Abbreviations marked by an asterisk (*) are either different from or not contained in ICAO Doc 8400.
ABCDEFGHIJKLMNOPQRSTUVWXYZ| 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* | Ampere |
| A-CDM* | Airport collaborative decision making |
| A-SMGCS* | Advanced surface movement guidance and control system |
| A/A | Air-to-air |
| A/G | Air-to-ground |
| AAA | (or AAB, AAC, etc. in sequence) Amended meteorological message (message type designator) |
| 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 |
| ACFT | Aircraft |
| ACID* | Aircraft identification |
| ACK | Acknowledge |
| ACL | Altimeter check location |
| ACL* | ATC clearances and instructions |
| ACM* | ATC Communications Management |
| ACN | Aircraft classification number |
| ACP | Acceptance (message type designator) |
| ACPT | Accept or accepted |
| ACT | Active or activated or activity |
| ACU* | Air control unit |
| AD | Aerodrome |
| ADA | Advisory area |
| ADC | Aerodrome chart |
| ADC* | Air defence controller |
| ADDN | Addition or additional |
| ADEP* | Airport of departure |
| ADES* | Airport of destination |
| ADF | Automatic direction-finding equipment |
| ADIZ | Air defence identification zone |
| ADJ | Adjacent |
| ADNC* | Air Defence Notification Cell |
| ADO | Aerodrome office (specify service) |
| ADP* | Automatic data processing |
| ADR | Advisory route |
| ADS | The address [when this abbreviation is used to request a repetition, the question mark (IMI) precedes the abbreviation, e.g. IMI ADS] (to be used in AFS as a procedure signal) |
| ADS-B | Automatic dependent surveillance - broadcast |
| ADS-C | Automatic dependent surveillance - contract |
| 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 |
| AFIZ* | Aerodrome flight information zone |
| AFM | Yes or affirm or affirmative or that is correct |
| 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 communication |
| AIM* | ATFM information message |
| 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 |
| AIRPROX* | Aircraft proximity |
| AIS | Aeronautical Information Services |
| ALA | Alighting area |
| ALERFA | Alert phase |
| ALO* | Air Liaison Officer |
| 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 |
| AMC* | Airspace Management Cell |
| AMC* | ATC microphone check |
| AMD | Amend or amended (used to indicate amended meteorological message; message type designator) |
| AMDT | Amendment (AIP amendment) |
| AMHS* | ATS message handling system |
| AMO* | Aerodrome Meteorological Office |
| AMS | Aeronautical mobile service |
| AMSL | Above mean sea level |
| AMSS | Aeronautical mobile satellite service |
| ANA* | Administration de la navigation aérienne |
| ANC | Aeronautical chart - 1:500 000 (followed by name/title) |
| ANCS | Aeronautical navigation chart - small scale (followed by name/title and scale) |
| ANM* | ATFM notification message |
| ANS | Answer |
| AO | Aircraft 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 (followed by name/title) |
| APN | Apron |
| APOC* | Airport operations centre |
| 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 |
| AR* | Authorization required |
| ARC | Area chart |
| ARES* | Airspace reservation |
| 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) |
| ARR | Arrive or arrival |
| 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 |
| ASHTAM | Special series of NOTAM notifying, by means of a specific format, change in activity of a volcano, a volcanic eruption and/or volcanic ash cloud that is of significance to aircraft operations |
| ASPH | Asphalt |
| ASR* | Aerodrome surveillance radar |
| 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) |
| ATCC* | Air traffic control centre (military abbreviation) |
| ATCSMAC | Air traffic control surveillance minimum altitude chart (followed by name/title) |
| ATD | Actual time of departure |
| ATFCM* | Air traffic flow and capacity management |
| 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 |
| AUP* | Airspace Use Plan |
| AUTH | Authorized or authorization |
| AUTO | Automatic |
| AUW | All up weight |
| AUX | Auxiliary |
| AVBL | Available or availability |
| AVG | Average |
| AVGAS | Aviation gasoline |
| AWOS | Automatic 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 |
| BARO-VNAV | Barometric vertical navigation |
| BASE | Cloud base |
| BCFG | Fog patches |
| BCN | Beacon (aeronautical ground light) |
| BCST | Broadcast |
| BDRY | Boundary |
| BECMG | Becoming |
| BFR | Before |
| BKN | Broken |
| BL | Blowing (followed by DU = dust, SA = sand or SN = snow) |
