| IATA | ICAO | Airport name | Location served | Time | DST |
|---|
| -OA- |
|---|
| OAA | OASH | Forward Operating Base Shank | Gardez, Afghanistan | | |
| OAG | YORG | Orange Airport [1] | Orange, New South Wales, Australia | | |
| OAH | OASD | Shindand Air Base | Shindand, Afghanistan | | |
| OAI | OAIX | Bagram Airfield | Bagram, Afghanistan | | |
| OAJ | KOAJ | Albert J. Ellis Airport | Jacksonville, North Carolina, United States | | |
| OAK | KOAK | Oakland International Airport | Oakland, California, United States | | |
| OAL | SSKW | Capital do Café Airport [1] | Cacoal, Rondônia, Brazil | | |
| OAM | NZOU | Oamaru Airport | Oamaru, New Zealand | | |
| OAN | MHEA | El Arrayán Airport [1] | Olanchito, Honduras | | |
| OAR | KOAR | Marina Municipal Airport | Monterey / Marina, California, United States | | |
| OAS | OASA | Sharana Airstrip / Forward Operating Base Sharana | Sharana, Afghanistan | | |
| OAX | MMOX | Xoxocotlán International Airport | Oaxaca de Juárez, Oaxaca, Mexico | | |
| OAZ | OAZI | Camp Bastion Air Base | Girishk (Gereshk), Afghanistan | | |
| -OB- |
|---|
| OBA | | Oban Airport [1] | Oban, Queensland, Australia | | |
| OBC | HDOB | Obock Airport | Obock, Djibouti | | |
| OBD | | Obano Airport | Obano, Indonesia | | |
| OBE | KOBE | Okeechobee County Airport | Okeechobee, Florida, United States | | |
| OBF | EDMO | Oberpfaffenhofen Airport | Oberpfaffenhofen, Bavaria, Germany | | |
| OBI | SBTI | Óbidos Airport [1] | Óbidos, Pará, Brazil | | |
| OBL | EBZR | Oostmalle Airfield | Zoersel, Belgium | | |
| OBM | | Morobe Airport [1] | Morobe, Papua New Guinea | | |
| OBN | EGEO | Oban Airport [1] (North Connel Airport) | Oban, Scotland, United Kingdom | | |
| OBO | RJCB | Tokachi–Obihiro Airport | Obihiro, Hokkaido, Japan | | |
| OBS | LFHO | Aubenas Aerodrome [1] (Ardèche Méridionale Aerodrome) | Aubenas, Rhône-Alpes, France | | |
| OBU | PAOB | Kobuk Airport | Kobuk, Alaska, United States | | |
| OBX | AYOB | Obo Airport | Obo, Papua New Guinea | | |
| -OC- |
|---|
| OCA | | Ocean Reef Club Airport (FAA: 07FA) | Key Largo, Florida, United States | | |
| OCC | SECO | Francisco de Orellana Airport | Puerto Francisco de Orellana (Coca), Ecuador | | |
| OCE | KOXB | Ocean City Municipal Airport | Ocean City, Maryland, United States | | |
| OCF | KOCF | Ocala International Airport (Jim Taylor Field) | Ocala, Florida, United States | | |
| OCH | KOCH | A.L. Mangham Jr. Regional Airport | Nacogdoches, Texas, United States | | |
| OCJ | MKBS | Ian Fleming International Airport | Ocho Rios, Jamaica | | |
| OCM | YBGD | Boolgeeda Airport [1] | Boolgeeda, Western Australia, Australia | | |
| OCN | KOKB | Oceanside Municipal Airport (FAA: OKB) | Oceanside, California, United States | | |
| OCS | | Corisco International Airport [1] | Corisco Island, Equatorial Guinea | | |
| OCV | SKOC | Aguas Claras Airport [1] | Ocaña, Colombia | | |
