*Abbreviations marked with an asterisk (*) are either different from or are not contained in ICAO Doc 8400
| A - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| A | Amber |
| A/A | Air to air |
| A/G | Air-to-ground |
| AAA | Amended meteorological message |
| AAD | Assigned altitude deviation |
| AAIM | Aircraft autonomous integrity monitoring |
| AAL | Above aerodrome level |
| AAR | Air to air refuelling |
| ABI | Advance boundary information |
| ABM | Abeam |
| ABN | Aerodrome beacon |
| ABT | About |
| ABV | Above |
| AC | Altocumulus |
| ACARS | Aircraft communication addressing and reporting system |
| ACAS | Airborne collision avoidance system |
| ACC | Area control centre or area control |
| ACCID | Notification of an aircraft accident |
| ACD* | Airways Clearance Delivery |
| ACFT | Aircraft |
| ACK | Acknowledge |
| ACL | Altimeter check location |
| ACN | Aircraft classification number |
| ACP | Acceptance (message type designator) |
| ACPT | Accept or accepted |
| ACT | Active or activated or activity |
| AD | Aerodrome |
| ADA | Advisory area |
| ADC | Aerodrome chart |
| ADDN | Addition or additional |
| ADF | Automatic direction-finding equipment |
| ADIZ | Air defence identification zone |
| ADJ | Adjacent |
| ADO | Aerodrome office |
| ADR | Advisory route |
| ADS | Automatic dependent surveillance |
| ADSU | Automatic dependent surveillance unit |
| ADVS | Advisory service |
| ADZ | Advise |
| AES | Aircraft earth station |
| AFIL | Flight plan filed in the air |
| AFIS | Aerodrome flight information service |
| AFM | Yes or affirm or affirmative or that is correct |
| AFRS* | Aerodrome fire and rescue services |
| AFS | Aeronautical fixed service |
| AFT | After. . . . . . . . (time or place) |
| AFTN | Aeronautical fixed telecommunication network |
| AGA | Aerodromes, air routes and ground aids |
| AGL | Above ground level |
| AGN | Again |
| AIC | Aeronautical information circular |
| AIDC | Air traffic services interfacility data communications |
| AIM | Aeronautical information management |
| AIP | Aeronautical information publication |
| AIRAC | Aeronautical information regulation and control |
| AIREP | Air-report |
| AIRMET | Information concerning en-route weather phenomena which may affect the safety of low-level aircraft operations |
| AIS | Aeronautical information services |
| ALA | Alighting area |
| ALERFA | Alert phase |
| ALR | Alerting (message type designator) |
| ALRS | Alerting service |
| ALS | Approach lighting system |
| ALT | Altitude |
| ALTN | Alternate or alternating (light alternates in colour) |
| ALTN | Alternate (aerodrome) |
| AMA | Area minimum altitude |
| AMD | Amend or amended |
| AMDT | Amendment (AIP Amendment) |
| AMS | Aeronautical mobile service |
| AMSL | Above mean sea level |
| AMSS | Aeronautical mobile satellite service |
| ANC | Aeronautical chart - 1:500 000 (followed by name/title) |
| ANCS | Aeronautical navigation chart - small scale |
| ANS | Answer |
| ANZUK* | Australia, New Zealand and United Kingdom |
| AO | Airport operator |
| AOC | Aerodrome obstacle chart (followed by type and name/title) |
| AP | Airport |
| APAPI | Abbreviated precision approach path indicator |
| APCH | Approach |
| APDC | Aircraft parking/docking chart |
| APN | Apron |
| APP | Approach control office or approach control or approach control service |
| APR | April |
| APRX | Approximate or approximately |
| APSG | After passing |
| APU | Auxiliary power unit |
| APV | Approach procedure with vertical guidance |
| ARC | Area chart |
| ARFOR | Area forecast (in aeronautical meteorological code) |
| ARNG | Arrange |
| ARO | Air traffic services reporting office |
| ARP | Aerodrome reference point |
| ARP | Air-report (message type designator) |
| ARQ | Automatic error correction |
| ARR | Arrival (message type designator) |
| ARS | Special air-report (message type designator) |
| ARST | Arresting [specify (part of) aircraft arresting equipment] |
| AS | Altostratus |
| ASAP | As soon as possible |
| ASC | Ascend to or ascending to |
| ASDA | Accelerate-stop distance available |
| ASE | Altimetry system error |
| ASO* | Aeroshell oil |
| ASPH | Asphalt |
| ASTO* | Aeroshell turbine oil |
| AT | At (followed by time at which weather change is forecast to occur) |
| AT-VASIS | Abbreviated T visual approach slope indicator system |
| ATA | Actual time of arrival |
| ATC | Air traffic control (in general) |
| ATD | Actual time of departure |
| ATFM | Air traffic flow management |
| ATIS | Automatic terminal information service |
| ATM | Air traffic management |
| ATN | Aeronautical telecommunication network |
| ATP | At time or place |
| ATS | Air traffic services |
| ATTN | Attention |
| ATZ | Aerodrome traffic zone |
| AUG | August |
| AUTH | Authorized |
| AUTO | Automatic |
| AUW | All up weight |
| AUX | Auxiliary |
| AVBL | Available or availability |
| AVG | Average |
