| 601 | ICR | ICARO Service | Callsign: Icaro, | RCH | AVCODES |
| 602 | ICR | Eagle Aero | | | ICAO1 |
| 603 | ICRC | I C R LOGISTICS LLC | | | SCAC4 |
| 604 | ICRK | Indian Creek R.R. Co. | added 1/1984; eliminated 1/1990; 1/1994-7/2005 | | NAKINA |
| 605 | ICRK | Indian Creek R.R. Co. | eliminated 1/90; 1/94-7/2000 | | NRHS |
| 606 | ICRK | Island Creek Coal Co. | added 1/79; 1/80; eliminated 7/89 | | NRHS |
| 607 | ICRK | Island Creek Corp. | added 7/89; 1/94-7/2000 | | NRHS |
| 608 | ICRK | INDIAN CREEK RAILROAD CO. | | | PWRC |
| 609 | ICRK | Indian Creek Railroad | | | RSRV |
| 610 | ICRL | INTERCON CARRIERS LC | | | SCAC4 |
| 611 | ICRO | INTER-CROSS | | | SCAC4 |
| 612 | ICRP | INTERTRANS CORPORATION | | | SCAC4 |
| 613 | ICRS | INTERMODAL CARGO SERVICES INC | | | SCAC4 |
| 614 | ICRU | RESOURCE OVERSEAS GENERAL TRADING L.L.C. | | UAE | BIC |
| 615 | ICRU | *(ICHU) RETIRED 10-22-92 ATP | | | PWRC |
| 616 | ICRU | *INGETRA AG | | | PWRC |
| 617 | ICRU | Ingetra | | | RSRV |
| 618 | ICRV | IMPERIAL CARRIER SERVICES, LLC | | | SCAC4 |
| 619 | ICRX | Island Creek Corp. | added 7/1989; 1/1994-7/2005 (not listed) | | NAKINA |
| 620 | ICRX | Island Creek Coal Co. | added 1/1979; 1/1980; eliminated 7/1989 | | NAKINA |
| 621 | ICRX | *IRON CLIFFS RAILWAY COMPANY | | | PWRC |
| 622 | ICRX | +ISLAND CREEK CORPORATION {ISLAND CREEK COAL COMPANY] | | | PWRC |
| 623 | ICRX | Island Creek Coal | | | RSRV |
| 624 | ICRZ | CANADIAN NATIONAL RWY [ILLINOIS CENTRAL GULF RAILROAD] [ILLINOIS CENTRAL RR] | | | PWRC |
| 625 | ICRZ | Illinois Central Railroad (Canadian National Railway) | | | RSRV |
| 626 | ICRZ | ILLINOIS CENTRAL RAILROAD COMPANY | | | SCAC4 |
| 627 | ICS | International Charter Services, S.A. de C.V. | Callsign: Interservi, | MEX | AVCODES |
| 628 | ICS | ICS Inter Ceil Service | Name changed from Intercargo Service. Associated with Air Charter, Air Inter, E.A.S and TAT | F | AVCODES |
| 629 | ICS | Intercargo Service | Name changed to ICS Inter Ceil Service. Associated with Air Charter, Air Inter, E.A.S and TAT | F | AVCODES |
| 630 | ICS | CHC Ireland Designated Activity Company | Callsign: Irish Coastguard, Name changed from Bond Helicopters (Ireland) Limited. | IRL | AVCODES |
| 631 | ICS | International Charter Services | | | ICAO1 |
| 632 | ICSA | INTER-CON TRANSPORTATION SERVICES C | | | SCAC4 |
| 633 | ICSB | INNOVATIVE COURIER SOLUTIONS INC | | | SCAC4 |
| 634 | ICSC | INTERNATIONAL CORE SUPPLY INC | | | SCAC4 |
| 635 | ICSF | INVENTORY CONTROL SERVICES INC | | | SCAC4 |
| 636 | ICSG | ICS LOGISTICS LLC | | | SCAC4 |
| 637 | ICSJ | INNOVATIVE CONTROL SOLUTIONS | | | SCAC4 |
| 638 | ICSM | INDUSTRIAL CONTRACTING SOLUTIONS IN | | | SCAC4 |
