Notes:
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 | |
| A | Amber |
| AAA | (or AAB, AAC...etc., in sequence) Amended meteorological message (message type designator) |
| A/A | Air-to-air |
| AAD | Assigned altitude deviation |
| AAIM | Aircraft autonomous integrity monitoring |
| AAL | Above aerodrome level |
| ABI | Advance boundary information |
| ABM | Abeam |
| ABN | Aerodrome beacon |
| ABT | About |
| ABV | Above |
| AC | Altocumulus |
| ACARS | (to be pronounced "AY-CARS") 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 |
| 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 | (to be pronounced "AY-DIZ") Air Defence Identification Zone |
| ADJ | Adjacent |
| ADO | Aerodrome office (specify service) |
| 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 |
| AFS | Aeronautical fixed service |
| AFT... | After...(time or place) |
| AFTN | Aeronautical Fixed Telecommunication Network |
| A/G | Air-to-ground |
| AGA | Aerodrome, air routes and ground aids |
| AGL | Above ground level |
| AGN | Again |
| AIC | Aeronautical information circular |
| AIDC | Air traffic services inter-facility data communication |
| AIM* | ATFM Information Message |
| 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 (used to indicate amended meteorological message; message type designator) |
| AMDT | Amendment (AIP amendment) |
| AMS | Aeronautical mobile service |
| AMSL | Above mean sea level |
| AMSS | Aerodrome mobile satellite service |
| ANC... | Aeronautical chart - 1:500 000 (followed by name/title) |
| ANCS... | Aeronautical navigation chart - small scale (followed by name/title and scale) |
| ANS | Answer |
| AOC... | Aerodrome obstacle chart (followed by type and name/title) |
| AP | Airport |
| APAPI | (to be pronounced "AY-PAPI") Abbreviated precision approach path indicator |
| APCH | Approach |
| APDC... | Aircraft parking/docking chart (followed by name/title) |
| APN | Apron |
| APP | Approach control office or approach control or approach control service |
| APR | April |
| APRX | Approximate or approximately |
| APSG | After passing |
| APV | Approve or approved or approval |
| ARC | Area chart |
| ARCC* | Aviation rescue co-ordination centre |
| 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 | Arrive or arrival |
| ARR | Arrival (message type designator) |
| ARS | Special air-report (message type designator) |
| ARST | Arresting (specify (part of) aircraft arresting equipment) |
| AS | Altostratus |
| 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 (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 |
| AT-VASIS | (to be pronounced "AY-TEE-VASIS") Abbreviated T visual approach slope indicator system |
| ATZ | Aerodrome Traffic Zone |
| AUG | August |
| AUTH | Authorized or authorization |
| AUW | All up weight |
| AUX | Auxiliary |
| AVBL | Available or availability |
| AVG | Average |
| AVGAS | Aviation Gasoline |
| 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 |
| 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 |
| 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 (preceded by runway designation number to identify a parallel runway) |
| C | Degrees celsius (Centigrade) |
| CA | Course to an altitude |
| CAT | Category |
| CAA* | Civil Aviation Agency |
| CAT | Clear air turbulence |
| CAVOK | (to be pronounced "KAV-OH-KAY") visibility, cloud and present weather better than prescribed values or conditions |
| CB | (to be pronounced "CEE BEE") Cumulonimbus |
| CC | Cirrocumulus |
| CCA | (or CCB, CCC....etc.. in sequence) corrected meteorological message (message type designator) |
| CD | Candela |
| CDN | Co-ordination (message type designator) |
| CF | Change frequency to ... |
| CF | Course to a fix |
| CGL | Circling guidance light(s) |
| CH | Channel |
| CHG | Modification (message type designator) |
| CI | Cirrus |
| CIDIN | Common ICAO data interchange network |
| CIT | Near or over large towns |
| 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 (used in METAR/SPECI) |
| CLSD | Close or closed or complete |
| CM | Centimetre |
| CMB | Climb to or climbing to |
| CMPL | Completion or completed or complete |
| CNL | Cancel or cancelled |
| CNL | Flight plan cancellation message (message type designator) |
| CNS | Communication, navigation and surveillance |
