Abbreviations marked by an asterisk (*) are either different from or 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 GLOSSARY OF TERMS | |
| A | Amber |
| *A | Approach (Used to specify the purpose of a Radio Navigation Aid) |
| *A | FRA Arrival Connecting Point |
| AAA | Amended meteorological message |
| A/A | Air-to-air |
| 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 |
| *A-CDM | Airport Collaborative Decision Making |
| ACFT | Aircraft |
| ACK | Acknowledge |
| ACL | Altimeter check location |
| ACN | Aircraft Classification Number |
| ACP | Acceptance |
| 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 |
| ADIZ | Air defence identification zone |
| ADJ | Adjacent |
| *ADMIN | Administration |
| ADO | Aerodrome office |
| ADR | Advisory route |
| ADS | Automatic dependent surveillance |
| 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 dependant surveillance - broadcast |
| ADS-C | Automatic dependant 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 |
| AFM | Yes or affirm or affirmative or that is correct |
| AFS | Aeronautical fixed service |
| AFT | After… |
| AFTN | Aeronautical Fixed Telecommunication Network |
| A/G | Air-to ground |
| AGA | Aerodromes, air routes and ground aids |
| AGL | Above ground level |
| AGN | Again |
| *AGNIS | Azimuth Guidance for Nose-In Stand |
| AIC | Aeronautical Information Circular |
| AIDC | Air traffic services inter-facility data communication |
| 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 effect the safety of low-level aircraft operations |
| AIS | Aeronautical Information Services |
| ALA | Alighting area |
| ALERFA | Alert phase |
| ALR | Alerting |
| ALRS | Alerting service |
| ALS | Approach lighting system |
| ALT | Altitude |
| ALTN | Alternate or alternating |
| ALTN | Alternate |
| AMA | Area minimum altitude |
| AMD | Amend or amended |
| AMDT | Amendment |
| AMS | Aeronautical mobile service |
| AMSL | Above mean sea level |
| AMSS | Aeronautical mobile satellite service |
| ANC | Aeronautical Chart 1:500 000 |
| ANCS | Aeronautical Navigation Chart Small Scale |
| ANS | Answer |
| *ANSP | Aeronautical Navigation Service Provider |
| AO | Oceanic control area |
| AO | Aircraft Operator |
| AOC | Aerodrome obstacle chart |
| *AOC | Air Operator Certificate |
| *AOS | A-CDM portal |
| 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 Procedures with Vertical guidance |
| ARC | Area chart |
| ARNG | Arrange |
| ARO | Air traffic services reporting office |
| ARP | Aerodrome reference point |
| ARP | Air-report |
| ARQ | Automatic error correction |
| ARR | Arrive |
| ARR | Arrival |
| ARS | Special air-report |
| ARST | Arresting |
| AS | Altrostratus |
| *AS | Aerodrome Surface |
| ASAP | As soon as possible |
| ASC | Ascent to or ascending to |
| ASDA | Accelerate stop distance available |
| ASE | Altimetry system error |
| ASPEEDG | Airspeed gain |
| ASPEEDL | Airspeed loss |
| ASPH | Asphalt |
| AT… | At (followed by time at which weather change is forecast to occur) |
| ATA | Actual time of arrival |
| ATC | Air Traffic Control |
| ATD | Actual time of departure |
| ATFM | Air traffic flow management |
| ATIS | Automatic terminal information service |
| ATM | Air traffic management |
| *ATM | Automated Teller Machine or Automatic Teller Machine |
| ATN | Aeronautical telecommunication network |
| ATP | At… |
| ATS | Air traffic services |
| *ATSU | Air traffic service unit |
| ATTN | Attention |
| AT-VASIS | Abbreviated T visual approach slope indicator system |
| ATZ | Aerodrome traffic zone |
| AUG | August |
| AUTH | Authorized or authorization |
| AUTO | Automatic |
| AUW | All up weight |
| AUX | Auxiliary |
| AVBL | Available or availability |
| AVG | Average |
| *AVDGS | Advanced Visual Docking Guidance System |
| 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 GLOSSARY OF TERMS | |
| B | Blue |
| BA | Braking action |
