O
- O
- OAD
- OAS (1)
- OAS (2)
- OAS (3)
- OAT
- OAU
- OBS
- OBST
- obstacle
- obstacle-free zone
- obstacle assessment surface
- obstacle clearance altitude
- obstacle clearance altitude (height)
- obstacle clearance height
- obstacle clearance limit
- obstacle clearance surface
- obstacle free zone
- obstacle identification surface
- obstacle limitation surface
- obstacle protection surface
- OC
- OCA
- OCA/H
- OCAS
- ocean station vessel
- OCH
- OCL
- OCS
- OD
- ODP
- ODP (2)
- OEB
- OECD
- OECD business and industry advisory committee
- OECS
- OEI
- OEM
- OEP
- OEW
- offer responsible airline
- OFIS
- OFP
- OFV
- OFZ
- OGE
- OGV
- OIS
- OJT
- OLDI
- OLF
- OLS
- OM
- OMGWS
- omni bearing selector
- on-line data interchange
- on-the-job training
- on condition
- one engine inoperative
- one stop security
- online framework
- OPD
- operating empty weight
- operational flight information service
- operational flight plan
- operational windshear warning system
- operations
- operations evaluation board
- OPS (1)
- OPS (2)
- OPSPECS
- optimized profile descent
- optimum speed tilt rotor
- optionally or operationally piloted vehicle
- OPV
- ORA
- ORB
- ORE
- ORG
- organização de aviação civil internacional
- organization for economic co-operation and development
- organization of african unity
- organization of american states
- organization of central american states
- organization of eastern caribbean states
- organized track system
- origin-destination
- original equipment manufacturer
- OROCA
- oscar
- OSS
- OSTR
- OSV
- other
- OTHR
- OTS
- out of ground effect
- outer main gear wheel span
- outer marker
- outflow valve
- outlet guide vane, or straightener vane
- outside air temperature
- OVC
- overcast
- OWWS
- oxides of nitrogen
- OXY
- oxygen resuscitation equipment