North atlantinc MNPS airspace
11.4 DEVIATIONS AROUND SEVERE WEATHER
11.4.1 If the aircraft is required to deviate from track to avoid weather (e.g. thunderstorms), the pilot should request a revised clearance from ATC and obtain essential traffic information, if possible prior to deviating. However, if such prior ATC clearance cannot be obtained, the procedures described below should be adopted and in the meantime efforts should be continued to obtain an appropriate ATC clearance.
a) If possible, deviate away from the organised track or route system;
b) Establish communications with and alert nearby aircraft broadcasting, at suitable intervals: aircraft identification, flight level, aircraft position (including ATS route designator or the track code) and intentions, on the frequency in use and on frequency 121.5 MHz (or, as a back-up, on the VHF inter-pilot air-to-air frequency 123.45 MHz);
c) Watch for conflicting traffic both visually and by reference to ACAS/TCAS (if equipped);
d) Turn on all aircraft exterior lights.
e) For deviations of less than 10 NM, aircraft should remain at the level assigned by ATC;
f) For deviations of greater than 10 NM, when the aircraft is approximately 10 NM from track, initiate a level change of 300 ft.
- If flying generally Eastbound (i.e. a magnetic track of 000° to 179°) and deviating left (ie north) of track then descend 300 ft; if, however, deviating right (i.e. south) of track then climb 300 ft.
- If flying generally Westbound (i.e. a magnetic track of 180° to 359°) and deviating left (i.e. south) of track then climb 300 ft; if, however, deviating right (i.e. north) of track then descend 300 ft.
g) When returning to track, regain the last assigned flight level, when the aircraft is within approximately 10 NM of centre line.
11.4.2 The pilot should inform ATC when weather deviation is no longer required, or when a weather deviation has been completed and the aircraft has returned to the centre line (or previously adopted SLOP Offset) of its cleared route.