| BASE | Cloud base |
| BCFG | Fog patches |
| BCN | Beacon |
| BCST | Broadcast |
| BDRY | Boundary |
| BECMG | Becoming |
| BFR | Before |
| BKN | Broken |
| BL | Blowing |
| BLDG | Building |
| BLO | Below clouds |
| BLW | Below… |
| BOMB | Bombing |
| BR | Mist |
| BRF | Short |
| BRG | Bearing |
| BRKG | Braking |
| BS | Commercial broadcasting station |
| BTL | Between layers |
| BTN | Between |
| 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 GLOSSARY OF TERMS | |
| C | Centre |
| C | Degrees Celsius |
| CAA | Civil Aviation Authority or Civil Aviation Administration |
| CAT | Category |
| CAT | Clear air turbulence |
| CAVOK | Visibility, cloud and present weather better than prescribed values or conditions |
| CB | Cumulonimbus |
| CC | Cirrocumulus |
| CCA | Corrected meteorological message |
| CCO | Continuous climb operation |
| CD | Candela |
| CDN | Co-ordination message |
| CDO | Continuous descent operation |
| CDR | Conditional route |
| *CET | Civil Evening Twilight |
| CF | Change frequency to… |
| CFM | Confirm or I confirm |
| CGL | Circling guidance light(s) |
| CH | Channel |
| CH | This is a channel – continuity - check of transmission to permit comparison of your record of channel sequence numbers of messages received on the channel |
| CHG | Modification message |
| 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 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 |
| *CMT | Civil Morning Twilight |
| CNL | Cancel or cancelled |
| CNL | Flight plan cancellation |
| CNS | Communications, navigation and surveillance |
| COM | Communications |
| CONC | Concrete |
| COND | Condition |
| CONS | Continuous |
| CONST | Construction or constructed |
| CONT | Continue(s) or continued |
| COOR | Coordinate, or co-ordination |
| COORD | Coordinates |
| COP | Change-over point |
| COR | Correct or corrected or correction |
| COT | At the coast |
| COV | Cover or covered or covering |
| CPDLC | Controller – pilot data link communications |
| CPL | Current flight plan message |
| CRC | Cyclic redundancy check |
| CRM | Collision risk model |
| CRP | Compulsory reporting point |
| CRZ | Cruise |
| CS | Cirrostratus |
| CS | Call sign |
| CTA | Control area |
| CTA | *Common Travel 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 GLOSSARY OF TERMS | |
| D | Downward |
| D | Danger area |
| *D | FRA Departure Connecting Point |
| DA | Decision altitude |
| D - ATIS | Data link automatic terminal information service |
| DCD | Double channel duplex |
| DCKG | Docking |
| *DCL | Digital Clearance |
| DCP | Datum crossing point |
| DCPC | Direct controller-pilot communications |
| DCS | Double channel simplex |
| DCT | Direct |
| DE | From |
| DEC | December |
| DEG | Degrees |
| DEP | Depart or departure or departure message |
| DES | Descend to or descending to |
| DEST | Destination |
| DETRESFA | Distress phase |
| DEV | Deviation or deviating |
| DFDR | Digital flight data recorder |
| DFTI | Distance from touch down indicator |
| DH | Decision height |
| DIF | Diffuse |
| DIST | Distance |
| DIV | Divert or diverting |
| DLA | Delay or delayed |
| DLA | Delay |
| DLIC | Data link initiation capability |
| DLY | Daily |
| DME | Distance measuring equipment |
| DNG | Danger or dangerous |
| DOF | Date of flight |
| *DOC | ICAO Document |
| *DOC | Designated Operational Coverage |
| DOM | Domestic |
| DP | Dew point temperature |
| DPT | Depth |
| DR | Dead reckoning |
| DR | Low drifting |
| DRG | During |
| DS | Dust storm |
| 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 |
| DUR | Duration |
| D–VOLMET | Data link VOLMET |
| 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 GLOSSARY OF TERMS | |
| E | East or Eastern longitude |
| *E | Enroute (Used to specify the purpose of a Radio Navigation Aid) |
| *E | FRA Horizontal Entry Point |
| *e.g. | Eempli Gratia |
