| 1 | IP | Atyrau Aue Joly | ICAO: JOL, Callsign: Edil, IATA Prefix: 312, On 13 July 2009, Atyrau Airways was included in the List of air carriers banned in the European Union. Shortly thereafter (in October 2009), its airline license was revoked. | KZ | AVCODES |
| 2 | IP | Inter European Airways Ltd. | ICAO: IEA, Callsign: Aspro, Merged into Airtours International Airways Ltd on 02 September 1993. | GB | AVCODES |
| 3 | IP | Airlines of Tasmania Pty Ltd. | ICAO: ATM, Callsign: Airtas, Designator IP recalled by IATA. ICAO designator changed from XAL | AUS | AVCODES |
| 4 | IP | Interregional Fluggesellschaft mbH | Callsign: Interregional, | D | AVCODES |
| 5 | IP | P.T. Pelita Air Service | ICAO: PAS, Callsign: Pelita, IATA Prefix: 019, Designator 6D recalled by IATA. IATA designator changed from 6D*. Designator 6D* reinstated by IATA | RI | AVCODES |
| 6 | IP | Unifly | Callsign: India Papa, Name changed to Unifly Srl | I | AVCODES |
| 7 | IP | Unifly Srl | ICAO: IPP, Callsign: India Papa, Name changed from Unifly | I | AVCODES |
| 8 | IP | Orbest Orizonia Airlines S.A. | ICAO: IWD, IATA Prefix: 560, Founded in 1998 as Iberworld. - Commenced operations on 11 April 1998. - Ceased operations on 05 May 2013. Name changed from Iberworld Airlines S.A.U. w.e.f. 01 May 2011. ORBEST is a member of the ORIZONIA CORPORACION group | E | AVCODES |
| 9 | IP | Apsara International Air Co. Ltd. | ICAO: AQQ, Callsign: Apsara, Founded in 2013. Commenced operations on 08 October 2014. Ceased operations. | K | AVCODES |
| 10 | IP | One Airlines S.p.A. | ICAO: ONS, Callsign: Air Dreams, Founded in July 2013. Commenced operations in October 2013. Ceased operations on 24 June 2020. | RCH | AVCODES |
| 11 | IPA | IPEC Aviation Pty. Ltd. | Callsign: IPEC, | AUS | AVCODES |
| 12 | IPA | IPEC Aviation | | | ICAO1 |
| 13 | IPA | IPA Ferroviaria S.p.a. | | I | TRAFFIC |
| 14 | IPAC | INDUSTRIAL PACKING INC | | | SCAC4 |
| 15 | IPAK | ICEPAK INC. | | | SCAC1 |
| 16 | IPAK | ICEPAK INC | | | SCAC4 |
| 17 | IPAP | INTERNATIONAL PAPER | | | SCAC4 |
| 18 | IPAU | INTELLIGENT PRIZE ARCHITECTURAL SOL | | | SCAC4 |
| 19 | IPBX | Innophos, Inc. | 7/2005; added 4/2006 | | NAKINA |
| 20 | IPBX | INNOPHOS, INC. | | | PWRC |
| 21 | IPBX | INNOPHOS Inc. | | | RSRV |
| 22 | IPBX | INNOPHOS INC | | | SCAC4 |
| 23 | IPC | Intercontinental Pacific Airways, Inc. | IATA: IS, Callsign: Interpac, IATA designator changed to IO | RP | AVCODES |
| 24 | IPC | Intercontinental Pacific Airways, Inc. | IATA: IO, Callsign: Interpac, IATA designator changed from IS* | RP | AVCODES |
| 25 | IPCI | INTERNATIONAL PAPER CO ( INTERMODAL | | | SCAC4 |
| 26 | IPCM | INTERDOM PARTNERS LLC | | | SCAC4 |
