- Opheim AirportIdent: S00Serves: Opheim
- Ophir AirportIdent: Z17Serves: Ophir
- Orange County AirportIdent: KMGJServes: Montgomery
- Orange County AirportIdent: KOMHServes: Orange
- Orange County AirportIdent: KORGServes: Orange
- Orange Grove Naval Auxiliary Landing FieldIdent: KNOGServes: Orange Grove
- Orange Municipal AirportIdent: KOREServes: Orange
- Orange Poultry Farm AirportIdent: 4NY1Serves: Chester
- Orban AirportIdent: 51CServes: DeWitt
- Orchard Ranch AirportIdent: WY38Serves: Ten Sleep
- Oreck AirportIdent: MS88Serves: Poplarville
- Oregon Sky Ranch AirportIdent: OG33Serves: Milton/Freewater
- Ori AirportIdent: WI86Serves: Kansasville
- Orlampa Inc Airport / Fantasy of FlightIdent: FA08Serves: Polk City
- Orlando Apopka AirportIdent: KX04Serves: Apopka
- Orlando North AirparkIdent: FA83Serves: Zellwood
- Orleans AirportIdent: K7I4Serves: Orleans
- Ormond Beach Municipal AirportIdent: KOMNServes: Ormond Beach
- Orofino Municipal AirportIdent: S68Serves: Orofino
- Orogrande AirportIdent: 75CServes: Orogrande
- Oroville Municipal AirportIdent: KOVEServes: Oroville
- Orr AirportIdent: 24NEServes: Lakeside
- Orr FieldIdent: NE25Serves: North Platte
- Orr Ranch AirportIdent: 33NEServes: Hay Springs
- Orr Regional AirportIdent: KORBServes: Orr
- Orth Pasture AirportIdent: US-2216Serves: Junction
- Orthodontic StripIdent: 5IN6Serves: Westville
- Ortner AirportIdent: KI64Serves: Wakeman
- Ortonville Municipal Airport/Martinson FieldIdent: KVVVServes: Ortonville
- Orum AerodromeIdent: 86NEServes: Blair
- Osage City Municipal AirportIdent: 53KServes: Osage City
- Osage Municipal AirportIdent: KD02Serves: Osage
- Osborn AirfieldIdent: 02FAServes: Groveland
- Osborne AirportIdent: 8CA0Serves: Victorville
- Osborne Municipal AirportIdent: KK75Serves: Osborne
- Osceola Municipal AirportIdent: K7M4Serves: Osceola
- Osceola Municipal AirportIdent: KI75Serves: Osceola
- Oscoda County/Dennis Kauffman Memorial AirportIdent: 51MServes: Mio
- Oscoda Wurtsmith AirportIdent: KOSCServes: Oscoda
- Oshkosh Sky Ranch AirportIdent: 2WN8Serves: Omro
- Oskaloosa Municipal AirportIdent: KOOAServes: Cedar
- Oslo Corners AirportIdent: US-7587Serves: Iola
- Oso Canyon AirportIdent: US-13020Serves: Ozona
- Ostlunds AirportIdent: US-1251Serves: Billings
- Oswego County AirportIdent: KFZYServes: Fulton
- Oswego Municipal AirportIdent: K67Serves: Oswego
- Otero Mill AirportIdent: 72NMServes: La Luz
- Othello Municipal AirportIdent: KS70Serves: Othello
- Ott Farms AirportIdent: 7TS8Serves: Dimmitt
- Ott's Landing AirportIdent: 0FA1Serves: Arcadia
- Ottawa Executive AirportIdent: KZ98Serves: Zeeland
- Ottawa Municipal AirportIdent: KOWIServes: Ottawa
- Otterbach Farm AirportIdent: 81LLServes: Mendota
- Ottertail Lake AirportIdent: US-1274Serves: Three Forks
- Ottman Landing AirportIdent: 5WN9Serves: Maiden Rock
- Ottos AirportIdent: 88WSServes: Verona
- Our Domain AirportIdent: 7MD0Serves: Marydel
- Ousel Falls AirportIdent: MT94Serves: Big Sky
- Outback AirportIdent: 5XS7Serves: Lockney
- Outback Ranch AirstripIdent: AZ01Serves: Wenden