| *EAD | European AIS Database |
| *EASA | European Aviation Safety Agency |
| EAT | Expected approach time |
| EB | Eastbound |
| *EC | European Community |
| EDA | Elevation differential area |
| EDTO | Extended diversion time operations |
| *EEA | European Economic Area |
| *EEC | European Economic Community |
| EEE | Error |
| EET | Estimated elapsed time |
| EFC | Expect further clearance |
| EGNOS | European geostationary navigation overlay service |
| EHF | Extremely high frequency |
| ELBA | Emergency location beacon-aircraft |
| ELEV | Elevation |
| ELR | Extra long range |
| ELT | Emergency locator transmitter |
| EM | Emission |
| Electronic Mail | |
| EMBD | Embedded in a layer |
| EMERG | Emergency |
| *En | English Language |
| END | Stop-end |
| ENE | East-north-east |
| ENG | Engine |
| ENR | En route |
| ENRC | Enroute chart |
| EOBT | Estimated off-block time |
| EQPT | Equipment |
| ESE | East-south-east |
| EST | Estimate or estimated or estimate |
| 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 |
| *EU | European Union |
| *EUR | Europe |
| EV | Every |
| EXC | Except |
| EXER | Exercise or exercising or to exercise |
| EXP | Expected or expending |
| 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 GLOSSARY OF TERMS | |
| F | Fixed |
| *FAA | Federal Aviation Administration |
| 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 |
| *FBZ | Flight Plan Buffer Zone |
| FC | Funnel cloud |
| FCST | Forecast |
| FCT | Friction coefficient |
| FDPS | Flight data processing system |
| *FDR | Flight Data Recorder |
| 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 |
| FM…. | From (followed by time weather change is forecast to begin) |
| FMS | Flight management system |
| FMU | Flow management unit |
| FNA | Final approach |
| FPAP | Flight pass alignment point |
| FPL | Flight plan |
| FPM | Feet per minute |
| FPR | Flight plan route |
| FR | Fuel remaining |
| *FRA | Free Route Airspace |
| FREQ | Frequency |
| FRI | Friday |
| FRNG | Firing |
| FRONT | Front |
| FRQ | Frequent |
| FSL | Full stop landing |
| *FSR | Fuel Saving Route |
| FSS | Flight service station |
| FST | First |
| ft | Feet |
| 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 GLOSSARY OF TERMS | |
| G | Green |
| G | Variations from the mean wind speed |
| GA | Go ahead, resume sending |
| GA | General Aviation |
| *GAT | General Air Traffic |
| G/A | Ground to air |
| G/A/G | Ground to air and air to ground |
| GAGAN | GPS and geostationary earth orbit augmented navigation |
| GARP | GBAS azimuth referencia point |
| GAMET | Area forecast for low-level flights |
| GBAS | Ground-based augmentation system |
| GCA | Ground control approach system or ground control approach |
| 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 |
| GOC | General Officer Commanding |
| GP | Glide path |
| *GP | General Purpose |
| 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 |
| GRVL | Gravel |
| GS | Ground speed |
| GS | Small hail and/or snow pellets |
| 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 GLOSSARY OF TERMS | |
| 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 | Handling agent |
| HAPI | Helicopter approach path indicator |
| HCH | Heliport crossing height |
| HBN | Hazard beacon |
| HDF | High frequency direction finding station |
| HDG | Heading |
| HEL | Helicopter |
| HF | High frequency |
| HGT | Height or height above |
| *HLA | High Level Airspace |
| HJ | Sunrise to sunset |
| HLDG | Holding |
| HLS | Helicopter landing site |
| HM | Holding/Racetrack to a manual termination |
| *HMU | Height Monitoring Units |
| HN | Sunset to sunrise |
| HO | Service available to meet operational requirements |
| HOL | Holiday |
| HOSP | Hospital aircraft |
| HPA | Hectopascal |
| HLP | Heliport |
| HR | Hours |
| HRP | Heliport reference point |
| HS | Service available during hours of scheduled operations |