| OCW | KOCW | Washington–Warren Airport (Warren Field) | Washington, North Carolina, United States | | |
| -OD- |
|---|
| ODA | FEFW | Ouadda Airport [1] | Ouadda, Central African Republic | | |
| ODB | LEBA | Córdoba Airport | Córdoba, Andalusia, Spain | | |
| ODC | | Oakdale Airport [1] (FAA: O27) | Oakdale, California, United States | | |
| ODD | YOOD | Oodnadatta Airport [1] | Oodnadatta, South Australia, Australia | | |
| ODE | EKOD | Hans Christian Andersen Airport | Odense, Denmark | | |
| ODH | EGVO | RAF Odiham | Odiham, England, United Kingdom | | |
| ODJ | FEGO | Ouanda Djallé Airport [1] | Ouanda Djallé, Central African Republic | | |
| ODL | | Cordillo Downs Airport [1] | Cordillo Downs, South Australia, Australia | | |
| ODM | | Garrett County Airport [1] (FAA: 2G4) | Oakland, Maryland, United States | | |
| ODN | WBGI | Long Seridan Airport [1] | Long Seridan, Sarawak, Malaysia | | |
| ODO | UIKB | Bodaybo Airport [1] | Bodaybo, Irkutsk Oblast, Russia | | |
| ODR | YORV | Ord River Airport [1] | Ord River, Western Australia, Australia | | |
| ODS | UKOO | Odesa International Airport | Odesa, Ukraine | | |
| ODW | KOKH | A.J. Eisenberg Airport (FAA: OKH) | Oak Harbor, Washington, United States | | |
| ODY | VLOS | Oudomsay Airport | Muang Xay (Oudomxai), Laos | | |
| -OE- |
|---|
| OEC | WPOC | Oecusse Airport | Oecussi, East Timor | | |
| OEL | UUOR | Oryol Yuzhny Airport | Oryol (Orel), Oryol Oblast, Russia | | |
| OEM | SMPA | Vincent Fayks Airport | Paloemeu, Suriname | | |
| OEO | KOEO | L.O. Simenstad Municipal Airport | Osceola, Wisconsin, United States | | |
| OER | ESNO | Örnsköldsvik Airport | Örnsköldsvik, Sweden | | |
| OES | SAVN | Antoine de Saint Exupéry Airport | San Antonio Oeste, Río Negro, Argentina | | |
| -OF- |
|---|
| OFF | KOFF | Offutt Air Force Base | Omaha, Nebraska, United States | | |
| OFI | DIOF | Ouango Fitini Airport [1] | Ouango Fitini, Ivory Coast | | |
| OFJ | BIOF | Ólafsfjörður Airport [1] | Ólafsfjörður, Iceland | | |
| OFK | KOFK | Norfolk Regional Airport (Karl Stefan Memorial Field) | Norfolk, Nebraska, United States | | |
| OFU | NSAS | Ofu Airport (FAA: Z08) | Ofu Island, American Samoa | | |
| -OG- |
|---|
| OGA | KOGA | Searle Field | Ogallala, Nebraska, United States | | |
| OGB | KOGB | Orangeburg Municipal Airport | Orangeburg, South Carolina, United States | | |
| OGD | KOGD | Ogden-Hinckley Airport | Ogden, Utah, United States | | |
| OGE | | Ogeramnang Airport [1] | Ogeramnang, Papua New Guinea | | |
| OGG | PHOG | Kahului Airport | Kahului, Hawaii, United States | | |
| OGL | SYGO | Ogle Airport | Georgetown, Guyana | | |
| OGM | | Ustupu-Ogobsucum Airport [1] | Ustupo, Panama | | |
| OGN | ROYN | Yonaguni Airport | Yonaguni, Yaeyama Islands, Japan | | |
| OGO | DIAU | Abengourou Airport [1] | Abengourou, Ivory Coast | | |
| OGR | FTTB | Bongor Airport | Bongor, Chad | | |
