  ft (450 m), the TREND forecast shall also indicate changes in cloud amount from FEW, or SCT increasing to BKN or OVC, or changes from BKN or OVC decreasing to FEW or SCT.
• (iii) When no clouds of operational significance are forecast and ‘CAVOK’ is not appropriate, the abbreviation ‘NSC’ shall be used. (5) Vertical visibility When the sky is expected to remain or become obscured and vertical visibility observations are available at the aerodrome, and the vertical visibility is forecast to improve and change to or pass through one or more of the following values, or when the vertical visibility is forecast to deteriorate and pass through one or more of the following values: 100, 200, 500 or 1 000 ft (30, 60, 150 or 300 m), the TREND forecast shall indicate the change. (6) Additional criteria The aerodrome meteorological office and the users may agree on additional criteria to be used, based on local aerodrome operating minima. (7) Use of change groups
• (i) When a change is expected to occur, the TREND forecast shall begin with one of the change indicators ‘BECMG’ or ‘TEMPO’.
• (ii) The change indicator ‘BECMG’ shall be used to describe forecast changes where the meteorological conditions are expected to reach or pass through specified values at a regular or irregular rate. The period during which, or the time at which, the change is forecast to occur shall be indicated using the abbreviations ‘FM’, ‘TL’ or ‘AT’, as appropriate, each followed by a time group in hours and minutes.
• (iii) The change indicator ‘TEMPO’ shall be used to describe forecast temporary fluctuations in the meteorological conditions which reach or pass specified values and last for a period of less than 1 hour in each instance and, in the aggregate, cover less than one half of the period during which the fluctuations are forecast to occur. The period during which the temporary fluctuations are forecast to occur shall be indicated using the abbreviations ‘FM’ and/or ‘TL’, as appropriate, each followed by a time group in hours and minutes. (8) Use of the probability indicator The indicator ‘PROB’ shall not be used in TREND forecasts.

MET.TR.230 Forecasts for take-off

• (a) A forecast for take-off shall refer to a specified period of time and shall contain information on expected conditions over the runway complex in regard to surface wind direction and speed and any variations thereof, temperature, pressure, and any other elements as agreed between the aerodrome meteorological office and the operators.

• (b) The order of the elements and the terminology, units and scales used in forecasts for take-off shall be the same as those used in reports for the same aerodrome.

MET.TR.235 Aerodrome warnings and wind shear warnings and alerts

• (a) Wind shear warnings shall be issued in accordance with the template in Appendix 4.

• (b) The sequence number referred to in the template in Appendix 4 shall correspond to the number of wind shear warnings issued for the aerodrome since 00.01 UTC on the day concerned.

• (c) Wind shear alerts shall give concise, up-to-date information related to the observed existence of wind shear involving a headwind/tailwind change of 15 kt or more which could adversely affect aircraft on the final approach path or initial take-off path and aircraft on the runway during the landing roll or take-off run.

• (d) Wind shear alert shall, if practicable, relate to specific sections of the runway and distances along the approach path or take-off path as agreed between the aerodrome meteorological office, the appropriate ATS units and the operators concerned.

Chapter 3 — Technical requirements for meteorological watch offices

MET.TR.250 SIGMET

• (a) SIGMET shall be issued in accordance with the template shown in Appendix 5.

• (b) SIGMET shall consist of three types:
• (1) SIGMET for en-route weather phenomena other than volcanic ash or tropical cyclones;
• (2) SIGMET for volcanic ash;
• (3) SIGMET for tropical cyclones.

• (c) The sequence number of SIGMET shall consist of three characters comprising one letter and two numbers.

• (d) Only one of the phenomena listed in Appendix 5 shall be included in a SIGMET, using the appropriate abbreviations and the following threshold value of surface wind speed of 34 kt or more for tropical cyclones.

• (e) SIGMET concerning thunderstorms or a tropical cyclone shall not include references to associated turbulence and icing.

MET.TR.255 AIRMET

• (a) AIRMET shall be issued in accordance with the template shown in Appendix 5.

• (b) The sequence number referred to in the template in Appendix 5 shall correspond to the number of AIRMET issued for the flight information region since 00.01 UTC on the day concerned.

• (c) Only one of the phenomena in Appendix 5 shall be included in an AIRMET, using the appropriate abbreviations and the following threshold values, when the phenomenon is below flight level 100, or below flight level 150 in mountainous areas, or higher, where necessary:
• (1) widespread surface wind speed above 30 kt with relevant direction and units;
• (2) widespread areas affected by reduction of visibility to less than 5 000 m, including the weather phenomenon causing the reduction of visibility;
• (3) widespread areas of broken or overcast cloud with height of base less than 1 000 ft above ground level;

• (d) AIRMET concerning thunderstorms or cumulonimbus clouds shall not include references to associated turbulence and icing.

MET.TR.260 Area forecasts for low-level flights

• (a) When chart form is used for area forecasts for low-level flights, the forecast of upper wind and upper-air temperature shall be issued for points separated by no more than 300 NM and for, as a minimum, the following altitudes: 2 000 , 5 000 and 10 000  ft (600, 1 500 and 3 000  m) and 15 000  ft (4 500  m) in mountainous areas. The issuance of forecasts of upper wind and upper-air temperature at an altitude of 2 000 ft (600 m) may be subject to local orographic considerations as determined by the competent authority.