| 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 |
| BVLOS* | Beyond visual line of sight |
| 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 |
| CANAC* | Computer Assisted National Air traffic control Centre |
| CAS* | Close Air Support |
| CAT | Category |
| CAT | Clear air turbulence |
| CAVOK | Visibility, cloud and present weather better than prescribed values or conditions |
| CB | Cumulonimbus |
| CBA* | Cross-border area |
| CC | Cirrocumulus |
| CCA | (or CCB, CCC, etc. in sequence) Corrected meteorological message (message type designator) |
| CCO | Continuous climb operations |
| CCTV* | Closed circuit television |
| CD | Candela |
| CDN | Co-ordination (message type designator) |
| CDO | Continuous descent operations |
| CDR | Conditional route |
| CENOR* | Central and Northern region (an organisaton of NATO nations that developed specifications for aeronautical charts for the use of MIL crew) |
| CEU* | Central executive unit |
| CF | Change frequency to . . . |
| CF | Course to a fix |
| CFIT* | Controlled flight into terrain |
| CFM | Confirm or I confirm (to be used in AFS as a procedure signal) |
| 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 |
| COMAO* | Composite Air Operations |
| COMOPSAIR* | Commando Air Operations |
| CONC | Concrete |
| COND | Condition |
| CONS | Continuous |
| CONST | Construction or constructed |
| CONT | Continue(s) or continued |
| COOR | Coordinate or coordination |
| COORD | Coordinates |
| COP | Change-over point |
| COR | Correct or correction or corrected (used to indicate corrected meteorological message; 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) |
| CPSRA* | Critical part of the security restricted area |
| CRC | Cyclic redundancy check |
| CRC* | Control and reporting centre |
| CRM | Collision risk model |
| CRNA* | Centre en Route de la Navigation Aérienne |
| CRP | Compulsory reporting point |
| CRZ | Cruise |
| CS | Call sign |
| CS | Cirrostratus |
| CSAR* | Combat search and rescue |
| CTA | Control area |
| CTAM | Climb to and maintain |
| CTC | Contact |
| CTL | Control |
| CTN | Caution |
| CTOT* | Calculated take-off time |
| 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 | Downward (tendency in RVR during previous 10 minutes) |
| D | Danger area (followed by identification) |
| D-ATIS | Data link automatic terminal information service |
| D-FIS* | Data link flight information service |
| D-VOLMET | Data link VOLMET |
| DA | Decision altitude |
| DAT* | Significant data related to data link capability |
| dB* | Decibel |
| DCD | Double channel duplex |
| DCKG | Docking |
| DCL* | Data link clearance delivery service |
| 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 (used to precede the call sign of the calling station; to be used in AFS as a procedure signal) |
| DEC | December |
| DEG | Degrees |
| DEP | Depart or departure |
| DEP | Departure (message type designator) |
| DEPO | Deposition |
| DER | Departure end of the runway |
| DES | Descend to or descending to |
| DEST | Destination |
| DETRESFA | Distress phase |
| DEV | Deviation or deviating |
| DF | Direction finding |
| DFDR | Digital flight data recorder |
| DFTI | Distance from touchdown indicator |
| DGS* | Docking guidance system |
| DH | Decision height |
| DIF | Diffuse |
| DIST | Distance |
| DIV | Divert or diverting |
| DLA | Delay or delayed |
| DLA | Delay (message type designator) |
| DLIC | Data link initiation capability |
| DLY | Daily |
| DME | Distance measuring equipment |
| DNG | Danger or dangerous |
| DOC* | Designated operational coverage |
| DOF | Date of flight |
| DOM | Domestic |
| DP | Dew point temperature |
| DPM* | Motorized deltaplane |
| DPT | Depth |
| DR | Dead reckoning |
| DR | Low drifting (followed by DU = dust, SA = sand or SN = snow) |
| 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 is a duplicate message (signal for use in the tele-typewriter service only; to be used in AFS as a procedure signal) |
| 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 |
| eAIP* | Electronic aeronautical information publication |
| EAT | Expected approach time |
| EAUP* | European airspace use plan |
| EAW* | Early access weekend routes |
| EB | Eastbound |
| ECAC* | European Civil Aviation Conference |
| EDA | Elevation differential area |
| EDTO | Extended diversion time operations |
| EEE | Error (signal for use in the teletypewriter service only; to be used in AFS as a procedure signal) |
| EET | Estimated elapsed time |
