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 |
| LMM* | Locator Middle with Marker |
| LMT | Local mean time |
| LNG | Long (used to indicate the type of approach desired or required) |
| LO | Locator, outer |
| LOC | Localizer |
| LOM* | Locator Outer with Marker |
| 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 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 |
| 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) |