Aeronautical Code signals
The Aeronautical Code signals are radio signal codes. They are part of a larger set of Q Codes allocated by the ITU-R. The QAA–QNZ code range includes phrases applicable primarily to the aeronautical service, as defined by the International Civil Aviation Organisation.
First defined in ICAO publication "Doc 6100-COM/504/1" in 1948 and in "ICAO Procedures for Air Navigation Services, Abbreviations and Codes (PAN a S-ABC)" [Doc8400-4] (4th edition 1989), the majority of the Q codes have slipped out of common use; for example today reports such as QAU ("I am about to jettison fuel") and QAZ ("I am flying in a storm") would be voice or computerized transmissions. But several remain part of the standard ICAO radiotelephony phraseology in aviation.
|QFE||Atmospheric pressure at a specified datum such as airfield runway threshold. When set, the altimeter reads the height above the specified datum.||Runway in use 22 Left, QFE 990 millibars|
|QFF||Atmospheric pressure at a place, reduced to MSL using the actual temperature at the time of observation as the mean temperature.|
|QNE||Atmospheric pressure at sea level in the International Standard Atmosphere (ISA), equal to 1013.25 mbar or hPa and used as reference for measuring the pressure altitude. When flight levels are used as an indication of altitude, 1013.25 hPa is used as mean sea level (QNH).|
|QNH||Atmospheric pressure at mean sea level (may be either a local, measured pressure or a regional forecast pressure (RPS)). When set on the altimeter it reads altitude.||Request Leeds QNH|
|QDM||Magnetic bearing to a station||(callsign) request QDM (callsign)|
|QDL||Series of bearings taken at regular intervals|
|QDR||Magnetic bearing from a station||(callsign) request QDR (callsign)|
|QFU||Magnetic bearing of the runway in use||Runway 22 in use, QFU 220|
|QGH||Controlled Descent through Clouds (Royal Air Force use)|
|QTE||True bearing/track from a station||(callsign) request QTE (callsign)|
|QTF||Position in relation to a point of reference or in latitude and longitude|
|QUJ||True bearing/track to a station|
|QGH||controller-interpreted DF let-down procedure, on UHF or VHF|