
| IAA | Igarka | Igarka | Russia |
| IAB | Wichita (KS) | Mcconnell AFB | USA |
| IAD | Washington, DC | Dulles International | USA |
| IAG | Niagara Falls (NY) | International | USA |
| IAH | Houston (TX) | George Bush Intercontinental | USA |
| IAM | In Amenas | In Amenas | Algeria |
| IAN | Kiana (AK) | Bob Barker Memorial | USA |
| IAQ | Bahregan | Bahregan | Iran |
| IAR | Yaroslavl | Yaroslavl | Russia |
| IAS | Iasi | Iasi | Romania |
| IAU | Iaura | Iaura | Papua New Guinea |
| IBA | Ibadan | Ibadan | Nigeria |
| IBE | Ibague | Ibague | Colombia |
| IBI | Iboki | Iboki | Papua New Guinea |
| IBO | Ibo | Ibo | Mozambique |
| IBP | Iberia | Iberia | Peru |
| IBZ | Ibiza | Ibiza | Balearic Islands, Spain |
| ICA | Icabaru | Icabaru | Venezuela |
| ICI | Cicia | Cicia | Fiji |
| ICK | Nieuw Nickerie | Nieuw Nickerie | Suriname |
| ICL | Clarinda IA | Municipal | USA |
| ICN | Seoul | Incheon International Airport | South Korea |
| ICO | Sicogon Island | Sicogon Island | Philippines |
| ICR | Nicaro | Nicaro | Cuba |
| ICT | Wichita (KS) | Mid-Continent | USA |
| ICY | Icy Bay (AK) | Icy Bay | USA |
| IDA | Idaho Falls (ID) | Fanning Field | USA |
| IDB | Idre | Idre | Sweden |
| IDF | Idiofa | Idiofa | Congo (DRC) |
| IDG | Ida Grove IA | Municipal | USA |
| IDI | Indiana (PA) | Indiana | USA |
| IDK | Indulkana | Indulkana | Australia |
| IDN | Indagen | Indagen | Papua New Guinea |
| IDO | Santa Isabel do Morro | Santa Isabel Do Morro | Brazil |
| IDP | Independence (KS) | Independence | USA |
| IDR | Indore | Indore | India |
| IDY | Ile d'Yeu | Ile d'Yeu | France |
| IEG | Zielona Gora | Babimost | Poland |
| IEJ | Iejima | Iejima | Japan |
| IES | Riesa | Riesa | Germany |
| IEV | Kiev | Zhulhany | Ukraine |
| IFA | Iowa Falls IA | Iowa Falls | USA |
| IFF | Iffley | Iffley | Australia |
| IFJ | Isafjordur | Isafjordur | Iceland |
| IFL | Innisfail | Innisfail | Australia |
| IFN | Isfahan | Isfahan | Iran |
| IFO | Ivano-Frankovsk | Ivano-Frankovsk | Ukraine |
| IFP | Bullhead City (AZ) | Laughlin Bullhead International | USA |
| IGA | Inagua | Inagua | Bahamas |
| IGB | Ingeniero Jacobacci | Ingeniero Jacobacci | Argentina |
| IGE | Iguela | Iguela | Gabon |
| IGG | Igiugig (AK) | Igiugig | USA |
| IGH | Ingham | Ingham | Australia |
| IGL | Izmir | Cigli Military Airport | Turkey |
| IGM | Kingman (AZ) | Kingman | USA |
| IGN | Iligan | Maria Cristina Airport | Philippines |
| IGO | Chigorodo | Chigorodo | Colombia |
| IGR | Iguazu | Cataratas | Argentina |
| IGU | Iguassu Falls | Cataratas | Brazil |
| IHA | Niihama | Niihama | Japan |
| IHN | Qishn | Qishn | Yemen |
| IHO | Ihosy | Ihosy | Madagascar |
| IHU | Ihu | Ihu | Papua New Guinea |
| IIA | Inishmaan | Inishmaan | Ireland |
| IIN | Nishinoomote | Nishinoomote | Japan |
| IIS | Nissan Island | Nissan Island | Papua New Guinea |
| IJK | Izhevsk | Izhevsk | Russia |
| IJU | Ijui | J.Batista Bos Filho | Brazil |
| IJX | Jacksonville (IL) | Municipal | USA |
| IKA | Tehran | Imam Khomeini International Airport | Iran |
| IKB | Wilkesboro (NC) | Wilkes County | USA |
| IKI | Iki | Iki | Japan |
| IKK | Kankakee (IL) | Greater Kankakee | USA |
| IKL | Ikela | Ikela | Congo (DRC) |
| IKO | Nikolski (AK) | Nikolski AFS | USA |
| IKP | Inkerman | Inkerman | Australia |
| IKS | Tiksi | Tiksi | Russia |
| IKT | Irkutsk | Irkutsk | Russia |
| ILA | Illaga | Illaga | Indonesia |
| ILB | Ilha Solteira | Ilha Solteira | Brazil |
| ILE | Killeen (TX) | Municipal | USA |
| ILF | Ilford | Ilford | Canada |
| ILG | Wilmington (DE) | Greater Wilmington | USA |
