Distress and Diversion

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The Distress and Diversion (D&D) Frequency is an international standard radio frequency for aviation distress. Set on 121.500 MHz it is the frequency for reporting a Pan Pan or a Mayday call. It is used in uncontrolled airspace, where ATC coverage is out of range, or when the current frequency is extremely busy.

In the United Kingdom there are two centres which deal with emergency calls - 'London Centre' based in West Drayton (London FIR) and 'Scottish Centre'(Scottish FIR). Depending on the aircraft's altitude and location (ie in the London or scottish flight information region), the personnel in the centres may be able to use Auto Triangulation to determine its exact position which can be useful to the pilot if the aircraft is lost or 'temporarily unsure of position'.