• (b) When chart form is used for area forecasts for low-level flights, the forecast of SIGWX phenomena shall be issued as low-level SIGWX forecast for flight levels up to 100, or up to flight level 150 in mountainous areas, or higher, where necessary. Low-level SIGWX forecasts shall include:
• (1) the following phenomena warranting the issuance of a SIGMET: severe icing, severe turbulence, cumulonimbus clouds and thunderstorms that are obscured, frequent, embedded or occurring at a squall line, sandstorms/dust storms and volcanic eruptions or a release of radioactive materials into the atmosphere, and which are expected to affect low-level flights;
• (2) the following elements in area forecasts for low-level flights: surface wind, surface visibility, significant weather phenomena, mountain obscuration, cloud, icing, turbulence, mountain wave and height of zero-degree isotherm.

• (c) When the competent authority has determined that the density of traffic operating below flight level 100, or up to flight level 150 in mountainous areas, or higher, where necessary, warrants the issuance of an AIRMET in combination with area forecasts for low-level flights, the area forecasts shall be issued to cover the layer between the ground and flight level 100, or up to flight level 150 in mountainous areas, or higher, where necessary, and shall contain information on en-route weather phenomena hazardous to low-level flights.

Chapter 4 – Technical requirements for volcanic ash advisory centres (VAACs)

MET.TR.265 Volcanic ash advisory centre responsibilities

The advisory information on volcanic ash shall be issued in accordance with the template shown in Appendix 6. When no abbreviations are available, English plain language text, to be kept to a minimum, shall be used.

Chapter 5 – Technical requirements for tropical cyclone advisory centres (TCACs)

MET.TR.270 Tropical cyclone advisory centre responsibilities

The advisory information on tropical cyclones shall be issued in accordance with the template shown in Appendix 7 for tropical cyclones when the maximum of the 10-minute mean surface wind speed is expected to reach or exceed 34 kt during the period covered by the advisory.

Chapter 6 — Technical requirements for world area forecast centres (WAFCs)

MET.TR.275 World area forecast centre responsibilities

• (a) WAFCs shall use processed meteorological data in the form of grid point values for the supply of gridded global forecasts and forecasts of significant weather phenomena.

• (b) For global gridded forecasts, WAFCs shall:
• (1) prepare forecasts of:
• (i) upper wind;
• (ii) upper-air temperature;
• (iii) humidity;
• (iv) direction, speed and flight level of maximum wind;
• (v) flight level and temperature of tropopause;
• (vi) areas of cumulonimbus clouds;
• (vii) icing;
• (viii) turbulence;
• (ix) geopotential altitude of flight levels; four times a day and be valid for fixed valid times at 6, 9, 12, 15, 18, 21, 24, 27, 30, 33 and 36 hours after the time (00.00, 06.00, 12.00 and 18.00 UTC) of the synoptic data on which the forecasts were based;
• (2) issue forecasts referred to in point (1) and complete their dissemination as soon as technically feasible, but not later than 5 hours after standard time of observation;
• (3) provide grid point forecasts in a regular grid comprising:
• (i) wind data for flight levels 50 (850 hPa), 80 (750 hPa), 100 (700 hPa), 140 (600 hPa), 180 (500 hPa), 210 (450 hPa), 240 (400 hPa), 270 (350 hPa), 300 (300 hPa), 320 (275 hPa), 340 (250 hPa), 360 (225 hPa), 390 (200 hPa), 410 (175 hPa), 450 (150 hPa), 480 (125 hPa) and 530 (100 hPa) with a horizontal resolution of 1,25° of latitude and longitude;
• (ii) temperature data for flight levels 50 (850 hPa), 80 (750 hPa), 100 (700 hPa), 140 (600 hPa), 180 (500 hPa), 210 (450 hPa), 240 (400 hPa), 270 (350 hPa), 300 (300 hPa), 320 (275 hPa), 340 (250 hPa), 360 (225 hPa), 390 (200 hPa), 410 (175 hPa), 450 (150 hPa), 480 (125 hPa) and 530 (100 hPa) with a horizontal resolution of 1,25° of latitude and longitude;
• (iii) humidity data for flight levels 50 (850 hPa), 80 (750 hPa), 100 (700 hPa), 140 (600 hPa) and 180 (500 hPa) with a horizontal resolution of 1,25° of latitude and longitude;
• (iv) geopotential altitude data for flight levels 50 (850 hPa), 80 (750 hPa), 100 (700 hPa), 140 (600 hPa), 180 (500 hPa), 210 (450 hPa), 240 (400 hPa), 270 (350 hPa), 300 (300 hPa), 320 (275 hPa), 340 (250 hPa), 360 (225 hPa), 390 (200 hPa), 410 (175 hPa), 450 (150 hPa) 480 (125 hPa) and 530 (100 hPa) with a horizontal resolution of 1,25° of latitude and longitude;
• (v) direction, speed and flight level of maximum wind with a horizontal resolution of 1,25° of latitude and longitude;
• (vi) flight level and temperature of tropopause with a horizontal resolution of 1,25° of latitude and longitude;
• (vii) icing for layers centred at flight levels 60 (800 hPa), 100 (700 hPa), 140 (600 hPa), 180 (500 hPa), 240 (400 hPa) and 300 (300 hPa) with a horizontal resolution of 0,25° of latitude and longitude;
• (viii) turbulence for layers centred at flight levels 100 (700 hPa), 140 (600 hPa), 180 (500 hPa), 240 (400 hPa), 270 (350 hPa), 300 (300 hPa), 340 (250 hPa), 390 (200 hPa) and 450 (150 hPa) with a horizontal resolution of 0,25° of latitude and longitude;
• (ix) horizontal extent and flight levels of base and top of cumulonimbus clouds with a horizontal resolution of 0,25° of latitude and longitude.