| OGS | KOGS | Ogdensburg International Airport | Ogdensburg, New York, United States | | |
| OGU | LTCB | Ordu–Giresun Airport | Ordu / Giresun, Turkey | | |
| OGV | FYNG | Ongava Airstrip [1] | Ongava, Namibia | | |
| OGX | DAUU | Ain Beida Airport | Ouargla, Algeria | | |
| OGZ | URMO | Beslan Airport | Vladikavkaz, North Ossetia-Alania, Russia | | |
| -OH- |
|---|
| OHA | NZOH | RNZAF Base Ohakea [1] | Bulls, New Zealand | | |
| OHB | | Ambohibary Airport [1] | Moramanga, Madagascar | | |
| OHD | LWOH | Ohrid "St. Paul the Apostle" Airport | Ohrid, North Macedonia | | |
| OHE | ZYMH | Mohe Gulian Airport | Mohe, Heilongjiang, China | | |
| OHH | UHSH | Okha Airport (Novostroyka Airport) | Okha, Sakhalin Oblast, Russia | | |
| OHI | FYOS | Oshakati Airport [1] | Oshakati, Namibia | | |
| OHO | UHOO | Okhotsk Airport | Okhotsk, Khabarovsk Krai, Russia | | |
| OHR | EDXY | Wyk auf Föhr Airport [1] | Wyk auf Föhr, Schleswig-Holstein, Germany | | |
| OHS | OOSH | Sohar Airport [1] | Sohar, Oman | | |
| OHT | OPKT | PAF Base Kohat | Kohat, Pakistan | | |
| -OI- |
|---|
| OIA | SDOW | Ourilândia do Norte Airport [1] | Ourilândia do Norte, Pará, Brazil | | |
| OIC | KOIC | Lt. Warren Eaton Airport | Norwich, New York, United States | | |
| OIM | RJTO | Oshima Airport [1] | Ōshima, Izu Islands, Japan | | |
| OIR | RJEO | Okushiri Airport | Okushiri, Okushiri Island, Japan | | |
| OIT | RJFO | Oita Airport | Oita, Kyushu, Japan | | |
| -OJ- |
|---|
| OJC | KOJC | Johnson County Executive Airport | Olathe, Kansas, United States | | |
| OJU | | Tanjung Api Airport | Ampana, Tojo Una-Una Regency, Central Sulawesi, Indonesia | | |
| -OK- |
|---|
| OKA | ROAH | Naha Airport | Okinawa, Ryukyu Islands, Japan | | |
| OKB | YORC | Orchid Beach Airport | Fraser Island, Queensland, Australia | | |
| OKC | KOKC | Will Rogers World Airport | Oklahoma City, Oklahoma, United States | | |
| OKD | RJCO | Okadama Airport [1] | Sapporo, Hokkaido, Japan | | |
| OKE | RJKB | Okinoerabu Airport [1] | Okinoerabujima, Amami Islands, Japan | | |
| OKF | FYOO | Okaukuejo Airport [1] | Okaukuejo, Namibia | | |
| OKG | | Okoyo Airport [1] | Okoyo, Republic of the Congo | | |
| OKH | EGXJ | RAF Cottesmore | Oakham, England, United Kingdom | | |
| OKI | RJNO | Oki Airport [1] | Dogo, Oki Islands, Japan | | |
| OKJ | RJOB | Okayama Airport | Okayama, Honshu, Japan | | |
| OKK | KOKK | Kokomo Municipal Airport | Kokomo, Indiana, United States | | |
| OKL | WAJO | Gunung Bintang Airport | Oksibil, Indonesia | | |
| OKM | KOKM | Okmulgee Regional Airport | Okmulgee, Oklahoma, United States | | |
| OKN | FOGQ | Okondja Airport [1] | Okondja, Gabon | | |
| OKO | RJTY | Yokota Air Base [1] | Fussa, Honshu, Japan | | |
| OKP | AYOJ | Oksapmin Airport [1] | Oksapmin, Papua New Guinea | | |
| OKQ | WAKO | Okaba Airport [1] | Okaba, Indonesia | | |
| OKR | YYKI | Yorke Island Airport [1] | Yorke Island, Queensland, Australia | | |
