| 1 | IA | Iraqi Airways | ICAO: IAW, Callsign: Iraqi, IATA Prefix: 073, Founded in 1945 | IRQ | AVCODES |
| 2 | IA | Iraqi Airways | Callsign: Iraqair, ICAO callsign changed to Iraqi | IRQ | AVCODES |
| 3 | IA | Macair Jet S.A. | ICAO: MCJ, Callsign: Jetmac, IATA Prefix: 177, IATA designator changed to A0. Designator VM recalled by IATA. | RA | AVCODES |
| 4 | IAA | PT Indonesian Airlines Av iapatria | IATA: IO, Callsign: Indo Lines, | RI | AVCODES |
| 5 | IAA | Inex Adria Aviopromet | IATA: JP, Callsign: Juliett Papa, | YU | AVCODES |
| 6 | IAA | Indonesian Airlines | IATA: IO | | ICAO1 |
| 7 | IAAC | Irish Army Air Corps | 1920 - 1997 | IRL | TRAFFIC |
| 8 | IAAU | INTERASIA LINES SINGAPORE PTE.LTD | | SGP | BIC |
| 9 | IAAU | INTERASIA LINES LTD | | | SCAC4 |
| 10 | IAAW | INTERNATIONAL PAPER-LAURENS CONTAIN | | | SCAC4 |
| 11 | IAB | Infinity Asia Co., Ltd | Callsign: Infinity Air, | T | AVCODES |
| 12 | IABA | INTER AMERICAN BUILDERS AGENCIES CO | | | SCAC4 |
| 13 | IAC | Indian Airlines Corporation | IATA: IC, Callsign: Indair, IATA Prefix: 058, Name changed to NACIL d/b/a Indian Airlines. | IND | AVCODES |
| 14 | IAC | NACIL d/b/a Indian Airlines | IATA: IC, Callsign: Indair, IATA Prefix: 058, Meregd into Air India. Name changed from Indian Airlines Corporation. | IND | AVCODES |
| 15 | IAC | Interaviation Charter | Callsign: Intercharter, | RO | AVCODES |
| 16 | IAC | Ibex Air Charter | Callsign: Ibex Airlines, | RL | AVCODES |
| 17 | IAC | Indian Airlines | IATA: IC | | ICAO1 |
| 18 | IACA | BIG ACE TRUCKING INC | | | SCAC4 |
| 19 | IACB | INTRADECO APPAREL INC | | | SCAC4 |
| 20 | IACG | INSEL AIR CARGO | | | SCAC4 |
| 21 | IACN | INTER ACTION COURIER INTERNATIONAL | | | SCAC4 |
| 22 | IACT | INTERNATIONAL ACTIVITIES CORPORATIO | | | SCAC4 |
| 23 | IACU | I.A.C.C. INTERNATIONAL ASSOCIATED | | ET | BIC |
| 24 | IACU | I A C C | | | SCAC4 |
| 25 | IACX | Canadian Industrial Alcohol Co., Ltd. | 7/1930-7/1932 | | NAKINA |
| 26 | IACX | CANADIAN INDUSTRIAL ALCOHOL CO., LTD. | | | PWRC |
| 27 | IAD | Airday Srl | IATA: 7S, Callsign: Airday, IATA designator changed to IM* | I | AVCODES |
| 28 | IAD | Airday Srl | IATA: IM, Callsign: Airday, Name changed to Fly Wez Srl. IATA designator changed from 7S | I | AVCODES |
| 29 | IAD | Fly Wex Srl | IATA: IM, Callsign: Flywex, Desigantor IM* recalled by IATA. Name changed from Airday Srl | I | AVCODES |
| 30 | IAD | Air Asia (India) Private Limited t/a AirAsia India | IATA: I5, Callsign: Ariya, Founded on 28 March 2013. Commenced operations on 12 June 2014. Name changed to Air Asia (India) Ltd. ICAO callsign changed to Red Knight. | IND | AVCODES |
