|
Contraction
|
Definition
|
Usage
|
|
O/F
|
on file
|
GEN
|
|
O/R
|
on request
|
GEN
|
|
O/T
|
overtime
|
GEN
|
|
OA
|
overhead approach
|
ATC
|
|
OAC
|
oceanic area control
|
GEN
|
|
OAG
|
Official Airline
Guide
|
GEN
|
|
OANDR
|
operation and
regulation
|
GEN
|
|
OAOI
|
on and off
instruments
|
ATC
|
|
OARTS
|
oceanic air route
tracking system
|
GEN
|
|
OAS
|
obstacle assessment
surface
|
ICAO
|
|
OAT
|
outside air
temperature
|
GEN
|
|
OB
|
on board
|
GEN
|
|
OBL
|
obliterate
|
GEN
|
|
OBND
|
outbound
|
ATC
|
|
OBS
|
observation
|
NWS
|
|
OBSC
|
obscure, obscured,
or obscuring |
ICAO
|
|
OBST
|
obstacle
|
ICAO
|
|
OBST
|
obstruct
|
GEN
|
|
OBSTN
|
obstruction
|
GEN
|
|
OC
|
obstruction chart
|
GEN
|
|
OC
|
on course
|
ATC
|
|
OCA
|
obstacle clearance
altitude
|
ICAO
|
|
OCA
|
oceanic control area
|
ICAO
|
|
OCAC
|
oceanic ATC
|
GEN
|
|
OCAS
|
out of controlled
airspace
|
ATC
|
|
OCFNT
|
occluded front
|
NWS
|
|
OCH
|
obstacle clearance
height
|
ICAO
|
|
OCL
|
obstacle clearance
limit
|
ICAO
|
|
OCLD
|
occlude
|
NWS
|
|
OCLN
|
occlusion
|
NWS
|
|
OCNL
|
occasional
|
GEN
|
|
OCR
|
occur
|
GEN
|
|
OCS
|
obstacle clearance
surface
|
ICAO
|
|
OCTLA
|
out of control area
|
ATC
|
|
ODALS
|
omnidirectional
approach lighting
system
|
GEN
|
|
ODAPS
|
Oceanic Display and
Planning System
|
ATC
|
|
OFAS
|
overseas flight
assistance service
|
GEN
|
|
OFC
|
office
|
GEN
|
|
OFFL
|
official
|
GEN
|
|
OFM
|
out for maintenance
|
GEN
|
|
OFP
|
occluded frontal
passage
|
NWS
|
|
OFP
|
original flight plan
|
GEN
|
|
OFSHR
|
offshore
|
NWS
|
|
OFW
|
off watch
|
GEN
|
|
OFXT
|
outer fix time
|
ATC
|
|
OFZ
|
Obstacle free zone
|
ICAO
|
|
OG
|
on ground
|
ATC
|
|
OGN
|
Originate
|
ICAO
|
|
OHD
|
overhead
|
ICAO
|
|
OI
|
on instruments
|
ATC
|
|
OINT
|
omni intersection
|
GEN
|
|
OIS
|
operational
information system
|
ATC
|
|
OJT
|
onthejob
training
|
GEN
|
|
OK
|
operating normally
|
GEN
|
|
OK
|
We agree or it is
correct
|
ICAO
|
|
OLDI
|
On line data
interchange
|
ICAO
|
|
OLS
|
optical landing
system
|
ATC
|
|
OM
|
outer marker
|
ICAO
|
|
OMSG
|
our message
|
GEN
|
|
OMTNS
|
over mountains
|
NWS
|
|
ONER
|
oceanic navigational
error report
|
ATC
|
|
ONSHR
|
on shore
|
NWS
|
|
ONT
|
Ontario
|
NWS
|
|
ONW
|
on watch
|
GEN
|
|
OOT
|
out of tolerance
|
GEN
|
|
OPA
|
opaque, white type
of ice formation
|
ICAO
|
|
OPC
|
operational control
|
ICAO
|
|
OPDT
|
opposite direction
traffic
|
GEN
|
|
OPER
|
operate
|
GEN
|
|
OPMET
|
operational
meteorological
(information)
|
ICAO
|
|
OPN
|
open
|
ICAO
|
|
OPN
|
operation
|
GEN
|
|
OPNML
|
operations normal
|
GEN
|
|
OPR
|
operate, operator,
operational
|
ICAO
|
|
OPS
|
operations
|
ICAO
|
|
OPSNET
|
operations network
|
ATC
|
|
ORD
|
order, indication of
|
ICAO
|
|
ORGPHC
|
orographic
|
NWS
|
|
ORIG
|
original
|
GEN
|
|
ORL
|
overrun lights
|
GEN
|
|
ORS
|
over range station
|
ATC
|
|
OSV
|
ocean station vessel
|
NWS
|
|
OT
|
on time
|
ATC
|
|
OTAS
|
on top and smooth
|
NWS
|
|
OTFC
|
overflight
traffic
|
GEN
|
|
OTLK
|
outlook
|
NWS
|
|
OTP
|
on top
|
ATC
|
|
OTR
|
other
|
GEN
|
|
OTRW
|
otherwise
|
GEN
|
|
OTS
|
organized track
system
|
GEN
|
|
OTS
|
out of service
|
GEN
|
|
OUBD
|
outbound
|
ICAO
|
|
OV
|
location (PIREP
only)
|
ATC
|
|
OVC
|
overcast
|
NWS
|
|
OVD
|
overdue
|
GEN
|
|
OVHD
|
overhead
|
GEN
|
|
OVLA
|
overlay
|
GEN
|
|
OVNGT
|
overnight
|
GEN
|
|
OVR
|
over
|
GEN
|
|
OVRN
|
overrun
|
GEN
|
|
OVSEA
|
overseas
|
GEN
|
|
OVTK
|
overtake
|
GEN
|
|
OW
|
one way
|
GEN
|
|
OWF
|
optimum working
frequency
|
GEN
|
|
OXY
|
oxygen
|
GEN
|
