MET.TR.115 Meteorological bulletins

Regulation (EU) 2021/1338

(a) Meteorological bulletins shall be disseminated using specified data types and code forms appropriate to the information being provided.

(b) Meteorological bulletins containing operational meteorological information shall be disseminated via communication systems appropriate to the information being provided and the users for which it is intended.

AMC1 MET.TR.115(a) Meteorological bulletins

ED Decision 2022/004/R

DATA TYPES AND CODE FORMS FOR METEOROLOGICAL INFORMATION

The data types and code forms applicable to specified meteorological information should be as follows:

(a) ICAO Meteorological Information Exchange Model (IWXXM) GML form;

(b) alphanumeric code form;

(c) abbreviated plain language form;

(d) ‘gridded binary’ (GRIB) code form;

(e) ‘binary universal form for the representation of meteorological data’ (BUFR) code form;

(f) portable network graphics (PNG) form.

GM1 MET.TR.115(a) Meteorological bulletins

ED Decision 2022/004/R

DATA TYPES AND CODE FORMS FOR METEOROLOGICAL INFORMATION

The specifications for data types and code forms for meteorological information should be as follows:

—             IWXXM GML form;

—             IWXXM context (class) diagrams with identified features, types and allowed enumerations are published in the WMO Manual on Codes (WMO-No. 306) Volume I.3, Part D ‘Representations derived from data models’;

—             Guidance on the implementation of IWXXM is provided in ICAO Doc 10003 ‘Manual on the ICAO Meteorological Information Exchange Model (IWXXM)’;

—             Guidance on the implementation and exchange of IWXXM in the EUR Region is provided in ICAO EUR Doc 033 ‘Guidelines for the Implementation of OPMET Data Exchange using IWXXM in the EUR Region’;

—             Alphanumeric code form as specified in the WMO Manual on Codes (WMO-No. 306),

—             Volume I.1, Part A ‘Alphanumeric Codes’;

—             Abbreviated plain language form as prescribed in the AMC (AMC1 MET.TR.115(a), AMC1 MET.TR.200(a), AMC1 MET.TR.200(a)(12), AMC3 MET.TR.215(a), AMC1 MET.TR.235(a), AMC1 MET.TR.235(c), AMC2 MET.TR.250(a), AMC1 MET.TR.255(a), AMC1 MET.TR.265, AMC1 MET.TR.270) describing the meteorological information being provided;

—             ‘Gridded binary’ (GRIB) code form as specified in the WMO Manual on Codes (WMO-No. 306), Volume I.2, Part B ‘Binary Codes’;

—             ‘Binary universal form for the representation of meteorological data’ (BUFR) code form as specified in the WMO Manual on Codes (WMO-No. 306), Volume I.2, Part B ‘Binary Codes’;

—             portable network graphics (PNG) form.

GM2 MET.TR.115(a) Meteorological bulletins

ED Decision 2017/001/R

COMPOSITION AND FILING TIMES OF BULLETINS

(a) Whenever possible, exchanges of operational meteorological information should be made in consolidated bulletins of the same types of meteorological information.

(b) Meteorological bulletins required for scheduled transmissions should be filed regularly and at the prescribed scheduled times.

GM3 MET.TR.115(a) Meteorological bulletins

ED Decision 2022/004/R

HEADING

Detailed specifications on format and contents of the heading are given in the WMO Publication No 386, 'Manual on the Global Telecommunication System', Volume I, and in ICAO Doc 8896 ‘ICAO Manual of Aeronautical Meteorological Practice'.

SECTION 2 — SPECIFIC REQUIREMENTS

Chapter 1 — Technical requirements for aeronautical meteorological stations

MET.TR.200 Meteorological reports and other information

Regulation (EU) 2021/1338

(a) Local routine report, local special report, METAR and SPECI shall contain the following elements in the order indicated:

(1) identification of the type of report;

(2) location indicator;

(3) time of the observation;

(4) identification of an automated or missing report, when applicable;

(5) surface wind direction and speed;

(6) visibility;

(7) runway visual range, when the reporting criteria are met;

(8) present weather;

(9) cloud amount, cloud type only for cumulonimbus and towering cumulus clouds and height of cloud base or, where measured, vertical visibility;

(10) air temperature and dew-point temperature;

(11) QNH and, when applicable, in local routine and local special report, QFE;

(12) supplementary information, when applicable.

(b) In local routine report and local special report:

(1) if the surface wind is observed from more than one location along the runway, the locations for which these values are representative shall be indicated;

(2) when there is more than one runway in use and the surface wind related to these runways is observed, the available wind values for each runway shall be given, and the runways to which the values refer shall be reported;

(3) when variations from the mean wind direction are reported in accordance with point MET.TR.205(a)(3)(ii)(B), the two extreme directions between which the surface wind has varied shall be reported;

(4) when variations from the mean wind speed (gusts) are reported in accordance with point MET.TR.205(a)(3) (iii), they shall be reported as the maximum and minimum values of the wind speed attained.

(c) METAR and SPECI

(1) METAR and SPECI shall be issued in accordance with the template shown in Appendix 1.

(2) METAR shall be filed for transmission not later than 5 minutes after the actual time of observation.

(d) Information on visibility, runway visual range, present weather and cloud amount, cloud type and height of cloud base shall be replaced in all meteorological reports by the term ‘CAVOK’ when the following conditions occur simultaneously at the time of observation:

(1) visibility, 10 km or more, and the lowest visibility is not reported;

(2) no cloud of operational significance;

(3) no weather of significance to aviation.

(e) The list of criteria to provide local special report shall include:

(1) those values which most closely correspond to the operating minima of the operators using the aerodrome;

(2) those values which satisfy other local requirements of the air traffic services (ATS) units and of the operators;

(3) an increase in air temperature of 2 °C or more from that given in the latest local report, or an alternative threshold value as agreed between the meteorological services providers, the appropriate ATS unit and the operators concerned;

(4) the available supplementary information concerning the occurrence of significant meteorological conditions in the approach and climb-out areas;

(5) when noise-abatement procedures are applied and the variation from the mean surface wind speed has changed by 5 kt or more from that at the time of the latest local report, the mean speed before and/or after the change being 15 kt or more;

(6) when the mean surface wind direction has changed by 60° or more from that given in the latest report, the mean speed before and/or after the change being 10 kt or more;

(7) when the mean surface wind speed has changed by 10 kt or more from that given in the latest local report;

(8) when the variation from the mean surface wind speed (gusts) has changed by 10 kt or more from that at the time of the latest local report, the mean speed before and/or after the change being 15 kt or more;

(9) when the onset, cessation or change in intensity of any of the following weather phenomena occurs:

(i) freezing precipitation;

(ii) moderate or heavy precipitation, including showers thereof; and

(iii) thunderstorm, with precipitation;

(10) when the onset or cessation of any of the following weather phenomena occurs:

(i) freezing fog;

(ii) thunderstorm, without precipitation;

(11) when the amount of a cloud layer below 1 500 ft (450 m) changes:

(i) from scattered (SCT) or less to broken (BKN) or overcast (OVC); or

(ii) from BKN or OVC to SCT or less.

(f) When so agreed between the meteorological services provider and the competent authority, local special reports and SPECI, when applicable shall be issued whenever the following changes occur:

(1) when the wind changes through values of operational significance; the threshold values shall be established by the meteorological services provider in consultation with the appropriate ATS unit and operators concerned, taking into account changes in the wind which would:

(i) require a change in runway(s) in use;

(ii) indicate that the runway tailwind and crosswind components have changed through values representing the main operating limits for typical aircraft operating at the aerodrome;

(2) when the visibility is improving and changes to or passes through one or more of the following values, or when the visibility is deteriorating and passes through one or more of the following values:

(i) 800, 1 500 or 3 000 m;

(ii) 5 000 m, in cases where a significant number of flights are operated in accordance with the visual flight rules;

(3) when the runway visual range is improving and changes to or passes through one or more of the following values, or when the runway visual range is deteriorating and passes through one or more of the following values: 50, 175, 300, 550 or 800 m;

(4) when the onset, cessation or change in intensity of any of the following weather phenomena occurs:

(i) dust storm;

(ii) sandstorm;

(iii) funnel cloud (tornado or waterspout);

(5) when the onset or cessation of any of the following weather phenomena occurs:

(i) low drifting dust, sand or snow;

(ii) blowing dust, sand or snow;

(iii) squall;

(6) when the height of base of the lowest cloud layer of BKN or OVC extent is lifting and changes to or passes through one or more of the following values, or when the height of base of the lowest cloud layer of BKN or OVC extent is lowering and passes through one or more of the following values:

(i) 100, 200, 500 or 1 000 ft;

(ii) 1 500 ft, in cases where significant numbers of flights are operated in accordance with the visual flight rules;

(7) when the sky is obscured and the vertical visibility is improving and changes to or passes through one or more of the following values, or when the vertical visibility is deteriorating and passes through one or more of the following values: 100, 200, 500 or 1 000 ft;

(8) any other criteria based on local aerodrome operating minima, as agreed between the meteorological services providers and the operators.

AMC1 MET.TR.200(a) Meteorological reports and other information

ED Decision 2022/004/R

TEMPLATE FOR LOCAL ROUTINE REPORT AND LOCAL SPECIAL REPORT

Local routine reports and local special reports should be issued in abbreviated plain language, in accordance with the template below.

GM1 MET.TR.200(a) Meteorological reports and other information

ED Decision 2022/004/R

RANGES AND RESOLUTIONS — LOCAL ROUTINE REPORT AND LOCAL SPECIAL REPORT

(a) The ranges and resolutions for the numerical elements included in the local routine report and local special report are shown below.

(¹) Under certain circumstances, as specified in AMC1 MET.TR.205(e)(3); otherwise, a resolution of 100 ft is to be used.

(b)  The explanations for the abbreviations can be found in ICAO Doc 8400 ‘Procedures for Air Navigation Services — ICAO Abbreviations and Codes (PANS-ABC)’.

GM2 MET.TR.200(a) Meteorological reports and other information

ED Decision 2022/004/R

LOCAL ROUTINE REPORT AND LOCAL SPECIAL REPORT — EXAMPLES OF ELEMENTS

Non-exhaustive examples of the different elements used in the formulation of local routine reports and local special reports are provided below.

GM1 MET.TR.200(a)(2) Meteorological reports and other information

ED Decision 2022/004/R

LOCATION INDICATORS

The location indicators and their significations are published in ICAO Doc 7910 ‘Location Indicators’.

