Page 149 - UK ATM ANS Regulations (Consolidated) 201121

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

MET.TR.255 AIRMET
(a) The content and order of elements in an AIRMET shall be in accordance with the template
shown in Appendix 5A.
(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 5A 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 (15 m/s) 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
(300 m) above ground level.
(d) AIRMET concerning thunderstorms or cumulonimbus clouds shall not include references
to associated turbulence and icing.
(e) AIRMET, 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.
MET.TR.255(a) GM1 AIRMET

MET.TR.255(a) GM2 AIRMET

MET.TR.255(b) GM1 AIRMET
FIR
The flight information region may be divided in sub-areas.
MET.TR.255(c) GM1 AIRMET
CRITERIA RELATED TO PHENOMENA
In reference to the criteria related to phenomena, please refer to GM1 MET.TR.250(d).
MET.TR.255(d) AMC1 AIRMET
CRITERIA RELATED TO PHENOMENA
In reference to sandstorm/dust storm, please refer to AMC1 MET.TR.250(d).
MET.TR.255(e) GM1 AIRMET
AIRMET — DIGITAL FORM
(a) When AIRMET is disseminated in digital form, this is in addition to the AIRMET code form.
(b) Guidance on the information exchange model, GML, and metadata profile is provided in
ICAO Doc 10003 ‘Manual on the ICAO Meteorological Information Exchange Model’.
MET.TR.260 Area forecasts for low-level flights
(a) When chart form is used for area forecasts for low-level flights, the forecast of upper wind
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