| EFC | Expect further clearance |
| EFIS | Electronic flight instrument system |
| EGNOS | European geostationary navigation overlay service |
| EHF | Extremely high frequency (30 000 to 300 000 MHZ) |
| EHS* | Enhanced surveillance |
| ELBA | Emergency location beacon - aircraft |
| ELEV | Elevation |
| ELR | Extra long range |
| ELS* | Elementary surveillance |
| 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 |
| ENR | En-route |
| ENRC | En-route chart (followed by name/title) |
| EOBT | Estimated off block time |
| EQPT | Equipment |
| EQS | Equatorial latitudes southern hemisphere |
| ESA* | Emergency safety altitude |
| ESE | East-south-east |
| EST | Estimate or estimated or estimate (message type designator) |
| EST* | Estimated (preceded by time-group) |
| ETA | Estimated time of arrival or estimating arrival |
| ETD | Estimated time of departure or estimating departure |
| ETO | Estimated time over significant point |
| ETOT* | Estimated take-off time |
| EUR RODEX | European regional OPMET data exchange |
| EUROAT* | Eurocontrol harmonised rules for operational air traffic |
| EUUP* | European updated airspace use plan |
| EV | Every |
| EVS | Enhanced vision system |
| EXC | Except |
| excl* | Excluded |
| 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 |
| FA | Course from a fix to an altitude |
| FAB* | Functional airspace block |
| FAC | Facilities |
| FAF | Final approach fix |
| FAL | Facilitation of international air transport |
| FANS* | Future air navigation system |
| FAP | Final approach point |
| FAS | Final approach segment |
| FASID* | Facilities and Services Implementation Document |
| FATO | Final approach and take-off area |
| FAX | Facsimile transmission |
| FBL | Light (used to indicate the intensity of weather phenomena, interference or static reports, e.g. FBL RA = light rain) |
| FBZ* | Flight planning buffer zone |
| 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 |
| FLIP* | Flight information publication |
| FLR | Flares |
| FLT | Flight |
| FLTCK | Flight check |
| FLUC | Fluctuating or fluctuation or fluctuated |
| FLW | Follow(s) or following |
| FLY | Fly or flying |
| FM | Course from a fix to manual termination (used in navigation database coding) |
| FM | From |
| FM | From (followed by time weather change is forecast to begin) |
| FMC | Flight management computer |
| FMP* | Flow management position |
| FMS | Flight management system |
| FMU | Flow management unit |
| FNA | Final approach |
| FOD* | Foreign object damage |
| FPAP | Flight path alignment point |
| FPL | Flight plan |
| FPM | Feet per minute |
| FPR | Flight plan route |
| FPS* | Federal Public Service |
| FR | Fuel remaining |
| Fr* | French |
| FRA* | Free route airspace |
| FREQ | Frequency |
| FRI | Friday |
| FRNG | Firing |
| FRONT | Front (relating to weather) |
| FROST | Frost (used in aerodrome warnings) |
| FRQ | Frequent |
| FSL | Full stop landing |
| FSS | Flight service station |
| FST | First |
| FT | Feet (dimensional unit) |
| FTE | Flight technical error |
| FTP | Fictitious threshold point |
| FTT | Flight technical tolerance |
| 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* | Gram |
| G | Green |
| G | Variations from the mean wind speed (gusts) (used in METAR/SPECI and TAF) |
| G/A | Ground-to-air |
| G/A/G | Ground-to-air and air-to-ground |
| GA | General Aviation |
| GA | Go ahead, resume sending (to be used in AFS as a procedure signal) |
| 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 |
| GAT* | General air traffic |
| GBAS | Ground-based augmentation system |
| GCA | Ground controlled approach system or ground controlled approach |
| Ge* | German |
| GEN | General |
| GEO | Geographic or true |
| GES | Ground earth station |
| GLD | Glider |
| GLONASS | Global orbiting navigation satellite system |
| GLS | GBAS landing system |
| GMC | Ground movement chart (followed by name/title) |
| GND | Ground |
| GNDCK | Ground check |
| GNSS | Global navigation satellite system |
| GOV | Government |
| GP | Glide path |
| GPA | Glide path angle |
| GPIP | Glide path intercept point |
| 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 expressed in binary form (aeronautical meteorological code) |
| GRVL | Gravel |
| GS | Ground speed |
| GS | Small hail and/or snow pellets |
| GSM* | Global System for Mobile Communications |
| 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 the centre of high pressure |
| H... | Significant wave height (followed by figures in METAR/SPECI) |