| OKS | KOKS | Garden County Airport | Oshkosh, Nebraska, United States | | |
| OKT | UWUK | Oktyabrsky Airport | Oktyabrsky, Bashkortostan, Russia | | |
| OKU | FYMO | Mokuti Lodge Airport [1] | Mokuti Lodge, Namibia | | |
| OKV | | Okao Airport [1] | Okao, Papua New Guinea | | |
| OKY | YBOK | Oakey Army Aviation Centre [1] | Oakey, Queensland, Australia | | |
| -OL- |
|---|
| OLA | ENOL | Ørland Airport [1] | Ørland, Norway | | |
| OLB | LIEO | Olbia Costa Smeralda Airport | Olbia, Sardinia, Italy | | |
| OLC | SDCG | Senadora Eunice Michiles Airport [1] | São Paulo de Olivença, Amazonas, Brazil | | |
| OLD | KOLD | Old Town Municipal Airport and Seaplane Base (Dewitt Field) | Old Town, Maine, United States | | |
| OLE | KOLE | Cattaraugus County-Olean Airport | Olean, New York, United States | | |
| OLF | KOLF | L. M. Clayton Airport | Wolf Point, Montana, United States | | |
| OLH | | Old Harbor Airport (FAA: 6R7) | Old Harbor, Alaska, United States | | |
| OLI | BIRF | Rif Airport [1] | Ólafsvík, Iceland | | |
| OLJ | NVSZ | Olpoi Airport [1] (North West Santo Airport) | Olpoi, Vanuatu | | |
| OLK | SGOL | Fuerte Olimpo Airport | Fuerte Olimpo, Paraguay | | |
| OLL | | Oyo Ollombo Airport | Oyo, Republic of the Congo | | |
| OLM | KOLM | Olympia Regional Airport | Olympia, Washington, United States | | |
| OLN | SAVM | Lago Musters Airport [1] | Sarmiento, Chubut, Argentina | | |
| OLO | LKOL | Olomouc Airport (Neředín Airport) | Olomouc, Czech Republic | | |
| OLP | YOLD | Olympic Dam Airport [1] | Olympic Dam, South Australia, Australia | | |
| OLQ | | Olsobip Airport [1] | Olsobip, Papua New Guinea | | |
| OLR | OASL | Forward Operating Base Salerno | Khost, Afghanistan | | |
| OLS | KOLS | Nogales International Airport | Nogales, Arizona, United States | | |
| OLU | KOLU | Columbus Municipal Airport | Columbus, Nebraska, United States | | |
| OLV | KOLV | Olive Branch Airport | Olive Branch, Mississippi, United States | | |
| OLX | | Olkiombo Airstrip [1] | Olkiombo, Kenya | | |
| OLY | KOLY | Olney-Noble Airport | Olney / Noble, Illinois, United States | | |
| OLZ | UEMO | Olyokminsk Airport | Olyokminsk, Yakutia, Russia | | |
| -OM- |
|---|
| OMA | KOMA | Eppley Airfield | Omaha, Nebraska, United States | | |
| OMB | FOOH | Omboué Hospital Airport [1] | Omboué, Gabon | | |
| OMC | RPVO | Ormoc Airport | Ormoc, Philippines | | |
| OMD | FYOG | Oranjemund Airport [1] | Oranjemund, Namibia | | |
| OME | PAOM | Nome Airport | Nome, Alaska, United States | | |
| OMF | OJMF | King Hussein Air Base | Mafraq, Jordan | | |
| OMG | FYOE | Omega Airport [1] | Omega, Namibia | | |
| OMH | OITR | Urmia Airport [1] | Urmia (Urūmiyeh), Iran | | |
| OMI | OIAJ | Omidiyeh Air Base | Omidiyeh, Iran | | |
| OMJ | RJDU | Ōmura Airport [1] | Nagasaki / Ōmura, Kyushu, Japan | | |
| OMK | KOMK | Omak Airport | Omak, Washington, United States | | |
