4.3.2.2 shall be extracted, as appropriate, from meteorological reports providing information in accordance with the following:
4.3.2.3.1 Mean surface wind direction and speed and significant variations therefrom
4.3.2.3.1.1 In meteorological reports, the direction shall be given in degrees true and the speed in km/h (kt). All
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directional and speed variations shall refer to the preceding 10-minute period. Directional variation shall be given when the total variation is 60 degrees or more; when the mean speed is above 6 km/h (3 kt) and the wind varies less than 180 degrees, it shall be expressed as the two extreme directions between which the wind has varied; otherwise, it shall be indicated as VRB, followed by the mean speed, with no indication of the mean wind direction. Speed variations (gusts) shall be reported only when the variation from the mean speed is 20 km/h (10 kt) or more.
Note.— Information on surface wind direction provided to ATS units by the associated meteorological office is referenced to degrees true North. Information on surface wind direction obtained from the ATS surface wind indicator and passed to pilots by ATS units is given in degrees magnetic.
4.3.2.3.1.2 In meteorological reports disseminated locally at the aerodrome:
a) the averaging period for mean surface wind direction and speed shall be 2 minutes;
b) speed variations shall be expressed as the maximum and minimum values attained;
c) in reports to departing aircraft, light and variable surface winds of 6 km/h (3 kt) or less shall include a range of wind directions, whenever possible.
4.3.2.3.1.3 In meteorological reports disseminated beyond the aerodrome:
a) the averaging period for mean surface wind direction and speed shall be 10 minutes;
b) speed variations shall be expressed as the maximum value attained. Minimum wind speed shall not be included.
4.3.2.3.2 Visibility, including significant
directional variations
4.3.2.3.2.1 When the visibility is less than 500 m, it shall be expressed in steps of 50 m; when it is 500 m or more but less than 5 000 m, in steps of 100 m; 5 000 m or more but less than 10 km, in kilometre steps; and when it is 10 km or more, only 10 km shall be given, except when the conditions for the use of CAVOK apply.
IX. Air Traffic Services Messages
4.3.2.3.2.2 In meteorological reports disseminated locally at the aerodrome, the visibility shall be representative of:
a) the take-off and climb out areas for departing aircraft;
b) the approach and landing area for arriving aircraft.
4.3.2.3.2.3 In meteorological reports disseminated beyond the aerodrome, the visibility shall be representative of the aerodrome and its immediate vicinity. In case of significant directional variations in visibility:
a) the lowest visibility shall be reported;
b) additional values shall be given with indications of the direction of observation.
4.3.2.3.3 Runway visual range
4.3.2.3.3.1 Runway visual range values up to 800 m shall be given in increments of 25 to 60 m, in accordance with available observations, and values above 800 m shall be given in increments of 100 m. Runway visual range values which do not fit the reporting scale in use shall be rounded down to the nearest lower step in the reporting scale.
4.3.2.3.3.2 In meteorological reports disseminated locally at the aerodrome, the averaging period for RVR shall be 1 minute and:
a) when the runway visual range is above the maximum value which can be determined by the system in use, it shall be reported as more than the specified distance,
e.g. RVR RWY 14 ABV 1 200M where the figure 1 200 is the maximum value that can be determined by the system;
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