A

Amber

AAA

(or AAB, AAC...etc., in sequence) Amended meteorological message (message type designator)

A/A

Air-to-air

AAL

Above aerodrome level

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

Address (when this abbreviation is used to request a repetition, the question mark (IMI) precedes the abbreviation, e.g. IMI ADS) (to be used in AFS as a procedure signal)

ADS-B

Automatic dependent surveillance - broadcast

ADS-C

Automatic dependent surveillance - contract

ADSU

Automatic dependent surveillance unit

ADVS

Advisory service

ADZ

Advise

AES

Aircraft earth station

AFIL

Flight plan filed in the air

AFIS

Aerodrome flight information service

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

Aerodromes, air routes and ground aids

AGCC*

Arab Gulf Cooperation Council

AGL

Above ground level

AIC

Aeronautical information circular

AIM

Aeronautical information management

AIP

Aeronautical information publication

AIRAC

Aeronautical information regulation and control

AIREP

Air-report

AIRMET

Information concerning en-route weather phenomena which may affect the safety of low-level aircraft operations

AIS

Aeronautical information services

ALA

Alighting area

ALERFA

Alert phase

ALR

Alerting (message type designator)

ALRS

Alerting service

ALS

Approach lighting system

ALT

Altitude

ALTN

Alternate or alternating (light alternates in colour)

ALTN

Alternate (aerodrome)

AMA

Area minimum altitude

AMD

Amend or amended (used to indicate amended meteorological message; message type designator)

AMDT

Amendment (AIP amendment)

AMS

Aeronautical mobile service

AMSL

Above mean sea level

AMSS

Aeronautical mobile satellite service

ANC

Aeronautical chart - 1:500 000 (followed by name/ title)

ANS

Answer

AO

Aircraft operator

AOC

Aerodrome obstacle chart

AP

Airport

APAPI

(to be pronounced “AY-PAPI”) Abbreviated precision approach path indicator

APCH

Approach

APN

Apron

APP

Approach control office or approach control or approach control service

APR

April

APRX

Approximate or approximately

APSG

After passing

APU

Auxiliary power unit

APV

Approach procedure with vertical guidance

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)

ARST

Arresting (specify (part of) aircraft arresting equipment)

AS

Altostratus

ASAP

As soon as possible

ASC

Ascend or ascending to

ASDA

Accelerate-stop distance available

ASPH

Asphalt

ASR*

Altimeter setting region

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

ATZ

Aerodrome traffic zone

AUG

August

AUTH

Authorized or authorization

AUW

All-up weight

AUX

Auxiliary

AVASIS

Abbreviated visual approach slope indicator system

AVBL

Available or availability

AVG

Average

AVGAS

Aviation gasoline

AVTUR*

Aviation turbine fuel

AWTA

Advise at what time able

AWY

Airway

AZM

Azimuth

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

Centre (preceded by runway designation number to identify a parallel runway)

C

Degrees Celsius (Centigrade)

C

Degrees Celsius (Centigrade)

CAA

Civil aviation authority or civil aviation administration

CAS

Controlled airspace

CAT

Category

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...

CFM

Confirm or I confirm (to be used in AFS as a procedure signal)

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

CLR

Clear(s) or cleared to... or clearance

CLSD

Close or closed or closing

CM

Centimetre

CMB

Climb to or climbing to

CMPL

Completion or completed or complete

CNL

Cancel or cancelled

CNL

Flight plan cancellation (message type designator)

CNS

Communications, navigation and surveillance

COM

Communications

CONC

Concrete

COND

Condition

CONS

Continuous

CONST

Construction or constructed

CONT

Continue(s) or continued

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)

CRP

Compulsory reporting point

CRZ

Cruise

CS

Cirrostratus

CS

Call sign

CTA

Control area

CTAM

Climb to and maintain

CTC

Contact

CTL

Control

CTN

Caution

CTR

Control zone

CU

Cumulus

CUF

Cumuliform

CUST

Customs

CW

Continuous wave

CWY

Clearway

D

Danger area (followed by identification)