| OML | | Omkalai Airport [1] | Omkalai, Papua New Guinea | | |
| OMM | OOMX | Marmul Airport [1] | Marmul, Oman | | |
| OMN | | Zomin Airport [1] | Zomin, Uzbekistan | | |
| OMO | LQMO | Mostar Airport | Mostar, Bosnia and Herzegovina | | |
| OMR | LROD | Oradea International Airport | Oradea, Romania | | |
| OMS | UNOO | Omsk Tsentralny Airport | Omsk, Omsk Oblast, Russia | | |
| OMY | | Thbeng Meanchey Airport [1] (Preah Vinhear Airport) | Phnom Tbeng Meanchey, Cambodia | | |
| -ON- |
|---|
| ONA | KONA | Winona Municipal Airport (Max Conrad Field) | Winona, Minnesota, United States | | |
| ONB | AYQQ | Ononge Airport [1] | Ononge, Papua New Guinea | | |
| OND | FYOA | Ondangwa Airport [1] | Ondangwa, Namibia | | |
| ONE | | Onepusu Airport [1] | Onepusu, Solomon Islands | | |
| ONG | YMTI | Mornington Island Airport [1] | Mornington Island, Queensland, Australia | | |
| ONH | | Oneonta Municipal Airport (FAA: N66) | Oneonta, New York, United States | | |
| ONI | WABD | Moanamani Airport [1] | Moanemani (Moanamani), Indonesia | | |
| ONJ | RJSR | Odate–Noshiro Airport | Ōdate / Noshiro, Honshu, Japan | | |
| ONK | UERO | Olenyok Airport | Olenyok, Yakutia, Russia | | |
| ONL | KONL | O'Neill Municipal Airport (John L. Baker Field) | O'Neill, Nebraska, United States | | |
| ONM | KONM | Socorro Municipal Airport | Socorro, New Mexico, United States | | |
| ONO | KONO | Ontario Municipal Airport | Ontario, Oregon, United States | | |
| ONP | KONP | Newport Municipal Airport | Newport, Oregon, United States | | |
| ONQ | LTAS | Zonguldak Airport | Zonguldak, Turkey | | |
| ONR | YMNK | Monkira Airport [1] | Monkira, Queensland, Australia | | |
| ONS | YOLW | Onslow Airport [1] | Onslow, Western Australia, Australia | | |
| ONT | KONT | Ontario International Airport | Ontario, California, United States | | |
| ONU | NFOL | Ono-i-Lau Airport [1] | Ono-i-Lau, Fiji | | |
| ONX | MPEJ | Enrique Adolfo Jiménez Airport | Colón, Panama | | |
| ONY | KONY | Olney Municipal Airport | Olney, Texas, United States | | |
| -OO- |
|---|
| OOA | KOOA | Oskaloosa Municipal Airport | Oskaloosa, Iowa, United States | | |
| OOK | PAOO | Toksook Bay Airport | Toksook Bay, Alaska, United States | | |
| OOL | YBCG | Gold Coast Airport (Coolangatta Airport) | Gold Coast, Queensland, Australia | | |
| OOM | YCOM | Cooma–Snowy Mountains Airport [1] | Cooma, New South Wales, Australia | | |
| OOR | YMOO | Mooraberree Airport [1] | Mooraberree, Queensland, Australia | | |
| OOT | NGON | Onotoa Airport [1] | Onotoa, Kiribati | | |
| -OP- |
|---|
| OPA | BIKP | Kópasker Airport [1] | Kópasker, Iceland | | |
| OPB | | Open Bay Airport [1] | Open Bay, Papua New Guinea | | |
| OPF | KOPF | Miami-Opa Locka Executive Airport | Miami, Florida, United States | | |
| OPI | YOEN | Oenpelli Airport [1] | Gunbalanya (Oenpelli), Northern Territory, Australia | | |
| OPL | KOPL | St. Landry Parish Airport (Ahart Field) | Opelousas, Louisiana, United States | | |