| H24 | Continuous day and night service |
| HA | Holding/racetrack to an altitude |
| HAA* | Height above aerodrome elevation |
| HAPI | Helicopter approach path indicator |
| HAT* | Height above touch-down |
| HBN | Hazard beacon |
| HCH | Helicopter crossing height |
| HDF | High frequency direction-finding station |
| HDG | Heading |
| HEL | Helicopter |
| HEMS* | Helicopter emergency medical service |
| HF | High frequency (3 000 to 30 000 KHZ) |
| HF | Holding/racetrack to a fix |
| HFDL* | High frequency data link |
| HGT | Height or height above |
| HJ | Sunrise to sunset |
| HLDG | Holding |
| HLP | Heliport |
| HLS | Helicopter landing site |
| HM | Holding/racetrack to a manual termination |
| HN | Sunset to sunrise |
| HNH | High latitudes northern hemisphere |
| HO | Service available to meet operational requirements |
| HOL | Holiday |
| HOSP | Hospital aircraft |
| HPA | Hectopascal |
| HPMA* | High performance military aircraft |
| HR | Hours |
| HRP | Heliport reference point |
| HS | Service available during hours of scheduled operations |
| HSH | High latitudes southern hemisphere |
| HT* | High tension |
| HTA* | Helicopter training area |
| HUD | Head-up display |
| HUM | Humanitarian |
| HURCN | Hurricane |
| HVDF | High and very high frequency direction-finding stations (at the same location) |
| HVY | Heavy |
| HVY | Heavy (used to indicate the intensity of weather phenomena, e.g. HVY RA = heavy rain) |
| HX | No specific working hours |
| HYR | Higher |
| HZ | Haze |
| HZ | Hertz (cycles 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 (followed by name/title) |
| IAF | Initial approach fix |
| IAO | In and out of clouds |
| IAP | Instrument approach procedure |
| IAR | Intersection of air routes |
| IAS | Indicated airspeed |
| IATA* | International Air Transport Association |
| IBN | Identification beacon |
| ICAO | International Civil Aviation Organization |
| ICE | Icing |
| ICF* | Initial contact frequency |
| ID | Identifier or identify |
| IDENT | Identification |
| IF | Intermediate approach fix |
| IFF | Identification friend/foe |
| IFPS* | Integrated Initial Flight Plan Processing System |
| IFPU* | Integrated Initial Flight Plan Processing Unit |
| IFR | Instrument flight rules |
| IGA | International general aviation |
| ILS | Instrument landing system |
| IM | Inner marker |
| IMC | Instrument meteorological conditions |
| IMG | Immigration |
| IMI | Interrogation sign (question mark) (to be used in AFS as a procedure signal) |
| IMPR | Improve or improving |
| IMT | Immediate or immediately |
| INA | Initial approach |
| INBD | Inbound |
| INC | In cloud |
| INCERFA | Uncertainty phase |
| incl* | Included |
| 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 |
| INTL | International |
| INTRG | Interrogator |
| INTRP | Interrupt or interruption or interrupted |
| INTSF | Intensify or intensifying |
| INTST | Intensity |
| IR | Ice on runway |
| IRM* | Institut Royal Météorologique de Belgique |
| IRS | Inertial reference system |
| IRU* | Inertial reference unit |
| 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 | |
| JAA* | Joint Aviation Authorities |
| JAN | January |
| 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 |
| KIAS | Knots indicated airspeed |
| KM | Kilometres |
| KMH | Kilometres per hour |
| KMI* | Koninklijk Meteorologisch Instituut |
| KPA | Kilopascal |
| KT | Knots |
| kVA* | Kilovolt-ampere |
| 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 (runway identification) |
| L | Litre |
| L | Locator (see LM, LO) |
| L | Low pressure area or the centre of low pressure |
| LAM | Logical acknowledgement (message type designator) |
| LAN | Inland |
| LARA* | Local and sub-Regional Airspace Management Support System |
| LAT | Latitude |
| LB* | Pounds |
| LCA | Local or locally or location or located |
| LCN* | Load classification number |
| LCTA* | Lower control area |
| LDA | Landing distance available |
| LDAH | Landing distance available, helicopter |
| LDG | Landing |
| LDI | Landing direction indicator |
| LED* | Light-emitting diode |
| LEN | Length |
| LF | Low frequency (30 to 300 KHZ) |
| LFA* | Low flying area |
| LGT | Light or lighting |
| LGTD | Lighted |
| LIH | Light intensity high |
| LIL | Light intensity low |
| LIM | Light intensity medium |
| LINE | Line (used in SIGMET) |
| LLFC* | Low level forecast chart |
| LM | Locator, middle |
| LMT | Local mean time |
| LNAV | Lateral navigation |
| LNG | Long (used to indicate the type of approach desired or required) |