• (c) For global forecasts of en-route significant weather phenomena, WAFCs shall:
• (1) prepare SIGWX forecasts four times a day and shall be valid for fixed valid times at 24 hours after the time (00.00, 06.00, 12.00 and 18.00 UTC) of the synoptic data on which the forecasts were based. The dissemination of each forecast shall be completed as soon as technically feasible, but not later than 7 hours after standard time of observation under normal operations and not later than 9 hours after standard time of observation during backup operations;
• (2) issue SIGWX forecasts as high-level SIGWX forecasts for flight levels between 250 and 630;
• (3) include in SIGWX forecasts the following items:
• (i) tropical cyclone provided that the maximum of the 10-minute mean surface wind speed is expected to reach or exceed 34 kt;
• (ii) severe squall lines;
• (iii) moderate or severe turbulence (in cloud or clear air);
• (iv) moderate or severe icing;
• (v) widespread sandstorm/dust storm;
• (vi) cumulonimbus clouds associated with thunderstorms and with points (i) to (v);
• (vii) non-convective cloud areas associated with in-cloud moderate or severe turbulence and/or moderate or severe icing;
• (viii) flight level of tropopause;
• (ix) jet streams;
• (x) information on the location of volcanic eruptions that are producing ash clouds of significance to aircraft operations, comprising: volcanic eruption symbol at the location of the volcano and, in a separate text box on the chart, the volcanic eruption symbol, the name of the volcano, if known, and the latitude/longitude of the eruption. In addition, the legend of SIGWX charts should indicate ‘CHECK SIGMET, ADVISORIES FOR TC AND VA, AND ASHTAM AND NOTAM FOR VA’;
• (xi) information on the location of a release of radioactive materials into the atmosphere of significance to aircraft operations, comprising: the radioactive materials in the atmosphere symbol at the location of the release and, in a separate box on the chart, the radioactive materials in the atmosphere symbol, latitude/longitude of the site of the release and, if known, the name of the site of the radioactive source. In addition, the legend of SIGWX charts on which a release of radiation is indicated should contain ‘CHECK SIGMET AND NOTAM FOR RDOACT CLD’.
• (4) The following criteria shall be applied for SIGWX forecasts:
• (i) points (i) to (vi) of point (3) shall only be included if expected to occur between the lower and upper levels of the SIGWX forecast;
• (ii) the abbreviation ‘CB’ shall only be included when it refers to the occurrence or expected occurrence of cumulonimbus clouds:
• (A) affecting an area with a maximum spatial coverage of 50 % or more of the area concerned;
• (B) along a line with little or no space between individual clouds; or
• (C) embedded in cloud layers or concealed by haze;
• (iii) the inclusion of ‘CB’ shall be understood to include all weather phenomena normally associated with cumulonimbus clouds, i.e. thunderstorm, moderate or severe icing, moderate or severe turbulence, and hail;
• (iv) where a volcanic eruption or a release of radioactive materials into the atmosphere warrants the inclusion of the volcanic activity symbol or the radioactivity symbol in SIGWX forecasts, the symbols shall be included on SIGWX forecasts irrespective of the height to which the ash column or radioactive material is reported or expected to reach;
• (v) in the case of coincident or the partial overlapping of points (i), (x) and (xi) of point (3), the highest priority shall be given to point (x), followed by points (xi) and (i). The point with the highest priority shall be placed at the location of the event, and an arrow shall be used to link the location of the other point(s) to its (their) associated symbol(s) or text box(es).

• (d) Medium-level SIGWX forecasts for flight levels between 100 and 450 for limited geographical areas shall be issued.

Appendix 1

Template for METAR and SPECI

Key:

M	=	inclusion mandatory;
---	---	---
C	=	inclusion conditional, dependent on meteorological conditions or method of observation;
---	---	---
O	=	inclusion optional.

• Note 1: The ranges and resolutions for the numerical elements included in METAR and SPECI are provided in a separate table below this template.

• Note 2: The explanations for the abbreviations can be found in ICAO Document 8400 Procedures for Air Navigation Services – Abbreviations and Codes (PANS-ABC).

• Note 3: Row numbers in the ‘Ref.’ column are included only for clarity and ease of reference, and are not part of the METAR and SPECI.

