| Flughafenkürzel |
Stadt / Flughafen |
| ORQ |
Norwalk, CT |
| OIC |
Norwich, NY - Lt. Warren Eaton Airport |
| OWD |
Norwood, MA - Norwood Memorial Airport |
| NOT |
Novato, CA - Gnoss Field |
| NUI |
Nuiqsut, AK - Niuqsut Airport |
| NUL |
Nulato, AK - Nulato Airport |
| NUP |
Nunapitchuk, AK - Nunapitchuk Airport |
| ZNC |
Nyack, AK |
| ONL |
O'Neill, NE - The O'Neill Municipal Airport-John L. Baker Field |
| ODW |
Oak Harbor, WA - Oak Harbor Air Park |
| NUW |
Oak Harbor, WA - Whidbey Island Naval Air Station (Ault Field) |
| OBT |
Oakland, CA - Coliseum Street |
| OAK |
Oakland, CA - Metropolitan Oakland International Airport |
| JCE |
Oakland, CA - Oakland Convention Center Heliport |
| ODM |
Oakland, MD - Garrett County Airport |
| OEL |
Oakley, KS - Oakley Municipal Airport |
| OTN |
Oaktown, IN - Green Airport |
| OIN |
Oberlin, KS - Oberlin Municipal Airport |
| OCF |
Ocala, FL - Ocala Regional Airport/Jim Taylor Field |
| OCE |
Ocean City, MD - Ocean City Municipal Airport |
| OCI |
Oceanic, AK |
| OCN |
Oceanside, CA - Oceanside Municipal Airport |
| OCQ |
Oconto, WI - Oconto Municipal Airport |
| OLZ |
Oelwein, IA - Oelwein Municipal Airport |
| OGA |
Ogallala, NE - Searle Field |
| HIF |
Ogden, UT - Hill Air Force Base |
| OGD |
Ogden, UT - Ogden-Hinckley Airport |
| OGS |
Ogdensburg, NY - Ogdensburg International Airport |
| OIL |
Oil City, PA - Splane Memorial Airport |
| OBE |
Okeechobee, FL - Okeechobee County Airport |
| DWN |
Oklahoma City, OK - Downtown Airpark |
| HSD |
Oklahoma City, OK - Sundance Airpark |
| TIK |
Oklahoma City, OK - Tinker Air Force Base |
| PWA |
Oklahoma City, OK - Wiley Post Airport |
| OKC |
Oklahoma City, OK - Will Rogers World Airport |
| OKM |
Okmulgee, OK - Okmulgee Municipal Airport |
| OJC |
Olathe, KS/Kansas City, MO - Johnson County Executive Airport |
| JCI |
Olathe, KS/Kansas City, MO - Johnson County Industrial Airport |
| OLH |
Old Harbor, AK - Old Harbor Airport |
| OLD |
Old Town, ME - Dewitt Field/Old Town Municipal Airport |
| OLE |
Olean, NY - Cattaraugus County-Olean Airport |
| KOY |
Olga Bay, AK - Olga Bay Seaplane Base |
| OLV |
Olive Branch, MS - Olive Branch Airport |
| ONY |
Olney, TX - Olney Municipal Airport |
| OLY |
Olney-Noble, IL - Olney-Noble Airport |
| OLM |
Olympia, WA - Olympia Airport |
| OMA |
Omaha, NE - Eppley Airfield |
| MIQ |
Omaha, NE - Millard Airport |
| OFF |
Omaha, NE - Offutt Air Force Base |
| OMK |
Omak, WA - Omak Airport |