| LO | Locator, outer |
| LOC | Localizer |
| LOM* | Compass locator at OM |
| LONG | Longitude |
| LORAN | Long range air navigation system |
| LOSS | Airspeed or headwind loss |
| LPV | Localizer performance with vertical guidance |
| LR | The last message received by me was . . .(to be used in AFS as a procedure signal) |
| LRG | Long range |
| LS | The last message sent by me was . . . or Last message was . . .(to be used in AFS as a procedure signal) |
| LSA* | Light sport aircraft |
| LT* | Left turn |
| LTA | Lower control area |
| LTD | Limited |
| LTP | Landing threshold point |
| Lu* | Luxembourgish |
| LV | Light and variable (relating to wind) |
| LVE | Leave or leaving |
| LVL | Level |
| LVO* | Low Visibility Operations |
| LVP | Low visibility procedures |
| LWEP* | Live weapons emergency procedure |
| 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 | Metres (preceded by figures) |
| M | Mach number (followed by figures) |
| M | Indicator for minimum value of runway visual range (used in the METAR/SPECI code forms) |
| MAA | Maximum authorized altitude |
| MAG | Magnetic |
| MAHF | Missed approach holding fix |
| MAINT | Maintenance |
| MAN* | Manual |
| MAP | Aeronautical maps and charts |
| MAPT | Missed approach point |
| MAR | At sea |
| MAR | March |
| MARSA* | Military authority assumes responsibility for separation of aircraft |
| 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 (in abbreviated plain language) |
| METAR | Aviation routine weather report (in aeronautical meteorological 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 |
| MILFAG* | Military Low Flying Area Golf |
| MIN | Minutes |
| MIPS* | Military instrument procedure standardization |
| MIS | Missing . . . (transmission identification; to be used in AFS as a procedure signal) |
| MJ* | Megajoule |
| MKR | Marker radio beacon |
| MLS | Microwave landing system |
| MLW* | Maximum landing weight |
| MM | Middle marker |
| MM* | millimetre |
| MNH | Middle latitudes northern hemisphere |
| MNM | Minimum |
| MNPS | Minimum navigation performance specifications |
| MNT | Monitor or monitoring or monitored |
| MNTN | Maintain |
| MOA | Military operating area |
| MOC | Minimum obstacle clearance (required) |
| MOCA | Minimum obstacle clearance altitude |
| MOD | Moderate (used to indicate the intensity of weather phenomena, interference or static reports, e.g. MOD RA = moderate rain) |
| MON | Above mountains |
| MON | Monday |
| MOPS | Minimum operational performance standards |
| MOPSC* | Maximum operational passenger seating configuration |
| MOV | Move or moving or movement |
| MPH* | Statute miles per hour |
| MPM* | Metres per minute |
| 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 |
| MSC* | Mission Support Centre |
| MSG | Message |
| MSH | Middle latitudes southern hemisphere |
| MSL | Mean sea level |
| MSR | Message . . . (transmission identification) has been misrouted (signal for use in the teletypewriter service only; to be used in AFS as a procedure signal) |
| MSSR | Monopulse secondary surveillance radar |
| MT | Mountain |
| MTOM | Maximum take-off mass |
| MTOW* | Maximum authorized take-off weight |
| MTU | Metric units |
| MTW | Mountain waves |
| MVA* | Minimum vectoring altitude |
| 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* | Newton |
| N | No distinct tendency (in RVR during previous 10 minutes) |
| N | North or northern latitude |
| NADP | Noise abatement departure procedure |
| NASC | National AIS system centre |
| NAT | North Atlantic |
| NATO* | North Atlantic Treaty Organisation |
| NAV | Navigation |
| NAVAID | Navigation aid |
| NB | Northbound |
| NBFR | Not before |
| NC | No change |
| NCD | No cloud detected (used in automated METAR/SPECI) |
| NDB | Non-directional radio beacon |
| NDV | No directional variations available (used in automated METAR/SPECI) |
| 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 |
| Nl* | Dutch |
| NM | Nautical miles |
| NML | Normal |
| NN | No name, unnamed |
| NNE | North-north-east |
| NNW | North-north-west |
| NO | No (negative; to be used in AFS as a procedure signal) |
| 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 operation zone |
| NPA | Non precision approach |
| NR | Number |
| NRH | No reply heard |
| NS | Nimbostratus |
| NSC | Nil significant cloud |
| NSE | Navigation system error |
| NSW | Nil significant weather |
| NTL | National |
| NTZ | No transgression zone |
| NVA* | Night Vision Aid |
| NVG* | Night Vision Goggles |