Ref.	Element	Detailed content	Template(s)	Template(s)	Template(s)	Template(s)	Template(s)	Template(s)
1	Identification of the type of report (M)	Type of report (M)	METAR, METAR COR, SPECI or SPECI COR	METAR, METAR COR, SPECI or SPECI COR	METAR, METAR COR, SPECI or SPECI COR	METAR, METAR COR, SPECI or SPECI COR	METAR, METAR COR, SPECI or SPECI COR	METAR, METAR COR, SPECI or SPECI COR
2	Location indicator (M)	ICAO location indicator (M)	nnnn	nnnn	nnnn	nnnn	nnnn	nnnn
3	Time of the observation (M)	Day and actual time of the observation in UTC (M)	nnnnnnZ	nnnnnnZ	nnnnnnZ	nnnnnnZ	nnnnnnZ	nnnnnnZ
4	Identification of an automated or missing report (C)	Automated or missing report identifier (C)	AUTO or NIL	AUTO or NIL	AUTO or NIL	AUTO or NIL	AUTO or NIL	AUTO or NIL
5	END OF METAR IF THE REPORT IS MISSING.	END OF METAR IF THE REPORT IS MISSING.	END OF METAR IF THE REPORT IS MISSING.	END OF METAR IF THE REPORT IS MISSING.	END OF METAR IF THE REPORT IS MISSING.	END OF METAR IF THE REPORT IS MISSING.	END OF METAR IF THE REPORT IS MISSING.	END OF METAR IF THE REPORT IS MISSING.
6	Surface wind (M)	Wind direction (M)	nnn or/// [^E0017]	nnn or/// [^E0017]	VRB	VRB	VRB	VRB
		Wind speed (M)	[P]nn[n] or// [^E0017]	[P]nn[n] or// [^E0017]	[P]nn[n] or// [^E0017]	[P]nn[n] or// [^E0017]	[P]nn[n] or// [^E0017]	[P]nn[n] or// [^E0017]
		Significant speed variations (C)	G[P]nn[n]	G[P]nn[n]	G[P]nn[n]	G[P]nn[n]	G[P]nn[n]	G[P]nn[n]
		Units of measurement (M)	KT	KT	KT	KT	KT	KT
		Significant directional variations (C)	nnnVnnn	nnnVnnn	—	—	—	—
7	Visibility (M)	Prevailing or minimum visibility (M)	nnnn or//// [^E0017]	nnnn or//// [^E0017]	nnnn or//// [^E0017]	nnnn or//// [^E0017]	C A V O K	C A V O K
		Minimum visibility and direction of the minimum visibility (C)	nnnn[N] or nnnn[NE] or nnnn[E] or nnnn[SE] or nnnn[S] or nnnn[SW] or nnnn[W] or nnnn[NW]	nnnn[N] or nnnn[NE] or nnnn[E] or nnnn[SE] or nnnn[S] or nnnn[SW] or nnnn[W] or nnnn[NW]	nnnn[N] or nnnn[NE] or nnnn[E] or nnnn[SE] or nnnn[S] or nnnn[SW] or nnnn[W] or nnnn[NW]	nnnn[N] or nnnn[NE] or nnnn[E] or nnnn[SE] or nnnn[S] or nnnn[SW] or nnnn[W] or nnnn[NW]	C A V O K	C A V O K
8	Runway visual range (C) [^E0018]	Name of the element (M)	R	R	R	R	C A V O K	C A V O K
8	Runway visual range (C) [^E0018]	Runway (M)	nn[L]/or nn[C]/or nn[R]/	nn[L]/or nn[C]/or nn[R]/	nn[L]/or nn[C]/or nn[R]/	nn[L]/or nn[C]/or nn[R]/	C A V O K	C A V O K
8	Runway visual range (C) [^E0018]	Runway visual range (M)	[P or M]nnnn or//// [^E0017]	[P or M]nnnn or//// [^E0017]	[P or M]nnnn or//// [^E0017]	[P or M]nnnn or//// [^E0017]	C A V O K	C A V O K
8	Runway visual range (C) [^E0018]	Runway visual range past tendency (C)	U, D or N	U, D or N	U, D or N	U, D or N	C A V O K	C A V O K
9	Present weather (C)	Intensity or proximity of present weather (C)	– or +	—	—	VC	C A V O K	C A V O K
9	Present weather (C)	Characteristics and type of present weather (M)	DZ or RA or SN or SG or PL or DS or SS or FZDZ or FZRA or FZUP [^E0020] or FC [^E0019] or SHGR or SHGS or SHRA or SHSN or SHUP [^E0020] or TSGR or TSGS or TSRA or TSSN or TSUP [^E0020] or UP [^E0020]	FG or BR or SA or DU or HZ or FU or VA or SQ or PO or TS or BCFG or BLDU or BLSA or BLSN or DRDU or DRSA or DRSN or FZFG or MIFG or PRFG or // [^E0017]	FG or BR or SA or DU or HZ or FU or VA or SQ or PO or TS or BCFG or BLDU or BLSA or BLSN or DRDU or DRSA or DRSN or FZFG or MIFG or PRFG or // [^E0017]	FG or PO or FC or DS or SS or TS or SH or BLSN or BLSA or BLDU or VA	C A V O K	C A V O K
10	Cloud (M)	Cloud amount and height of cloud base or vertical visibility (M)	FEWnnn or SCTnnn or BKNnnn or OVCnnn or FEW/// [^E0017] or SCT/// [^E0017] or BKN/// [^E0017] or OVC/// [^E0017] or ///nnn [^E0017] or ////// [^E0017]	VVnnn or VV/// [^E0017]	VVnnn or VV/// [^E0017]	NSC or NCD [^E0020]	C A V O K	C A V O K
	Cloud (M)	Cloud type (C)	CB or TCU or/// [^E0017], [^E0021]	—	—	NSC or NCD [^E0020]	C A V O K	C A V O K
11	Air and dew-point temperature (M)	Air and dew-point temperature (M)	[M]nn/[M]nn or///[M]nn [^E0017] or [M]nn/// [^E0017] or///// [^E0017]	[M]nn/[M]nn or///[M]nn [^E0017] or [M]nn/// [^E0017] or///// [^E0017]	[M]nn/[M]nn or///[M]nn [^E0017] or [M]nn/// [^E0017] or///// [^E0017]	[M]nn/[M]nn or///[M]nn [^E0017] or [M]nn/// [^E0017] or///// [^E0017]	[M]nn/[M]nn or///[M]nn [^E0017] or [M]nn/// [^E0017] or///// [^E0017]	[M]nn/[M]nn or///[M]nn [^E0017] or [M]nn/// [^E0017] or///// [^E0017]
12	Pressure values (M)	Name of the element (M)	Q	Q	Q	Q	Q	Q