AMC1 MET.TR.200(a)(4) Meteorological reports and other information

ED Decision 2022/004/R

AUTOMATED REPORTING

Local routine report, local special report, METAR and SPECI from automatic observing systems should be identified with the word ‘AUTO’.

GM1 MET.TR.200(a)(4) Meteorological reports and other information

ED Decision 2022/004/R

AUTOMATED REPORTING

Local routine report, local special report, METAR and SPECI from automatic observing systems may be used as agreed between the aeronautical meteorological stations and the users.

AMC1 MET.TR.200(a)(12) Meteorological reports and other information

ED Decision 2022/004/R

SUPPLEMENTARY INFORMATION — SEMI-AUTOMATIC OBSERVING SYSTEM

(a) In local routine report, local special report, METAR and SPECI, when reported by a semi-automatic observing system, the following recent weather phenomena should be reported, up to a maximum of three groups, in the supplementary information:

(1) freezing precipitation;

(2) moderate or heavy precipitation, including showers thereof;

(3) blowing snow;

(4) dust storm, sandstorm;

(5) thunderstorm;

(6) funnel cloud, tornado or water spout; and

(7) volcanic ash.

(b) In local routine report and local special report when reported by a semi-automatic observing system, the following significant meteorological conditions, or combinations thereof, should be reported in the supplementary information:

(1) cumulonimbus clouds (CB);

(2) thunderstorm (TS);

(3) moderate or severe turbulence (MOD TURB, SEV TURB);

(4) wind shear (WS);

(5) hail (GR);

(6) severe squall line (SEV SQL);

(7) moderate or severe icing (MOD ICE, SEV ICE);

(8) freezing precipitation (FZDZ, FZRA);

(9) severe mountain waves (SEV MTW);

(10) dust storm, sandstorm (DS, SS);

(11) blowing snow (BLSN); and

(12) funnel cloud (tornado or water spout) (FC).

The location of the condition should be indicated. Where necessary, additional information should be included using abbreviated plain language.

AMC2 MET.TR.200(a)(12) Meteorological reports and other information

ED Decision 2022/004/R

SUPPLEMENTARY INFORMATION — AUTOMATIC OBSERVING SYSTEM

In local routine report, local special report, METAR and SPECI, when reported by an automatic observing system, the following recent weather phenomena should be reported, up to a maximum of three groups, in the supplementary information:

(a) FZDZ, FZRA and FZUP;

(b) moderate or heavy DZ, RA and SN;

(c) thunderstorm; and

(d) moderate or heavy unknown precipitation (UP).

AMC3 MET.TR.200(a)(12) Meteorological reports and other information

ED Decision 2022/004/R

SUPPLEMENTARY INFORMATION — WIND SHEAR

Information on wind shear should be included as supplementary information in local routine report, local special report, METAR and SPECI, where local circumstances so warrant.

AMC4 MET.TR.200(a)(12) Meteorological reports and other information

ED Decision 2022/004/R

SUPPLEMENTARY INFORMATION — SEA-SURFACE TEMPERATURE AND STATE OF THE SEA

In METAR and SPECI, information on sea-surface temperature and the state of the sea or the significant wave height, from aeronautical meteorological stations established on offshore structures in support of helicopter operations, should be included in the supplementary information.

AMC5 MET.TR.200(a)(12) Meteorological reports and other information

ED Decision 2017/001/R

SUPPLEMENTARY INFORMATION — SIGNIFICANT METEOROLOGICAL CONDITIONS

(a) Observations made at aerodromes should include the available supplementary information concerning significant meteorological conditions, particularly those in the approach and climb-out areas.

(b) Where practicable, the information should identify the location of the meteorological condition.

GM1 MET.TR.200(a)(12) Meteorological reports and other information

ED Decision 2022/004/R

SUPPLEMENTARY INFORMATION — RECENT WEATHER PHENOMENA

‘Recent weather phenomena’ is understood as being the weather phenomena observed at the aerodrome during the period since the last issued routine report or last hour, whichever is the shorter, but not at the time of observation.

GM2 MET.TR.200(a)(12) Meteorological reports and other information

ED Decision 2022/004/R

SUPPLEMENTARY INFORMATION — LOCAL CIRCUMSTANCES

Local circumstances include but are not necessarily limited to wind shear of non-transitory nature such as might be associated with low-level temperature inversions or local topography.

GM3 MET.TR.200(a)(12) Meteorological reports and other information

ED Decision 2022/004/R

SUPPLEMENTARY INFORMATION — WIND SHEAR

The inclusion of wind shear in the supplementary information is understood to be addressed, as a minimum, in local routine report, local special report, METAR and SPECI when reported by a semi-automatic observing system.

GM1 MET.TR.200(b) & (c) Meteorological reports and other information

ED Decision 2022/004/R

EXAMPLE OF METAR AND LOCAL ROUTINE REPORT

GM1 MET.TR.200(b) Meteorological reports and other information

ED Decision 2022/004/R

EXAMPLE OF SPECI AND LOCAL SPECIAL REPORT

AMC1 MET.TR.200(c) Meteorological reports and other information

ED Decision 2022/004/R

METAR AND SPECI — CODE FORM

METAR and SPECI, and corrections thereto, should be encoded using:

(a) the IWXXM GML form as specified in point (a) of AMC1 MET.TR.115(a); and

(b) the alphanumeric code form for METAR as specified in point (b) of AMC1 MET.TR.115(a).

GM1 MET.TR.200(e)(5) Meteorological reports and other information

ED Decision 2020/008/R

NOISE ABATEMENT PROCEDURES

Noise abatement procedures are those in accordance with 7.2.6 of ICAO Doc 4444 ‘Procedures for Air Navigation Services (PANS-ATM)' as last amended.

GM1 MET.TR.200(f) Meteorological reports and other information

ED Decision 2022/004/R

ISSUANCE OF LOCAL SPECIAL REPORTS

Point (f) of MET.TR.200 relates to the list of criteria to provide local special reports and SPECI when a meteorological change occurs. The agreement between the meteorological service provider and the competent authority is introduced as these criteria are usually agreed with the competent authority. Also, in introducing this agreement, the nature of the transposed provision (Appendix 3, 2.3.3 Recommendation) of ICAO Annex 3 remains.

AMC1 MET.TR.200(f)(8) Meteorological reports and other information

ED Decision 2022/004/R

ISSUANCE OF SPECI

Other criteria based on local aerodrome operating minima are to be considered in accordance with point (j) of AMC1 MET.TR.220(f).

MET.TR.205 Reporting of meteorological elements

Regulation (EU) 2021/1338

(a) Surface wind direction and speed

(1) In local routine report, local special report, METAR and SPECI, the surface wind direction and speed shall be reported in steps of 10 degrees true and 1 kt respectively.

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

(3) In local routine report, local special report, METAR and SPECI:

(i) the units of measurement used for the wind speed shall be indicated;

(ii) variations from the mean wind direction during the past 10 minutes shall be reported as follows, if the total variation is 60° or more, alternatively:

(A) when the total variation is 60° or more and less than 180° and the wind speed is 3 kt or more, such directional variations shall be reported as the two extreme directions between which the surface wind has varied;

(B) when the total variation is 60° or more and less than 180° and the wind speed is less than 3 kt, the wind direction shall be reported as variable with no mean wind direction;

(C) when the total variation is 180° or more, the wind direction shall be reported as variable with no mean wind direction;

(iii) variations from the mean wind speed (gusts), during the past 10 minutes shall be reported when the maximum wind speed exceeds the mean speed by, alternatively:

(A) 5 kt or more in local routine report and local special report when noise abatement procedures are applied;

(B) 10 kt or more otherwise;

(iv) when a wind speed of less than 1 kt is reported, it shall be indicated as calm;

(v) when a wind speed of 100 kt or more is reported, it shall be indicated to be more than 99 kt;

(vi) when variations from the mean wind speed (gusts) are reported in accordance with point MET.TR.205(a), the maximum value of the wind speed attained shall be reported;

(vii) when the 10-minute period includes a marked discontinuity in the wind direction and/or speed, only variations from the mean wind direction and mean wind speed occurring since the discontinuity shall be reported.

(b) Visibility

(1) In local routine report, local special report, METAR and SPECI, the visibility shall be reported in steps of 50 m when the visibility is less than 800 m; in steps of 100 m when it is 800 m or more, but less than 5 km; in kilometre steps when the visibility is 5 km or more, but less than 10 km; and it shall be given as 10 km when the visibility is 10 km or more, except when the conditions for the use of CAVOK apply.

(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, visibility along the runway or runways shall be reported together with the units of measurement used to indicate visibility.

(c) Runway visual range (RVR)

(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.

GM1 MET.TR.205(a)(3)(iii)(A) Reporting of meteorological elements 

ED Decision 2020/008/R

NOISE ABATEMENT PROCEDURES

The noise abatement procedures are those in accordance with 7.2.6 of ICAO Doc 4444 ‘Procedures for Air Navigation Services (PANS-ATM)’.

AMC1 MET.TR.205(b)(1) Reporting of meteorological elements 

ED Decision 2022/004/R

VISIBILITY

In METAR and SPECI, visibility should be reported as prevailing visibility. When the visibility is not the same in different directions and:

(a) when the lowest visibility is different from the prevailing visibility, and (1) less than 1 500 m or (2) less than 50 % of the prevailing visibility, and less than 5 000 m, the lowest visibility observed should also be reported and, when possible, its general direction in relation to the aerodrome reference point indicated by reference to one of the eight points of the compass;

(b) if the lowest visibility is observed in more than one direction, then the most operationally significant direction should be reported; and

(c) when the visibility is fluctuating rapidly, and the prevailing visibility cannot be determined, only the lowest visibility should be reported, with no indication of direction.

AMC1 MET.TR.205(b)(3) Reporting of meteorological elements 

ED Decision 2022/004/R

VISIBILITY — VALUES

In local routine report and local special report, when instrumented systems are used for the measurement of visibility:

(a) if the visibility is observed from more than one location along the runway, the values representative of the touchdown zone should be reported first, followed, as necessary, by the values representative of the mid-point and stop-end of the runway, and the locations for which these values are representative should be indicated; and

(b) when there is more than one runway in use and the visibility is observed related to these runways, the available visibility values for each runway should be reported, and the runways to which the values refer should be indicated.

