MET.TR.205 Reporting of meteorological elements

(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.