| AVGAS | Aviation gasoline |
| AWOS | Automated Weather Observation System |
| AWTA | Advise at what time able |
| AWY | Airway |
| AZM | Azimuth |
| B - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| B | Blue |
| BA | Braking action |
| BASE | Cloud base |
| BCFG | Fog patches |
| BCN | Beacon (aeronautical ground light) |
| BCST | Broadcast |
| BDRY | Boundary |
| BECMG | Becoming |
| BFR | Before |
| BKN | Broken |
| BLDG | Building |
| BLO | Below clouds |
| BLW | Below. . . . . . . . |
| BOMB | Bombing |
| BR | Mist |
| BRF | Short (used to indicate the type of approach desired or required) |
| BRG | Bearing |
| BRKG | Braking |
| BS | Commercial broadcasting station |
| BTL | Between layers |
| BTN | Between |
| BUFR | Binary universal form for the representation of meteorological data |
| C - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| C | Centre (runway identification) |
| C | Degrees Celsius (Centigrade) |
| CA | Course to an altitude |
| CAA | Civil Aviation Authority or Civil Aviation Administration |
| CAAM* | Civil Aviation Authority of Malaysia |
| CAAS* | Civil Aviation Authority of Singapore |
| CAT | Category |
| CAT | Clear air turbulence |
| CAVOK | Visibility, cloud and present weather better than prescribed values or conditions |
| CB | Cumulonimbus |
| CC | Cirrocumulus |
| CCA | (or CCB, CCC .. etc.,in sequence) Corrected meteorological message (message type designator) |
| CCO | Continuous climb operations |
| CD | Candela |
| CDN | Coordination (message type designator) |
| CDO | Continuous descent operations |
| CDR | Continuous route |
| CF | Change frequency to... |
| CFM | Confirm or I confirm |
| CGL | Circling guidance light(s) |
| CH | Channel |
| CHEM | Chemical |
| CHG | Modification (message type designator) |
| CI | Cirrus |
| CIDIN | Common ICAO data interchange network |
| CIV | Civil |
| CK | Check |
| CL | Centre line |
| CLA | Clear type of ice formation |
| CLBR | Calibration |
| CLD | Cloud |
| CLG | Calling |
| CLIMB-OUT | Climb-out area |
| CLR | Clear(s) or cleared to. . . . . . . . or clearance |
| CLRD | Runway(s) cleared |
| CLSD | Close or closed or closing |
| CM | Centimetre |
| CMB | Climb to or climbing to |
| CMPL | Completion or completed or complete |
| CNL | Cancel or cancelled |
| CNL | Flight plan cancellation (message type designator) |
| CNS | Communications, navigation and surveillance |
| COM | Communications |
| CONC | Concrete |
| COND | Condition |
| CONS | Continuous |
| CONST | Construction or constructed |
| CONT | Continue(s) or continued |
| COORD | Coordinates |
| COP | Change-over point |
| COR | Correct or correction or corrected (message type designator) |
| COT | At the coast |
| COV | Cover or covered or covering |
| CPDLC | Controller-pilot data link communications |
| CPL | Current flight plan (message type designator) |
| CRC | Cyclic redundancy check |
| CRM | Collision risk model |
| CRP | Compulsory reporting point |
| CRZ | Cruise |
| CS | Call sign (used to request a callsign) |
| CS | Cirrostratus |
| CTA | Control area |
| CTAM | Climb to and maintain |
| CTC | Contact |
| CTL | Control |
| CTN | Caution |
| CTR | Control zone |
| CU | Cumulus |
| CUF | Cumuliform |
| CUST | Customs |
| CVR | Cockpit voice recorder |
| CW | Continuous wave |
| CWY | Clearway |
| D - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| D | Danger area (followed by identification) |
| D-ATIS | Data link automatic terminal information service |
| D-VOLMET | Data link VOLMET |
| DA | Decision altitude |
| DCD | Double channel duplex |
| DCKG | Docking |
| DCP | Datum crossing point |
| DCPC | Direct controller-pilot communications |
| DCS | Double channel simplex |
| DCT | Direct (in relation to flight plan clearances and type of approach) |
| DE | From |
| DEC | December |
| DEG | Degrees |
| DEP | Departure (message type designator) |
| DEPO | Deposition |
| DES | Descend to or descending to |
| DEST | Destination |
| DETRESFA | Distress phase |
| DEV | Deviation or deviating |
| DFDR | Digital flight data recorder |
| DFTI | Distance from touchdown indicator |
| DGCA* | Director-General of Civil Aviation |
| DH | Decision height |
| DIA* | Diameter |
| DIF | Diffuse |
| DIST | Distance |
| DIV | Divert or diverting |
| DLA | Delay (message type designator) |
| DLA | Delay or delayed |
| DLIC | Data link initiation capability |
| DME | Distance measuring equipment |
| DNG | Danger or dangerous |
| DOF | Date of flight |
| DOM | Domestic |
| DP | Dew point temperature |
| DPT | Depth |
| DR | Dead reckoning |
| DRG | During |
| DS | Duststorm |
| DSB | Double sideband |
| DTAM | Descend to and maintain |
| DTG | Date-time group |
| DTHR | Displaced runway threshold |
| DTRT | Deteriorate or deteriorating |
| DTW | Dual tandem wheels |
| DU | Dust |
| DUC | Dense upper cloud |
| DUPE | This a duplicate message |
| DUR | Duration |
| DVOR | Doppler VOR |