AMC1 MET.TR.205(c) Reporting of meteorological elements

ED Decision 2022/004/R

RUNWAY VISUAL RANGE (RVR) — TOUCHDOWN ZONE VALUES

In METAR and SPECI:

(a) only the value representative of the touchdown zone should be reported and no indication of location on the runway should be included; and

(b) where there is more than one runway available for landing, touchdown zone RVR values should be included for all such runways, up to a maximum of four, and the runways to which the values refer should be indicated.

AMC1 MET.TR.205(c)(1) Reporting of meteorological elements

ED Decision 2022/004/R

RUNWAY VISUAL RANGE (RVR) — THRESHOLD LIMITS

(a) 50 m should be considered the lower limit, and 2 000 m the upper limit for RVR.

(b) Beyond these limits, local routine report, local special report, METAR and SPECI should merely indicate that the RVR is less than 50 or more than 2 000 m.

AMC1 MET.TR.205(c)(3) Reporting of meteorological elements

ED Decision 2022/004/R

RUNWAY VISUAL RANGE (RVR) — VALUES FOR METAR AND SPECI

(a) When instrumented systems are used for the assessment of RVR, the variations in RVR during the 10-minute period immediately preceding the observation should be included if the RVR values during the 10-minute period have shown a distinct tendency, such that the mean during the first 5 minutes varies by 100 m or more from the mean during the second 5 minutes of the period.

(b) When the variation of the RVR values shows an upward or downward tendency, this should be indicated by the abbreviation ‘U’ or ‘D’, respectively. In cases when actual fluctuations during the 10-minute period show no distinct tendency, this should be indicated using the abbreviation ‘N’.

(c) When indications of tendency are not available, no abbreviations should be included.

AMC1 MET.TR.205(c)(4)(iii) Reporting of meteorological elements 

ED Decision 2017/001/R

RUNWAY VISUAL RANGE (RVR) — VALUES REPRESENTATION

(a) RVR assessments should be representative of:

(1) the touchdown zone of the runway intended for Category I instrument approach and landing operations;

(2) the touchdown zone and the mid-point of the runway intended for Category II instrument approach and landing operations; and

(3) the touchdown zone, mid-point and stop-end of the runway intended for Category III instrument approach and landing operations.

(b) Where RVR is determined by human observers, it should be reported to the appropriate local ATS units, whenever there is a change in the value to be reported in accordance with the reporting scale.

(c) The transmission of such reports should normally be completed within 15 seconds after the termination of the observation.

AMC1 MET.TR.205(d) Reporting of meteorological elements

ED Decision 2022/004/R

PRESENT WEATHER PHENOMENA — AUTOMATIC OBSERVING SYSTEM

In local routine report, local special report, METAR and SPECI reported by an automatic observing system, the following types of present weather phenomena should be reported, using their respective abbreviations and relevant criteria, as appropriate:

(a) Precipitation:

(1) drizzle (DZ);

(2) rain (RA);

(3) snow (SN); and

(4) Unidentified precipitation (UP)

(b) Obscurations (hydrometeors);

(1) Fog (FG): reported when visibility is less than 1 000 m  ;

(2) Mist (BR): reported when visibility is at least 1 000 m, but not more than 5 000 m;

(c) Obscurations (lithometeors). Haze (HZ) should be used when the obscuration consists predominantly of lithometeors and the visibility is 5 000 m or less; and

(d) Temporary failure of system/sensor: the present weather should be replaced by ‘//’ when it cannot be observed due to a temporary failure of the system/sensor.

AMC2 MET.TR.205(d) Reporting of meteorological elements

ED Decision 2022/004/R

PRESENT WEATHER PHENOMENA — SEMI-AUTOMATIC OBSERVING SYSTEM

In local routine report, local special report, METAR and SPECI reported by a semi-automatic observing system, the following types of present weather phenomena should be reported, using their respective abbreviations and relevant criteria, as appropriate:

(a) Precipitation:

(1) drizzle (DZ);

(2) rain (RA);

(3) snow (SN);

(4) snow grains (SG);

(5) ice pellets (PL);

(6) hail (GR): reported when the diameter of the largest hailstones is 5 mm or more;

(7) small hail and/or snow pellets (GS): reported when the diameter of the largest hailstones is less than 5 mm.

(b) Obscurations (hydrometeors):

(1) fog (FG): reported when visibility is less than 1 000 m, except when qualified by ‘MI’, ‘BC’, ‘PR’ or ‘VC’.

(2) mist (BR): reported when visibility is at least 1 000 m, but not more than 5 000 m;

(c) Obscurations (lithometeors)

The following should be used only when the obscuration consists predominantly of lithometeors and the visibility is 5 000 m or less, except ‘SA’ when qualified by ‘DR’ and volcanic ash:

(1) sand (SA);

(2) dust (widespread) (DU);

(3) haze (HZ);

(4) smoke (FU); and

(5) volcanic ash (VA).

(d) Other phenomena:

(1) dust/sand whirls (dust devils) (PO);

(2) squall (SQ);

(3) funnel cloud (tornado or waterspout) (FC);

(4) dust storm (DS);

(5) sandstorm (SS).

AMC3 MET.TR.205(d) Reporting of meteorological elements

ED Decision 2022/004/R

PRESENT WEATHER PHENOMENA — UNIDENTIFIED PRECIPITATION (UP)

In automated local routine report, local special report, METAR and SPECI, in addition to drizzle (DZ), rain (RA) and snow (SN), the abbreviation ‘UP’ should be used for unidentified precipitation when the type of precipitation cannot be identified by the automatic observing system.

AMC1 MET.TR.205(d)(3) Reporting of meteorological elements

ED Decision 2022/004/R

PRESENT WEATHER PHENOMENA — CHARACTERISTICS

(a) In local routine report, local special report, METAR and SPECI, only when reported by a semi-automatic observing system, the following characteristics of present weather phenomena, as necessary, should be reported using their respective abbreviations and relevant criteria, as appropriate:

(1) Shower (SH): used to report showers. Showers observed in the vicinity of the aerodrome should be reported as ‘VCSH’ without qualification regarding type or intensity of precipitation.

(2) Blowing (BL): used with types of present weather phenomena raised by the wind to a height of 6 ft (2 m) or more above the ground.

(3) Low drifting (DR): used with types of present weather phenomena raised by the wind to less than 6 ft (2 m) above ground level.

(4) Shallow (MI): less than 6 ft (2 m) above ground level.

(5) Patches (BC): fog patches randomly covering the aerodrome.

(6) Partial (PR): a substantial part of the aerodrome covered by fog while the remainder is clear.

(b) In automated local routine report, local special report, METAR and SPECI, when showers (SH) referred to above cannot be determined based upon a method that takes account of the presence of convective cloud, the precipitation should not be characterised by ‘SH’.

AMC2 MET.TR.205(d)(3) Reporting of meteorological elements

ED Decision 2022/004/R

PRESENT WEATHER PHENOMENA — INTENSITY

In local routine report, local special report, METAR and SPECI, the relevant intensity or, as appropriate, the proximity to the aerodrome of the reported present weather phenomena should be indicated as follows:

—             Used with types of present weather phenomena. Light intensity should be indicated only for precipitation.

Vicinity (VC)

Between approximately 8 and 16 km of the aerodrome reference point and used only in METAR and SPECI with present weather when not reported under AMC1 MET.TR.205(d)(3) and MET.TR.205(d)(3).

GM1 MET.TR.205(d)(3)(i) Reporting of meteorological elements

ED Decision 2020/008/R

PRESENT WEATHER PHENOMENA — TS LIGHTNING DETECTION EQUIPMENT

(a) At aerodromes with human observers, lightning detection equipment may supplement human observations.

(b) For aerodromes with automatic observing systems, guidance on the use of lightning detection equipment intended for thunderstorm reporting is given in ICAO Doc 9837 ‘Manual on Automatic Meteorological Observing Systems at Aerodromes'.

AMC1 MET.TR.205(e)(1) Reporting of meteorological elements

ED Decision 2022/004/R

CLOUD

In local routine report, local special report, METAR and SPECI:

(a) the cloud amount should be reported using the abbreviations ‘FEW’ (1 to 2 oktas), ‘SCT’ (3 to 4 oktas), ‘BKN’ (5 to7 oktas) or ‘OVC’ (8 oktas);

(b) cumulonimbus clouds and towering cumulus clouds should be indicated as ‘CB’ and ‘TCU’, respectively;

(c) the vertical visibility should be reported in steps of 100 ft (30 m) up to 2 000 ft (600 m);

(d) if there are no clouds of operational significance and no restriction on vertical visibility and the abbreviation ‘CAVOK’ is not appropriate, the abbreviation ‘NSC’ should be used;

(e) when several layers or masses of cloud of operational significance are observed, their amount and height of cloud base should be reported in increasing order of the height of cloud base, and in accordance with the following criteria:

(1) the lowest layer or mass, regardless of the amount to be reported as FEW, SCT, BKN or OVC, as appropriate;

(2) the next layer or mass, covering more than 2/8 to be reported as SCT, BKN or OVC, as appropriate;

(3) the next higher layer or mass, covering more than 4/8 to be reported as BKN or OVC, as appropriate; and

(4) cumulonimbus and/or towering cumulus clouds, whenever observed and not reported in (1) to (3).

(f) when the cloud base is diffuse or ragged or fluctuating rapidly, the minimum height of cloud base or cloud fragments, should be reported; and

(g) when an individual layer (mass) of cloud is composed of cumulonimbus and towering cumulus clouds with a common cloud base, the type of cloud should be reported as cumulonimbus only.

AMC2 MET.TR.205(e)(1) Reporting of meteorological elements

ED Decision 2022/004/R

CLOUD — AUTOMATIC OBSERVING SYSTEM

When an automatic observing system is used to report local routine report, local special report, METAR and SPECI:

(a) when the cloud type cannot be observed, the cloud type in each cloud group should be replaced by ‘///’;

(b) when no clouds are detected, it should be indicated by using the abbreviation ‘NCD’;

(c) when cumulonimbus clouds or towering cumulus clouds are detected and the cloud amount and/or the height of cloud base cannot be observed, the cloud amount and/or the height of cloud base should be replaced by ‘///’; and

(d) when the sky is obscured and the value of the vertical visibility cannot be determined due to a temporary failure of the system/sensor, the vertical visibility should be replaced by ‘///’.

AMC1 MET.TR.205(e)(3) Reporting of meteorological elements

ED Decision 2022/004/R

CLOUD — HEIGHT OF CLOUD BASE

At aerodromes where low-visibility procedures are established for approach and landing, as agreed between the aeronautical meteorological station and the appropriate ATS unit, in local routine report and local special report, the height of cloud base should be reported in steps of 50 ft up to and including 300 ft and in steps of 100 ft between 300 ft  and 10 000 ft, and the vertical visibility in steps of 50 ft up to and including 300 ft and in steps of 100 ft between 300 ft and 2 000 ft.