| HUM | Humanitarian |
| HURCN | Hurricane |
| HVDF | High and very high frequency direction finding stations |
| HVY | Heavy |
| HX | No specific working hours |
| HYR | Higher |
| HZ | Haze |
| Hz | Hertz |
| 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 GLOSSARY OF TERMS | |
| *I | FRA Intermediate Point |
| *i.e. | id est (that is) |
| *IAA | Irish Aviation Authority |
| IAC | Instrument approach chart |
| IAF | Initial approach fix |
| *IAIP | Integrated Aeronautical Information Package |
| *IAMSAR | International Aeronautical and Maritime Search and Rescue |
| 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 identify |
| IDENT | Identification |
| *IDF | Initial departure fix |
| IF | Intermediate approach fix |
| IFF | Identification friend/foe |
| *IFPS | Integrated Initial Flight Plan Processing System |
| IFR | Instrument flight rules |
| IGA | International general aviation |
| ILS | Instrument landing system |
| IM | Inner marker |
| IMC | Instrument meteorological conditions |
| IMG | Immigration |
| IMI | Interrogation sign |
| IMPR | Improve or improving |
| IMT | Immediate or immediately |
| INA | Initial approach |
| INBD | Inbound |
| INC | In cloud |
| INCORP | Incorporated |
| INCERFA | Uncertainty phase |
| *incl | Inclusive |
| IRS | Inertial Reference System |
| 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 |
| *IRs | Implementing Rules |
| 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 GLOSSARY OF TERMS | |
| JAN | January |
| *JAR | Joint Aviation Requirement |
| 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 GLOSSARY OF TERMS | |
| kg | Kilogrammes |
| kHz | Kilohertz |
| km | Kilometres |
| km/h | Kilometres/hour |
| kPa | Kilo pascal |
| kts | 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 GLOSSARY OF TERMS | |
| L | Left |
| L | Locator |
| L | Low pressure area or the centre of low pressure |
| L | Litre |
| LAM | Logical acknowledgement |
| LAN | Inland |
| LAT | Latitude |
| LCA | Local or Locally or location or located |
| LDA | Landing distance available |
| LDAH | Landing distance available, helicopter |
| LDG | Landing |
| LDI | Landing direction indicator |
| LEN | Length |
| LF | Low frequency |
| LGT | Light or lighting |
| LGTD | Lighted |
| LIH | Light intensity high |
| LIL | Light intensity low |
| LIM | Light intensity medium |
| *LLZ | Localizer |
| LM | Locator, middle |
| *LNAV | Lateral Navigation |
| LMT | Local Mean Time |
| LNG | Long |
| LO | Locator outer |
| LOC | Localizer |
| *LOM | Locator Outer Marker |
| LONG | Longitude |
| LORAN | LORAN (Long Range Navigation Systems) |
| *LPV | Localizer performance with vertical guidance. |
| LR | The last message received by me was …. |
| LRG | Long range |
| LS | The last message sent by me was …. |
| LTA | Lower control area |
| LTD | Limited |
| LTP | Landing threshold point |
| LV | Light and variable |
| 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 GLOSSARY OF TERMS | |
| M | Mach number |
| M | Metres |
| M | Minimum values of runway visual range |
| MAA | Maximum authorized altitude |
| MAG | Magnetic |
| MAINT | Maintenance |
| MAP | Aeronautical maps and charts |
| MAPT | Missed approach point |
| MAR | March |
| MAR | At sea |
| *MASPS | Minimum Aviation System Performance Standards |
| MATF | Missed approach turning fix |
| MATZ | Military aerodrome traffic zone |
| MAX | Maximum |
| MAY | May |
| MBST | Microburst |
| MCA | Minimum crossing altitude |
| MCTR | Military control zone |
| *MCH | Minimum crossing height |
| 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 |
| MET | Meteorological or meteorology |
| METAR | Aviation routine weather report |
| METREPORT | Local routine meteorological report |
| MF | Medium frequency |
| MHA | Minimum holding altitude |
| MHDF | Medium and high frequency direction- finding stations |
| MHVDF | Medium, high and very high frequency direction-finding stations |