12	Pressure values (M)	QNH (M)	nnnn or//// [^E0017]	nnnn or//// [^E0017]	nnnn or//// [^E0017]	nnnn or//// [^E0017]	nnnn or//// [^E0017]	nnnn or//// [^E0017]
13	Supplementary information (C)	Recent weather (C)	RERASN or REFZDZ or REFZRA or REDZ or RE[SH]RA or RE[SH]SN or RESG or RESHGR or RESHGS or REBLSN or RESS or REDS or RETSRA or RETSSN or RETSGR or RETSGS or RETS or REFC or REVA or REPL or REUP [^E0020] or REFZUP [^E0020] or RETSUP [^E0020] or RESHUP [^E0020] or RE// [^E0017]	RERASN or REFZDZ or REFZRA or REDZ or RE[SH]RA or RE[SH]SN or RESG or RESHGR or RESHGS or REBLSN or RESS or REDS or RETSRA or RETSSN or RETSGR or RETSGS or RETS or REFC or REVA or REPL or REUP [^E0020] or REFZUP [^E0020] or RETSUP [^E0020] or RESHUP [^E0020] or RE// [^E0017]	RERASN or REFZDZ or REFZRA or REDZ or RE[SH]RA or RE[SH]SN or RESG or RESHGR or RESHGS or REBLSN or RESS or REDS or RETSRA or RETSSN or RETSGR or RETSGS or RETS or REFC or REVA or REPL or REUP [^E0020] or REFZUP [^E0020] or RETSUP [^E0020] or RESHUP [^E0020] or RE// [^E0017]	RERASN or REFZDZ or REFZRA or REDZ or RE[SH]RA or RE[SH]SN or RESG or RESHGR or RESHGS or REBLSN or RESS or REDS or RETSRA or RETSSN or RETSGR or RETSGS or RETS or REFC or REVA or REPL or REUP [^E0020] or REFZUP [^E0020] or RETSUP [^E0020] or RESHUP [^E0020] or RE// [^E0017]	RERASN or REFZDZ or REFZRA or REDZ or RE[SH]RA or RE[SH]SN or RESG or RESHGR or RESHGS or REBLSN or RESS or REDS or RETSRA or RETSSN or RETSGR or RETSGS or RETS or REFC or REVA or REPL or REUP [^E0020] or REFZUP [^E0020] or RETSUP [^E0020] or RESHUP [^E0020] or RE// [^E0017]	RERASN or REFZDZ or REFZRA or REDZ or RE[SH]RA or RE[SH]SN or RESG or RESHGR or RESHGS or REBLSN or RESS or REDS or RETSRA or RETSSN or RETSGR or RETSGS or RETS or REFC or REVA or REPL or REUP [^E0020] or REFZUP [^E0020] or RETSUP [^E0020] or RESHUP [^E0020] or RE// [^E0017]
13	Supplementary information (C)	Wind shear (C)	WS Rnn[L] or WS Rnn[C] or WS Rnn[R] or WS ALL RWY	WS Rnn[L] or WS Rnn[C] or WS Rnn[R] or WS ALL RWY	WS Rnn[L] or WS Rnn[C] or WS Rnn[R] or WS ALL RWY	WS Rnn[L] or WS Rnn[C] or WS Rnn[R] or WS ALL RWY	WS Rnn[L] or WS Rnn[C] or WS Rnn[R] or WS ALL RWY	WS Rnn[L] or WS Rnn[C] or WS Rnn[R] or WS ALL RWY
13	Supplementary information (C)	Sea-surface temperature and state of the sea or significant wave height (C)	W[M]nn/Sn or W///Sn [^E0017] or W[M]nn/S/ [^E0017] or W[M]nn/Hn[n][n] or W///Hn[n][n] [^E0017] or W[M]nn/H/// [^E0017]	W[M]nn/Sn or W///Sn [^E0017] or W[M]nn/S/ [^E0017] or W[M]nn/Hn[n][n] or W///Hn[n][n] [^E0017] or W[M]nn/H/// [^E0017]	W[M]nn/Sn or W///Sn [^E0017] or W[M]nn/S/ [^E0017] or W[M]nn/Hn[n][n] or W///Hn[n][n] [^E0017] or W[M]nn/H/// [^E0017]	W[M]nn/Sn or W///Sn [^E0017] or W[M]nn/S/ [^E0017] or W[M]nn/Hn[n][n] or W///Hn[n][n] [^E0017] or W[M]nn/H/// [^E0017]	W[M]nn/Sn or W///Sn [^E0017] or W[M]nn/S/ [^E0017] or W[M]nn/Hn[n][n] or W///Hn[n][n] [^E0017] or W[M]nn/H/// [^E0017]	W[M]nn/Sn or W///Sn [^E0017] or W[M]nn/S/ [^E0017] or W[M]nn/Hn[n][n] or W///Hn[n][n] [^E0017] or W[M]nn/H/// [^E0017]
14	Trend forecast (O)	Change indicator (M)	NOSIG	BECMG or TEMPO	BECMG or TEMPO	BECMG or TEMPO	BECMG or TEMPO	BECMG or TEMPO
14	Trend forecast (O)	Period of change (C)	NOSIG	FMnnnn and/or TLnnnn or ATnnnn	FMnnnn and/or TLnnnn or ATnnnn	FMnnnn and/or TLnnnn or ATnnnn	FMnnnn and/or TLnnnn or ATnnnn	FMnnnn and/or TLnnnn or ATnnnn
14	Trend forecast (O)	Wind (C)	NOSIG	nnn[P]nn[G[P]nn]KT	nnn[P]nn[G[P]nn]KT	nnn[P]nn[G[P]nn]KT	nnn[P]nn[G[P]nn]KT	nnn[P]nn[G[P]nn]KT
14	Trend forecast (O)	Prevailing visibility (C)	NOSIG	nnnn	nnnn	nnnn	nnnn	C A V O K	C A V O K
14	Trend forecast (O)	Weather phenomenon: intensity (C)	NOSIG	– or +	– or +	NSC or NCD [^E0020]	C A V O K	C A V O K	C A V O K	—	N S W
14	Trend forecast (O)	Weather phenomenon: characteristics and type (C)	NOSIG	DZ or RA or SN or SG or PL or DS or SS or FZDZ or FZRA or SHGR or SHGS or SHRA or SHSN or TSGR or TSGS or TSRA or TSSN	DZ or RA or SN or SG or PL or DS or SS or FZDZ or FZRA or SHGR or SHGS or SHRA or SHSN or TSGR or TSGS or TSRA or TSSN	NSC or NCD [^E0020]	C A V O K	C A V O K	C A V O K	FG or BR or SA or DU or HZ or FU or VA or SQ or PO or FC or TS or BCFG or BLDU or BLSA or BLSN or DRDU or DRSA or DRSN or FZFG or MIFG or PRFG	N S W
14	Trend forecast (O)	Cloud amount and height of cloud base or vertical visibility (C)	NOSIG	FEWnnn or SCTnnn or BKNnnn or OVCnnn	FEWnnn or SCTnnn or BKNnnn or OVCnnn	NSC or NCD [^E0020]	C A V O K	C A V O K	C A V O K	VVnnn or VV///	N S C
14	Trend forecast (O)	Cloud type (C)	NOSIG	CB or TCU	CB or TCU	NSC or NCD [^E0020]	C A V O K	C A V O K	C A V O K	—	N S C