MET.TR.210 Observing meteorological elements

Regulation (EU) 2021/1338

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.

AMC1 MET.TR.210 Observing meteorological elements

ED Decision 2017/001/R

HUMAN OBSERVATION

Observers at an aerodrome should be located, as far as practical, so as to provide data which is representative of the area for which the observations are required.

GM1 MET.TR.210 Observing meteorological elements

ED Decision 2017/001/R

HUMAN OBSERVATION

When a semi-automatic observing system is used, the observer should be located, as far as practical, so as to supply data which is representative of the area for which the observations are required.

GM2 MET.TR.210 Observing meteorological elements

ED Decision 2022/004/R

OPERATIONALLY DESIRABLE ACCURACY OF OBSERVATION

AMC1 MET.TR.210(a) Observing meteorological elements 

ED Decision 2022/004/R

SURFACE WIND

(a) When local routine report and local special report are used for departing or arriving aircraft, the surface wind observations for these reports should be representative of conditions along the runway or the touchdown zone respectively.

(b) For METAR and SPECI, the surface wind observations should be representative of the conditions above the whole runway where there is only one runway, and the whole runway complex where there is more than one runway.

GM1 MET.TR.210(a) Observing meteorological elements

ED Decision 2017/001/R

SURFACE WIND — TAKE-OFF AND LANDING

Since, in practice, the surface wind cannot be measured directly on the runway, surface wind observations for take-off and landing are expected to be the best practicable indication of the winds which an aircraft will encounter during take-off and landing.

AMC1 MET.TR.210(a)(1) Observing meteorological elements

ED Decision 2020/008/R

SURFACE WIND — SITING

(a) Reported surface wind should be representative of a wind at a height of 30 ± 3 ft (10 ± 1 m) above the ground.

(b) Representative surface wind observations should be obtained by the use of sensors appropriately sited.

(c) Sensors for surface wind observations for local routine report and local special report should be sited to give the best practicable indication of conditions along the runway and touchdown zones.

(d) At aerodromes where topography or prevalent weather conditions cause significant differences in surface wind at various sections of the runway, additional sensors should be provided.

GM1 MET.TR.210(a)(1) Observing meteorological elements

ED Decision 2017/001/R

SURFACE WIND — SITING

Specifications concerning the siting of equipment and installations on operational areas, aiming at reducing the hazard to aircraft to a minimum, are contained in the EASA CS ADR-DSN.T.915 ‘Siting of equipment and installations on operational areas’.

AMC1 MET.TR.210(a)(2) Observing meteorological elements

ED Decision 2017/001/R

SURFACE WIND — DISPLAY

The mean values of, and significant variations in, the surface wind direction and speed for each sensor should be derived and displayed by automated equipment.

AMC1 MET.TR.210(a)(3) Observing meteorological elements

ED Decision 2022/004/R

SURFACE WIND — AVERAGING

The averaging period for measuring variations from the mean wind speed (gusts) reported in accordance with MET.TR.205(a)(3)(iii) should be 3 seconds for local routine report, local special report, METAR, SPECI, and for wind displays used for depicting variations from the mean wind speed (gusts) in ATS units.

GM1 MET.TR.210(a)(3)(ii) Observing meteorological elements

ED Decision 2022/004/R

SURFACE WIND — AVERAGING — MARKED DISCONTINUITY

A marked discontinuity occurs when there is an abrupt and sustained change in wind direction of 30° or more, with a wind speed of 10 kt before or after the change, or a change in wind speed of 10 kt or more, lasting at least 2 minutes.

AMC1 MET.TR.210(b)(1) Observing meteorological elements

ED Decision 2022/004/R

VISIBILITY — GENERAL

(a) When instrumented systems are used for the measurement of visibility, their output should be updated at least every 60 seconds to permit provision of current representative values.

(b) When instrumented systems are used for the measurement of visibility, it should be measured at a height of approximately 7.5 ft (2.5 m) above the runway.

(c) When local routine report and local special report are used for departing aircraft, the visibility observations for these reports should be representative of the conditions along the runway.

(d) When local routine report and local special report are used for arriving aircraft, the visibility observations for these reports should be representative of the touchdown zone of the runway.

(e) For METAR and SPECI, the visibility observations should be representative of the aerodrome.

AMC1 MET.TR.210(b)(2) Observing meteorological elements

ED Decision 2017/001/R

VISIBILITY — SITING

(a) When instrumented systems are used for the measurement of visibility, representative visibility observations should be obtained by the use of sensors appropriately sited.

(b) Sensors for visibility observations for local routine reports and local special reports should be sited to give the best practicable indications of visibility along the runway and touchdown zone.

AMC1 MET.TR.210(b)(4) Observing meteorological elements

ED Decision 2017/001/R

VISIBILITY — AVERAGING

The averaging period for visibility should be 1 minute for local routine reports and local special reports and for visibility displays in ATS units.

GM1 MET.TR.210(b)(4) Observing meteorological elements

ED Decision 2017/001/R

VISIBILITY — AVERAGING — MARKED DISCONTINUITY

A marked discontinuity occurs when there is an abrupt and sustained change in visibility, lasting at least 2 minutes, which reaches or passes through one or more of the following values: 800, 1 500 or 3 000 and, in cases where significant numbers of flights are operated in accordance with the visual flight rules,  5 000 m.

AMC1 MET.TR.210(c) Observing meteorological elements

ED Decision 2017/001/R

RUNWAY VISUAL RANGE (RVR) — ASSESSMENT

RVR should be assessed:

(a) at a height of approximately 7.5 ft (2.5 m) above the runway for instrument systems or at a height of approximately 15 ft (5 m) above the runway by a human observer;

(b) at a lateral distance from the runway centre line of not more than 120 m.

GM1 MET.TR.210(c) Observing meteorological elements

ED Decision 2020/008/R

RUNWAY VISUAL RANGE (RVR) — ASSESSMENT

A detailed understanding of the assessment of RVR is described in ICAO Doc 9328 'Manual on ‘RVR — Observing and reporting practices’.

AMC1 MET.TR.210(c)(2) Observing meteorological elements

ED Decision 2022/004/R

RUNWAY VISUAL RANGE (RVR) — SITING

(a) The site for observations to be representative of the touchdown zone should be located about 300 m along the runway from the threshold.

(b) The sites for observations to be representative of the mid-point and stop-end of the runway should be located at a distance of 1 000 to 1 500 m along the runway from the threshold and at a distance of about 300 m from the other end of the runway.

(c) The exact position of these sites and, if necessary, additional sites should be decided after considering aeronautical, meteorological and climatological factors such as long runways, swamps and other fog-prone areas.

AMC1 MET.TR.210(c)(3) Observing meteorological elements

ED Decision 2022/004/R

RUNWAY VISUAL RANGE (RVR) — RUNWAY LIGHT INTENSITY

(a) Instrumented systems should consider the runway light intensity.

(b) When instrumented systems are used for the assessment of RVR, computations should be made separately for each available runway.

(c) For local routine report and local special report, the light intensity to be used for the computation should be:

(1) for a runway with the lights switched on and a light intensity of more than 3 % of the maximum light intensity available, the light intensity actually in use on that runway;

(2) for a runway with the lights switched on and a light intensity of 3 % or less of the maximum light intensity available, the optimum light intensity that would be appropriate for operational use in the prevailing conditions; and

(3) for a runway with lights switched off (or at the lowest setting pending the resumption of operations), the optimum light intensity that would be appropriate for operational use in the prevailing conditions.

(d) In METAR and SPECI, the RVR should be based on the maximum light intensity available on the runway.

GM1 MET.TR.210(c)(3) Observing meteorological elements

ED Decision 2022/004/R

RUNWAY VISUAL RANGE (RVR) — USE OF INSTRUMENTED SYSTEMS

(a) Since accuracy can vary from one instrument design to another, performance characteristics are to be checked before selecting an instrument for assessing the runway visual range.

(b) The calibration of a forward-scatter meter has to be traceable and verifiable to a transmissometer standard, whose accuracy has been verified over the intended operational range.

(c) Guidance on the use of transmissometers and forward-scatter meters in instrumented Runway Visual Range systems is given in ICAO Doc 9328 'Manual of Runway Visual Range Observing and Reporting Practices'.

GM2 MET.TR.210(c)(3) Observing meteorological elements

ED Decision 2022/004/R

RUNWAY VISUAL RANGE (RVR)

Instrumented systems based on transmissometer or forward-scatter meters must be used to assess RVR on runways intended for Categories II and III instrument approach and landing operations. For Category I instrument approach, other means to assess RVR exist and the assessment of RVR by means of instrumented systems based on transmissometer or forward-scatter meters are therefore not required. However, if the competent authority considers that an instrument system is required at certain aerodromes, it may decide so. Therefore, the requirement in MET.TR.210(c)(2) provides this option, which is consistent with the ICAO Annex 3 approach.

GM1 MET.TR.210(c)(5)(ii)(B) Observing meteorological elements

ED Decision 2022/004/R

RUNWAY VISUAL RANGE (RVR) — AVERAGING

A marked discontinuity occurs when there is an abrupt and sustained change in RVR, lasting at least 2 minutes, which reaches or passes through the values 800, 550, 300 and 175 m.

AMC1 MET.TR.210(d)(1) Observing meteorological elements

ED Decision 2022/004/R

PRESENT WEATHER — GENERAL

(a) For local routine report and local special report, the present weather information should be representative of the conditions at the aerodrome.

(b) For METAR and SPECI, the present weather information should be representative of the conditions at the aerodrome and, for certain specified present weather phenomena, in its vicinity.

AMC1 MET.TR.210(d)(2) Observing meteorological elements

ED Decision 2017/001/R

PRESENT WEATHER — SITING

When instrumented systems are used for observing present weather phenomena listed under AMC2 MET.TR.205(d), MET.TR.205(d)(3) and AMC1 MET.TR.205(d)(3), representative information should be obtained by the use of sensors appropriately sited.

AMC1 MET.TR.210(e) Observing meteorological elements

ED Decision 2022/004/R

CLOUDS — GENERAL

(a) Cloud observations for local routine report and local special report should be representative of the runway threshold(s) in use.

(b) Cloud observations for METAR and SPECI should be representative of the aerodrome and its vicinity.