D

Downward (tendency in RVR during previous 10 minutes)

DA

Decision altitude

DCD

Double channel duplex

DCKG

Docking

DCS

Double channel simplex

DCT

Direct (in relation to flight plan clearances and type of approach)

DEC

December

DEG

Degrees

DENEB

Fog dispersal operations

DEP

Depart or departure

DEP

Departure (message type designator)

DES

Descend to or descending to

DEST

Destination

DETRESFA

Distress phase

DEV

Deviation or deviating

DFTI

Distance from touchdown indicator

DH

Decision height

DIF

Diffuse

DIST

Distance

DIV

Divert or diverting

DLA

Delay (message type designator)

DLA

Delay or delayed

DLY

Daily

DME

Distance measuring equipment

DNG

Danger or dangerous

DOD*

Department of Defence

DOF

Date of flight

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

DRU*

Desert Rescue Unit

DS

Duststorm

DSB

Double sideband

DTAM

Descend to and maintain

DTG

Date-time group

DTRT

Deteriorate or deteriorating

DTW

Dual tandem wheels

DU

Dust

DUC

Dense upper cloud

DUR

Duration

DVOR

Doppler VOR

DW

Dual wheels

DZ

Drizzle

E

East or eastern longitude

EAT

Expected approach time

EB

Eastbound

EET

Estimated elapsed time

EFC

Expect further clearance

ELBA

Emergency location beacon-aircraft

ELEV

Elevation

ELR

Extra long range

ELT

Emergency locator transmitter

EMBD

Embedded in layer (to indicate cumulonimbus embedded in layers of other clouds)

EMERG

Emergency

END

Stop-end (related to RVR)

ENE

East north east

ENG

Engine

ENRT

En route

EOBT

Estimated off-block time

EQPT

Equipment

ER

Here... or herewith

ESE

East south east

EST

Estimate or estimated or estimate (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

EXTN*

Extension

F

Fixed

FAC

Facilities

FAF

Final approach fix

FAL

Facilitation of international air transport

FAP

Final approach point

FAS

Final approach segment

FATO

Final approach and takeoff 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

FEB

February

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)

FMC

Flight management computer

FMS

Flight management system

FLU

Flow management unit

FNA

Final approach

FPAP

Flight path alignment point

FPL

Flight plan

FPM

Feet per minute

FPR

Flight plan route

FR

Fuel remaining

FREQ

Frequency

FRI

Friday

FRNG

Firing

FRONT

Front (relating to weather)

FRQ

Frequent

FSL

Full stop landing

FSS

Flight service station

FST

First

FT

Feet (dimensional unit)

FU

Smoke

FZ

Freezing

FZDZ

Freezing drizzle

FZFG

Freezing fog

FZRA

Freezing rain

G

Green

G/A

Ground-to-air

G/A/G

Ground-to-air and air-to-ground

GA

General aviation

GALL

Imperial gallons

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

GND

Ground

GNDCK

Ground check

GNSS

Global navigation satellite system

GOV

Government

GP

Glide path

GPS

Global positioning system

GPU

Ground power unit

GPWS

Ground proximity warning system

GR

Hail

GRASS

Grass landing area

GRID

Processed meteorological data in the form of grid point values (in aeronautical meteorological code)

GRVL

Gravel

GS

Ground speed

GS

Small hail and/or snow pellets

GUND

Geoid Undulation

H24

Continuous day and night service

HAA*

Height above aerodrome

HAT*

Height above threshold

HAPI

Helicopter approach path indicator

HBN

Hazard beacon

HDG

Heading

HDF

High frequency direction-finding station

HEL

Helicopter

HF

High frequency (3 000 to 30 000 KHz)

HGT

Height or height above

HIALS

High intensity approach light system

HIRL

High intensity runway lights

HJ

Sunrise to sunset

HLDG

Holding

HN

Sunset to sunrise

HO

Service available to meet operational requirements

HOL

Holiday

HOSP

Hospital aircraft

HPA

Hectopascal

HQ*

Headquarters

HR

Hours

HS

Service available during hours of scheduled operations

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)