When a meteorological element is temporarily missing, or its value is considered temporarily as incorrect, it is replaced by a solidus (‘/’) for each digit of the abbreviation of the text message and indicated as missing to ensure reliable translation into other code forms.

To be included if the visibility or the runway visual range is < 1 500 m for up to a maximum of four runways.

‘Heavy’ is used to indicate ‘tornado’ or ‘waterspout’; ‘moderate’ (no qualifier) to indicate ‘funnel cloud not reaching the ground’.

For automated reports only.

In the case of automated reports, solidi (‘///’) may replace the relevant cloud type, as appropriate, dependent on the capability of the automatic observing system. Furthermore, solidi may replace cloud amount and/or cloud height of reported CB or TCU layer.

Ranges and resolutions for the numerical elements included in METAR and SPECI	Ranges and resolutions for the numerical elements included in METAR and SPECI	Ranges and resolutions for the numerical elements included in METAR and SPECI	Ranges and resolutions for the numerical elements included in METAR and SPECI	Ranges and resolutions for the numerical elements included in METAR and SPECI
Ref.	Elements	Elements	Range	Resolution
1	Runway:	(no units)	01–36	1
2	Wind direction:	°true	000–360	10
3	Wind speed:	KT	00–99 P99	1 N/A (100 or greater)
4	Visibility:	M	0000–0750	50
		M	0800–4 900	100
		M	5 000 –9 000	1 000
		M	10 000 or greater	0 (fixed value: 9 999 )
5	Runway visual range:	M	0000–0375	25
		M	0400–0750	50
		M	0800–2 000	100
6	Vertical visibility:	100’s FT	000–020	1
7	Clouds: height of cloud base:	100’s FT	000–099 100-200	1 10
8	Air temperature: Dew-point temperature:	°C	–80 – +60	1
9	QNH:	hPa	0850–1 100	1
10	Sea-surface temperature:	°C	–10 – +40	1
11	State of the sea:	(no units)	0–9	1
12	Significant wave height:	M	0–999	0,1

Appendix 2

Fixed areas of coverage of WAFS forecasts in chart form

Mercator projection

Image omitted; see official source Image omitted; see official source

Polar stereographic projection (northern hemisphere)

Image omitted; see official source Image omitted; see official source

Polar stereographic projection (southern hemisphere)

Image omitted; see official source Image omitted; see official source

Appendix 3

Template for TAF

Key:

M	=	inclusion mandatory;
---	---	---
C	=	inclusion conditional, dependent on meteorological conditions or method of observation;
---	---	---
O	=	inclusion optional.

• Note 1: The ranges and resolutions for the numerical elements included in TAF are provided in a separate table below this template.