AMC1 MET.TR.210(e)(2) Observing meteorological elements

ED Decision 2020/008/R

CLOUDS — SITING

(a) When instrumented systems are used for the measurement of the cloud amount and the height of cloud base, representative observations should be obtained by the use of sensors appropriately sited.

(b) For local routine report and local special report, in the case of aerodromes with precision approach runways, sensors for cloud amount and height of cloud base should be sited to give the best practicable indications of the cloud amount and height of cloud base at the threshold of the runway in use. For that purpose, a sensor should be installed at a distance of less than 4 000 ft (1 200 m) before the landing threshold.

AMC1 MET.TR.210(f) Observing meteorological elements

ED Decision 2022/004/R

AIR TEMPERATURE AND DEW-POINT TEMPERATURE

Observations of air temperature and dew-point temperature for local routine report, local special report, METAR and SPECI, should be representative of the whole runway complex.

AMC1 MET.TR.210(g)(3) Observing meteorological elements

ED Decision 2017/001/R

ATMOSPHERIC PRESSURE — REFERENCE LEVEL

(a) The reference level for the computation of QFE should be the aerodrome elevation.

(b) For non-precision approach runways, whose thresholds are 7 ft (2 m) or more below the aerodrome elevation, and for precision approach runways, the QFE, if required, should refer to the relevant threshold elevation.

Chapter 2 — Technical requirements for aerodrome meteorological offices

MET.TR.215 Forecasts and other information

Regulation (EU) 2021/1338

(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.

AMC1 MET.TR.215(a) Forecasts and other information

ED Decision 2017/001/R

METEOROLOGICAL INFORMATION FOR OPERATORS AND FLIGHT CREW

Meteorological information provided to operators and flight crew members should be provided by means of one or more of the following:

(a) written or printed material, including specified charts and forms;

(b) data in a digital form;

(c) briefing;

(d) consultation;

(e) display; or

(f) an automated pre-flight information system providing self-briefing and flight documentation facilities while retaining access by operators and aircrew members to consultation, as necessary, with the aerodrome meteorological office.

AMC2 MET.TR.215(a) Forecasts and other information

ED Decision 2017/001/R

SPECIFIC INFORMATION FOR HELICOPTER OPERATIONS

(a) Meteorological information for pre-flight planning and in-flight replanning by operators of helicopters flying to offshore structures should include data covering the layers from sea level to flight level 100.

(b) Particular mention should be made of the expected surface visibility, the amount, type, where available, base and tops of cloud below flight level 100, sea state and sea-surface temperature, mean sea-level pressure, and the occurrence and expected occurrence of turbulence and icing.

AMC3 MET.TR.215(a) Forecasts and other information

ED Decision 2020/008/R

AUTOMATED PRE-FLIGHT INFORMATION SYSTEMS

Automated pre-flight information systems for the supply of meteorological information for self-briefing, pre-flight planning and flight documentation should:

(a) provide for the continuous and timely updating of the system database and monitoring of the validity and integrity of the meteorological information stored;

(b) permit access to the system by operators and flight crew members and also by other aeronautical users concerned through suitable telecommunications means;

(c) use access and interrogation procedures based on abbreviated plain language and, as appropriate, ICAO location indicators, and aeronautical meteorological code data-type designators prescribed by WMO, or based on a menu-driven user interface, or other appropriate mechanisms as agreed between the meteorological services provider and the operators concerned; and

(d) provide for rapid response to a user request for information.

GM1 MET.TR.215(a) Forecasts and other information

ED Decision 2022/004/R

AUTOMATED PRE-FLIGHT INFORMATION SYSTEMS

(a) ICAO abbreviations and codes and location indicators are given respectively in ICAO Doc 8400 'Procedures for Air Navigation Services — ICAO Abbreviations and Codes (PANS-ABC)' and ICAO Doc 7910 'Location Indicators'.

(b) Aeronautical meteorological code data-type designators are given in the WMO Publication No 386 'Manual on the Global Telecommunication System'.

GM1 MET.TR.215(b) Forecasts and other information

ED Decision 2017/001/R

RESCUE COORDINATION CENTRES

(a) The elements which are not distributed routinely are:

(1) state of ground, and in particular any snow cover or flooding;

(2) sea-surface temperature, state of the sea, ice cover (if any) and ocean currents, if relevant to the search area; and

(3) sea-level pressure data.

(b) On request from the rescue coordination centre, the designated aerodrome meteorological office or meteorological watch office should arrange to obtain details of the flight documentation which was supplied to the missing aircraft, together with any amendments to the forecast which were transmitted to the aircraft in flight.

GM2 MET.TR.215(b) Forecasts and other information

ED Decision 2017/001/R

RESCUE COORDINATION CENTRES

Information to be supplied to rescue coordination centres includes:

(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 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; and

(g) sea-level pressure data.

AMC1 MET.TR.215(d)(5) Forecasts and other information

ED Decision 2017/001/R

HEIGHT INDICATIONS REFERENCES TO EN-ROUTE METEOROLOGICAL CONDITIONS

All references to en-route meteorological conditions, such as height indications of upper winds, turbulence or bases and tops of clouds, should be expressed in flight levels. Height indications referred to en-route meteorological conditions may also be expressed in pressure, altitude or, for low-level flights, in height above ground level.

AMC1 MET.TR.215(e) Forecasts and other information

ED Decision 2020/008/R

FLIGHT DOCUMENTATION

(a) Where the forecasts are supplied in chart form, flight documentation for low-level flights, including those in accordance with the visual flight rules, operating up to flight level 100 or up to flight level 150 in mountainous areas or higher, where necessary, should contain the following as appropriate to the flight:

(1) information from relevant SIGMET and AIRMET;

(2) upper wind and upper-air temperature charts; and

(3) significant weather charts.

(b) Where the forecasts are not supplied in chart form, flight documentation for low-level flights, including those in accordance with the visual flight rules, operating up to flight level 100 or up to flight level 150 in mountainous areas or higher, where necessary, should contain the following information as appropriate to the flight: SIGMET and AIRMET information.

AMC1 MET.TR.215(e)(1) & (2) Forecasts and other information

ED Decision 2017/001/R

FLIGHT DOCUMENTATION — LEGEND FOR THE CHARTS

When the flight documentation related to forecasts of upper wind and upper-air temperature and SIGWX phenomena is presented in the form of charts, it should be in accordance with the below sheet of notations used in flight documentation.

GM1 MET.TR.215(e)(1) & (2) Forecasts and other information

ED Decision 2022/004/R

MODEL CHARTS

This guidance provides examples of model charts.

(a) UPPER WIND AND TEMPERATURE CHART FOR STANDARD ISOBARIC SURFACE

MODEL IS

Example 1. Arrows, feathers and pennants (Mercator projection)

(b) UPPER WIND AND TEMPERATURE CHART FOR STANDARD ISOBARIC SURFACE

MODEL IS

Example 2. Arrows, feathers and pennants (Polar stereographic projection)

(c) SIGNIFICANT WEATHER CHART (HIGH LEVEL)

MODEL SWH

Example. Polar stereographic projection (showing the jet stream vertical extent)

(d) SIGNIFICANT WEATHER CHART (MEDIUM LEVEL)

MODEL SWM

(e) SIGNIFICANT WEATHER CHART (LOW LEVEL)

MODEL SWL

Example 1

(f) SIGNIFICANT WEATHER CHART (LOW LEVEL)

MODEL SWL

Example 2

AMC2 MET.TR.215(e)(1) & (2) Forecasts and other information

ED Decision 2017/001/R

FORMAT OF FLIGHT DOCUMENTATION

The location indicators and the abbreviations used should be explained in the flight documentation.

AMC1 MET.TR.215(f) Forecasts and other information

ED Decision 2020/008/R

CHARTS

Charts included in flight documentation should have a high standard of clarity and legibility and should have the following physical characteristics:

(a) For convenience, the largest size of charts should be about 42 × 30 cm (standard A3 size) and the smallest size should be about 21 × 30 cm (standard A4 size). The choice between these sizes should depend on the route lengths and the amount of detail that needs to be given in the charts as agreed between the aerodrome meteorological office and the users concerned;

(b) Major geographical features, such as coastlines, major rivers and lakes, should be depicted in a way that makes them easily recognisable;

(c) For charts prepared by computer, meteorological data should take preference over basic chart information, the former cancelling the latter wherever they overlap;

(d) Major aerodromes should be shown as a dot and identified by the first letter of the name of the city the aerodrome serves as given in Table AOP of the EUR air navigation plan;

(e) A geographical grid should be shown with meridians and parallels represented by dotted lines at each 10°-latitude and longitude; dots should be spaced one degree apart;

(f) Latitude and longitude values should be indicated at various points throughout the charts; and

(g) Labels on the charts for flight documentation should be clear and simple and should present the name of the world area forecast centre or, for non-WAFS products, the originating centre, the type of chart, date and valid time and, if necessary, the types of units used in an unambiguous way.

AMC2 MET.TR.215(f) Forecasts and other information

ED Decision 2022/004/R

CHARTS

(a) The minimum number of charts for flights between flight level 250 and flight level 630 should include a high-level SIGWX chart (flight level 250 to flight level 630) or a medium-level SIGWX chart (flight level 100 to flight level 450), if appropriate, and a forecast flight level 340 wind and temperature chart.

(b) The actual charts provided for pre-flight and in-flight planning and for flight documentation should be agreed between the meteorological providers and the users concerned.

GM1 MET.TR.215(f) Forecasts and other information

ED Decision 2017/001/R

CHARTS — SHORT-HAUL FLIGHTS

For short-haul flights, charts should be prepared covering limited areas at a scale of 1:15 × 10⁶ as required.

GM2 MET.TR.215(f) Forecasts and other information

ED Decision 2022/004/R

MAP PROJECTIONS — CORRECT CONVERSION BETWEEN DIFFERENT MAP PROJECTIONS

When plotting shapes, particularly polygons, on maps, appropriate corrections are necessary if they are plotted on projections different to those used in the production of the original forecast area.

GM1 MET.TR.215(g) Forecasts and other information

ED Decision 2020/008/R

FORECASTS IN CHART FORM

(a) Charts related to concatenated route-specific upper wind and upper-air temperature forecasts should be provided as agreed between the meteorological service provider and the operator concerned.

(b) Guidance on the design, formulation and use of concatenated charts is given in ICAO DOC 8896 'Manual of Aeronautical Meteorological Practice' as last amended.