| ILH | Illisheim | Illis Airbase | Germany |
| ILI | Iliamna (AK) | Iliamna | USA |
| ILK | Ilaka | Ilaka | Madagascar |
| ILL | Willmar (MN) | Willmar | USA |
| ILM | Wilmington (NC) | New Hanover County | USA |
| ILN | Wilmington (OH) | Clinton Field | USA |
| ILO | Iloilo | Iloilo International Airport | Philippines |
| ILP | Ile Des Pins | Ile Des Pins | New Caledonia |
| ILQ | Ilo | Ilo | Peru |
| ILR | Ilorin | Ilorin | Nigeria |
| ILU | Kilaguni | Kilaguni | Kenya |
| ILX | Ileg | Ileg | Papua New Guinea |
| ILY | Islay | Glenegedale | United Kingdom |
| ILZ | Zilina | Zilina | Slovakia |
| IMA | Iamalele | Iamalele | Papua New Guinea |
| IMB | Imbaimadai | Imbaimadai | Guyana |
| IMD | Imonda | Imonda | Papua New Guinea |
| IMF | Imphal | Municipal | India |
| IMG | Inhaminga | Inhaminga | Mozambique |
| IMI | Ine Island | Ine Island | Marshall Islands |
| IMK | Simikot | Simikot | Nepal |
| IML | Imperial (NE) | Imperial | USA |
| IMM | Immokalee (FL) | Immokalee | USA |
| IMN | Imane | Imane | Papua New Guinea |
| IMO | Zemio | Zemio | Central African Republic |
| IMP | Imperatriz | Imperatriz | Brazil |
| IMT | Iron Mountain (MI) | Ford | USA |
| IMZ | Nimroz | Nimroz | Afghanistan |
| INA | Inta | Inta | Russia |
| INB | Independence | Independence | Belize |
| INC | Yinchuan | Yinchuan | PR China |
| IND | Indianapolis (IN) | Indianapolis International | USA |
| INE | Chinde | Chinde | Mozambique |
| INF | In Guezzam | In Guezzam | Algeria |
| ING | Lago Argentino | Lago Argentino | Argentina |
| INH | Inhambane | Inhambane | Mozambique |
| INI | Nis | Nis | Serbia |
| INJ | Injune | Injune | Australia |
| INK | Wink (TX) | Wink | USA |
| INL | International Falls (MN) | Falls International | USA |
| INM | Innamincka | Innamincka | Australia |
| INN | Innsbruck | Kranebitten | Austria |
| INO | Inongo | Inongo | Congo (DRC) |
| INQ | Inisheer | Inisheer | Ireland |
| INR | Sault Ste Marie (MI) | Kincheloe AFB | USA |
| INS | Indian Springs (NV) | Af Aux | USA |
| INT | Winston Salem (NC) | Smith-Reynolds | USA |
| INU | Nauru Island | Nauru International Airport | Nauru |
| INV | Inverness | Inverness | United Kingdom |
| INW | Winslow (AZ) | Winslow | USA |
| INX | Inanwatan | Inanwatan | Indonesia |
| INY | Inyati | Inyati | South Africa |
| INZ | In Salah | In Salah | Algeria |
| IOA | Ioannina | Ioannina | Greece |
| IOK | Iokea | Iokea | Papua New Guinea |
| IOM | Isle Of Man | Ronaldsway | United Kingdom |
| ION | Impfondo | Impfondo | Congo (ROC) |
| IOP | Ioma | Ioma | Papua New Guinea |
| IOR | Inishmore | Kilronan | Ireland |
| IOS | Ilheus | Eduardo Gomes | Brazil |
| IOU | Ile Ouen | Ile Ouen | New Caledonia |
| IOW | Iowa City IA | Iowa City | USA |
| IPA | Ipota | Ipota | Vanuatu |
| IPC | Easter Island | Mataveri International | Chile |
| IPE | Ipil | Ipil | Philippines |
| IPG | Ipiranga | Ipiranga | Brazil |
| IPH | Ipoh | Ipoh | Malaysia |
| IPI | Ipiales | San Luis | Colombia |
| IPL | Imperial (CA) | Imperial County Airport | USA |
| IPN | Ipatinga | Usiminas | Brazil |
| IPT | Williamsport (PA) | Lycoming County | USA |
| IPU | Ipiau | Ipiau | Brazil |
| IPW | Ipswich | Ipswich | United Kingdom |
| IQM | Qiemo | Qiemo | PR China |
| IQN | Qingyang | Qingyang | PR China |
| IQQ | Iquique | Cavancha | Chile |
| IQT | Iquitos | C.F. Secada | Peru |
| IRA | Kirakira | Kirakira | Solomon Islands |
| IRB | Iraan (TX) | Municipal | USA |
| IRC | Circle (AK) | Circle City | USA |
| IRD | Ishurdi | Ishurdi | Bangladesh |
| IRE | Irece | Irece | Brazil |
| IRG | Lockhart River | Lockhart River | Australia |
