| 1 | IX | Flandre Air Service | ICAO: FRS, Callsign: Flandair, Merged into Regional Compagnie Aerienne Europeene 01 April 2001. Designator IX recalled by IATA | F | AVCODES |
| 2 | IX | Select Air Luftverkehrsges mbH | | A | AVCODES |
| 3 | IX | Internacional de Aviacion (INAIR) | | PA | AVCODES |
| 4 | IX | Internacional de Aviacion, S.A. | ICAO: IAP, Callsign: Inair, | PA | AVCODES |
| 5 | IX | Air India Charters Limited | ICAO: AXB, Callsign: Express India, Designator IX* recalled by IATA | IND | AVCODES |
| 6 | IX | Air India Charters Limited | ICAO: AXB, Callsign: Express India, IATA Prefix: 236, Designator IX* reinstated by IATA | IND | AVCODES |
| 7 | IX | Independent Oil & Gas Co. | 7/1930 | | NAKINA |
| 8 | IX | INDEPENDENT OIL & GAS CO. | | | PWRC |
| 9 | IXEU | INTEROX QUIMICA SA | | | PWRC |
| 10 | IXEU | Interox Quimica | | | RSRV |
| 11 | IXFH | INDEX FRESH | | | SCAC4 |
| 12 | IXIC | INFINITI XPRESS INC | | | SCAC4 |
| 13 | IXIN | IDEAL TRANSPORT INC | | | SCAC4 |
| 14 | IXLP | IXL PROPANE INC | | | SCAC4 |
| 15 | IXMU | IXOM OPERATIONS PTY LTD | | AUS | BIC |
| 16 | IXPI | INTERSTATE EXPRESS INC | | | SCAC4 |
| 17 | IXPR | INTEREXPRESS INC | | | SCAC4 |
| 18 | IXPT | INTERNATIONAL EXPRESS TRUCKING INC | | | SCAC4 |
| 19 | IXR | iXAir Business Jets | Callsign: X-Bird, | F | AVCODES |
| 20 | IXR | Ixair | | | ICAO1 |
| 21 | IXSL | IRONEX SUPPLY LTD | | | SCAC4 |
| 22 | IXSU | INTERLOX SEM CO LTD | | | SCAC4 |
| 23 | IXT | Lineas Aereas de Ixtlan, S.A. de C.V. | Callsign: Ixtlan, | MEX | AVCODES |
| 24 | IXTC | INTERMODE TRANSPORTATION COMPANY | | | SCAC4 |
| 25 | IXTL | INDEX TRANSPORTATION SERVICES LLC | | | SCAC4 |
| 26 | IXWU | INTEROX CHEMICALS LTD | | | PWRC |
| 27 | IXWU | Interox Chemicals | | | RSRV |
| 28 | IXWU | EUROTAINER SAS | | | SCAC4 |
| 29 | IXX | Dolphin Express Airlines, Inc. | Callsign: Island Express, | USA | AVCODES |
| 30 | IXX | Dolphin Express Airlines | | | ICAO1 |
| 31 | IXXU | INDAIA LOGISTIK GMBH | | D | BIC |