AMC1 MET.TR.215(i) Forecasts and other information

ED Decision 2017/001/R

CLIMATOLOGICAL INFORMATION — PERIOD OF OBSERVATION

Aeronautical climatological information should be based on observations made over a period of at least five years. The period should be indicated in the information supplied.

AMC2 MET.TR.215(i) Forecasts and other information

ED Decision 2017/001/R

CLIMATOLOGICAL DATA RELATED TO SITES FOR NEW AERODROMES

Climatological data related to sites for new aerodromes and to additional runways at existing aerodromes should be collected starting as early as possible before the commissioning of those aerodromes or runways.

AMC3 MET.TR.215(i) Forecasts and other information

ED Decision 2017/001/R

CLIMATOLOGICAL SUMMARIES

Aerodrome climatological summaries should follow the procedures prescribed by the World Meteorological Organization and should be made available in a form to meet a specific user request.

AMC4 MET.TR.215(i) Forecasts and other information

ED Decision 2017/001/R

CLIMATOLOGICAL TABLE

An aerodrome climatological table should indicate:

(a) mean values and variations therefrom, including maximum and minimum values, of meteorological elements; and/or

(b) the frequency of occurrence of present weather phenomena affecting flight operations at the aerodrome; and/or

(c) the frequency of occurrence of specified values of one, or of a combination of two or more, elements.

AMC5 MET.TR.215(i) Forecasts and other information

ED Decision 2017/001/R

CLIMATOLOGICAL TABLE

Aerodrome climatological tables should include information required for the preparation of aerodrome climatological summaries.

AMC6 MET.TR.215(i) Forecasts and other information

ED Decision 2017/001/R

CLIMATOLOGICAL SUMMARIES

Aerodrome climatological summaries should cover:

(a) frequencies of the occurrence of runway visual range/visibility and/or height of base of the lowest cloud layer of BKN or OVC extent below specified values at specified times;

(b) frequencies of visibility below specified values at specified times;

(c) frequencies of the height of base of the lowest cloud layer of BKN or OVC extent below specified values at specified times;

(d) frequencies of occurrence of concurrent wind direction and speed within specified ranges;

(e) frequencies of surface temperature in specified ranges of 5°C at specified times; and

(f) mean values and variations therefrom, including maximum and minimum values of meteorological elements required for operational planning purposes, including take-off performance calculations.

GM1 MET.TR.215(i) Forecasts and other information

ED Decision 2017/001/R

CLIMATOLOGICAL INFORMATION

In cases where it is impracticable to meet the requirements for aeronautical climatological information on a national basis, the collection, processing and storage of observational data may be effected through computer facilities available for international use, and the responsibility for the preparation of the required aeronautical climatological information may be delegated by agreement between the competent authorities concerned.

GM2 MET.TR.215(i) Forecasts and other information

ED Decision 2020/008/R

CLIMATOLOGICAL SUMMARIES — MODELS

Models of climatological summaries related to (a) to (e) of AMC6 MET.TR.215(i) are given in the WMO Publication No 49, Technical Regulations, Volume II, Part III – ‘AERONAUTICAL CLIMATOLOGY’.

GM3 MET.TR.215(i) Forecasts and other information

ED Decision 2022/004/R

CLIMATOLOGICAL DATA FOR AERODROME PLANNING PURPOSES

Climatological data required for aerodrome planning purposes is set out in GM1 ADR-DSN.B.025 ‘Data to be used’.

MET.TR.220 Aerodrome forecasts

Regulation (EU) 2021/1338

(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.

GM1 MET.TR.220 Aerodrome forecasts

ED Decision 2020/008/R

TAF — EXAMPLES

GM2 MET.TR.220 Aerodrome forecasts

ED Decision 2022/004/R

TAF — EXAMPLE OF CANCELLATION

GM3 MET.TR.220 Aerodrome forecasts

ED Decision 2022/004/R

TAF — ACCURACY

The accuracy of TAF should be monitored using appropriate verification methodologies as agreed with the competent authority. The verification should identify the accuracy of the forecast against the required change criteria for the forecast elements: wind direction, wind speed, visibility, precipitation, cloud amount, and cloud height. Where provided, maximum and minimum temperature forecasts in TAF should be verified.

GM1 MET.TR.220(a)(8) Aerodrome forecasts

ED Decision 2017/001/R

VISIBILITY

The visibility included in TAF refers to the forecast prevailing visibility.

AMC1 MET.TR.220(b) Aerodrome forecasts

ED Decision 2022/004/R

TAF — CODE FORM

TAF, and amendments thereto, should be encoded using:

(a) the IWXXM GML form as specified in point (a) of AMC1 MET.TR.115(a); and

(b) the alphanumeric code form for TAF as specified in point (b) of AMC1 MET.TR.115(a).

AMC1 MET.TR.220(c) Aerodrome forecasts

ED Decision 2022/004/R

PERIOD OF VALIDITY

(a) The periods of validity for an up to 9-hour TAF should commence at 00, 03, 06, 09, 12, 15, 18 and 21 UTC and for a 24- and a 30-hour TAF at 00, 06, 12 and 18 UTC or 03, 09, 15, and 21 UTC.

(b) The 24- and 30-hour TAF periods of validity should be determined based on the types of operations, as agreed between the aerodrome meteorological office and the operators concerned.

(c) A routine TAF valid for up to 9 hours should be issued every 3 hours, and those valid for 24 or 30 hours should be issued every 6 hours.

(d)  If so agreed between the competent authority and the meteorological services provider, TAF valid for 24 or 30 hours may be issued every 3 hours, and the validity should commence at 00, 03, 06, 09, 12, 15, 18 and 21 UTC.

(e) At aerodromes with limited hours of operation, the beginning of the period of validity of a TAF should commence at least 1 hour prior to the aerodrome resuming operations, or more as agreed between the aerodrome meteorological office and the operators concerned, to meet planning requirements for flights that arrive at the aerodromes as soon as it is opened for use.

GM1 MET.TR.220(e)(2)(i) Aerodrome forecasts

ED Decision 2022/004/R

TAF — PHENOMENA REDUCING VISIBILITY

When the visibility is forecast to be 5 000 m or less, the forecast weather phenomenon reducing visibility may be included in TAF, e.g. phenomena, and combinations thereof, such as FG, BR, HZ,
-RA, -SN, etc.

AMC1 MET.TR.220(f) Aerodrome forecasts

ED Decision 2017/001/R

TAF — USE OF CHANGE GROUPS

The criteria used for the inclusion of change groups in TAF or amendments to TAF should be based on the following:

(a) when the mean surface wind direction is forecasted to change by 60° or more, the mean speed before and/or after the change being 10 kt (5 m/s) or more;

(b) when the mean surface wind speed is forecasted to change by 10 kt (5 m/s) or more;

(c) when the variation from the mean surface wind speed (gusts) is forecasted to change by 10 kt (5 m/s) or more, the mean speed before and/or after the change being 15 kt (7.5 m/s) or more;

(d) when the surface wind is forecasted to change through values of operational significance;

(e) when the visibility is forecasted to improve and change to or pass through one or more of the following values, or when the visibility is forecasted to deteriorate and pass through one or more of the following values:

(1) 150, 350, 600, 800, 1 500 or 3 000 m; and

(2) 5 000 m in cases where significant numbers of flights are operated in accordance with the visual flight rules;

(f) when any of the following weather phenomena, or combinations thereof, are forecasted to begin or end:

(1) low drifting dust, sand or snow;

(2) blowing dust, sand or snow;

(3) squall; and

(4) funnel cloud (tornado or waterspout);

(g) when the height of base of the lowest layer or mass of cloud of BKN or OVC extent is forecasted to lift and change to or pass through one or more of the following values, or when the height of the lowest layer or mass of cloud of BKN or OVC extent is forecasted to lower and pass through one or more of the following values:

(1) 100, 200, 500 or 1 000 ft (30, 60, 150 or 300 m); or

(2) 1 500 ft (450 m) in cases where significant numbers of flights are operated in accordance with the visual flight rules;

(h) when the amount of a layer or mass of cloud below 1 500 ft (450 m) is forecasted to change:

(1) from NSC, FEW or SCT to BKN or OVC; or

(2) from BKN or OVC to NSC, FEW or SCT;

(i) when the vertical visibility is forecasted to improve and change to or pass through one or more of the following values, or when the vertical visibility is forecasted 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); and

(j) any other criteria based on local aerodrome operating minima, as agreed between the aerodrome meteorological office and the operators.

GM1 MET.TR.220(f)(1) Aerodrome forecasts

ED Decision 2022/004/R

TAF — USE OF CHANGE AND TIME INDICATORS

Guidance on the use of change and time indicators in TAF is given below:

AMC1 MET.TR.220(g) Aerodrome forecasts  

ED Decision 2017/001/R

USE OF PROBABILITY INDICATORS

(a) The number of change and probability groups should be kept to a minimum.

(b) The probability of occurrence of an alternative value of a forecast element or elements should be placed after the element or elements forecast and be followed by the alternative value of the element or elements.

GM1 MET.TR.220(g) Aerodrome forecasts

ED Decision 2017/001/R

USE OF PROBABILITY INDICATORS

(a) A probability of an alternative value or change of less than 30 % should not be considered sufficiently significant to be indicated.

(b) A probability of an alternative value or change of 50 % or more should not be considered a probability but, instead, should be indicated, as necessary, by use of the change indicators ‘BECMG’ or ‘TEMPO’ or by subdivision of the validity period using the abbreviation ‘FM’. The probability group should neither be used to qualify the change indicator ‘BECMG’ nor the time indicator ‘FM’.

MET.TR.225 Forecasts for landing

Regulation (EU) 2021/1338

(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.

AMC1 MET.TR.225(c)(1)(iii) Forecasts for landing

ED Decision 2017/001/R

THRESHOLD VALUES

The threshold values should be established by the aerodrome meteorological office in consultation with the appropriate ATS units and operators concerned, taking into account changes in the wind which would:

(a) require a change in runway(s) in use; and

(b) indicate that the runway tailwind and crosswind components will change through values representing the main operating limits for typical aircraft operating at the aerodrome.

GM1 MET.TR.225(c)(2)(iii) Forecasts for landing

ED Decision 2020/008/R

VISIBILITY

In TREND forecasts appended to local routine report and local special report, visibility refers to the forecast visibility along the runway(s).

AMC1 MET.TR.225(c)(7)(ii) Forecasts for landing

ED Decision 2017/001/R

USE OF CHANGE GROUPS — BECMG

(a) When the change is forecast to begin and end wholly within the trend forecast period, the beginning and end of the change should be indicated by using the abbreviations ‘FM’ and ‘TL’, respectively, with their associated time groups.