| IRI | Iringa | Nduli | Tanzania |
| IRJ | La Rioja | La Rioja | Argentina |
| IRK | Kirksville (MO) | Municipal | USA |
| IRN | Iriona | Iriona | Honduras |
| IRO | Birao | Birao | Central African Republic |
| IRP | Isiro | Matari | Congo (DRC) |
| IRS | Sturgis (MI) | Kirsch Municipal | USA |
| ISA | Mount Isa | Mount Isa | Australia |
| ISB | Islamabad | Islamabad International | Pakistan |
| ISC | Isles Of Scilly | St Marys | United Kingdom |
| ISD | Iscuande | Iscuande | Colombia |
| ISE | Isparta | Isparta | Turkey |
| ISG | Ishigaki | New Ishigaki Airport | Japan |
| Ischia | Elisuperficie (Giovanni Paolo 2°) Heliport | Italy | |
| ISI | Isisford | Isisford | Australia |
| ISJ | Isla Mujeres | Isla Mujeres | Mexico |
| ISK | Nasik | Gandhinagar Airport | India |
| ISL | Isabel Pass (AK) | Isabel Pass | USA |
| ISM | Kissimmee (FL) | Municipal | USA |
| ISN | Williston (ND) | Sloulin Field International | USA |
| ISO | Kinston (NC) | Stallings Field | USA |
| ISP | Islip (NY) | Long Island Macarthur | USA |
| ISQ | Manistique (MI) | Schoolcraft County | USA |
| ISS | Wiscasset (ME) | Wiscasset | USA |
| IST | Istanbul | Istanbul Atatürk Airport | Turkey |
| ISU | Sulaimaniyah | Sulaimaniyah International Airport | Kurdistan, Iraq |
| ISW | Wisconsin Rapids (WI) | Alexander Field | USA |
| ITA | Itacoatiara | Itacoatiara | Brazil |
| ITB | Itaituba | Itaituba | Brazil |
| ITE | Itubera | Itubera | Brazil |
| ITH | Ithaca (NY) | Tompkins County | USA |
| ITI | Itambacuri | Itambacuri | Brazil |
| ITK | Itokama | Itokama | Papua New Guinea |
| ITM | Osaka | Osaka-Itami International Airport | Japan |
| ITN | Itabuna | Itabuna | Brazil |
| ITO | Hilo (HI) | Hilo International | USA |
| ITP | Itaperuna | Itaperuna | Brazil |
| ITQ | Itaqui | Itaqui | Brazil |
| ITR | Itumbiara | Itumbiara | Brazil |
| IUE | Niue Island | Hanan | Niue |
| IUL | Ilu | Ilu | Indonesia |
| IUM | Summit Lake | Summit Lake | Canada |
| IUS | Inus | Inus | Papua New Guinea |
| IVA | Ambanja | Ambanja | Madagascar |
| IVC | Invercargill | Invercargill | New Zealand |
| IVG | Ivangrad (Berane) | Dolac Airport | Montenegro |
| IVH | Ivishak (AK) | Ivishak | USA |
| IVL | Ivalo | Ivalo | Finland |
| IVO | Chivolo | Chivolo | Colombia |
| IVR | Inverell | Inverell | Australia |
| IVW | Inverway | Inverway | Australia |
| IWA | Ivanova | Ivanova | Russia |
| IWD | Ironwood (MI) | Gogebic County | USA |
| IWJ | Iwami | Iwami | Japan |
| IWO | Iwo Jima | Iwo Jima Air Base | Japan |
| IWS | Houston (TX) | West Houston | USA |
| IXA | Agartala | Singerbhil | India |
| IXB | Bagdogra | Bagdogra | India |
| IXC | Chandigarh | Chandigarh | India |
| IXD | Allahabad | Bamrauli | India |
| IXE | Mangalore | Bajpe | India |
| IXG | Belgaum | Sambre | India |
| IXH | Kailashahar | Kailashahar | India |
| IXI | Lilabari | Lilabari | India |
| IXJ | Jammu | Satwari Airport | India |
| IXK | Keshod | Keshod | India |
| IXL | Leh | Leh | India |
| IXM | Madurai | Madurai | India |
| IXN | Khowai | Khowai | India |
| IXP | Pathankot | Pathankot | India |
| IXQ | Kamalpur | Kamalpur | India |
| IXR | Ranchi | Ranchi | India |
| IXS | Silchar | Kumbhirgram | India |
| IXT | Pasighat | Pasighat | India |
| IXU | Aurangabad | Chikkalthana | India |
| IXV | Along | Along | India |
| IXW | Jamshedpur | Sonari Airport | India |
| IXY | Kandla | Kandla | India |
| IXZ | Port Blair | Port Blair | India |
| IYK | Inyokern (CA) | Kern County | USA |
| IZM | Izmir | Izmir Metropolitan Area | Turkey |
| IZO | Izumo | Izumo | Japan |
| IZT | Ixtepec | Ixtepec | Mexico |