| 27 | IPCT | ISC SHIPPING | | | SCAC4 |
| 28 | IPCU | INDEPENDENT CONTAINER LINE | | | PWRC |
| 29 | IPCU | Independent Container Line | | | RSRV |
| 30 | IPCU | INLET PETROLEUM COMPANY | | | SCAC4 |
| 31 | IPCX | International Paper Co. | 8/1920-1/1980; eliminated 10/1981; added 10/1984; 1/1994-7/2005 | | NAKINA |
| 32 | IPCX | International Paper Co. | 4/38-1/80; eliminated 10/81; added 10/84; 1/94-7/2000 | | NRHS |
| 33 | IPCX | INTERNATIONAL PAPER COMPANY | | | PWRC |
| 34 | IPCX | International Paper | | | RSRV |
| 35 | IPCX | INTERNATIONAL PAPER COMPANY | | | SCAC4 |
| 36 | IPCZ | INTERNATIONAL PAPER CO. | | | PWRC |
| 37 | IPDI | INTERAMERICAN PUBLIC DISTRIBUTION CORPORATION | | | SCAC1 |
| 38 | IPEA | INTERNATIONAL POWER EXPRESS SA DE C | | | SCAC4 |
| 39 | IPEC | INDECK POWER EQUIPMENT CO | | | SCAC4 |
| 40 | IPELC | IPE Locomotori 2000 SRL | | I | TRAFFIC |
| 41 | IPEQ | INDUSTRIAL SUPPLY INC | | | SCAC4 |
| 42 | IPEX | Indeck Power Equipment, Co. | added 4/1997; 7/2000; eliminated 10/2004; 7/2005 (not listed) | | NAKINA |
| 43 | IPEX | Indeck Power Equipment, Co. | added 4/97; 7/2000 | | NRHS |
| 44 | IPEX | INDECK POWER EQUIPMENT COMPANY | | | PWRC |
| 45 | IPEX | Indeck Power Equipment | | | RSRV |
| 46 | IPF | Iraqi Prime Minister Office | Callsign: Iraqi Presidential Flight, | IRQ | AVCODES |
| 47 | IPFU | INSTITUT POLAIRE FRANCAIS PAUL-EMILE VICTOR | | F | BIC |
| 48 | IPFX | Iowa Picufuc Fruit Express | | USA | TRAFFIC |
| 49 | IPGU | INSTANT PRODUCTS GROUP PTY LTD | | AUS | BIC |
| 50 | IPHJ | IVCEC, PETAR HRVOJE | | | SCAC4 |
| 51 | IPHV | INTERNATIONAL PAPER (HANOVER MD) | | | SCAC4 |
| 52 | IPIU | IRIS LINES, INC. | | RP | BIC |
| 53 | IPIX | The International Printing Ink Corp. | 7/1930-7/1937 | | NAKINA |
| 54 | IPIX | INTERNATIONAL PRINTING INK CORP. | | | PWRC |
| 55 | IPK | INTERNATIONAL PAPER-KWIDZYN Sp. z o.o. | | PL | VKM |
| 56 | IPKC | IDS USA INC | | | SCAC4 |
| 57 | IPKT | INTERMOUNTAIN PEAK TRANSPORT | | | SCAC4 |
| 58 | IPL | Air Charter Services (Pty) Ltd, South Africa | Callsign: Imlala Air, | ZA | AVCODES |
| 59 | IPL | Airpull Aviation | | | ICAO1 |
| 60 | IPLC | INERGY PROPANE LLC | | | SCAC4 |
| 61 | IPLN | INDEPENDENT TRANSPORTATION LOGISTIC | | | SCAC4 |
| 62 | IPLX | Illinois Power Co. | added 1/1965; 7/1965-1/1980; eliminated 4/1989; 1/1994-7/2005 (not listed) | | NAKINA |
| 63 | IPLX | Illinois Power Co. | added 1/65; 7/65-1/80; eliminated 4/89; 1/94-7/2000 | | NRHS |
| 64 | IPLX | ILLINOIS POWER CO. | | | PWRC |
| 65 | IPLX | Illinois Power | | | RSRV |
| 66 | IPM | IPM Europe | Callsign: Shipex, | GB | AVCODES |