| COM | Communications |
| CONC | Concrete |
| COND | Condition |
| CONS | Continuous |
| CONST | Construction or constructed |
| CONT | Continue 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) |
| CRC | Ciclic redundancy check |
| CRZ | Cruise |
| CS | Call sign |
| 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 | Downward (tendency in RVR during previous 10 minutes) |
| DA | Decision altitude |
| D-ATIS | (to be pronounced "DEE-ATIS") Data link automatic terminal information service |
| 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) |
| DEC | December |
| DECCA* | Navigation system |
| DEG | Degrees |
| DEP | Depart or departure |
| DEP | Departure (message type designator) |
| DER | Departure end of the runway |
| DES | Descend to or descending to |
| DEST | Destination |
| DETRESFA | Distress Phase |
| DEV | Deviation or deviating |
| DF* | Direct to a fix |
| DFDR | Digital flight data recorder |
| DFTI | Distances from touch down indicator |
| DH | Decision height |
| DIF | Diffuse |
| DIST | Distance |
| DIV | Divert or diverting |
| DLA | Delay (message type designator) |
| DLA | Delay or delayed |
| DLIC | Data link initiation capability |
| DLY | Daily |
| DME | Distance Measuring Equipment |
| DNG | Danger or dangerous |
| DOM | Domestic |
| DP | Dew point temperature |
| 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 |
| 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 | |
| E | East or eastern longitude |
| EAT | Expected approach time |
| EB | Eastbound |
| EDA | Elevation differential area |
| EET | Estimated elapsed time |
| EFC | Expect further clearance |
| EGNOS | (to be pronounced "EGG-NOS") 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 location 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... | Enroute chart (followed by name/time) |
| EOBT | Estimated Off-Block Time |
| EQPT | Equipment |
| ESE | East south east |
| EST | Estimate or Estimated or Estimate (as message type designator) |
| ETA | Estimated Time of Arrival or Estimating Arrival |
| ETD | Estimated Time of Departure or Estimating Departure |
| ETO | Estimated time over significant point |
| EV | Every |
| EXC | Except |
| EXER | Exercises or exercising or to exercise |
| EXP | Expect or expected or expecting |
| EXTD | Extend or extending |
| 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, e.g. FBL RA = light rain) |
| 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 |
| FIZ* | Flight information zone |
| 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 | Flow Management System |
| FMU | Flow Management Unit |
| FNA | Final approach |
| FPAP | Flight path alignment point |
| FPL | Filed Flight Plan (message type designator) |
| FPM | Feet per minute |
| FPR | Flight plan route |
| FR | Fuel remaining |
| FRA* | Free Route Airspace |
| FRASC* | Free Route Airspace South Caucasus |
| FREQ | Frequency |
| FRI | Friday |
| FRNG | Firing |
| FRONT | Front (relating to weather) |
| FRQ | Frequent |
| FSL | Full stop landing |
| FSS | Flight service |
| 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... | Variations from the mean wind speed (gusts) (followed by figures in METAR/SPECI and TAF) |
| GA | Go ahead, resume sending (to be used in AFS as a procedure signal) |
| G/A | Ground-to-air |
| G/A/G | Ground-to-air and air-to-ground |
| GAGAN | GPS and geostationary earth orbit augmented navigation |
| GAMET | Area forecast for low-level flights |
| GARP | GBAS azimuth reference point |
| GAT* | General Air Traffic |
| GBAS | (to be pronounced "GEE-BAS") Ground-based augmentation system |
| GCA | Ground controlled approach system or ground controlled approach |
| GEN | General |
| GEO | Geographic or true |
| GES | Ground earth station |
| GLD | Glider |
| GLONASS | (to be pronounced "GLO-NAS") Global orbiting navigation satellite system |
| GMC... | Ground movement chart (followed by name/title) |
| GND | Ground |
| GNDCK | Ground check |
| GNSS | Global navigation satellite system |
| GP | Glide path |
| GPS | Global Positioning System |
| GR | Hail |
| GRAS | (to be pronounced "GRASS") Ground-based regional augmentation system |
| GRASS | Grass landing area |
| GRIB | Processed meteorological data in the form of grid point values (aeronautical meteorological code) |
