Page 145 - UK ATM ANS Regulations (Consolidated) 201121

Part MET - ANNEX V - Specific Requirements for the Providers of Meteorological
Services

MET.TR.235(a) AMC1 Aerodrome warnings and wind shear warnings and alerts
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.
MET.TR.235(a) GM2 Aerodrome warnings and wind shear warnings and alerts
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.
MET.TR.235(c) AMC1 Aerodrome warnings and wind shear warnings and alerts
FORMAT OF WIND SHEAR WARNINGS
(a) The use of text additional to the abbreviations listed in the template in Table 6 of Appendix
1 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.
MET.TR.235(c) GM1 Aerodrome warnings and wind shear warnings and alerts
WIND SHEAR TYPES
Regulation references changes to GM1 MET.TR.235(a)
MET.TR.235(c) GM1 Aerodrome warnings and wind shear warnings and alerts
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.
MET.TR.235(d) GM1 Aerodrome warnings and wind shear warnings and alerts
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.
MET.TR.250 SIGMET
(a) The content and order of elements in a SIGMET shall be in accordance with the template
shown in Appendix 5A.
(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 5A shall be included in a SIGMET, using the
appropriate abbreviations and the following threshold value of surface wind speed of 34 kt
(17 m/s) or more for tropical cyclone.
(e) SIGMET concerning thunderstorms or a tropical cyclone shall not include references to
associated turbulence and icing.
(f) SIGMET, if disseminated in digital form, shall be:
(1) formatted in accordance with a globally interoperable information exchange model
and shall use geography markup language (GML);
(2) accompanied by the appropriate metadata.
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