Q-Codes and Standard Abbreviations
Q-codes are three-letter codes starting with "Q" — originally developed for telegraphy (CW Morse). Most are obsolete today, but some are indispensable in aviation. In addition there are standard abbreviations used in AIPs, NOTAMs, and METAR/TAF.
Source: ITU Radio Regulations Appendix 14 (Q-codes); ICAO Doc 8400 ICAO Abbreviations and Codes.
Q-codes still used in aviation
Pressure and altitude — the "Q" pressure codes
| Code | Meaning |
|---|---|
| QNH | Altimeter setting so that the altimeter reads field elevation AMSL on the ground |
| QFE | Altimeter setting so that the altimeter reads 0 ft on the ground |
| QNE | Standard pressure 1013.25 hPa (29.92 inHg) — used above transition altitude |
Practical use:
- QNH is standard at most fields worldwide.
- QFE is still common in UK and Eastern Europe for pattern and approaches.
- QNE is the international standard for flight levels above transition altitude.
Direction-finding codes
| Code | Meaning |
|---|---|
| QDM | Magnetic bearing to the station |
| QDR | Magnetic bearing from the station |
| QTE | True bearing from the station |
| QUJ | True bearing to the station |
Today's use: QDM is occasionally used by ATC to give a pilot a steering instruction:
- "DEMRA, steer QDM 270 to Munich".
Mnemonic:
- QDM = Q-Direction-Magnetic-to station ("M" like "to me")
- QDR = Q-Direction-Magnetic-Reverse (from station)
- QTE = Q-True-Exit from station
- QUJ = Q-True-toward station (J like "to")
QDR and QTE are seldom used directly in modern radio navigation — VOR radial serves the same purpose.
Other still-used codes
| Code | Meaning |
|---|---|
| QFU | Magnetic runway direction (in degrees) |
| QGH | Approach procedure with direction finding (rare today) |
| QSY | Frequency change (in radio traffic "QSY to 124.45" = "switch to 124.45") |
| QSL | "Received" (used in maritime/amateur radio, rare in ATC) |
Standard abbreviations (not Q-codes) in AIP, NOTAM, METAR
Besides Q-codes, many standardised abbreviations are common in aviation. Selection of the most frequent:
Time abbreviations
| Abbreviation | Meaning | Use |
|---|---|---|
| H24 | 24-hour service | "Frequency H24" = available 24/7 |
| HX | No specific opening hours | Aerodromes operated PPR only |
| HJ | Daytime (sunrise to sunset) | "Service HJ" = day only |
| HN | Night (sunset to sunrise) | |
| HO | Service on demand |
Position abbreviations
| Abbreviation | Meaning |
|---|---|
| ABM | abeam — laterally beside the waypoint (pilot is on a perpendicular line beside the reference point) |
| ABV | above |
| BLW | below |
| NE / SE / NW / SW | northeast / southeast / northwest / southwest |
| OVHD | overhead (directly above) |
| OVR | over |
Obstacle and terrain abbreviations
| Abbreviation | Meaning |
|---|---|
| OBST | obstacle |
| OBSC | obscured / obscurations |
| MEF | Maximum Elevation Figure (on ICAO chart) |
| MSA | Minimum Safe Altitude |
| TWR | Tower |
| APP | Approach |
| APRON | Apron |
| THR | Threshold |
| TDZ | Touchdown Zone |
| MOV | Movement / moving |
Weather abbreviations (METAR, TAF, SIGWX)
| Abbreviation | Meaning |
|---|---|
| FEW | Few — 1-2 oktas cloud cover (1–2/8) |
| SCT | Scattered — 3-4 oktas (3–4/8) |
| BKN | Broken — 5-7 oktas (5–7/8) |
| OVC | Overcast — 8/8 = 100 % covered |
| NSC | No significant cloud |
| CAVOK | Ceiling and Visibility OK (visibility ≥10 km, no clouds below 5000 ft, no significant weather phenomena) |
| VRB | Variable (wind) |
| CB | Cumulonimbus |
| TCU | Towering cumulus |
| NOSIG | No significant change |
Historical Q-codes (obsolete today but known)
- QAA: estimated time of arrival (replaced by ETA).
- QBI: instrument conditions (replaced by IMC).
- QFP: final approach (replaced by "final").
- QGE: distance from station (replaced by DME).
- QGO: aerodrome closed.
Q-codes in modern radio
Rarely used directly in transmission:
- "QNH 1013" is normal: altimeter setting.
- "QFE 1015" in UK.
- "QFU 261" as runway direction (runway 26R/L).
Other Q-codes are used in ATIS scripts and AIPs, less in voice communication.
Practical recommendation
- QNH / QFE / QNE / QDM: must be known.
- Other Q-codes: good to know, rarely used in cockpit.
- Standard abbreviations (H24, HX, ABM, OBST, FEW/SCT/BKN/OVC): must be known — frequent in AIPs, METARs and charts.
- For queries: use standard phrases ("altimeter setting", "bearing", "frequency").
Cross-reference
- Subject 050 Lesson "Pressure": physical basis for QNH/QFE/QNE.
- Subject 050 Lesson "METAR": full METAR coding.
- Subject 070 Lesson "Descent": transition altitude/level.