| 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 |
| OAT* | Operational air traffic |
| 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 |
| OCNL | Occasional or occasionally |
| OCS | Obstacle clearance surface |
| OCT | October |
| OFZ | Obstacle free zone |
| OGN | Originate (to be used in AFS as a procedure signal) |
| OHD | Overhead |
| OIS | Obstacle identification surface |
| OK | We agree / it is correct (to be used in AFS as a procedure signal) |
| OLDI | On-line data interchange |
| OM | Outer marker |
| OMGWS* | Outer main gear wheel span |
| OPA | Opaque, white type of ice formation |
| OPC | 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 |
| ORCAM* | Originating region code assignment method |
| ORD | Order |
| ORP* | Operational readiness platform |
| ORRP* | On request reporting point |
| OSV | Ocean station vessel |
| OTP | On top |
| OTS | Organized track system |
| OUBD | Outbound |
| OVC | Overcast |
| OVH* | Overhead |
| 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 | Indicator for maximum value of wind speed or runway visual range (used in the METAR/SPECI and TAF code forms) |
| 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 |
| PARL | Parallel |
| PATC | Precision approach terrain chart (followed by name/title) |
| 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 |
| PER | Performance |
| PERM | Permanent |
| PFO* | Permanent flying order |
| PIB | Pre-flight information bulletin |
| PJE | Parachute jumping exercise |
| PL | Ice pellets |
| PL* | Plain language |
| PLA | Practice low approach |
| PLVL | Present level |
| PN | Prior notice required |
| PNR | Point of no return |
| PO | Dust/sand whirls (dust devils) |
| POB | Persons on board |
| POC* | Point of contact |
| POSS | Possible |
| PPI | Plan position indicator |
| PPR | Prior permission required |
| PPSN | Present position |
| PRFG | Aerodrome partially covered by fog |
| PRI | Primary |
| PRKG | Parking |
| PRM* | Persons with reduced mobility |
| PROB | Probability |
| PROC | Procedure |
| PROP | Propeller |
| PROV | Provisional |
| PRP | Point-in-space reference point |
| PS | Plus |
| PSG | Passing |
| PSI* | Pounds per square inch |
| 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 | |
| QC* | Quota count |
| QDL | Do you intend to ask me for a series of bearings? or I intend to ask you for a series of bearings (to be used in radiotelegraphy as a Q Code) |
| 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 (distance figures and units) (to be used in radiotelegraphy as a Q Code) |
| QJH | Shall I run my test tape/a test sentence? or Run your test tape/a test sentence (to be used in AFS as a Q Code) |
| QNH | Altimeter sub-scale setting to obtain elevation when on the ground |
| QRA* | Quick reaction alert |
| QSP | Will you relay to . . . free of charge? or I will relay to . . . free of charge (to be used in AFS as a Q Code) |
| QTA | Shall I cancel telegram number . . .? or Cancel telegram number . . . (to be used in AFS as a Q Code) |
| 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 (to be used in radiotelegraphy as a Q Code) |
| QUAD | Quadrant |
| QUJ | Will you indicate the TRUE track to reach you? or The TRUE track to reach me is . . . degrees at . . . hours (to be used in radiotelegraphy as a Q Code) |
| 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 (runway identification) |
| R | Rate of turn |
| R | Red |
| R | Radial from VOR (followed by three figures) |
| R | Restricted area (followed by identification) |
| R | Runway (used in the METAR/SPECI code forms) |
| R | Received (acknowledgement of receipt; to be used in AFS as a procedure signal) |
| RA | Rain |
| RA | Resolution advisory |
| RAC | Rules of the air and air traffic services |
| RAD* | Route availability document |
| 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 |
| RCAM* | Runway condition assessment matrix |
| RCC | Rescue co-ordination centre |
| RCF | Radiocommunication failure (message type designator) |
| RCH | Reach or reaching |
| RCL | Runway centre line |
| RCLL | Runway centre line light(s) |
| RCLR | Recleared |
| RCP | Required communication performance |
| RCR* | Runway condition report |
| RDH | Reference datum height (for ILS) |
| 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 |
| REJ* | Rejected |
| RENL | Runway end light(s) |
| REP | Report or reporting or reporting point |
| REQ | Request or requested |
| RERTE | Re-route |
| RESA | Runway end safety area |