| DW | Dual wheels |
| DZ | Drizzle |
| E - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| E | East or eastern longitude |
| EAT | Expected approach time |
| EB | Eastbound |
| EDA | Elevation differential area |
| EDTO | Extended diversion time operations |
| EEE# | Error (to be used in AFS as a procedure signal) |
| EET | Estimated elapsed time |
| EFC | Expect further clearance |
| EGNOS | European geostationary navigation overlay service |
| EHF | Extremely high frequency (30 000 to 300 000 MHz) |
| ELBA | Emergency location beacon - aircraft |
| ELEV | Elevation |
| ELR | Extra long range |
| ELT | Emergency locator transmitter |
| EM | Emission |
| EMBD | Embedded in a layer (to indicate cumulonimbus embedded in layers of other clouds) |
| EMERG | Emergency |
| EN* | English |
| END | Stop-end (related to RVR) |
| ENE | East north east |
| ENG | Engine |
| ENRC | Enroute chart |
| ENRT | En route |
| EOBT | Estimated off-block time |
| EQPT | Equipment |
| ESE | East-south-east |
| EST | Estimate or estimated or estimation (message type designator) |
| ETA | Estimated time of arrival or estimating arrival |
| ETC* | Et cetera |
| ETD | Estimated time of departure or estimating departure |
| ETO | Estimated time over significant point |
| EV | Every |
| EVS | Enhanced vision system |
| EXC | Except |
| EXER | Exercises or exercising or to exercise |
| EXP | Expect or expected or expecting |
| EXTD | Extend or extending or Extended |
| F - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| F | Fixed |
| FAC | Facilities |
| FAF | Final approach fix |
| FAL | Facilitation of international air transport |
| FAP | Final approach point |
| FATO | Final approach and take-off area |
| FAX | Facsimile transmission |
| FBL | Light (used to indicate the intensity of weather phenomena, interference or static reports |
| FC | Funnel cloud (tornado or water spout) |
| FCST | Forecast |
| FCT | Friction coefficient |
| FDPS | Flight data processing system |
| FEB | February |
| FEW | Few |
| FG | Fog |
| FIC | Flight information centre |
| FIR | Flight information region |
| FIS | Flight information service |
| FISA | Automated flight information service |
| FL | Flight level |
| FLD | Field |
| FLG | Flashing |
| FLR | Flares |
| FLT | Flight |
| FLTCK | Flight check |
| FLUC | Fluctuating or fluctuation or fluctuated |
| FLW | Follow(s) or following |
| FLY | Fly or flying |
| FM | From |
| FMS | Flight management system |
| FMU | Flow management unit |
| FNA | Final approach |
| FPAP | Flight path alignment point |
| FPL | Flight plan |
| FPM | Feet per minute |
| FPR | Flight plan route |
| FR | Fuel remaining |
| FREQ | Frequency |
| FRI | Friday |
| FRNG | Firing |
| FRONT | Front (relating to weather) |
| FRQ | Frequent |
| FSL | Full stop landing |
| FSS | Flight service station |
| FST | First |
| FT | Feet (dimensional unit) |
| FTP | Fictitious threshold point |
| FU | Smoke |
| FZ | Freezing |
| FZDZ | Freezing drizzle |
| FZFG | Freezing fog |
| FZRA | Freezing rain |
| G - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| G | Green |
| G/A | Ground-to-air |
| G/A/G | Ground-to-air and air-to-ground |
| GA | Go ahead, resume sending (to be used in AFS as a procedure signal) |
| GA | General aviation |
| GAGAN | GPS and geostationary earth orbit augmented navigation |
| GAIN | Airspeed or headwind gain |
| GAMET | Area forecast for low-level flights |
| GARP | GBAS azimuth reference point |
| GBAS | Ground-based augmentation system |
| GCA | Ground controlled approach system or ground controlled approach |
| GEN | General |
| GEO | Geographic or true |
| GLD | Glider |
| GLONASS | Global orbiting navigation satellite system |
| GMC | Ground movement chart |
| GND | Ground |
| GNDCK | Ground check |
| GNSS | Global navigation satellite system |
| GOV | Government |
| GP | Glide path |
| GPO* | General Post Office |
| GPS | Global positioning system |
| GPU | Ground power unit |
| GPWS | Ground proximity warning system |
| GR | Hail |
| GRAS | Ground-based regional augmentation system |
| GRASS | Grass landing area |
| GRIB | Processed meteorological data in the form of grid point values (in aeronautical meteorological code) |
| GRVL | Gravel |
| GS | Ground speed |
| GUND | Geoid undulation |
| H - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| H | High pressure area or centre of high pressure |
| H | Significant wave height (followed by figures in METAR/SPECI) |
| H+* | Hour plus. . . . . . . . minutes past the hour |
| H24 | Continuous day and night service |
| H24 | Continuous day and night service |
| HAPI | Helicopter approach path indicator |
| HBN | Hazard beacon |
| HDF | High frequency direction-finding station |
| HDG | Heading |
| HEL | Helicopter |
| HEL - H* | Heavy helicopter (radius of action in excess of 100 NM and capacity for evacuating more than 5 persons) |