IAC

Instrument approach chart

IAF

Initial approach fix

IAO

In and out of clouds

IAP

Instrument approach procedure

IAR

Intersection of air routes

IAS

Indicated air speed

IBN

Identification beacon

IC

Diamond dust (very small ice crystals in suspension)

ICAO

International Civil Aviation Organization

ICE

Icing

ID

Identifier or identify

IDENT

Identification

IF

Intermediate approach fix

IFF

Identification friend/foe

IFR

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

INCL*

Inclusive

INCORP

Incorporated

INFO

Information

INOP

Inoperative

INP

If not possible

INPR

In progress

INS

Inches (dimensional unit)

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

I/V

Instrument/visual

JAN

January

JTST

Jet stream

JUL

July

JUN

June

KG

Kilograms

KHZ

Kilohertz

KM

Kilometres

KMH

Kilometres per hour

KPA

Kilopascal

KT

Knots

KW

Kilowatts

L

Left (runway identification)

L

Locator (see LM, LO)

LAM

Logical acknowledgement (message type designator)

LAN

Inland

LAT

Latitude

LCTR*

Locator

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

LNAV

(to be pronounced “EL-NAV”) Lateral navigation

LNG

Long (used to indicate the type of approach desired or required)

LO

Locator, outer

LOC

Localizer

LOC

Local or locally or location or located

LONG

Longitude

LORAN

LORAN (long range air navigation system)

LRG

Long range

LRU*

Land Rescue Unit

LSQ

Line squall

LTD

Limited

LTT

Landline teletypewriter

LV

Light and variable (relating to wind)

LVE

Leave or leaving

LVL

Level

LYR

Layer or layered

LTRS

Litres

M

Mach number (followed by figures)

M

Metres (preceded by figures)

MAA

Maximum authorized altitude

MAG

Magnetic

MAINT

Maintenance

MAP

Aeronautical maps and charts

MAPT

Missed approach point

MAR

At sea

MAR

March

MAS

Manual A1 simplex

MAX

Maximum

MAY

May

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 above threshold (for visual approach slope indicator systems)

MEL

Minimum Equipment List

MET

Meteorological or meteorology

METAR

Aerodrome routine meteorological report (in meteorological code)

MF

Medium frequency (300 to 3 000 KHz)

MHA

Minimum holding altitude

MHDF

Medium and high frequency direction-finding stations (at the same location)

MHVDF

Medium, high and very high frequency direction-finding stations (at the same location)

MHZ

Megahertz

MID*

Middle East

MID

Mid-point (related to RVR)

MIFG

Shallow fog

MIL

Military

MIN

Minutes

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)

MOD*

Ministry of Defence

MON

Above mountains

MON

Monday

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/MET reporting point

MRT*

Mountain Rescue Team

MS

Minus

MSA

Minimum sector altitude

MSAW

Minimum safe altitude warning

MSG

Message

MSL

Mean sea level

MT

Mountain

MTU

Metric units

MTW

Mountain waves

MVDF

Medium and very high frequency direction-finding stations (at the same location)

MWO

Meteorological watch office

MX

Mixed type of ice formation (white and clear)

N

North or northern latitude

N

No distinct tendency (in RVR during previous 10 minutes)

N/A*

Not applicable

NAT

North Atlantic

NAV

Navigation

NB

Northbound

NBFR

Not before

NC

No change

NDB

Non-directional radio beacon

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

NOC*

No objection certificate

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

NR

Number

NRH

No reply heard

NS

Nimbostratus

NSC

Nil significant cloud

NSW

Nil significant weather

NW

North-west

NWB

North-westbound

NXT

Next

OAC

Oceanic area control centre

OAMC*

Oman Airports Management Company S.A.O.C

OAS

Obstacle assessment surface

OAS*

Oman Aviation Service Company

OBS

Observe or observed or observation

OBSC

Obscure or obscured or obscuring

OBST

Obstacle

OCA

Obstacle clearance altitude

OCA

Oceanic control area

OCC

Occulting (light)