| 67 | IPM | Itapemirim Transportes Aéreos Ltda d/b/a ITA | IATA: 8I, Callsign: Aeroita, Founded on 23 September 2020. Commenced operations on 29/06/2021. Ceased operations on 17 December 2021. AOC revoked on 05 May 2022. | BR | AVCODES |
| 68 | IPM | IPM Europe | | | ICAO1 |
| 69 | IPMF | INTERNATIONAL PAPER (MURFREESBORO C | | | SCAC4 |
| 70 | IPML | IPM LINES LLC | | | SCAC4 |
| 71 | IPMO | INTERNATIONAL PAPER (MORRISTOWN CON | | | SCAC4 |
| 72 | IPMU | IPM TECHNOLOGIES | | F | BIC |
| 73 | IPMX | INTERSTATE PAPER MILL | | | PWRC |
| 74 | IPN | Industri Pesawat Terbang Nurtanio | Callsign: Nurtanio, Name changed to Industri Pesawat Terbang Nusantara, PT. ICAO callsign changed to Nusantata | RI | AVCODES |
| 75 | IPN | Industri Pesawat Terbang Nusantara, PT. | Callsign: Nusantata, Name changed to Industri Pesawat Terbang Nurtanio, PT. ICAO callsign changed to Nurtanio | RI | AVCODES |
| 76 | IPN | Industri Pesawat Terbang Nusantara | | | ICAO1 |
| 77 | IPNS | INTERSTATE TRANSPORT INC | | | SCAC4 |
| 78 | IPO | Proaviation | Founded on 21 May 2009. | IS | AVCODES |
| 79 | IPOC | INTERNATIONAL PAPER (EIGHTY FOUR CO | | | SCAC4 |
| 80 | IPOK | IMCORP | | | SCAC4 |
| 81 | IPOR | INTERPORT SERVICES INC | | | SCAC4 |
| 82 | IPOU | INTERMODAL PARTNERSHIP OU | | EST | BIC |
| 83 | IPOX | A & R Leasing, L.L.C. | added 7/1997; 7/2000; eliminated 1/2004; 7/2005 (not listed) | | NAKINA |
| 84 | IPOX | A & R Leasing, L.L.C. | added 7/97; 7/2000 | | NRHS |
| 85 | IPOX | A & R LEASING, LLP | | | PWRC |
| 86 | IPOX | A and R Leasing | | | RSRV |
| 87 | IPOX | A & R LEASING LIMITED LIABILITY COR | | | SCAC4 |
| 88 | IPP | Unifly Srl | IATA: IP, Callsign: India Papa, Name changed from Unifly | I | AVCODES |
| 89 | IPPC | IDAHO POTATO PACKERS CORPORATION OF | | | SCAC4 |
| 90 | IPPI | IMPACT POWER PRODUCTS INC | | | SCAC4 |
| 91 | IPPP | INTERNATIONAL POWER PRESS CORP | | | SCAC4 |
| 92 | IPPX | Intermountain Power Agency | added 1/1985; eliminated 4/1985; added 1/1986; 1/1994; eliminated 7/1999; 7/2000-7/2005 (not listed) | | NAKINA |
| 93 | IPPX | Iowa Poultry Products Association (North Western Refrigerator Line Co.) | 7/1935 | | NAKINA |
| 94 | IPPX | Iowa Poultry Products Association | 7/1932 | | NAKINA |
| 95 | IPPX | Intermountain Power Agency | added 1/85; eliminated 4/85; added 1/86; 1/94; eliminated 7/99; 7/2000 | | NRHS |
| 96 | IPPX | *IOWA POULTRY PRODUCTS ASSOCIATION | | | PWRC |
| 97 | IPPX | +INTERMOUNTAIN POWER AGENCY | | | PWRC |
| 98 | IPPX | Intermountain Power Agency | | | RSRV |
| 99 | IPPX | INTERMOUNTAIN POWER PROJECT | | | SCAC4 |
| 100 | IPR | Independent Carrier (ICAR) | IATA: C3, Callsign: Air Icar, IATA Prefix: 655, IATA designator changed from C3* | UA | AVCODES |