| HEL - L* | Light helicopter (radius of action of 50 NM and capacity of evacuating one person) |
| HEL- M* | Medium helicopter (radius of action of 50 to 100 NM and capacity for evacuating 2 - 5 persons) |
| HF | High frequency (3 000 to 30 000 KHz) |
| HGT | Height or height above |
| HJ | Sunrise to sunset |
| HL* | Height loss |
| HLDG | Holding |
| HLP | Heliport |
| HLS | Helicopter landing site |
| HM | Holding/racetrack to a manual termination |
| HMAS* | Her Majesty's Australian Service |
| HMS* | Her Majesty's Service |
| HN | Sunset to sunrise |
| HO | Service available to meet operational requirements |
| HOL | Holiday |
| HOSP | Hospital aircraft |
| HPA | Hectopascal |
| HQ* | Headquarters |
| HR | Hours |
| HS | Service available during hours of scheduled operations |
| HUD | Head-up display |
| HUM | Humanitarian |
| HURCN | Hurricane |
| HVDF | High and very high frequency direction- finding stations (at the same location) |
| HVY | Heavy |
| HX | No specific working hours |
| HYR | Higher |
| HZ | Haze |
| HZ | Hertz (cycle per second) |
| I - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| IAC | Instrument approach chart |
| IAF | Initial approach fix |
| IAO | In and out of clouds |
| IAP | Instrument approach procedure |
| IAR | Intersection of air routes |
| IAS | Indicated air speed |
| IBN | Identification beacon |
| ICAO | International Civil Aviation Organization |
| ICE | Icing |
| ID | Identifier or identity |
| IDENT | Identification |
| IF | Intermediate approach fix |
| IFF | Identification friend/foe |
| IFR | Instrument flight rules |
| IGA | International general aviation |
| ILS | Instrument landing system |
| IM | Inner marker |
| IMC | Instrument meteorological conditions |
| IMG | Immigration |
| IMPR | Improve or improving |
| IMT | Immediate or immediately |
| INA | Initial approach |
| INBD | Inbound |
| INC | In cloud |
| INCERFA | Uncertainty phase |
| INCORP | Incorporated |
| INFO | Information |
| INOP | Inoperative |
| INP | If not possible |
| INPR | In progress |
| INS | Inertial navigation system |
| INSTL | Install or Installed or Installation |
| INSTR | Instrument |
| INT | Intersection |
| INTER* | Intermittent |
| INTL | International |
| INTRG | Interrogator |
| INTRP | Interrupt or interruption or interrupted |
| INTSF | Intensify or intensifying |
| INTST | Intensity |
| IR | Ice on runway |
| ISA | International standard atmosphere |
| ISB | Independent sideband |
| ISOL | Isolated |
| J - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| JAN | January |
| JATCC* | Joint ATC Centre |
| JTST | Jet stream |
| JUL | July |
| JUN | June |
| K - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| KG | Kilograms |
| KHZ | Kilohertz |
| KM | Kilometres |
| KMH | Kilometres per hour |
| KPA | Kilopascal |
| KT | Knots |
| KW | Kilowatts |
| L - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| L | Left (preceded by runway designation number to identify a parallel runway) |
| L | Left (runway identification) |
| L | Locator (see LM, LO) |
| L | Low pressure area or the centre of low Pressure |
| L | Litre |
| LAM | Logical acknowledgement (message type designator) |
| LAN | Inland |
| LAT | Latitude |
| LDA | Landing distance available |
| LDAH | Landing distance available, helicopter |
| LDG | Landing |
| LDI | Landing direction indicator |
| LEN | Length |
| LF | Low frequency (30 to 300 KHz) |
| LGT | Light or lighting |
| LGTD | Lighted |
| LIH | Light intensity high |
| LIL | Light intensity low |
| LIM | Light intensity medium |
| LM | Locator, middle |
| LMT | Local mean time |
| LNG | Long (used to indicate the type of approach desired or required) |
| LO | Locator, outer |
| LOC | Localizer |
| LONG | Longitude |
| LORAN | LORAN (long range air navigation system) |
| LOSS | Airspeed or headwind loss |
| LR | The last message received by me was.... |
| LRG | Long range |
| LS | The last message sent by me was...or Last message was...(to be used in AFS as a procedure signal) |
| LSQ | Line squall |
| LTA | Lower control area |
| LTD | Limited |
| LTP | Landing threshold point |
| LV | Light and variable (relating to wind) |
| LVE | Leave or leaving |
| LVL | Level |
| LYR | Layer or layered |
| M - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| M | Mach Number (followed by figures) |
| M | Metres (preceded by figures) |
| MAA | Maximum authorized altitude |
| MAG | Magnetic |
| MAINT | Maintenance |
| MAP | Aeronautical maps and charts |
| MAPT | Missed approach point |
| MAR | At sea |
| MAR | March |
| MAS* | Malaysia Airline System |
| MATF | Missed approach turning fix |
| MATZ | Military aerodrome traffic zone |
| MAX | Maximum |
| MAY | May |
| MBST | Microburst |
| MCA | Minimum crossing altitude |
| MCTR | Military control zone |
| MCW | Modulated continuous wave |
| MDA | Minimum descent altitude |
| MDF | Medium frequency direction-finding station |
| MDH | Minimum descent height |