| 31 | IAD | Air Asia (India) Ltd. t/a AirAsia India | IATA: I5, Callsign: Red Knight, Founded on 28 March 2013. Commenced operations on 12 June 2014. Name changed from Air Asia (India) Private Limited. ICAO callsign changed from Ariya. | IND | AVCODES |
| 32 | IAD | AIX Connect Private Limited t/a AirAsia India | IATA: I5, Callsign: Red Knight, Founded on 28 March 2013. Commenced operations on 12 June 2014. Name changed from Air Asia (India) Private Limited. ICAO callsign changed from Ariya. | IND | AVCODES |
| 33 | IAD | Fly Wex | | | ICAO1 |
| 34 | IAE | Interstate Airlines Limited | Callsign: Interstate, | WAN | AVCODES |
| 35 | IAE | AC Insat-Aero Ltd | | RUS | AVCODES |
| 36 | IAE | Closed Joint Stock Company IrAero | IATA: IO, Callsign: IrAero, | RUS | AVCODES |
| 37 | IAE | AC Insat-Aero | | | ICAO1 |
| 38 | IAEC | INFINITY AUTO EXPRESS INC | | | SCAC4 |
| 39 | IAED | IOWA EXPRESS FREIGHTWAYS, INC | | | SCAC1 |
| 40 | IAEI | I A E ENTERPRISES INC | | | SCAC4 |
| 41 | IAEP | INTER AMERICAN EXPRESS | | | SCAC4 |
| 42 | IAF | Israeli Air Force | | IL | AVCODES |
| 43 | IAF | Israeli Air Force | | | ICAO1 |
| 44 | IAF | Indian Air Force | | IND | TRAFFIC |
| 45 | IAFC | IMPORTED ARTISTS FILM COMPANY | | | SCAC4 |
| 46 | IAFE | | | YV | TRAFFIC |
| 47 | IAG | EPAG Groupe Air France | | | ICAO1 |
| 48 | IAGA | INAGUA LINES, INC. | | | SCAC1 |
| 49 | IAGA | INAGUA LINES INC | | | SCAC4 |
| 50 | IAGS | INTERMARE AGENCY SERVICES INC | | | SCAC4 |
| 51 | IAH | Island Airlines Hawaii | Callsign: Alakai, | USA | AVCODES |
| 52 | IAI | Israel Aircraft Industries Ltd. | Callsign: Israel Aircraft, Designator BK recalled by IATA | IL | AVCODES |
| 53 | IAI | Israel Aircraft Industries Ltd. | IATA: BK, Callsign: Bravo Kilo, Designator BK recalled by IATA. ICAO callsign changed to Israel Aircraft | IL | AVCODES |
| 54 | IAI | Israel Aircraft Industries | | | ICAO1 |
| 55 | IAIL | INNERSYSTEMS AUTOMOTIVE INC | | | SCAC4 |
| 56 | IAIN | IBC AIRWAYS INC | | | SCAC4 |
| 57 | IAIS | Iowa Interstate R.R., Ltd. | added 1/1985; 1/1994-7/2005 | | NAKINA |
| 58 | IAIS | Iowa Interstate R.R., Ltd. | added 1/85; 1/94-7/2000 | | NRHS |
| 59 | IAIS | IOWA INTERSTATE RAILROAD, LTD. | | | PWRC |
| 60 | IAIS | Iowa Interstate Railroad | | | RSRV |
| 61 | IAIS | Iowa Interstate | | USA | TRAFFIC |
| 62 | IAIU | Intertronic Solutions | | | RSRV |
| 63 | IAJ | Islandair Jersey Limited | Callsign: Jarland, | GB | AVCODES |
| 64 | IAJ | Islandair Jersey | | | ICAO1 |