| 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 | |
| H | High pressure area or the centre of high pressure |
| H24 | Continuous Day and Night Service |
| HAPI | Helicopter approach path indicator |
| HBN | Hazard beacon |
| HDF | High frequency direction-finding station |
| HDG | Heading |
| HEL | Helicopter |
| HF | High Frequency (3 000 to 30 000 kHz) |
| HGT | Height or height above |
| HIALS* | High-intensity approach lighting system |
| HJ | Sunrise to sunset |
| HLDG | Holding |
| HN | Sunset to sunrise |
| HO | Service available to meet operational requirements |
| HOL | Holiday |
| HOSP | Hospital aircraft |
| HPA | Hectopascal |
| HR | Hours |
| HS | Service Available During Hours of Scheduled Operations |
| 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 (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 |
| IATA* | International Aviation Transport Association |
| IBN | Identification Beacon |
| IC | Diamond dust (very small ice crystals in suspension, also known as diamond dust) |
| ICARD* | ICAO Codes And Routes Designator |
| ICAO* | International Civil Aviation Organization |
| ICE | Icing |
| ID | Identifier or identify |
| 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 |
| 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 |
| 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 |
| 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 | Locator (see LM, LO) |
| L | Low pressure area or the centre of low pressure |
| 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 | Long Range Air Navigation System |
| LR | The last message received by me was...(to be used in AFS as procedure signal) |
| LRG | Long range |
| LS | The last message sent by me was... or Last message was...(to be used in AFS as procedure signal) |
| LT* | Local Time |
| LTD | Limited |
| LTP | Landing threshold point |
| LTT | Landline teletypewriter |
| 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) |
| M... | Minimum value of runway range (followed by figures in METAR/SPECI) |
| MAA | Maximum authorized altitude |
| MAG | Magnetic |
| MAINT | Maintenance |
| MAP | Aeronautical maps and charts |
| MAPT | Missed approach point |
| MAR | March |
| MAR | At sea |
| MAS | Manual A1 simplex |
| MAX | Maximum |
| MAY | May |
| MBST | Microburst |
| MCA | Minimum crossing altitude |
| MCW | Modulated continuous wave |
| MDA | Minimum descent altitude |
| MDF | Medium frequency direction-finding station |
| MDH | Minimum descent height |
| MEA | Minimum en-route altitude |
| MEHT | Minimum eye height over threshold (for visual approach slope indicator system) |
| MET | Meteorological or meteorology |
| METAR | Aviation routine weather report (in aeronautical meteorological code) |
| MF | Medium frequency (300 kHz to 3 000 kHz) |
| MHDF | Medium and high frequency direction-finding station (at the same location) |
| MHVDF | Medium, high and very high frequency direction-finding station (at the same location) |
| MHZ | Megahertz |
| MID | Mid-point (related to RVR) |
| MIFG | Shallow fog |
| MIL | Military |
| MIN | Minutes |
| MIS | Missing... (transmission identification) (to be used in AFS as a procedure signal) |
| 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 reports e.g. MOD RA = Moderate Rain) |
| MON | Monday |
| MON | Above mountains |
| 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 |
| MRCC* | Maritime Rescue Coordination Center |
| MRG | Medium range |
| MRP | ATS/MET reporting point |
| MS | Minus |
| MSA | Minimum Sector Altitude |
| MSAS | (to be pronounced "EM-SAS") Multifunctional transport satellite (MTSAT) satellite-based augmentation system |
| MSAW | Minimum safe altitude warning |
| MSG | Message |
| MSL | Mean sea level |
| MSSR | Monopulse Secondary Surveillance Radar |
| MT | Mountain |
| MTOW* | Maximum Take-off Weight |
| MTU | Metric units |
| MTW | Mountain waves |
| MVDF | Medium and very high frequency direction-finding station (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 |
| N | No distinct tendency (in RVR during previous 10 minutes) |
| NASC | National AIS system centre |
| NAT | North atlantic |
| NAV | Navigation |
| NB | North bound |
| 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 |
| NM | Nautical Miles |