| MEA | Minimum en-route altitude |
| MEDEVAC | Medical evacuation flight |
| MEHT | Minimum eye height over threshold (for visual approach slope indicator systems) |
| MET | Meteorological or meteorology |
| MET REPORT | Local routine meteorological report |
| METAR | Aviation routine weather report (in aeronautical meteorology code) |
| MF | Medium frequency [300 to 3 000 kHz] |
| MHA | Minimum holding altitude |
| MHDF | Medium and high frequency direction finding stations (at the same location) |
| MHVDF | Medium, high and very high frequency direction-finding stations (at the same location) |
| MHZ | Megahertz |
| MID | Mid-point (related to RVR) |
| MIFG | Shallow fog |
| MIL | Military |
| MIN | Minutes |
| MINDEF | Ministry of Defence |
| MIS | Missing |
| MKR | Marker radio beacon |
| MLS | Microwave landing system |
| MM | Middle marker |
| MNM | Minimum |
| MNPS | Minimum navigation performance specifications |
| MNT | Monitor or monitoring or monitored |
| MNTN | Maintain |
| MOA | Military operating area |
| MOC | Minimum obstacle clearance (required) |
| MOD | Moderate (used to indicate the intensity of weather phenomena, interference or static report, e.g. MOD RA = moderate rain) |
| MON | Above mountain |
| MON | Monday |
| MOPS | Minimum operational performance standards |
| MOV | Move or moving or movement |
| MPH* | Statute miles per hour |
| MPS | Metres per second |
| MRA | Minimum reception altitude |
| MRG | Medium range |
| MRP | ATS/MET reporting point |
| MS | Minus |
| MSA | Minimum sector altitude |
| MSAS | Multi-functional transport satellite (MTSAT) satellite-based augmentation system |
| MSAW | Minimum safe altitude warning |
| MSG | Message |
| MSL | Mean sea level |
| MSR | Message has been misrouted |
| MSSR | Monopulse secondary surveillance radar |
| MT | Mountain |
| MTOM | Maximum take-off mass |
| MTU | Metric units |
| MTW | Mountain waves |
| MVDF | Medium and very high frequency direction finding stations (at the same location) |
| MWO | Meteorological watch office |
| MX | Mixed type of ice formation (white and clear) |
| N - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| N | North or northern latitude |
| NASC | National AIS system centre |
| NAT | North Atlantic |
| NAV | Navigation |
| NAVAID | Navigation aid |
| NB | Northbound |
| NBFR | Not before |
| NC | No change |
| NCD | No cloud detected |
| NDB | Non-directional radio beacon |
| NDV | No directional variations available |
| NE | North-east |
| NEB | North-eastbound |
| NEG | No or negative or permission not granted or that is not correct |
| NGT | Night |
| NIL | None or I have nothing to send to you |
| NM | Nautical miles |
| NML | Normal |
| NN | No name, unnamed |
| NNE | North north east |
| NNW | North north west |
| NOF | International NOTAM Office |
| NONSTD | Non-standard |
| NOSIG | No significant change (used in trend-type landing forecasts) |
| NOTAM | A notice distributed by means of telecommunication containing information concerning the establishment, condition or change in any aeronautical facility, service, procedure or hazard, the timely knowledge of which is essential to personnel concerned with flight operations |
| NOTAMC | Cancelling NOTAM |
| NOTAMN | New NOTAM |
| NOTAMR | Replacing NOTAM |
| NOV | November |
| NOZ | Normal operating zone |
| NR | Number |
| NRH | No reply heard |
| NS | Nimbostratus |
| NSC | Nil significant cloud |
| NSW | Nil significant weather |
| NTL | National |
| NTZ | No transgression zone |
| NW | North-west |
| NWB | North-westbound |
| NXT | Next |
| O - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| O/R | On request |
| OAC | Oceanic area control centre |
| OAS | Obstacle assessment surface |
| OBS | Observe or observed or observation |
| OBSC | Obscure or obscured or obscuring |
| OBST | Obstacle |
| OCA | Obstacle clearance altitude |
| OCA | Oceanic control area |
| OCC | Occulting (light) |
| OCH | Obstacle clearance height |
| OCL* | Obstacle clearance limit |
| OCNL | Occasional or occasionally |
| OCS | Obstacle clearance surface |
| OCT | October |
| OFZ | Obstacle free zone |
| OGN | Originate |
| OHD | Overhead |
| OK | We agree or it is correct |
| OLDI | On-line data interchange |
| OM | Outer marker |
| OPA | Opaque, white type of ice formation |
| OPC | The control indicated is operational control |
| OPMET | Operational meteorological (information) |
| OPN | Open or opening or opened |
| OPR | Operator or operate or operative or operating or operational |
| OPS | Operations |
| ORD | Order |
| OSV | Ocean station vessel |
| OTP | On top |
| OTS | Organized track system |
| OUBD | Outbound |
| OVC | Overcast |
| P - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| P | Maximum value of wind speed or runway visual range |
| P | Prohibited area (followed by identification) |
| PA | Precision approach |
| PALS | Precision approach lighting system (specify category) |