OCH

Obstacle clearance height

OCL

Obstacle clearance limit

OCNL

Occasional or occasionally

OCR*

Oman Coastal Regiment

OCS

Obstacle clearance surface

OCT

October

OFTS*

Operational fixed telecommunication service

OFZ

Obstacle free zone

OHD

Overhead

OM

Outer marker

OMR*

Rial Omani

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 messages for volcanic ash and tropical cyclones)

OTP

On top

OTS

Organized track system

OUBD

Outbound

OVC

Overcast

P...

Prohibited area (followed by identification)

PACA

Public Authority for Civil Aviation

PALS

Precision approach lighting system (specify category)

PANS

Procedures for air navigation services

PAPI

Precision approach path indicator

PAR

Precision approach radar

PARL

Parallel

PAX

Passenger(s)

PCD

Proceed or proceeding

PCN

Pavement classification number

PDO*

Petroleum Development (Oman) Limited

PE

Ice pellets

PER

Performance

PERM

Permanent

PJE

Parachute jumping exercise

PLA

Practice low approach

PLVL

Present level

PN

Prior notice required

PNR

Point of no return

PO

Dust devils

PO*

Post Office

POB

Persons on board

POSS

Possible

PPI

Plan position indicator

PPR

Prior permission required

PPSN

Present position

PRI

Primary

PRKG

Parking

PROB

Probability

PROC

Procedure

PROV

Provisional

PS

Plus

PSG

Passing

PSN

Position

PSP

Pierced steel plank

PTN

Procedure turn

PTS

Polar track structure

PWR

Power

QBI

Compulsory IFR flight

QDM

Magnetic heading (zero wind)

QDR

Magnetic bearing

QFE

Atmospheric pressure at aerodrome elevation (or at runway threshold)

QFU

Magnetic orientation of runway

QNH

Altimeter sub-scale setting to obtain elevation when on the ground

QTE

True bearing

QUAD

Quadrant

R

Red

R...

Restricted area (followed by identification)

R

Right (runway identification)

RA

Rain

RAFC

Regional area forecast centre

RAFO*

Royal Air Force Oman

RAD*

Approach radar control

RAG

Ragged

RAG

Runway arresting gear

RAO*

Royal Army of Oman

RB

Rescue boat

RCA

Reach cruising altitude

RCC

Rescue co-ordination centre

RCF

Radio communication 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

Reroute

RETIL

Rapid exit taxiway indicator lights

RF*

Royal Flight of Oman

RG

Range (lights)

RIF

Reclearance in flight

RITE

Right (direction of turn)

RIV*

Rapid intervention vehicle

RL

Report leaving

RLA

Relay to

RLCE

Request level change en route

RLLS

Runway lead-in lighting system

RLNA

Request level not available

RMK

Remark

RNAV

(to be pronounced "AR_NAV") Area navigation

RNG

Radio range

RNO*

Royal Navy of Oman

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

ROP*

Royal Oman Police

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)

RTIL

Runway threshold identification light(s)

RTN

Return or returned or returning

RTS

Return to service

RTT

Radio teletypewriter

RTZL

Runway touchdown zone light(s)

RUT

Standard regional route transmitting frequencies

RV

Rescue vessel

RVR

Runway visual range

RWY

Runway

S

South or southern latitude

SA

Sand

SALS

Simple approach lighting system

SAN

Sanitary

SAR

Search and rescue

SARPS

Standards and Recommended Practices (ICAO)

SAT

Saturday

SATCOM

Satellite communication

SB

Southbound

SC

Stratocumulus

SCT

Scattered

SDBY

Stand by

SE

South-east

SEA*

South East Asia

SEB

South-eastbound

SEC

Seconds

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

SIGMET

Information concerning en-route weather phenomena which may affect the safety of aircraft operations