| OPO | LPPR | Francisco de Sá Carneiro Airport | Porto, Portugal | | |
| OPS | SWSI | Presidente João Figueiredo Airport | Sinop, Mato Grosso, Brazil | | |
| OPU | AYBM | Balimo Airport [1] | Balimo, Papua New Guinea | | |
| OPW | FYOP | Opuwa Airport [1] | Opuwo, Namibia | | |
| -OR- |
|---|
| ORA | SASO | Orán Airport | Orán, Salta, Argentina | | |
| ORB | ESOE | Örebro Airport | Örebro, Sweden | | |
| ORC | SKOE | Orocue Airport [1] | Orocué, Colombia | | |
| ORD | KORD | O'Hare International Airport | Chicago, Illinois, United States | UTC−06:00 | Mar-Nov |
| ORE | LFOZ | Orléans – Saint-Denis-de-l'Hôtel Airport [1] | Orléans, Centre-Val de Loire, France | | |
| ORF | KORF | Norfolk International Airport | Norfolk, Virginia, United States | | |
| ORG | SMZO | Zorg en Hoop Airport | Paramaribo, Suriname | | |
| ORH | KORH | Worcester Regional Airport | Worcester, Massachusetts, United States | | |
| ORI | KORI | Port Lions Airport | Port Lions, Alaska, United States | | |
| ORJ | SYOR | Orinduik Airport | Orinduik, Guyana | | |
| ORK | EICK | Cork Airport | Cork, Ireland | | |
| ORL | KORL | Orlando Executive Airport | Orlando, Florida, United States | | |
| ORM | EGBK | Sywell Aerodrome | Northampton, England, United Kingdom | | |
| ORN | DAOO | Oran Es Sénia Airport | Oran, Algeria | | |
| ORO | MHYR | Yoro Airport [1] | Yoro, Honduras | | |
| ORP | FBOR | Orapa Airport [1] | Orapa, Botswana | | |
| ORR | YYOR | Yorketown Airport | Yorketown, South Australia, Australia | | |
| ORS | | Orpheus Island Resort Waterport | Orpheus Island, Queensland, Australia | | |
| ORT | PAOR | Northway Airport | Northway, Alaska, United States | | |
| ORU | SLOR | Juan Mendoza Airport | Oruro, Bolivia | | |
| ORV | PFNO | Robert (Bob) Curtis Memorial Airport (FAA: D76) | Noorvik, Alaska, United States | | |
| ORW | OPOR | Ormara Airport [1] | Ormara, Pakistan | | |
| ORX | SNOX | Oriximiná Airport [1] | Oriximiná, Pará, Brazil | | |
| ORY | LFPO | Orly Airport | Paris, Île-de-France, France | | |
| ORZ | MZTH | Orange Walk Airport [1] | Orange Walk Town, Belize | | |
| -OS- |
|---|
| OSA [1] | | metropolitan area 1 | Osaka, Honshu, Japan | | |
| OSB | | Grand Glaize-Osage Beach Airport (FAA: K15) | Osage Beach, Missouri, United States | | |
| OSC | KOSC | Oscoda–Wurtsmith Airport | Oscoda, Michigan, United States | | |
| OSD | ESNZ | Åre Östersund Airport | Östersund, Sweden | | |
| OSE | | Omora Airport [1] | Omora, Papua New Guinea | | |
| OSF | UUMO | Ostafyevo International Airport | Moscow / Podolsk, Moscow Oblast, Russia | | |
| OSG | | Ossima Airport [1] | Ossima, Papua New Guinea | | |
| OSH | KOSH | Wittman Regional Airport | Oshkosh, Wisconsin, United States | | |
| OSI | LDOS | Osijek Airport | Osijek, Croatia | | |
| OSK | ESMO | Oskarshamn Airport | Oskarshamn, Sweden | | |
| OSL | ENGM | Oslo Airport, Gardermoen | Oslo, Norway | | |