| PANS | Procedures for air navigation services |
| PAPI | Precision approach path indicator |
| PAR | Precision approach radar |
| PARA* | Paragraph |
| PARL | Parallel |
| PATC... | Precision approach terrain chart |
| PAX | Passenger(s) |
| PBC | Performance-based communication |
| PBN | Performance-based navigation |
| PBS | Performance-based surveillance |
| PCD | Proceed or proceeding |
| PCL | Pilot-controlled lighting |
| PCN | Pavement classification number |
| PCT | Per cent |
| PDC | Pre-departure clearance |
| PDG | Procedure design gradient |
| PE | Ice pellets |
| PER | Performance |
| PERM | Permanent |
| PIB | Pre-flight information bulletin |
| PJE | Parachute jumping exercise |
| PL | Ice pellets |
| PLA | Practice low approach |
| PLVL | Present level |
| PN | Prior notice required |
| PNR | Point of no return |
| PO | Dust/sand whirls |
| POB | Persons on board |
| POSS | Possible |
| PPI | Plan position indicator |
| PPR | Prior permission required |
| PPSN | Present position |
| PRFG | Aerodrome partially covered by fog |
| PRI | Primary |
| PRKG | Parking |
| PROB | Probability |
| PROC | Procedure |
| PROP | Propeller |
| PROV | Provisional |
| PS | Plus |
| PSG | Passing |
| PSN | Position |
| PSP | Pierced steel plank |
| PSR | Primary surveillance radar |
| PSYS | Pressure system(s) |
| PTN | Procedure turn |
| PTS | Polar track structure |
| PWR | Power |
| Q - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| QDL | Do you intend to ask me for a series of bearings? or I intend to ask you for a series of bearings |
| QDM | Magnetic heading (zero wind) |
| QDR | Magnetic bearing |
| QFE | Atmospheric pressure at aerodrome elevation (or at runway threshold) |
| QFU | Magnetic orientation of runway |
| QGE | What is my distance to your station or Your distance to my station is |
| QJH | Shall I run my test tape/a test sentence? Or run your test tape/a test sentence |
| QNH | Altimeter sub-scale setting to obtain elevation when on the ground |
| QSP | Will you relay to.... free of charge? Or I will relay to........ free of charge |
| QTA | Shall I cancel telegram number...? or Cancel telegram number....... |
| QTE | True bearing |
| QTF | Will you give me the position of my station according to the bearings taken by the D/F stations which you control? or The position of your station according to the bearings taken by the D/F stations that I control was.....latitude.....longitude or other indication of position, class....at.......hours |
| QUAD | Quadrant |
| QUJ | Will you indicate the TRUE track to reach you? or The TRUE track to reach me in degrees at .....hours |
| R - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| R | Right (preceded by runway designation number to identify a parallel runway) |
| R | Red |
| R | Right (runway identification) |
| R | Restricted area (followed by identification) |
| R | Runway visual range |
| R | Radial from VOR (followed by three figures) |
| R* | Receive (acknowledgement of receipt) (to be used in AFS as a procedure signal) |
| RA | Rain |
| RAC | Rules of the air and Air Traffic Services |
| RAF* | Royal Air Force |
| RAG | Ragged |
| RAG | Runway arresting gear |
| RAI | Runway alignment indicator |
| RAIM | Receiver autonomous integrity monitoring |
| RASC | Regional AIS system centre |
| RASS | Remote altimeter setting source |
| RB | Rescue boat |
| RCA | Reach cruising altitude |
| RCC | Rescue coordination centre |
| RCF | Radio communication failure (message type designator |
| RCH | Reach or reaching |
| RCL | Runway centre line |
| RCLL | Runway centre line light(s) |
| RCLR | Recleared |
| RCP | Required communication performance |
| RDH | Reference datum height |
| RDL | Radial |
| RDO | Radio |
| RDOACT | Radioactive |
| RE | Recent (used to qualify weather phenomena e.g. RERA = recent rain |
| REC | Receive or receiver |
| REDL | Runway edge light(s) |
| REF | Reference to. . . .. . . or refer to. . . . . . . |
| REG | Registration |
| RENL | Runway end light(s) |
| REP | Report or reporting or reporting point |
| REQ | Request or requested |
| RERTE | Reroute |
| RESA | Runway end safety area |
| RF | Constant radius arc to a fix |
| RFC* | Radio facility chart |
| RFFS | Rescue and fire fighting services |
| RG | Range (lights) |
| RH* | Rescue helicopter |
| RHC | Right-hand circuit |
| RIF | Reclearance in flight |
| RIME | Rime (used in aerodrome warnings) |
| RL | Report leaving |
| RLA | Relay to |
| RLCE | Request level change en route |
| RLLS | Runway lead-in lighting system |
| RLNA | Request level not available |
| RMAC | Radar minimum altitude chart |
| RMAF* | Royal Malaysian Air Force |
| RMK | Remark |
| RNAV | Area navigation |
| RNG | Radio range |
| RNP | Required navigation performance |
| ROBEX | Regional OPMET bulletin exchange (scheme) |
| ROC | Rate of climb |
| ROD | Rate of descent |
| RON | Receiving only |