| MHz | Megahertz |
| MID | Mid-point |
| MIFG | Shallow fog |
| MIL | Military |
| MIN | Minutes |
| 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 |
| MOD | Moderate |
| MON | Above mountains |
| MON | Monday |
| MOPS | Minimum operational performance standards |
| MOTNE | Meteorological Operational Telecommunications Network Europe |
| MOV | Move or moving or movement |
| MPS | Metres per second |
| MRA | Minimum reception altitude |
| MRG | Medium range |
| MRP | ATS per 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 … |
| 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 position) |
| MWO | Meteorological watch office |
| MX | Mixed type of ice formation |
| 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 GLOSSARY OF TERMS | |
| N | North or Northern latitude |
| N | No distinct tendency |
| 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 |
| *NMOC | Coordination with the network manager |
| NNE | North - north-east |
| NNW | North - north-west |
| NO | No |
| NOF | International NOTAM office |
| NONSTD | Non-standard |
| *Nom | Nominal |
| NOSIG | No significant change |
| *NOTA | Northern Oceanic Transition Area |
| 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 |
| *NPZ | No planning 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 GLOSSARY OF TERMS | |
| 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 |
| OCH | Obstacle clearance height |
| *OCL | Oceanic Clearance Link |
| 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 | 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 |
| O/R | On request |
| ORD | Indication of an order |
| *ORM | Operational reply message |
| *OSI | Ordnance Survey Ireland |
| OSV | Ocean station vessel |
| OTLK | Outlook |
| 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 GLOSSARY OF TERMS | |
| P | Maximum values of runway visual range |
| P | Prohibited area |
| PA | Precision approach |
| PALS | Precision approach lighting system |
| PANS | Procedures for air navigation services |
| PAPI | Precision approach path indicator |
| PAR | Precision approach radar |
| PARL | Parallel |
| PATC | Precision approach terrain chart |
| PAX | Passenger(s) |
| PBC | Performance-based communications |
| PBN | Performance-based navigation |
| PBS | Performance-based surveillance |
| PCD | Proceed or proceeding |
| PCL | Pilot controlled lighting |
| PCN | Pavement classification number |
| PCT | Per cent |
| PDC | Predeparture clearance |
| PDG | Procedure design gradient |
| *PDS | Pre-departure sequencer |
| PER | Performance |
| PERM | Permanent |
| PIB | Preflight 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 (dust devils) |
| 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 GLOSSARY OF TERMS | |
| QDL | Do you intend to ask me for a series of bearings? or I intend to ask 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 |
| 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 |
| QUAD | Quadrant |
| QUJ | Will you indicate the TRUE track to reach you or The TRUE track to reach me is … 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 GLOSSARY OF TERMS | |
| R | Right |
| R | Red |
| R | Runway (followed by figures in METAR/SPECI) |
| R | Received |
| R | Restricted area |
| R | Radial from VOR (followed by three figures) |
| RA | Rain |
| RAC | Rules of the air and air traffic services |
| RAG | Ragged |
| 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 co-ordination centre |
| RCF | Radio communication failure message |
| RCH | Reach or reaching |
| RCL | Runway centre line |
| *RCL | A Voice, or Data Link message via ACARS, used to provide ETA at Oceanic Entry Point (OEP), requested flight level, and Mach |
| RCLL | Runway centre line light(s) |
| RCLR | Re cleared |
| RCP | Required Communication Performance |
| RDOACT | Radioactive |
| *RDARA | Regional and Domestic Air Route Area |
