OAT Operational air traffic
OBS Observe or observed or observation
OBS Omni bearing selector
OBSC Obscure or obscured or obscuring
OBST Obstacle
OCA Obstacle clearance altitude
OCH Obstacle clearance height
OCNL Occasional or occasionally
OCS Obstacle clearance surface
OCT October
OFZ Obstacle free zone
OM Outer marker
OPA Opaque, with type of ice formation
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
ORCAM Originating Region Code Assignment Method
OTP On top
P
P… Prohibited area (followed by identification)
PANS Procedures for air navigation services
PAPI Precision Approach Path Indicator
PAR Precision Approach Radar system
PCN Pavement classification number
PDG Procedure design gradient
PERM Permanent
PJE Parachute jumping exercise
PL Ice pellets
PLA Practice low approach
PLN Flight plan
PN Prior notice required
PO Dust/sand whirls (dust devils)
POB Persons on board
PPI Plan position indicator
PPR Prior permission required
PRFG Aerodrome partially covered by fog
PRKG Parking
PROB Probability
PROC Procedure
PROV Provisional
PS Plus
PSN Position
PSP Pierced steel plank
PTN Procedure turn
PWR Power
Q
QDM Magnetic heading (zero wind)
QDR Magnetic bearing
QFE Atmospheric pressure at aerodrome elevation (or at runway threshold)
QFU Magnetic orientation of runway
QNH Atmospheric pressure reduced to MSL by ICAO Standard Atmosphere and altimeter sub-scale setting to obtain aerodrome elevation when on the ground
QTE True bearing from the station
R
R Red
R… Restricted area (followed by identification)
R… Radial (followed by Mag track
R Right (runway identification)
RA Rain
RAF Royal Air Force
RAG Runway arresting gear
RASN Moderate rain and snow
RCA Reach cruising altitude
RCAF Royal Canadian Air Force
RCC Rescue coordination centre
RCF Radio communication failure message
RCL Runway centre line
RDH Reference datum height (for ILS )
RDL Radial
RDO Radio
RE Recent (used to qualify weather phenomena such as rain, e.g. recent rain = RERA)
REC Receive or receiver
REF Reference to… or to …
REG Registration
REP Reporting point
REQ Request or requested
RFL Requested flight level
RFP Replacement Flight Plan
RG Range (lights)
RIF Reclearance öin flight
RMK Remark
RNAV Area Navigation
RNG Radio Range
ROFOR Route forecast (in aeronautical meteorological code)
RON Receiving only
RPL Repetitive flight plan
RPS Radar position symbol
RPT Repeat or I repeat
RQS Request supplementary flight plan message
RSC Rescue sub-centre
RSP Responder beacon
RSR En-route surveillance radar
RT Right turn
RTD Delayed (used to indicate