(b) When the change is forecast to commence at the beginning of the trend forecast period but be completed before the end of that period, the abbreviation ‘FM’ and its associated time group should be omitted and only ‘TL’ and its associated time group should be used.

(c) When the change is forecast to begin during the trend forecast period and be completed at the end of that period, the abbreviation ‘TL’ and its associated time group should be omitted and only ‘FM’ and its associated time group should be used.

(d) When the change is forecast to occur at a specified time during the trend forecast period, the abbreviation ‘AT’ followed by its associated time group should be used.

(e) When the change is forecast to commence at the beginning of the trend forecast period and be completed by the end of that period, or when the change is forecast to occur within the trend forecast period but the time is uncertain, the abbreviations ‘FM’, ‘TL’ or ‘AT’ and their associated time groups should be omitted and the change indicator ‘BECMG’ should be used alone.

GM1 MET.TR.225(c)(7)(ii) Forecasts for landing

ED Decision 2022/004/R

TREND FORECASTS — USE OF CHANGE INDICATORS

Guidance on the use of change indicators in trend forecasts is given in the table below.

AMC1 MET.TR.225(c)(7)(iii) Forecasts for landing

ED Decision 2022/004/R

USE OF CHANGE GROUPS — TEMPO

(a) When the period of the temporary fluctuations in the meteorological conditions is forecast to begin and end wholly within the TREND forecast period, the beginning and end of the period of the temporary fluctuations should be indicated by using the abbreviations ‘FM’ and ‘TL’ respectively, with their associated time groups.

(b) When the period of the temporary fluctuations is forecast to commence at the beginning of the TREND forecast period but cease before the end of that period, the abbreviation ‘FM’ and its associated time group should be omitted and only ‘TL’ and its associated time group should be used.

(c) When the period of the temporary fluctuations is forecast to begin during the TREND forecast period and cease by the end of that period, the abbreviation ‘TL’ and its associated time group should be omitted and only ‘FM’ and its associated time group should be used.

(d) When the period of the temporary fluctuations is forecast to commence at the beginning of the TREND forecast period and cease by the end of that period, both abbreviations ‘FM’ and ‘TL’ and their associated time groups should be omitted and the change indicator ‘TEMPO’ should be used alone.

MET.TR.230 Forecasts for take-off

Regulation (EU) 2017/373

(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.

AMC1 MET.TR.230(a) Forecasts for take-off

ED Decision 2017/001/R

AMENDMENTS TO FORECASTS

(a) The criteria for the issuance of amendments to forecasts for take-off for surface wind direction and speed, temperature and pressure, and any other elements agreed locally should be agreed between the aerodrome meteorological office and the operators concerned.

(b) The criteria should be consistent with the corresponding criteria for special reports established for the aerodrome.

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

Regulation (EU) 2021/1338

(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.

AMC1 MET.TR.235 Aerodrome warnings and wind shear warnings and alerts

ED Decision 2022/004/R

AERODROME WARNINGS — TEMPLATE FOR AERODROME WARNINGS

(a)           Aerodrome warnings should be issued in accordance with the template below or in another format where required by operators or aerodrome meteorological offices.

(b) When the above template is used, the sequence number referred to in the template should correspond to the number of aerodrome warnings issued for the aerodrome since 00.01 UTC on the day concerned.

GM1 MET.TR.235 Aerodrome warnings and wind shear warnings and alerts

ED Decision 2022/004/R

RANGES AND RESOLUTIONS — AERODROME WARNINGS

(a) The ranges and resolutions for the numerical elements included in aerodrome warnings are shown below:

(b) The explanations for the abbreviations can be found in ICAO Doc 8400 'Procedures for Air Navigation Services — ICAO Abbreviations and Codes (PANS-ABC)'.

GM2 MET.TR.235 Aerodrome warnings and wind shear warnings and alerts

ED Decision 2022/004/R

AERODROME WARNINGS — EXAMPLES OF ELEMENTS

Non-exhaustive examples of the different elements used in the formulation of aerodrome warnings are provided below.

GM3 MET.TR.235 Aerodrome warnings and wind shear warnings and alerts

ED Decision 2022/004/R

Phenomenon (M) — TOX CHEM

When issuing an aerodrome warning due to information related to toxic chemical affecting an aerodrome and or volcanic ash deposition, the warning should be filed by means of the use of free text up to 32 characters, e.g. TOX CHEM FCST XXXX AIRPORT NEARBY WKN. (XXXX = ICAO Location Indicator)

AMC1 MET.TR.235(a) Aerodrome warnings and wind shear warnings and alerts

ED Decision 2020/008/R

AERODROME WARNINGS — FORMAT

(a) The additional text should be prepared in abbreviated plain language using approved ICAO abbreviations and numerical values. If no ICAO-approved abbreviations are available, English plain language text should be used.

(b) When quantitative criteria are necessary for the issuance of aerodrome warnings, the criteria used should be as agreed between the aerodrome meteorological office and the users concerned.

AMC1 MET.TR.235(c) Aerodrome warnings and wind shear warnings and alerts

ED Decision 2022/004/R

WIND SHEAR WARNINGS - FORMAT

(a) The use of text in addition to the abbreviations listed in the template in Appendix 4 should be kept to a minimum. The additional text should be prepared in abbreviated plain language using ICAO-approved abbreviations and numerical values.

(b) When an aircraft report is used to prepare a wind shear warning or to confirm a warning previously issued, the corresponding aircraft report, including the aircraft type, should be disseminated unchanged in accordance with the local arrangements to those concerned.

GM1 MET.TR.235(a) Aerodrome warnings and wind shear warnings and alerts

ED Decision 2020/008/R

WIND SHEAR TYPES

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.

GM2 MET.TR.235(a) Aerodrome warnings and wind shear warnings and alerts

ED Decision 2020/008/R

REPORTING THE INTENSITY OF WIND SHEAR

Specifications for reporting the intensity of wind shear are still under development. It is recognised, 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.

GM1 MET.TR.235(c) Aerodrome warnings and wind shear warnings and alerts

ED Decision 2020/008/R

DETECTION OF WIND SHEAR

Wind shear conditions are normally associated with the following phenomena:

(a) thunderstorms, microbursts, funnel cloud, tornado or waterspout, and gust fronts;

(b) frontal surfaces;

(c) strong surface winds coupled with local topography;

(d) sea breeze fronts;

(e) mountain waves, including low-level rotors in the terminal area;

(f) low-level temperature inversions.

GM1 MET.TR.235(d) Aerodrome warnings and wind shear warnings and alerts

ED Decision 2017/001/R

DISSEMINATION OF WIND SHEAR ALERTS

The wind shear alerts are disseminated from automated, ground-based, wind shear remote-sensing or detection equipment in accordance with local arrangements to those concerned.

Chapter 3 — Technical requirements for meteorological watch offices

MET.TR.250 SIGMET

Regulation (EU) 2021/1338

(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.

AMC1 MET.TR.250(a) SIGMET

ED Decision 2020/008/R

AIRSPACE

In cases where the airspace is divided into a flight information region (FIR) and an upper-flight information region (UIR), the SIGMET should be identified by the location indicator of the ATS unit serving the FIR.

AMC2 MET.TR.250(a) SIGMET

ED Decision 2022/004/R

SIGMET — CODE FORM

SIGMET, and cancellations thereof, should be encoded using:

(a) the IWXXM GML form as specified in point (a) of AMC1 MET.TR.115(a);

(b) abbreviated plain language as specified in point (c) of AMC1 MET.TR.115(a).

AMC3 MET.TR.250(a) SIGMET

ED Decision 2022/004/R

FORMAT

SIGMET, when issued in graphical format, should be as specified below:

(a) SIGMET FOR TROPICAL CYCLONE — MODEL STC

(b) SIGMET FOR VOLCANIC ASH — MODEL SVA, MERCATOR PROJECTION

(c) SIGMET FOR VOLCANIC ASH — MODEL SVA, POLAR STEREOGRAPHIC PROJECTION

(d) SIGMET FOR PHENOMENA OTHER THAN TROPICAL CYCLONES AND VOLCANIC ASH — MODEL SGE

AMC4 MET.TR.250(a) SIGMET

ED Decision 2022/004/R

COORDINATION WITH NEIGHBOURING METEOROLOGICAL WATCH OFFICES (MWOs)

An MWO should coordinate SIGMET with neighbouring MWO(s), especially when the en-route weather phenomenon extends or is expected to extend beyond the MWO’s specified area of responsibility, to ensure harmonised SIGMET provision.

GM1 MET.TR.250(a) SIGMET

ED Decision 2020/008/R

FLIGHT INFORMATION REGION

The SIGMET 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.

GM2 MET.TR.250(a) SIGMET

ED Decision 2020/008/R

EXAMPLE OF SIGMET, AND THE CORRESPONDING CANCELLATIONS

GM3 MET.TR.250(a) SIGMET

ED Decision 2020/008/R

EXAMPLE OF SIGMET FOR TROPICAL CYCLONE

GM4 MET.TR.250(a) SIGMET

ED Decision 2020/008/R

EXAMPLE OF SIGMET FOR VOLCANIC ASH

GM5 MET.TR.250(a) SIGMET

ED Decision 2022/004/R

EXAMPLE OF SIGMET FOR RADIOACTIVE CLOUD

GM6 MET.TR.250(a) SIGMET

ED Decision 2020/008/R

EXAMPLE OF SIGMET  FOR SEVERE TURBULENCE

GM7 MET.TR.250(a) SIGMET

ED Decision 2022/004/R

COORDINATION WITH NEIGHBOURING METEOROLOGICAL WATCH OFFICES (MWOs)

Guidance on the bilateral or multilateral coordination between MWOs of neighbouring States for the provision of SIGMET can be found in ICAO EUR Doc 014 ‘EUR SIGMET and AIRMET Guide’.

AMC1 MET.TR.250(c) SIGMET

ED Decision 2022/004/R

SEQUENCE NUMBER

(a) The three-character sequence number should be constructed using a single letter identifying the phenomenon, followed by two numeric characters corresponding to the number of SIGMET issued for that phenomenon for the specified flight information region since 00.01 UTC on the day concerned.