| RETIL* | Rapid exit taxiway indicator lighting |
| RF | Constant radius arc to a fix |
| RFFS | Rescue and fire fighting services |
| RFP* | Replacement flight plan (related to ATFM) |
| RG | Range (lights) |
| RHC | Right-hand circuit |
| RIF | Reclearance in flight |
| RIME | Rime (used in aerodrome warnings) |
| RIS* | Radar information service |
| RL | Report leaving |
| RLA | Relay to |
| RLCE | Request level change en route |
| RLLS | Runway lead-in lighting system |
| RLNA | Request level not available |
| RMIB* | Royal meteorological institute of Belgium |
| RMK | Remark |
| RMZ* | Radio mandatory zone |
| 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 |
| RPA* | Remotely piloted aircraft |
| RPAS* | Remotely piloted aircraft system |
| RPDS | Reference path data selector |
| RPI | Radar position indicator |
| RPL | Repetitive flight plan |
| RPLC | Replace or replaced |
| RPS | Radar position symbol |
| RPT | Repeat / I repeat (to be used in AFS as a procedure signal) |
| RQ | Indication of a request (to be used in AFS as a procedure signal) |
| 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 (message type designator) |
| RSA* | Restricted airspace |
| RSC | Rescue sub-centre |
| RSCD | Runway surface condition |
| RSP | Responder beacon |
| RSP | Required surveillance performance |
| RSR | En-route surveillance radar |
| RSS | Root sum square |
| RT* | Right turn |
| RTD | Delayed (used to indicate delayed meteorological message; 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 | Radioteletypewriter |
| 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 |
| RWY | Runway |
| RWYCC* | Runway Condition Code |
| 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 |
| S | State of the sea (followed by figures in METAR/SPECI) |
| SA | Sand |
| SALS | Simple approach lighting system |
| SAM* | Slot allocation message |
| 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) |
| SATVOICE | Satellite voice communication |
| SB | Southbound |
| SBAS | Satellite-based augmentation system |
| SC | Stratocumulus |
| SCT | Scattered |
| SD | Standard deviation |
| SDBY | Stand by |
| SDF | Step down fix |
| 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 |
| SFO | Simulated flame out |
| SG | Snow grains |
| SGL | Signal |
| SH | Showers (followed by RA = rain, SN = snow, PL = ice pellets, GR = hail, GS = small hail and/or snow pellets or combinations thereof, e.g. SHRASN = showers of rain and snow) |
| SHF | Super high frequency (3 000 to 30 000 MHZ) |
| SI | International system of units |
| 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 |
| SIGWX* | Significant weather |
| SIMUL | Simultaneous or simultaneously |
| SITA* | Sociéte Internationale des Télécommunications Aéronautique |
| 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 | Indicator for the aerodrome being closed due to snow on the runway |
| 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 |
| SOF* | Supervisor of flights |
| SPECI | Aviation selected special weather report (in aeronautical meteorological code) |
| SPECIAL | Special meteorological report (in abbreviated plain language) |
| SPI | Special position indicator |
| 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 |
| STANAG* | Standardization agreement (NATO) |
| STAR | Standard instrument arrival |
| STD | Standard |
| STF | Stratiform |
| STN | Station |
| STNR | Stationary |
| STOL | Short take-off and landing |
| STS | Status |
| 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 |
| SWC-LL* | Significant weather chart - low level |
| SWX | Space weather |
| SWXC | Space weather centre |
| SWY | Stopway |
| SYNOP* | Synopsis |
| 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 | True (preceded by a bearing to indicate reference to True North) |
| T* | Metric tons |
| T-VASIS | T visual approach slope indicator system |
| TA | Traffic advisory |
| TA | Transition altitude |
| TA/H | Turn at an altitude/height |
| TAA | Terminal arrival altitude |
| TACAN | UHF tactical air navigation aid |
| TAF | Aerodrome forecast |
| TAIL | Tail wind |
| TAR | Terminal area surveillance radar |
| TAS | True airspeed |
| TAX | Taxiing or taxi |
| TC | Tropical cyclone |
| TCAC | Tropical cyclone advisory centre |
| TCAS RA | Traffic alert and collision avoidance system resolution advisory |
| TCH | Threshold crossing height |
| TCN* | Terminal change notice |
| TCU | Towering cumulus |
| TDO | Tornado |
| TDZ | Touchdown zone |
| TECR | Technical reason |
| TEL | Telephone |