| RPI | Radar position indicator |
| RPLC | Replace or replaced |
| RPS | Radar position symbol |
| RPT | Repeat or I repeat |
| RQ | Request |
| RQMNTS | Requirements |
| RQP | Request flight plan (message type designator) |
| RQS | Request supplementary flight plan (message type designator) |
| RR | Report reaching |
| RRA | (or RRB, RRC... etc, in sequence) Delayed meteorological message |
| RSAF* | Republic of Singapore Air Force |
| RSC | Rescue sub-centre |
| RSCD | Runway surface condition |
| RSFC* | Royal Selangor Flying Club |
| RSP | Required surveillance performance |
| RSP | Responder beacon |
| RSR | En-route surveillance radar |
| RTD | Delayed (message type designator) |
| RTE | Route |
| RTF | Radiotelephone |
| RTG | Radiotelegraph |
| RTHL | Runway threshold light(s) |
| RTN | Return or returned or returning |
| RTODAH | Rejected take-off distance available, helicopter |
| RTS | Return to service |
| RTT | Radio teletypewriter |
| RTZL | Runway touchdown zone light(s) |
| RUT | Standard regional route transmitting frequencies |
| RV | Rescue vessel |
| RVA | Radar vectoring area |
| RVR | Runway visual range |
| RVSM | Reduced vertical separation minimum (300m (1000ft)) between FL290 and FL410 |
| RWY | Runway |
| S - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| S | South or southern latitude |
| SA | Sand |
| SALS | Simple approach lighting system |
| SAN | Sanitary |
| SAR | Search and rescue |
| SARPS | Standards and Recommended Practices (ICAO) |
| SAT | Saturday |
| SATCOM | Satellite communication (used only when referring generally to both voice and data satellite communication or only data satellite communication) |
| SATO* | Shell aircraft turbine oil |
| SATVOICE | Satellite voice communication |
| SB | Southbound |
| SBAS | Satellite-based augmentation system |
| SC | Stratocumulus |
| SCT | Scattered |
| SDBY | Stand by |
| SE | South-east |
| SEA | Sea (used in connection with sea-surface temperature and state of the sea |
| SEB | South-eastbound |
| SEC | Seconds |
| SECN | Section |
| SECT | Sector |
| SELCAL | Selective calling system |
| SEP | September |
| SER | Service or servicing or served |
| SEV | Severe (used e.g. to qualify icing and turbulence reports) |
| SFC | Surface |
| SG | Snow grains |
| SGL | Signal |
| SH | Shower |
| SHF | Super high freguency (3 000 to 30 000 MHz) |
| SIA* | Standard instrument approach |
| SID | Standard instrument departure |
| SIF | Selective identification feature |
| SIG | Significant |
| SIGMET | Information concerning en-route weather and other phenomena in the atmosphere that may affect the safety of aircraft operations |
| SIMUL | Simultaneous or simultaneously |
| SIWL | Single isolated wheel load |
| SKED | Schedule or scheduled |
| SLP | Speed limiting point |
| SLW | Slow |
| SMC | Surface movement control |
| SMR | Surface movement radar |
| SN | Snow |
| SNOCLO | Aerodrome closed due to snow |
| SNOWTAM | A special series NOTAM notifying the presence or removal of hazardous conditions due to snow, ice, slush or standing water associated with snow, slush and ice on the movement area, by means of a specific format |
| SOC* | Start of climb |
| SPECI | Aviation selected special weather report (in aeronautical meteorological code) |
| SPECIAL | Special meteorological report (in abbreviated plain language) |
| SPL | Supplementary flight plan (message type designator) |
| SPOC | SAR point of contact |
| SPOT | Spot wind |
| SQ | Squall |
| SQL | Squall line |
| SR | Sunrise |
| SRA | Surveillance radar approach |
| SRE | Surveillance radar element of precision approach radar system |
| SRG | Short range |
| SRR | Search and rescue region |
| SRY | Secondary |
| SS | Sandstorm |
| SS | Sunset |
| SSB | Single sideband |
| SSE | South south east |
| SSR | Secondary surveillance radar |
| SST | Supersonic transport |
| SSW | South south west |
| ST | Stratus |
| STA | Straight in approach |
| STAR | Standard instrument arrival |
| STD | Standard |
| STF | Stratiform |
| STN | Station |
| STNR | Stationary |
| STOL | Short take-off and landing |
| STS | STS |
| STWL | Stopway light(s) |
| SUBJ | Subject to |
| SUN | Sunday |
| SUP | Supplement (AIP Supplement) |
| SUPPS | Regional supplementary procedures |
| SVC | Service (message type only) |
| SVCBL | Serviceable |
| SW | South-west |
| SWB | South-westbound |
| SWY | Stopway |
| T - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| T | Temperature |
| T-VASIS | T visual approach slope indicator system |
| TA | Transition altitude |
| TAA | Terminal arrival altitude |
| TACAN | UHF tactical air navigation aid |
| TAF | Aerodrome forecast |
| TAIL | Tail wind |
| TAM* | Technical acknowledge message |
| TAR | Terminal area surveillance radar |
| TAS | True airspeed |
| TAX | Taxiing or taxi |
| TC | Tropical cyclone |
| TCAC | Tropical cyclone advisory centre |
| TCU | Towering cumulus |