| 65 | IAK | International Air Cargo Corporation (IACC) | Callsign: Air Cargo Egypt, Desginator CC recalled by IATA | ET | AVCODES |
| 66 | IAK | International Air Cargo Corporation (IACC) | IATA: CC, Callsign: Air Cargo Egypt, Desginator CC recalled by IATA | ET | AVCODES |
| 67 | IAK | International Air Cargo Corporation | | | ICAO1 |
| 68 | IAL | International Aeradio Plc. | Callsign: Aeradio, Desigantor XI recalled by IATA | GB | AVCODES |
| 69 | IAL | International Aeradio Plc. | IATA: XI, Callsign: Aeradio, Desigantor XI recalled by IATA | GB | AVCODES |
| 70 | IALC | I AM LOGISTICS INC | | | SCAC4 |
| 71 | IALD | INTERNATIONAL DISTRIBUTION SERVICES | | | SCAC4 |
| 72 | IALI | INTERNATIONAL ANGELS INC | | | SCAC4 |
| 73 | IALT | INTERCAL ASPHALT PRODUCTS INC | | | SCAC4 |
| 74 | IALU | JAPAN LINE, LTD | | | PWRC |
| 75 | IALU | Japan Line | | | RSRV |
| 76 | IAM | ARA Flugrettungs GmbH | Callsign: ARA-Ambulance, | A | AVCODES |
| 77 | IAM | Aeronautica Militare Italiana | Callsign: Italian Airforce, | I | AVCODES |
| 78 | IAME | INTERAMERICA | | | SCAC4 |
| 79 | IAMU | IAL SHIPPING AGENCY (S) PTE LTD | | | SCAC4 |
| 80 | IAN | Compania Interandina de Aviacion | Callsign: Interandes, | CO | AVCODES |
| 81 | IAN | Inter Aviation | Callsign: Interav, | RO | AVCODES |
| 82 | IAN | Ibom Airlines Limited | IATA: QI, Callsign: Ibom, | WAN | AVCODES |
| 83 | IANI | IAN INTERNATIONAL INC | | | SCAC4 |
| 84 | IANR | Iowa Northern Ry. | added 1/1982; 1/1994-7/2005 | | NAKINA |
| 85 | IANR | Iowa Northern Ry. | added 1/82; 1/94-7/2000 | | NRHS |
| 86 | IANR | IOWA NORTHERN RAILWAY CO. | | | PWRC |
| 87 | IANR | Iowa Northern Railway | | | RSRV |
| 88 | IANR | Iowa Northern Railway Co. | | USA | TRAFFIC |
| 89 | IANW | Iowa Northwestern R.R. | added 7/2003; 7/2005; eliminated 7/2005 | | NAKINA |
| 90 | IANW | IOWA NORTHWESTERN RAILROAD | | | PWRC |
| 91 | IANW | IOWA NORTHWESTERN RAILROAD | | | SCAC4 |
| 92 | IAP | Internacional de Aviacion, S.A. | IATA: IX, Callsign: Inair, | PA | AVCODES |
| 93 | IAPP | INDUSTRIAS APPAREL SA DE CV | | | SCAC4 |
| 94 | IAPU | HOLIDAY ON ICE PRODUCTIONS BV | | NL | BIC |
| 95 | IAPU | HOLIDAY ON ICE PRODUCTIONS BV | | | SCAC4 |
| 96 | IAPX | Air Liquide IC GP LLC d/b/a Air Liquide Industrial U.S. LP | added 7/2008 | | NAKINA |
| 97 | IAPX | Air Liquide America Corp. | added 1/1995; 7/2000-7/2005; eliminated 7/2008 | | NAKINA |
| 98 | IAPX | Liquid Air Corp. | added 1/1987; 1/1994; eliminated 1/1995 | | NAKINA |
| 99 | IAPX | Liquid Air, Inc. | added 10/1974; 1/1975-1/1980; eliminated 1/1987 | | NAKINA |
| 100 | IAPX | The Iowa Packing Co. | 7/1930 | | NAKINA |