| OSM | ORBM | Mosul International Airport [1] | Mosul, Iraq | | |
| OSN | RKSO | Osan Air Base [1] | Osan, South Korea | | |
| OSO | YOSB | Osborne Mine Airport [1] | Osborne Mine, Queensland, Australia | | |
| OSR | LKMT | Leoš Janáček Airport Ostrava | Ostrava, Czech Republic | | |
| OSS | UAFO | Osh Airport | Osh, Kyrgyzstan | | |
| OST | EBOS | Ostend–Bruges International Airport | Ostend / Bruges, Belgium | | |
| OSU | KOSU | Ohio State University Airport | Columbus, Ohio, United States | | |
| OSW | UWOR | Orsk Airport | Orsk, Orenburg Oblast, Russia | | |
| OSX | KOSX | Kosciusko-Attala County Airport | Kosciusko, Mississippi, United States | | |
| OSY | ENNM | Namsos Airport, Høknesøra | Namsos, Norway | | |
| OSZ | EPKZ | Koszalin-Zegrze Pomorskie Airport [1] | Koszalin, Poland | | |
| -OT- |
|---|
| OTA | | Mota Airport [1] | Mota, Ethiopia | | |
| OTC | FTTL | Bol-Bérim Airport | Bol, Chad | | |
| OTD | | Contadora Airport | Contadora Island, Panama | | |
| OTG | KOTG | Worthington Municipal Airport | Worthington, Minnesota, United States | | |
| OTH | KOTH | Southwest Oregon Regional Airport | North Bend, Oregon, United States | | |
| OTI | WAMR | Pitu Airport [1] | Morotai Island, Indonesia | | |
| OTJ | FYOW | Otjiwarongo Airport [1] | Otjiwarongo, Namibia | | |
| OTK | KTMK | Tillamook Airport [1] (FAA: TMK) | Tillamook, Oregon, United States | | |
| OTL | GQNB | Boutilimit Airport | Boutilimit, Mauritania | | |
| OTM | KOTM | Ottumwa Regional Airport | Ottumwa, Iowa, United States | | |
| OTN | | Ed-Air Airport (FAA: 2IG4) | Oaktown, Indiana, United States | | |
| OTP | LROP | Henri Coandă International Airport | Bucharest, Romania | | |
| OTR | MRCC | Coto 47 Airport | Coto 47, Costa Rica | | |
| OTS | | Anacortes Airport (FAA: 74S) | Anacortes, Washington, United States | | |
| OTT | | Andre Maggi Airport [1] | Cotriguaçu, Mato Grosso, Brazil | | |
| OTU | SKOT | Otú Airport [1] | Remedios, Colombia | | |
| OTV | AGGQ | Ontong Java Airport [1] | Ontong Java Atoll, Solomon Islands | | |
| OTY | | Oria Airport [1] | Oria, Papua New Guinea | | |
| OTZ | PAOT | Ralph Wien Memorial Airport | Kotzebue, Alaska, United States | | |
| -OU- |
|---|
| OUA | DFFD | Ouagadougou Airport | Ouagadougou, Burkina Faso | | |
| OUD | GMFO | Angads Airport | Oujda, Morocco | | |
| OUE | FCOU | Ouésso Airport [1] | Ouésso, Republic of the Congo | | |
| OUG | DFCC | Ouahigouya Airport | Ouahigouya, Burkina Faso | | |
| OUH | FAOH | Oudtshoorn Airport [1] | Oudtshoorn, South Africa | | |
| OUK | | Out Skerries Airport [1] | Out Skerries, Scotland, United Kingdom | | |
| OUL | EFOU | Oulu Airport | Oulu, Finland | | |
| OUM | | Oum Hadjer Airport | Oum Hadjer, Chad | | |
| OUN | KOUN | University of Oklahoma Westheimer Airport (Max Westheimer Airport) | Norman, Oklahoma, United States | | |
| OUR | FKKI | Batouri Airport | Batouri, Cameroon | | |