• Note 2: The explanations for the abbreviations can be found in ICAO Doc 8400 Procedures for Air Navigation Services – ICAO Abbreviations and Codes (PANS-ABC).

• Note 3: Row numbers in the ‘Ref.’ column are included only for clarity and ease of reference, and are not part of the TAF.

Ref.	Element	Detailed content	Template(s)	Template(s)	Template(s)	Template(s)
1	Identification of the type of forecast (M)	Type of forecast (M)	TAF or TAF AMD or TAF COR	TAF or TAF AMD or TAF COR	TAF or TAF AMD or TAF COR	TAF or TAF AMD or TAF COR
2	Location indicator (M)	ICAO location indicator (M)	nnnn	nnnn	nnnn	nnnn
3	Time of issue of the forecast (M)	Day and time of issue of the forecast in UTC (M)	nnnnnnZ	nnnnnnZ	nnnnnnZ	nnnnnnZ
4	Identification of a missing forecast (C)	Missing forecast identifier (C)	NIL	NIL	NIL	NIL
5	END OF TAF IF THE FORECAST IS MISSING.	END OF TAF IF THE FORECAST IS MISSING.	END OF TAF IF THE FORECAST IS MISSING.	END OF TAF IF THE FORECAST IS MISSING.	END OF TAF IF THE FORECAST IS MISSING.	END OF TAF IF THE FORECAST IS MISSING.
6	Days and period of validity of the forecast (M)	Days and period of validity of the forecast in UTC (M)	nnnn/nnnn	nnnn/nnnn	nnnn/nnnn	nnnn/nnnn
7	Identification of a cancelled forecast (C)	Cancelled forecast identifier (C)	CNL	CNL	CNL	CNL
8	END OF TAF IF THE FORECAST IS CANCELLED.	END OF TAF IF THE FORECAST IS CANCELLED.	END OF TAF IF THE FORECAST IS CANCELLED.	END OF TAF IF THE FORECAST IS CANCELLED.	END OF TAF IF THE FORECAST IS CANCELLED.	END OF TAF IF THE FORECAST IS CANCELLED.
9	Surface wind (M)	Wind direction (M)	nnn or VRB	nnn or VRB	nnn or VRB	nnn or VRB
9	Surface wind (M)	Wind speed (M)	[P]nn[n]	[P]nn[n]	[P]nn[n]	[P]nn[n]
9	Surface wind (M)	Significant speed variations (C)	G[P]nn[n]	G[P]nn[n]	G[P]nn[n]	G[P]nn[n]
9	Surface wind (M)	Units of measurement (M)	KT	KT	KT	KT
10	Visibility (M)	Prevailing visibility (M)	nnnn	nnnn	nnnn	C A V O K
11	Weather (C)	Intensity of weather phenomena (C) [^E0022]	– or +	– or +	—	C A V O K
11	Weather (C)	Characteristics and type of weather phenomena (C)	DZ or RA or SN or SG or PL or DS or SS or FZDZ or FZRA or SHGR or SHGS or SHRA or SHSN or TSGR or TSGS or TSRA or TSSN	DZ or RA or SN or SG or PL or DS or SS or FZDZ or FZRA or SHGR or SHGS or SHRA or SHSN or TSGR or TSGS or TSRA or TSSN	FG or BR or SA or DU or HZ or FU or VA or SQ or PO or FC or TS or BCFG or BLDU or BLSA or BLSN or DRDU or DRSA or DRSN or FZFG or MIFG or PRFG	C A V O K
12	Cloud (M) [^E0023]	Cloud amount and height of base or vertical visibility (M)	FEWnnn or SCTnnn or BKNnnn or OVCnnn	VVnnn or VV///	N S C	C A V O K
12	Cloud (M) [^E0023]	Cloud type (C)	CB or TCU	—	N S C	C A V O K
13	Temperature (O) [^E0024]	Name of the element (M)	TX	TX	TX	TX
13	Temperature (O) [^E0024]	Maximum temperature (M)	[M]nn/	[M]nn/	[M]nn/	[M]nn/
13	Temperature (O) [^E0024]	Day and time of occurrence of the maximum temperature (M)	nnnnZ	nnnnZ	nnnnZ	nnnnZ
13	Temperature (O) [^E0024]	Name of the element (M)	TN	TN	TN	TN
13	Temperature (O) [^E0024]	Minimum temperature (M)	[M]nn/	[M]nn/	[M]nn/	[M]nn/
13	Temperature (O) [^E0024]	Day and time of occurrence of the minimum temperature (M)	nnnnZ	nnnnZ	nnnnZ	nnnnZ
14	Expected significant changes to one or more of the above elements during the period of validity (C)	Change or probability indicator (M)	PROB30 [TEMPO] or PROB40 [TEMPO] or BECMG or TEMPO or FM	PROB30 [TEMPO] or PROB40 [TEMPO] or BECMG or TEMPO or FM	PROB30 [TEMPO] or PROB40 [TEMPO] or BECMG or TEMPO or FM	PROB30 [TEMPO] or PROB40 [TEMPO] or BECMG or TEMPO or FM
14	Expected significant changes to one or more of the above elements during the period of validity (C)	Period of occurrence or change (M)	nnnn/nnnn or nnnnnn	nnnn/nnnn or nnnnnn	nnnn/nnnn or nnnnnn	nnnn/nnnn or nnnnnn
14	Expected significant changes to one or more of the above elements during the period of validity (C)	Wind (C)	nnn[P]nn[G[P]nn]KT or VRBnnKT	nnn[P]nn[G[P]nn]KT or VRBnnKT	nnn[P]nn[G[P]nn]KT or VRBnnKT	nnn[P]nn[G[P]nn]KT or VRBnnKT
14	Expected significant changes to one or more of the above elements during the period of validity (C)	Prevailing visibility (C)	nnnn	nnnn	nnnn	C A V O K	C A V O K
14	Expected significant changes to one or more of the above elements during the period of validity (C)	Weather phenomenon: intensity (C)	– or +	—	N S C	C A V O K	C A V O K	N S W
14	Expected significant changes to one or more of the above elements during the period of validity (C)	Weather phenomenon: characteristics and type (C)	DZ or RA or SN or SG or PL or DS or SS or FZDZ or FZRA or SHGR or SHGS or SHRA or SHSN or TSGR or TSGS or TSRA or TSSN	FG or BR or SA or DU or HZ or FU or VA or SQ or PO or FC or TS or BCFG or BLDU or BLSA or BLSN or DRDU or DRSA or DRSN or FZFG or MIFG or PRFG	N S C	C A V O K	C A V O K	N S W
15		Cloud amount and height of base or vertical visibility (C)	FEWnnn or SCTnnn or BKNnnn or OVCnnn	VVnnn or VV///	N S C	C A V O K	C A V O K	N S C
15		Cloud type (C)	CB or TCU	—	N S C	C A V O K	C A V O K	N S C

