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 " , the majority of the Q codes have slipped out of common use; for example today reports such as QAU and QAZ would be voice or computerized transmissions. But several remain part of the standard ICAO radiotelephony phraseology in aviation.
| Code | Meaning | Sample use |
| 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 | Indicated altitude at the landing runway threshold when 1013.25 hPa or 29.92 inHg is set as altimeter setting. | |
| QNH | Atmospheric pressure at mean sea level. When set on the altimeter it reads altitude. | Request Leeds QNH |
| Code | Meaning | Sample use |
| QDM | Magnetic bearing to a station | request QDM |
| QDL | Series of bearings taken at regular intervals | |
| QDR | Magnetic bearing from a station | request QDR |
| QFU | Magnetic bearing of the runway in use | Runway 22 in use, QFU 220 |
| QGE | Distance | |
| QGH | Controlled Descent through Clouds | |
| QTE | True bearing/track from a station | request QTE |
| QTF | Position in relation to a point of reference or in latitude and longitude | |
| QUJ | True bearing/track to a station |
| Code | Meaning | Sample use |
| QGH | controller-interpreted DF let-down procedure, on UHF or VHF |