| OUS | SDOU | Jornalista Benedito Pimentel–Ourinhos State Airport [1] | Ourinhos, São Paulo, Brazil | | |
| OUT | FTTS | Bousso Airport | Bousso, Chad | | |
| OUU | | Ouanga Airport [1] | Ouanga, Gabon | | |
| OUZ | GQPZ | Tazadit Airport | Zouerate, Mauritania | | |
| -OV- |
|---|
| OVA | FMSL | Bekily Airport [1] | Bekily, Madagascar | | |
| OVB | UNNT | Tolmachevo Airport | Novosibirsk, Novosibirsk Oblast, Russia | | |
| OVD | LEAS | Asturias Airport (Oviedo Airport) | Oviedo, Asturias, Spain | | |
| OVE | KOVE | Oroville Municipal Airport | Oroville, California, United States | | |
| OVG | FAOB | Air Force Base Overberg [1] | Bredasdorp, South Africa | | |
| OVL | SCOV | El Tuqui Airport [1] | Ovalle, Chile | | |
| OVR | SAZF | Olavarría Airport | Olavarría, Buenos Aires, Argentina | | |
| OVS | USHS | Sovetsky Airport | Sovetsky, Khanty-Mansi Autonomous Okrug, Russia | | |
| -OW- |
|---|
| OWA | KOWA | Owatonna Degner Regional Airport | Owatonna, Minnesota, United States | | |
| OWB | KOWB | Owensboro–Daviess County Airport | Owensboro, Kentucky, United States | | |
| OWD | KOWD | Norwood Memorial Airport | Norwood, Massachusetts, United States | | |
| OWK | KOWK | Central Maine Airport of Norridgewock | Norridgewock, Maine, United States | | |
| -OX- |
|---|
| OXB | GGOV | Osvaldo Vieira International Airport | Bissau, Guinea-Bissau | | |
| OXC | KOXC | Waterbury–Oxford Airport | Oxford, Connecticut, United States | | |
| OXD | KOXD | Miami University Airport | Oxford, Ohio, United States | | |
| OXF | EGTK | Oxford Airport (London Oxford Airport) | Oxford, England, United Kingdom | | |
| OXO | | Orientos Airport [1] | Orientos, Queensland, Australia | | |
| OXR | KOXR | Oxnard Airport | Oxnard, California, United States | | |
| OXY | YMNY | Morney Airport [1] | Morney, Queensland, Australia | | |
| -OY- |
|---|
| OYA | SATG | Goya Airport [1] | Goya, Corrientes, Argentina | | |
| OYE | FOGO | Oyem Airport [1] | Oyem, Gabon | | |
| OYG | | Moyo Airport [1] | Moyo Town, Uganda | | |
| OYK | SBOI | Oiapoque Airport | Oiapoque, Amapá, Brazil | | |
| OYL | HKMY | Moyale Airport [1] | Moyale, Kenya | | |
| OYN | YOUY | Ouyen Airport [1] | Ouyen, Victoria, Australia | | |
| OYO | SAZH | Tres Arroyos Airport | Tres Arroyos, Buenos Aires, Argentina | | |
| OYP | SOOG | Saint-Georges-de-l'Oyapock Airport [1] | Saint-Georges-de-l'Oyapock, French Guiana | | |
| -OZ- |
|---|
| OZA | KOZA | Ozona Municipal Airport | Ozona, Texas, United States | | |
| OZC | RPMO | Labo Airport | Ozamiz, Philippines | | |
| OZG | GMAZ | Zagora Airport [1] | Zagora, Morocco | | |
| OZH | UKDE | Zaporizhzhia International Airport | Zaporizhzhia, Ukraine | | |
| OZP | LEMO | Morón Air Base [1] | Morón de la Frontera, Andalusia, Spain | | |
| OZR | KOZR | Cairns Army Airfield | Fort Novosel / Ozark, Alabama, United States | | |
| OZZ | GMMZ | Ouarzazate Airport | Ouarzazate, Morocco | | |