(b) The letters to be used as the first character for the SIGMET sequence number to indicate the specified en-route weather and other phenomena for which the SIGMET has been issued should be:

(c) When SIGMET is issued for test purposes (‘TEST’ status indicator used in the SIGMET), then the appropriate letter for exchange test purposes should be used, i.e. ‘Y’ for a TEST volcanic ash SIGMET. When SIGMET is issued for exercise purposes (‘EXER’ status indicator used in the SIGMET), then the letter chosen should correspond to that used under normal circumstances, i.e. ‘A’ for a SIGMET issued during a volcanic ash exercise.

AMC1 MET.TR.250(d) SIGMET

ED Decision 2020/008/R

CRITERIA RELATED TO PHENOMENA

Sandstorm/dust storm should be considered:

(a) heavy whenever the visibility is below 200 m and the sky is obscured; and

(b) moderate whenever the visibility is:

(1) below 200 m and the sky is not obscured; or

(2) between 200 and 600 m.

GM1 MET.TR.250(d) SIGMET

ED Decision 2022/004/R

CRITERIA RELATED TO PHENOMENA

(a) An area of thunderstorms and cumulonimbus clouds is considered:

(1) obscured (OBSC) if it is obscured by haze or smoke or cannot be readily seen due to darkness;

(2) embedded (EMBD) if it is embedded within cloud layers and cannot be readily recognised;

(3) isolated (ISOL) if it consists of individual features which affect, or are forecast to affect, an area with a maximum spatial coverage less than 50 % of the area concerned (at a fixed time or during the period of validity); and

(4) occasional (OCNL) if it consists of well-separated features which affect, or are forecast to affect, an area with a maximum spatial coverage between 50 and 75 % of the area concerned (at a fixed time or during the period of validity).

(b) An area of thunderstorms is considered frequent (FRQ) if within that area there is little or no separation between adjacent thunderstorms with a maximum spatial coverage greater than 75 % of the area affected, or forecast to be affected, by the phenomenon (at a fixed time or during the period of validity).

(c) Squall line (SQL) indicates a thunderstorm along a line with little or no space between individual clouds.

(d) Hail (GR) is used as a further description of the thunderstorm, as necessary.

(e) 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 (CAT). Turbulence is not used in connection with convective clouds.

(f) Turbulence is considered:

(1) severe whenever the peak value of the EDR equals or exceeds 0.45; and

(2) moderate whenever the peak value of the EDR is equal to or above 0.20 and below 0.45.

(g) Severe and moderate icing (ICE) refers to icing in other than convective clouds. Freezing rain (FZRA) should refer to severe icing conditions caused by freezing rain.

(h) A mountain wave (MTW) is considered:

(1) severe whenever an accompanying downdraft of 600 ft/min (3.0 m/s) or more and/or severe turbulence is observed or forecast; and

(2) moderate whenever an accompanying downdraft of 350–600 ft/min (1.75–3.0 m/s) and/or moderate turbulence is observed or forecast.

MET.TR.255 AIRMET

Regulation (EU) 2021/1338

(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.

AMC1 MET.TR.255(a) AIRMET

ED Decision 2022/004/R

AIRMET — CODE FORM

AIRMET, and cancellations thereof, should be encoded using:

(a) the IWXXM GML form as specified in point (a) of AMC1 MET.TR.115(a);

(b) abbreviated plain language as specified in point (c) of AMC1 MET.TR.115(a).

GM1 MET.TR.255(a) AIRMET

ED Decision 2020/008/R

EXAMPLE OF AIRMET FOR MODERATE MOUNTAIN WAVE

GM2 MET.TR.255(a) AIRMET

ED Decision 2020/008/R

EXAMPLE OF AIRMET, AND THE CORRESPONDING CANCELLATIONS

GM1 MET.TR.255(b) AIRMET

ED Decision 2020/008/R

FIR

The flight information region may be divided in sub-areas.

GM1 MET.TR.255(c) AIRMET

ED Decision 2020/008/R

CRITERIA RELATED TO PHENOMENA

In reference to the criteria related to phenomena, please refer to GM1 MET.TR.250(d).

AMC1 MET.TR.255(d) AIRMET

ED Decision 2020/008/R

CRITERIA RELATED TO PHENOMENA

In reference to sandstorm/dust storm, please refer to AMC1 MET.TR.250(d).

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

Regulation (EU) 2021/1338

(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.

AMC1 MET.TR.260 Area forecasts for low-level flights

ED Decision 2022/004/R

AMENDMENT OF AREA FORECASTS FOR LOW-LEVEL FLIGHTS

(a) In case that an area forecast for low-level flights is not issued in combination with AIRMET, the criteria for amendments to the area forecast for low-level flights should as a minimum include the weather phenomena hazardous to low-level flights, which would otherwise constitute the criteria for the issuance of AIRMET.

(b) When low-level forecast is issued as a SIGWX chart or as a wind and temperature (W+T) chart, it should, as appropriate, include the cloud/visibility information in the form of visibility/cloud base category which should be provided for well-defined sub-areas and/or route segments. For each sub-area and/or route segment, the reference height to which the cloud base information refers should be specified. 

(c) The graphical part of a SIGWX chart should depict the weather situation at the beginning of the validity period. Significant changes of initial weather parameters should be depicted together with time intervals determining the duration of expected changes.

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

MET.TR.265 Volcanic ash advisory centre responsibilities

Regulation (EU) 2021/1338

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.

AMC1 MET.TR.265 Volcanic ash advisory centre responsibilities

ED Decision 2022/004/R

VOLCANIC ASH ADVISORY — CODE FORM

Volcanic ash advisory should be disseminated using:

(a) the IWXXM GML form as specified in point (a) of AMC1 MET.TR.115(a);

(b) abbreviated plain language as specified in point (c) of AMC1 MET.TR.115(a).

AMC2 MET.TR.265 Volcanic ash advisory centre responsibilities

ED Decision 2022/004/R

VOLCANIC ASH ADVISORY INFORMATION — GRAPHICAL FORMAT

The volcanic ash advisory information listed in Appendix 6 to Annex V (Part-MET) to Regulation (EU) 2017/373, when prepared in graphical format, should be as specified below and issued using the portable network graphics (PNG) format as specified in point (f) of AMC1 MET.TR.115(a):

Example of volcanic ash advisory in graphical format from the London VAAC. Mercator projection.

Note: The example above is fictitious.

Example of volcanic ash advisory in graphical format from the Toulouse VAAC. Mercator projection.

Note: The example above is fictitious.

Example of volcanic ash advisory in graphical format from the Wellington VAAC. Polar stereographic projection.

Note: The example above is fictitious.

GM1 MET.TR.265 Volcanic ash advisory centre responsibilities

ED Decision 2022/004/R

EXAMPLES OF ADVISORY FOR VOLCANIC ASH

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

MET.TR.270 Tropical cyclone advisory centre responsibilities

Regulation (EU) 2021/1338

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.

AMC1 MET.TR.270 Tropical cyclone advisory centre responsibilities

ED Decision 2022/004/R

TROPICAL CYCLONE ADVISORY — CODE FORM

Tropical cyclone advisory should be disseminated using:

(a) the IWXXM GML form as specified in point (a) of AMC1 MET.TR.115(a);

(b) abbreviated plain language as specified in point (c) of AMC1 MET.TR.115(a).

AMC2 MET.TR.270 Tropical cyclone advisory centre responsibilities

ED Decision 2022/004/R

TROPICAL CYCLONE ADVISORY — GRAPHICAL FORMAT

The tropical cyclone advisory information listed in Appendix 7 to Annex V (Part-MET) to Regulation (EU) 2017/373, when prepared in graphical format, should be as specified below and issued using the portable network graphics (PNG) format as specified in point (f) of AMC1 MET.TR.115(a):

Example of tropical cyclone advisory in graphical format from the La Réunion TCAC.

Note: The example above is based on a real event.

GM1 MET.TR.270 Tropical cyclone advisory centre responsibilities

ED Decision 2022/004/R

ADVISORY FOR TROPICAL CYCLONES — EXAMPLE

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

MET.TR.275 World area forecast centre responsibilities

Regulation (EU) 2021/1338

(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.

AMC1 MET.TR.275(a) World area forecast centres (WAFCs) responsibilities

ED Decision 2017/001/R

GRIDDED GLOBAL FORECASTS

The telecommunications facilities used for the supply of world area forecast system products should:

(a) be the aeronautical fixed service or the public Internet;

(b) be continuous; and

(c) not have interruptions exceeding 10 minutes during any period of 6 hours.

AMC2 MET.TR.275(a) World area forecast centre responsibilities

ED Decision 2022/004/R

WORLD AREA FORECAST CENTRE GLOBAL GRIDDED FORECASTS — CODE FORM

World area forecast centre global gridded forecasts should be encoded using the GRIB code form as specified in point (d) of AMC1 MET.TR.115(a).

GM1 MET.TR.275(b)(3) World area forecast centre responsibilities

ED Decision 2022/004/R

GRID POINT FORECASTS

(a) Layers centred at a flight level referred to in MET.TR.275(b)(3)(vii) have a depth of 100 hPa.

(b) Layers centred at a flight level referred to in MET.TR.275(b)(3)(viii) have a depth of 100 hPa for flight levels below 240, then 50 hPa for flight levels 240 and above.

GM2 MET.TR.275(b)(3) World area forecast centre responsibilities

ED Decision 2022/004/R

GRID POINT FORECASTS

The turbulence referred to in MET.TR.275(b)(3)(viii) encompasses all types of turbulence, including clear-air turbulence and in-cloud turbulence.

GM3 MET.TR.275(b)(3) World area forecast centre responsibilities

ED Decision 2022/004/R

GRID POINT FORECASTS

The exact pressure levels (hPa) for MET.TR.275(b)(3) (i), (ii), (iii), (iv), (vii), and (viii) are provided in ICAO Doc 8896 ‘Manual of Aeronautical Meteorological Practice’.

AMC1 MET.TR.275(c) World area forecast centre responsibilities

ED Decision 2022/004/R

WORLD AREA FORECAST CENTRE (WAFC) GLOBAL FORECASTS OF SIGNIFICANT WEATHER — CODE FORM

World area forecast centre (WAFC) global forecasts of significant weather should be disseminated using:

(a) the IWXXM GML form as specified in point (a) of AMC1 MET.TR.115(a);

(b) the BUFR code form as specified in point (e) of AMC1 MET.TR.115(a).

AMC1 MET.TR.275(d) World area forecast centre responsibilities

ED Decision 2022/004/R

MEDIUM-LEVEL SIGWX FORECASTS

The medium-level SIGWX forecasts provided for flight levels between 100 and 450 for limited geographical areas should cover the areas as shown in Appendix 2.