| NML | Normal |
| NNE | North north east |
| NNW | North north west |
| NO | No (negative) (to be used in AFS as a procedure signal) |
| NOF | International NOTAM office |
| NOSIG | No Significant Change (used in trend-type landing forecasts) |
| NOTAM | A notice 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 |
| 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 | |
| OAC | Oceanic area control centre |
| OAS | Obstacle assessment surface |
| OBS | Observe or observed or observation |
| OBSC | Observe 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 |
| OLDI | On-line data interchange |
| OM | Out 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 |
| O/R | On request |
| ORD | Indication of an order |
| OSV | Ocean station vessel |
| OTLK | Outlook (used in SIGMET message for volcanic ash and tropical cyclones) |
| OTP | On top |
| OTS | Organized track system |
| OUBD | Out-bound |
| 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 ... | Prohibited area (followed by identification) |
| P... | Maximum value of wind speed or runway visual range (followed by figures in METAR/SPECI and TAF) |
| 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) |
| PCD | Proceed or proceeding |
| PCL | Pilot-controlled lighting |
| PCN | Pavement Classification Number |
| PDC | Pre-departure clearance |
| PDG | Procedure design gradient |
| PER | Performance |
| PERM | Permanent |
| PIB* | Pre-flight Information Bulletin |
| PJE | Parachute jumping exercise |
| PL | Ice pellets |
| PLA | Practice low approach |
| PLN | Flight plan |
| PLVL | Present level |
| PN | Prior notice required |
| PNR | Point of no return |
| PO | 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 |
| 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 | |
| QBI* | Compulsory IFR flight |
| QDL | Do you intend to ask me for series of bearings? or I intend to ask you for 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 |
| 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 (preceded by runway designation number to identify a parallel runway) |
| R | Red |
| R ... | Restricted area (followed by identification) |
| R... | Runway visual range (followed by figures in METAR/SPECI) |
| RA | Rain |
| RAC | Rules or the air and air traffic services |
| RAFC* | Regional area forecast centre |
| 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 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 |
| RDH | Reference datum height (for ILS) |
| RDL | Radial |
| RDO | Radio |
| 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 | Re-route |
| RESA | Runway end safety area |
| RG | Range (lights) |
| RHC | Right-hand circuit |
| RIF | Reclearance in flight |
| RITE | Right (direction of turn) |
| RL | Report leaving |
| RLA | Relay to |
| RLCE | Request level change en-route |
| RLLS | Runway lead-in lighting system |
| RLNA | Requested level not available |
| RMAC | Radar minimum altitude chart |
| RMK | Remark |
| RNAV | (to be pronounced "AR-NAV") Area Navigation |
| RNG | Radio range |
| RNP | Required Navigation Performance |
| ROBEX | Regional OPMET bulletin exchange(scheme) |
| ROC | Rate of climb |
| ROD | Rate of descent |
| ROFOR | Route forecast (in aeronautical meteorological code) |
| RON | Receiving only |
| RPI | Radar position indicator |
| RPL | Repetitive Flight Plan |
| RPLC | Replace or replaced |
| RPS | Radar position symbol |
| 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) |
| RSC | Rescue sub-centre |
| RSCD | Runway surface condition |
| RSP | Responder beacon |
| RSR | En-route surveillance radar |
| 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) |
| RU* | Russian |
| RUT | Standard regional route transmitting frequencies |
| RV | Rescue vessel |
| RVR | Runway Visual Range |
| RVSM | Reduced Vertical Separation Minimum |
| 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... | State of sea (followed by figures in METAR/SPECI) |
| S | South or southern latitude |
| SA | Sand |
| SALS | Simple approach lighting system |
| SAN | Sanitary |
| SAP | As soon as possible |
| SAR | Search and rescue |
| SARPS | Standards and recommended practices (ICAO) |
| SAT | Saturday |
| SATCOM | Satellite Communication |
| SB | Southbound |
| SBAS | (to be pronounced "ESS-BAS") Satellite-based augmentation system |
