- Odate Noshiro AirportIdent: RJSRCountry: Japan
- Offutt Air Force BaseIdent: KOFFCountry: United States
- Ogden Hinckley AirportIdent: KOGDCountry: United States
- Ogdensburg International AirportIdent: KOGSCountry: United States
- Oghab 44 AirbaseIdent: IR-0161Country: Iran
- Oiapoque AirportIdent: SBOICountry: Brazil
- Oita AirportIdent: RJFOCountry: Japan
- Okba Ibn Nafa Air BaseIdent: HL77Country: Libya
- Okhotsk AirportIdent: UHOOCountry: Russia
- Oki Global Geopark AirportIdent: RJNOCountry: Japan
- Okinoerabu AirportIdent: RJKBCountry: Japan
- Okondja AirportIdent: FOGQCountry: Gabon
- Oksibil AirportIdent: WAJOCountry: Indonesia
- Oktyabrskoe Air BaseIdent: UA-0010Country: Ukraine
- Okushiri AirportIdent: RJEOCountry: Japan
- Old Nabire AirportIdent: ID-0339Country: Indonesia
- Olenya Air BaseIdent: RU-4464Country: Russia
- Olsztyn-Mazury AirportIdent: EPSYCountry: Poland
- Olympia Regional AirportIdent: KOLMCountry: United States
- Olyokminsk AirportIdent: UEMOCountry: Russia
- Omboue Hospital AirportIdent: FOOHCountry: Gabon
- Omsk Severny AirportIdent: UNOSCountry: Russia
- Omsukchan AirportIdent: UHMFCountry: Russia
- Ondangwa AirportIdent: FYOACountry: Namibia
- Ontario Municipal AirportIdent: KONOCountry: United States
- Oran Tafraoui AirportIdent: DAOLCountry: Algeria
- Orang (Chongjin) AirportIdent: ZKHMCountry: North Korea
- Orange AirportIdent: YORGCountry: Australia
- Orange-Caritat (BA 115) Air BaseIdent: LFMOCountry: France
- Orangeburg Municipal AirportIdent: KOGBCountry: United States
- Oranjemund AirportIdent: FYOGCountry: Namibia
- Orcas Island AirportIdent: KORSCountry: United States
- Ordu–Giresun AirportIdent: LTCBCountry: Türkiye
- Orenburg Central AirportIdent: UWOOCountry: Russia
- Oreshkovo AirfieldIdent: RU-3686Country: Russia
- Orestes Acosta AirportIdent: MUMOCountry: Cuba
- Orlando Executive AirportIdent: KORLCountry: United States
- Orléans-Bricy (BA 123) Air BaseIdent: LFOJCountry: France
- Ormoc AirportIdent: RPVOCountry: Philippines
- Orsha Airport - Balbasovo Air BaseIdent: BY-0001Country: Belarus
- Orsk AirportIdent: UWORCountry: Russia
- Orán AirportIdent: SASOCountry: Argentina
- Osan Air BaseIdent: RKSOCountry: South Korea
- Oshawa Executive AirportIdent: CYOOCountry: Canada
- Oshima AirportIdent: RJTOCountry: Japan
- Osijek AirportIdent: LDOSCountry: Croatia
- Osovtsy Air BaseIdent: BY-0006Country: Belarus
- Ostrov Naval Air BaseIdent: RU-0064Country: Russia
- Oswaldo Guevara Mujica AirportIdent: SVACCountry: Venezuela
- Ottawa / Carp AirportIdent: CYRPCountry: Canada
- Ottawa / Gatineau AirportIdent: CYNDCountry: Canada
- Ottawa / Rockcliffe AirportIdent: CYROCountry: Canada
- Ottumwa Regional AirportIdent: KOTMCountry: United States
- Ouadi Doum Air BaseIdent: FTFYCountry: Chad
- Ouani AirportIdent: FMCVCountry: Comoros
- Oudtshoorn AirportIdent: FAOHCountry: South Africa
- Ouesso AirportIdent: FCOUCountry: Congo - Brazzaville
- Ouro Sogui AirportIdent: GOSMCountry: Senegal
- Ouvéa AirportIdent: NWWVCountry: New Caledonia
- Ovar Air BaseIdent: LPOVCountry: Portugal