SIGWX

Significant weather

SIMUL

Simultaneous or simultaneously

SITA*

Societe Internationale de Telecommunications Aeronautiques

SIWL

Single isolated wheel load

SKC

Sky clear

SKED

Schedule or scheduled

SLOP

Strategic lateral offset procedures

SLP

Speed limiting point

SLW

Slow

SMC

Surface movement control

SMR

Surface movement radar

SN

Snow

SOA*

Sultan of Oman Artillery

SOPR*

Sultan of Oman's Parachute Regiment

SPECI

Aerodrome special meteorological report (in meteorological code)

SPECIAL

Local special meteorological report (in abbreviated plain language)

SPL

Supplementary flight plan (message type designator)

SPOT

Spot wind

SQ

Squall

SR

Sunrise

SRA

Surveillance radar approach

SRE

Surveillance radar element of precision approach radar system

SRG

Short range

SRR

Search and rescue region

SRY

Secondary

SS

Sandstorm

SS

Sunset

SSB

Single sideband

SSE

South south east

SSR

Secondary surveillance radar

SST

Supersonic transport

SSW

South south west

ST

Stratus

STA

Straight in approach

STAR

Standard instrument arrival

STD

Standard

STF

Stratiform

STN

Station

STNR

Stationary

STOL

Short take-off and landing

STS

Status

STWL

Stopway light(s)

SUBJ

Subject to

SUN

Sunday

SUP

Supplement (AIP Supplement) SUPPS Regional supplementary procedures

SVC

Service message

SVCBL

Serviceable

SVFR*

Special visual flight rules

SW

South-west

SWB

South-westbound

SWY

Stopway

T

Temperature

TA

Transition 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

TCH

Threshold crossing height

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

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

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

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

TVOR

Terminal VOR

TWR

Aerodrome control tower or aerodrome control

TWY

Taxiway

TWYL

Taxiway-link

TYP

Type of aircraft

TYPH

Typhoon

U

Upward (tendency in RVR during previous 10 minutes)

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 (300-3 000 MHz)

UIC

Upper information centre

UIR

Upper flight information region

UK*

United Kingdom

ULR

Ultra long range

UNA

Unable

UNAP

Unable to approve

UNL

Unlimited

UNLGTD*

Unlighted

UNREL

Unreliable

U/S

Unserviceable

UTA

Upper control area

UTC

Co-ordinated Universal Time

VA

Volcanic ash

VAC

Visual approach chart

VAL

In valleys

VAN

Runway control van

VAR

Magnetic variation

VAR

Visual-aural radio range

VASIS

Visual approach slope indicator system

VC

Vicinity of the aerodrome (followed by FG=fog, FC=funnel cloud, SH=showers, PO=dust/sand whirls, BLDU=blowingdust, BLSA=blowing sand or BLSN=blowing snow, e.g. VCFG=vicinity fog)

VCY

Vicinity

VDF

Very high frequency direction-finding station

VER

Vertical

VFR

Visual flight rules

VHF

Very high frequency (30-300 MHz)

VIA

By way of...

VIP

Very important person

VIS

Visibility

VLF

Very low frequency (3 to 30 KHz)

VLR

Very long range

VMC

Visual meteorological conditions

VNAV

(to be pronounced “VEE-NAV”) Vertical Navigation

VOLMET

Meteorological information for aircraft in flight

VOR

VHF omnidirectional radio range

VORTAC

VOR and TACAN combination

VOT

VOR airborne equipment test facility

VRB

Variable

VSA

By visual reference to the ground

VSP

Vertical speed

VTOL

Vertical take-off and landing

W

West or western longitude

W

White

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

WHO*

World Health Organisation

WI

Within

WID

Width

WIE

With immediate effect or effective immediately

WILCO

Will comply

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

WSW

West south west

WT

Weight

WTSPT

Waterspout

WX

Weather

WXR

Weather radar

X

Cross

XBAR

Crossbar (of approach lighting system)

XNG

Crossing

XS

Atmospherics

Y

Yellow

YCZ

Yellow caution zone (runway lighting)

YR

Your

Z

Co-ordinated Universal Time (in meteorological messages)