| TDO | Tornado |
| TDZ | Touchdown zone |
| TECR | Technical reason |
| TEL | Telephone |
| TEMPO | Temporary or temporarily |
| TFC | Traffic |
| TGL | Touch-and-go landing |
| TGS | Taxiing guidance system |
| THR | Threshold |
| THRU | Through |
| THU | Thursday |
| TIBA | Traffic information broadcast by aircraft |
| TIL | Until |
| TIP | Until past. . . . . . . . (place) |
| TKOF | Take-off |
| TL | Till |
| TLOF | Touchdown and lift-off area |
| TMA | Terminal control area |
| TN | Minimum temperature |
| TNA | Turn altitude |
| TNH | Turn height |
| TO | To. . . . . . . . (place) |
| TOC | Top of climb |
| TOD* | Time of despatch |
| TODA | Take-off distance available |
| TODAH | Take-off distance available, helicopter |
| TOP | Cloud top |
| TOR* | Time of receipt |
| TORA | Take-off run available |
| TOX | Toxic |
| TP | Turning point |
| TR | Track |
| TRA | Temporary reserved airspace |
| TRANS | Transmits or transmitter |
| TREND | Trend forecast |
| TRG | Training |
| TRL | Transition level |
| TROP | Tropopause |
| TS | Thunderstorm |
| TT | Teletypewriter |
| TUE | Tuesday |
| TURB | Turbulence |
| TVOR | Terminal VOR |
| TWR | Aerodrome control tower or aerodrome control |
| TWY | Taxiway |
| TX | Maximum temperature |
| TX... | Maximum temperature (followed by figures in TAF) |
| TXL | Taxilane |
| TXT | Text |
| TXT* | Text (when the abbreviation is used to request a repetition, the question mark (IMI) precedes the abbreviation, e.g. IMI TXT) (to be used in AFS as a procedure signal) |
| TYP | Type of aircraft |
| TYPH | Typhoon |
| U - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| U | Upward |
| U/S | Unserviceable |
| UA | Unmanned aircraft |
| UAB | Until advised by. . . . . . . . |
| UAC | Upper area control centre |
| UAR | Upper air route |
| UAS | Unmanned aircraft system |
| UDF | Ultra high frequency direction-finding station |
| UFN | Until further notice |
| UHDT | Unable higher due traffic |
| UHF | Ultra high frequency (300 to 3 000 MHz) |
| UIC | Upper information centre |
| UIR | Upper flight information region |
| ULM | Ultra light motorized aircraft |
| ULR | Ultra long range |
| UNA | Unable |
| UNAP | Unable to approve |
| UNL | Unlimited |
| UNREL | Unreliable |
| UP | Unidentified precipitation |
| UTA | Upper control area |
| UTC | Co-ordinated Universal Time |
| V - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| VA | Volcanic ash |
| VAAC | Volcanic ash advisory centre |
| VAC | Visual approach chart |
| VAL | In valleys |
| VAN | Runway control van |
| VAR | Magnetic variation |
| VAR | Visual-aural radio range |
| VASIS | Visual approach slope indicator system |
| VC | Vicinity of the aerodrome |
| VCY | Vicinity |
| VDF | Very high frequency direction-finding station |
| VER | Vertical |
| VFR | Visual flight rules |
| VHF | Very high frequency (30 to 300 MHz) |
| VIA* | By way of |
| VIP | Very important person |
| VIS | Visibility |
| VLF | Very low frequency (3 to 30 KHz) |
| VLR | Very long range |
| VMC | Visual meteorological conditions |
| VNAV | (to be pronounced "VEE-NAV) Vertical navigation |
| VOL | Volume (followed by I, II...) |
| VOLMET | Meteorological information for aircraft in flight |
| VOR | VHF omnidirectional radio range |
| VORTAC | VOR and TACAN combination |
| VOT | VOR airborne equipment test facility |
| VPA | Vertical path angle |
| VRB | Variable |
| VSA | By visual reference to the ground |
| VSP | Vertical speed |
| VTOL | Vertical take-off and landing |
| VV | Vertical visibility |
| VVIP* | Very very important person |
| W - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| W | West or western longitude |
| W | White |
| WAAS | Wide area augmentation system |
| WAC | World Aeronautical Chart - ICAO 1:1 000 000 |
| WAFC | World area forecast centre |
| WB | Westbound |
| WBAR | Wing bar lights |
| WDI | Wind direction indicator |
| WDSPR | Widespread |
| WED | Wednesday |
| WEF | With effect from or effective from |
| WGS-84 | World Geodetic System - 1984 |
| WI | Within |
| WID | Width |
| WIE | With immediate effect or effective immediately |
| WILCO | Will comply |
| WIND | Wind |
| WIP | Work in progress |
| WKN | Weaken or weakening |
| WNW | West north west |
| WO | Without |
| WPT | Way-point |
| WRNG | Warning |
| WS | Wind shear |
| WSPD | Wind speed |
| WSW | West south west |
| WT | Weight |
| WTSPT | Waterspout |
| WWW | Worldwide web |
| WX | Weather |
| WXR | Weather radar |
| X - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| X | Cross |
| XBAR | Crossbar (of approach lighting system) |
| XNG | Crossing |
| XS | Atmospherics |
| Y - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| Y | Yellow |
| YCZ | Yellow caution zone (runway lighting) |
| YES | Yes (affirmative) |
| YR | Your |
| Z - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
| Z | Co-ordinated Universal Time (in meteorological messages) |