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

AERODROME WARNINGS — TEMPLATE FOR AERODROME WARNINGS 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.

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)'.

AERODROME WARNINGS — EXAMPLES OF ELEMENTS Non-exhaustive examples of the different elements used in the formulation of aerodrome warnings are provided below.

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)

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.

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.

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.

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.

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.

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.