| TEMPO | Temporary or temporarily |
| TF | Track to fix |
| TFC | Traffic |
| TGL | Touch-and-go landing |
| TGL* | Temporary Guidance Leaflet |
| 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 (followed by time by which weather change is forecast to end) |
| TLOF | Touchdown and lift-off area |
| TMA | Terminal control area |
| TMZ* | Transponder mandatory zone |
| TN | Indicator for minimum temperature (used in the TAF code form) |
| TNA | Turn altitude |
| TNC* | Terminal navigation charge |
| TNH | Turn height |
| TO | To . . . (place) |
| TOBT* | Target off block time |
| TOC | Top of climb |
| TODA | Take-off distance available |
| TODAH | Take-off distance available, helicopter |
| TOP | Cloud top |
| 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 (in aerodrome reports and forecasts, TS used alone means thunder heard but no precipitation at the aerodrome) |
| TS | Thunderstorm (followed by RA = rain, SN = snow, PL = ice pellets, GR = hail, GS = small hail and/or snow pellets or combinations thereof, e.g. TSRASN = thunderstorm with rain and snow) |
| TSA* | Temporary segregated area |
| TSAT* | Target start-up approval time |
| TSUNAMI | Tsunami (used in aerodrome warnings) |
| TT | Teletypewriter |
| TTOT* | Target take-off time |
| TUE | Tuesday |
| TURB | Turbulence |
| TVOR | Terminal VOR |
| TWR | Aerodrome control tower or aerodrome control |
| TWY | Taxiway |
| TX... | Maximum temperature (followed by figures in TAF) |
| TXL | Taxilane |
| 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 (tendency in RVR during previous 10 minutes) |
| U/S | Unserviceable |
| UA | Unmanned aircraft |
| UAB | Until advised by . . . |
| UAC | Upper area control centre |
| UAR | Upper air route |
| UAS | Unmanned aircraft system |
| UAT* | Universal access receiver |
| 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 (used in automated METAR/SPECI) |
| UPS* | Uninterrupted power supply |
| USAF* | United States Air Force |
| UTA | Upper control area |
| UTC | Coordinated Universal Time |
| UUP* | Updated Airspace Use Plan |
| UWT* | Upper winds and temperature |
| 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 | |
| V | Indicator for variations from the mean wind direction (used in the METAR/SPECI code forms) |
| VA | Heading to an altitude |
| VA | Volcanic ash |
| VAAC | Volcanic ash advisory centre |
| VAC | Visual approach chart (followed by name/title) |
| VAL | In valleys |
| VAN | Runway control van |
| VAR | Magnetic variation |
| VAR | Visual-aural radio range |
| VASIS | Visual approach slope indicator system |
| VAT* | Value-added tax |
| VC | Vicinity of the aerodrome (followed by FG = fog, FC = funnel clouds, SH = showers, PO = dust/sand whirls, BLDU = blowing dust, BLSA = blowing sand or BLSN = blowing snow, e.g. VC FG = vicinity fog) |
| VCY | Vicinity |
| VDF | Very high frequency direction-finding station |
| VDL* | Very high frequency data link |
| VDP* | Visual descent point |
| VER | Vertical |
| VFR | Visual flight rules |
| VHF | Very high frequency (30 to 300 MHZ) |
| VI | Heading to an intercept |
| VIP | Very important person |
| VIS | Visibility |
| VLA* | Very light aircraft |
| VLF | Very low frequency (3 to 30 KHZ) |
| VLOS* | Visual line of sight |
| VLR | Very long range |
| VM | Heading to a manual termination |
| VMC | Visual meteorological conditions |
| VNAV | 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 |
| VPT | Visual manoeuvre with prescribed track |
| VRB | Variable |
| VSA | By visual reference to the ground |
| VSP | Vertical speed |
| VSS* | Visual segment surface |
| VTF | Vector to final |
| VTOL | Vertical take-off and landing |
| VV | Vertical visibility (used in the METAR/SPECI and TAF code forms) |
| 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 |
| W | Indicator for sea-surface temperature (ued in the METAR/SPECI code forms) |
| WAAS | Wide area augmentation system |
| WAC | World Aeronautical Chart - ICAO 1:1 000 000 (followed by name/title) |
| 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 or wide |
| 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 |
| WPR* | Way-point reporting |
| WPT | Way-point |
| WRNG | Warning |
| WS | Wind shear |
| WSPD | Wind speed |
| WSW | West-south-west |
| WT | Weight |
| WTC* | Wake turbulence category |
| 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; to be used in AFS as a procedure signal) |
| 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 | Coordinated Universal Time (in meteorological messages) |