| RDH | Reference datum height |
| RDL | Radial |
| RDO | Radio |
| RE | Recent |
| 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 | RWY end safety area |
| *RET | Rapid Exit Taxiway |
| RF | Constant radius arc to fix |
| RFFS | Rescue and Fire Fighting Services |
| *RFL | Requested Flight Level |
| RG | Range |
| RHC | Right-hand circuit |
| RIF | Re clearance on flight |
| RIME | Rime (used in aerodrome warnings) |
| RL | Report leaving |
| RLA | Relay to |
| RLCE | Request level change enroute |
| RLLS | Runway lead-in lighting system |
| RLNA | Request level not available |
| *RMA | Regional Monitoring Agency |
| RMAC | Radar minimum altitude chart |
| RMK | Remark |
| *RMZ | Radio Mandatory Zone |
| RNAV | Area navigation |
| RNG | Radio range |
| RNP | Required navigation performance |
| ROBEX | Regional OPMET bulletin exchange |
| ROC | Rate of climb |
| ROD | Rate of descent |
| ROFOR | Route forecast |
| RON | Receiving only |
| *RPAS | Remotely Piloted Aircraft Systems |
| RPI | Radar position indicator |
| RPL | Repetitive flight plan |
| RPLC | Replace or replaced |
| RPS | Radar position symbol |
| RPT | Repeat or I repeat |
| RQ | Request |
| RQMNTS | Requirements |
| RQP | Request flight plan |
| RQS | Request supplementary flight plan |
| RR | Report reaching |
| RRA | Delayed meteorological message |
| RSC | Rescue sub-centre |
| RSCD | Runway surface condition |
| RSP | Required surveillance performance |
| RSP | Responder beacon |
| RSR | En-route surveillance radar |
| RTD | Delayed |
| RTE | Route |
| RTF | Radio telephone |
| RTG | Radio telegraph |
| RTHL | Runway threshold light(s) |
| *RTILS | Runway Threshold Identification Light system |
| 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 Minima |
| 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 GLOSSARY OF TERMS | |
| S | State of the sea |
| S | South or Southern latitude |
| *S.I. | Statutory Instrument |
| SA | Sand |
| SAD | *Single Administrative Document |
| SALS | Simple approach lighting system |
| SAN | Sanitary |
| SAR | Search and rescue |
| SARPS | Standards and recommended practices |
| 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 |
| SDBY | Stand by |
| SE | South-east |
| SEA | Sea |
| SEB | South-eastbound |
| SEC | Seconds |
| SECN | Section |
| SECT | Sector |
| SELCAL | Selective calling system |
| SEP | September |
| SER | Service or servicing or served |
| SEV | Severe |
| SFC | Surface |
| SG | Snow grains |
| SGL | Signal |
| SH | Showers |
| SHF | Super high frequency |
| *SIB | Safety Information Bulletin |
| SID | Standard instrument departure |
| SIF | Selective identification feature |
| SIG | Significant |
| SIGMET | Information concerning en-route weather and other phenomena in the atmosphere that may effect the safety of aircraft operations |
| SIMUL | Simultaneous or simultaneously |
| SIWL | Single isolated wheel load |
| SKC | Sky clear |
| SKED | Schedule or scheduled |
| *SLOP | Strategic Lateral Offset Procedure |
| SLP | Speed limiting point |
| SLW | Slow |
| SMC | Surface movement control |
| SMR | Surface movement radar |
| *SMS | Safety Management System |
| 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 pro format. |
| *SOBT | Scheduled off block time |
| *SOTA | Shannon Oceanic Transition Area |
| SPECI | Aviation selected special weather report |
| SPECIAL | Special meteorological report |
| SPL | Supplementary flight plan message |
| SPOC | SAR point of contact |
| SPOT | Spot wind |
| SQ | Squall |
| SQL | Squall line |
| SR | Sunrise |
| SRA | Surveillance radar approach |
| *SRA | State Regulatory Authority |
| SRE | Surveillance radar element of precision approach radar system |
| SRG | Short range |
| *SRH | Surveillance Radar |
| 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 | Status |
| STWL | Stopway light(s) |
| *SUA | Small unmanned aircraft |