To be included whenever applicable. No qualifier for moderate intensity.

Up to four cloud layers.

Consisting of up to a maximum of four temperatures (two maximum temperatures and two minimum temperatures).

Ranges and resolutions for the numerical elements included in TAF	Ranges and resolutions for the numerical elements included in TAF	Ranges and resolutions for the numerical elements included in TAF	Ranges and resolutions for the numerical elements included in TAF	Ranges and resolutions for the numerical elements included in TAF	Ranges and resolutions for the numerical elements included in TAF
Ref.	Elements	Elements	Elements	Range	Resolution
1	Wind direction:	° true	° true	000–360	10
2	Wind speed:	KT	KT	00–99	1
3	Visibility:	M	M	0000–0750	50
		M	M	0800–4 900	100
		M	M	5 000 –9 000	1 000
		M	M	10 000 or greater	0 (fixed value: 9 999 )
4	Vertical visibility:	100’s FT	100’s FT	000–020	1
5	Cloud: height of cloud base:	100’s FT	100’s FT	000–099 100–200	1 10
6	Air temperature (maximum and minimum):	Air temperature (maximum and minimum):	°C	–80 – +60	1

Appendix 4

Template for wind shear warnings

Key:

M	=	inclusion mandatory;
---	---	---
C	=	inclusion conditional, whenever applicable.

• Note 1: The ranges and resolutions for the numerical elements included in wind shear warnings are shown in Appendix 8.

• Note 2: The explanations for the abbreviations can be found in ICAO Doc 8400 Procedures for Air Navigation Services – ICAO Abbreviations and Codes (PANS-ABC).

• Note 3: Row numbers in the ‘Ref.’ column are included only for clarity and ease of reference, and are not part of the wind shear warning.

Ref.	Element	Detailed content	Template(s)
1	Location indicator of the aerodrome (M)	Location indicator of the aerodrome	nnnn
2	Identification of the type of message (M)	Type of message and sequence number	WS WRNG [n]n
3	Time of origin and validity period (M)	Day and time of issue and, where applicable, validity period in UTC	nnnnnn [VALID TL nnnnnn] or [VALID nnnnnn/nnnnnn]
4	IF THE WIND SHEAR WARNING IS TO BE CANCELLED, SEE DETAILS AT THE END OF THE TEMPLATE.	IF THE WIND SHEAR WARNING IS TO BE CANCELLED, SEE DETAILS AT THE END OF THE TEMPLATE.	IF THE WIND SHEAR WARNING IS TO BE CANCELLED, SEE DETAILS AT THE END OF THE TEMPLATE.
5	Phenomenon (M)	Identification of the phenomenon and its location	[MOD] or [SEV] WS IN APCH or [MOD] or [SEV] WS [APCH] RWYnnn or [MOD] or [SEV] WS IN CLIMB-OUT or [MOD] or [SEV] WS CLIMB-OUT RWYnnn or MBST IN APCH or MBST [APCH] RWYnnn or MBST IN CLIMB-OUT or MBST CLIMB-OUT RWYnnn
6	Observed, reported or forecast phenomenon (M)	Identification whether the phenomenon is observed or reported and expected to continue, or forecast	REP AT nnnn nnnnnnnn or OBS [AT nnnn] or FCST
7	Details of the phenomenon (C)	Description of the phenomenon causing the issuance of the wind shear warning	SFC WIND: nnn/nnKT nnnFT – WIND: nnn/nnKT or nnKT LOSS nnNM (or nnKM) FNA RWYnn or nnKT GAIN nnNM (or nnKM) FNA RWYnn
	OR
8	Cancellation of wind shear warning	Cancellation of wind shear warning referring to its identification	CNL WS WRNG [n]n nnnnnn/nnnnnn

Appendix 5

Template for SIGMET and AIRMET

Key:

M	=	inclusion mandatory;
---	---	---
C	=	inclusion conditional, whenever applicable; and