| 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 | UTC+02:00 | Mar-Oct |
| 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 | UTC+01:00 | Mar-Oct |
| OBO | RJCB | Tokachi–Obihiro Airport | Obihiro,Hokkaido, Japan | UTC+09:00 | |
| OBS | LFHO | Aubenas Aerodrome[1] (Ardèche Méridionale Aerodrome) | Aubenas,Rhône-Alpes, France | UTC+02:00 | Mar-Oct |
| 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 | UTC+02:00 | Mar-Oct |
| 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 | UTC+01:00 | Mar-Oct |
| 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 | UTC+09:00 | |
| 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 | UTC+08:00 | |
| 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 | UTC+02:00 | Mar-Oct |
| 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 | UTC+09:00 | |
| OIR | RJEO | Okushiri Airport | Okushiri,Okushiri Island, Japan | UTC+09:00 | |
| OIS | UDGS | Goris Airport | Shinuhayr, Armenia | | |
| OIT | RJFO | Oita Airport | Oita,Kyushu, Japan | UTC+09:00 | |
| -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 | UTC+09:00 | |
| 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 | UTC+09:00 | |
| OKE | RJKB | Okinoerabu Airport[1] | Okinoerabujima,Amami Islands, Japan | UTC+09:00 | |
| OKF | FYOO | Okaukuejo Airport[1] | Okaukuejo,Namibia | | |
| OKG | | Okoyo Airport[1] | Okoyo,Republic of the Congo | | |
| OKH | EGXJ | RAF Cottesmore | Oakham,England, United Kingdom | UTC+01:00 | Mar-Oct |
| OKI | RJNO | Oki Airport[1] | Dogo,Oki Islands, Japan | UTC+09:00 | |
| OKJ | RJOB | Okayama Airport | Okayama,Honshu, Japan | UTC+09:00 | |
| 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 | UTC+09:00 | |
| 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 | UTC+09:00 | |
| 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 | UTC+09:00 | |
| 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 | UTC+02:00 | Mar-Oct |
| 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 | UTC+01:00 | Mar-Oct |
| 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 | UTC+02:00 | Mar-Oct |
| ORZ | MZTH | Orange Walk Airport[1] | Orange Walk Town,Belize | | |
| -OS- |
|---|
| OSA[1] | | metropolitan area1 | 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 | UTC+01:00 | Mar-Oct |
| 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 | UTC+02:00 | Mar-Oct |
| 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 | UTC+01:00 | Mar-Oct |
| 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 | UTC+02:00 | Mar-Oct |
| OZR | KOZR | Cairns Army Airfield | Fort Novosel /Ozark,Alabama, United States | | |
| OZZ | GMMZ | Ouarzazate Airport | Ouarzazate,Morocco | | |