| *SUA | Special Use Airspace |
| SUBJ | Subject to |
| SUN | Sunday |
| SUP | 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 GLOSSARY OF TERMS | |
| T | Temperature |
| T | True |
| *T | Terminal (Used to specify the purpose of a Designated Point) |
| TA | Transition altitude |
| 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 |
| TCAS | Traffic Collision Avoidance System |
| TCU | Towering cumulus |
| TDO | Tornado |
| TDZ | Touchdown zone |
| TECR | Technical reason |
| TEL | Telephone |
| TEMPO | Temporary or temporarily |
| TEND | Trend forecast |
| 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… |
| TKOF | Take-off |
| TL | Till |
| TLOF | Touchdown and lift-off area |
| TMA | Terminal control area |
| *TMZ | Transponder Mandatory Zone |
| TN | Minimum temperature |
| TNA | Turn altitude |
| TNH | Turn Height |
| TO | To… |
| *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 |
| TP | Turning point |
| TR | Track |
| TRA | Temporary reserved airspace |
| TRANS | Transmits or transmitter |
| TREND | Trend forecast |
| TRL | Transition level |
| TRG | Training |
| *TRP | Tug Release Point |
| TROP | Tropopauza |
| TS | Thunderstorm |
| *TSAT | Target start up approval time |
| TT | Teletypewriter |
| TUE | Tuesday |
| TURB | Turbulence |
| T-VASIS | T visual approach slope indicator system |
| 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/ |
| 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 GLOSSARY OF TERMS | |
| U | Upward |
| UA | Unmanned aircraft |
| UAB | Until advised by… |
| UAC | Upper area control centre |
| UAR | Upper air route |
| UDF | Ultra high frequency direction-finding station |
| UFN | Until further notice |
| UHDT | Unable higher due traffic |
| UHF | Ultra high frequency |
| UIC | Upper Information Centre |
| UIR | Upper Flight Information Region |
| ULM | Ultra light motorized aircraft |
| UK | *United Kingdom |
| ULR | Ultra long range |
| UNA | Unable |
| UNAP | Unable to approve |
| UNL | Unlimited |
| UNREL | Unreliable |
| UP | Unidentified precipitation |
| U/S | Unserviceable |
| 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 GLOSSARY OF TERMS | |
| V | Variations from the mean wind direction |
| VA | Volcanic ash |
| VAC | Visual approach chart |
| *VACP | Volcanic Ash Contingency Plan |
| VAL | In valleys |
| VAN | Runway control van |
| VAR | Magnetic variation |
| VAR | Visual-aural radio range |
| VASIS | Visual approach slope indicator systems |
| VAT | *Value Added Tax |
| VC | Vicinity of the aerodrome |
| VCY | Vicinity |
| VDF | Very high frequency direction finding station |
| VER | Vertical |
| VFR | Visual flight rules |
| VHF | Very high frequency |
| VIP | Very important person |
| VIS | Visibility |
| VLF | Very low frequency |
| VLR | Very long range |
| *VMA | Visual manoeuvring (circling) area. The area in which obstacle clearance should be taken into consideration for aircraft carrying out a circling approach. |
| VMC | Visual meteorological conditions |
| VNAV | (to be pronounced VEE-NAV) Vertical Navigation |
| VOL | Volmet (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 |
| VTOL | Vertical take-off and landing |
| VV | Vertical visibility |
| 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 GLOSSARY OF TERMS | |
| W | Sea-surface temperature |
| 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 |
| WINTEM | Forecast upper wind and temperature for aviation |
| 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 | World wide 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 GLOSSARY OF TERMS | |
| *X | FRA Horizontal Exit Point |
| X | Cross |
| XBAR | Crossbar |
| 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 GLOSSARY OF TERMS | |
| Y | Yellow |
| YCZ | Yellow caution zone |
| YES | Yes |
| 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 GLOSSARY OF TERMS | |
| Z | Co-ordinated Universal Time |