| SC | Stratocumulus |
| SCT | Scattered |
| 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 |
| SG | Snow grains |
| SGL | Signal |
| SH ... | Showers (followed by RA=rain, SN=snow, PE=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) |
| SID | Standard Instrument Departure |
| SIF | Selective identification feature |
| SIG | Significant |
| SIGMET | Information concerning en-route weather phenomena which may affect the safety of operations |
| SIGWX* | Significant weather |
| SIMUL | Simultaneous or simultaneously |
| SIWL | Single isolated wheel load |
| SKC | Sky clear |
| SKED | Schedule or scheduled |
| SLP | Speed limiting point |
| SLW | Slow |
| SMC | Surface movement control |
| SMR | Surface movement radar |
| SN | Snow |
| SNOLCO | Aerodrome closed due to snow (used in METAR/SPECI) |
| SNOWTAM | A special series NOTAM given in a standard format providing a surface condition report notifying the presence or cessation of hazardous conditions due to snow, ice, slush, frost, standing water or water associated with snow, slush, ice or frost on the movement area |
| 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 in 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 southwest |
| 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) |
| SUBJ | Subject to |
| SUN | Sunday |
| SUP | Supplement (AIP supplement) |
| SUPPS | Regional supplementary procedures |
| SVC | Service message |
| 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 |
| 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 |
| TCAC | Tropical cyclone advisory centre |
| TCU | Towering cumulus |
| TDO | Tornado |
| TDZ | Touchdown zone |
| TECR | Technical reason |
| TEL | Telephone |
| TEMPO | Temporary or Temporarily |
| TEND* | Trend or tending to |
| TF | Track to fix |
| 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 (followed by time by which weather change is forecast to end) |
| TLOF | Touchdown and lift-off area |
| TMA | Terminal Control Area |
| TN... | Minimum temperature (followed by figures in TAF) |
| TNA | Turn altitude |
| TNH | Turn height |
| TO... | To...(place) |
| 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 |
| 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, PE= ice pellets, GR= hail, GS= small hail and/or snow pellets or combinations thereof, e.g. TSRASN= thunderstorm with rain and snow) |
| TT | Teletypewriter |
| TUE | Tuesday |
| TURB | Turbulence |
| T-VASIS | (to be pronounced "TEE-VASIS") T visual approach slope indicator system |
| TVOR | Terminal VOR |
| TWR | Aerodrome Control Tower or Aerodrome Control |
| TWY | Taxiway |
| TWYL | Taxiway-link |
| TX... | Maximum temperature (followed by figures in TAF) |
| 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) |
| 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 (300 to 3 000 MHz) |
| UIC | Upper information centre |
| UIR | Upper Flight Information Region |
| ULR | Ultra long range |
| UNA | Unable |
| UNAP | Unable to approve |
| UNL | Unlimited |
| UNREL | Unreliable |
| U/S | Unserviceable |
| UP | Unidentified precipitation (used in automated METAR/SPECI) |
| 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 | |
| V... | Variations from the mean wind direction (preceded and followed by figures in METAR/SPECI, e.g. 350V070) |
| 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 |
| VC... | Vicinity of the aerodrome (followed by FG=fog, FC=funnel cloud, 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 |
| VER | Vertical |
| VFR | Visual Flight Rules |
| VHF | Very High Frequency (30 to 300 Mhz) |
| VIP | Very Important Person |
| VIS | Visibility |
| VLF | Very low frequency (3 to 30 khz) |
| VLR | Very long range |
| VMC | Visual Meteorological Conditions |
| 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 (followed by figures in METAR/SPECI and TAF) |
| 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... | Sea-surface temperature (followed by figures in METAR/SPECI) |
| 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-84 |
| 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 |
| WW | Worldwide web |
| WX | Weather |
| 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) |
| 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) |