| 639 | ICSO | IBEX CONTAINER SERVICES | | | SCAC4 |
| 640 | ICSP | ICS PETROLEUM LTD | | | SCAC4 |
| 641 | ICSQ | INDUSTRIAL CARTAGE SERVICE INC | | | SCAC4 |
| 642 | ICSS | INTERNATIONAL COSMETICS | | | SCAC4 |
| 643 | ICST | ICS TECHNOLOGIES | | | SCAC4 |
| 644 | ICSU | TRITON CONTAINER INTERNATIONAL LTD | | BM | BIC |
| 645 | ICSU | (REAZ) TRANSAMERICA LEASING, INC. | | | PWRC |
| 646 | ICSU | TAL International | | | RSRV |
| 647 | ICSU | TRANSAMERICA ICS, INC. | | | SCAC3 |
| 648 | ICSU | TRANSAMERICA LEASING INC | | | SCAC4 |
| 649 | ICSV | IMPULSE COURIER SERVICE INC | | | SCAC4 |
| 650 | ICSW | INTERSTATE CARGO SERVICES INC | | | SCAC4 |
| 651 | ICSZ | *ICS INDUSTRIES | | | PWRC |
| 652 | ICSZ | *UNION PACIFIC RAILROAD, (REAZ) TRANSAMERICA LEASING, INC. | | | PWRC |
| 653 | ICSZ | TAL International (Union Pacific Railroad) | | | RSRV |
| 654 | ICSZ | TRANSAMERICA ICS, INC. | | | SCAC3 |
| 655 | ICSZ | TRANSAMERICA LEASING INC | | | SCAC4 |
| 656 | ICT | Intercontinental de Aviación | IATA: RS | | ICAO1 |
| 657 | ICTA | I C T LOGISTICS INC | | | SCAC4 |
| 658 | ICTC | INTERCITY TRANSPORTATION CO | | | PWRC |
| 659 | ICTG | INDUSTRIAL CONTRACTING & RIGGING IN | | | SCAC4 |
| 660 | ICTH | INTERNATIONAL CARGO TERMINALS INC | | | SCAC4 |
| 661 | ICTI | INTERSTATE CARGO TRANSPORT INC | | | SCAC4 |
| 662 | ICTL | INTER CANADIAN TRUCKING LTD | | | SCAC4 |
| 663 | ICTT | ICT INC | | | SCAC4 |
| 664 | ICTU | TANKSPAN LEASING LIMITED | | GB | BIC |
| 665 | ICTU | INTERCONTINENTAL TANKS LIMITED | | | SCAC4 |
| 666 | ICTX | Independent Coal Tar Co. | 1/1943-4/1947 | | NAKINA |
| 667 | ICTX | INDEPENDENT COAL TART CO. | | | PWRC |
| 668 | ICU | Asia Air Medical (Beijing) Ltd | Callsign: Asia Medical, | PRC | AVCODES |
| 669 | ICU | Reignwood Asia Aviation Co., Ltd. | Callsign: Asia Medical, | PRC | AVCODES |
| 670 | ICUA | ICUSA | | | SCAC4 |
| 671 | ICUS | INCON USA INC | | | SCAC4 |
| 672 | ICUU | INDEPENDENT CONTAINER LINE LTD | | USA | BIC |
| 673 | ICUU | Independent Container Line | | | RSRV |
| 674 | ICUU | INDEPENDENT CONTAINER LINE (ICL) | | | SCAC4 |
| 675 | ICV | Cargolux Italia S.p.A. | IATA: C8, Callsign: Cargo Med, IATA Prefix: 356, ICAO Callsign changed to Cargolux Italia. | I | AVCODES |
| 676 | ICV | Cargolux Italia S.p.A. | IATA: C8, Callsign: Cargolux Italia, IATA Prefix: 356, ICAO Callsign changed from Cargo Med. | I | AVCODES |
| 677 | ICVC | INGLE COURIER SERVICE INC | | | SCAC4 |
| 678 | ICW | Icaro Servicios Aereos, S.L. | | E | AVCODES |
| 679 | ICWT | I.C.W. TRANSPORT, INC | | | SCAC1 |
| 680 | ICWT | I C W TRANSPORT INC | | | SCAC4 |
| 681 | ICX | International Charter Xpress Ltd Co. | Callsign: Intex, | USA | AVCODES |
| 682 | ICX | International Charter Xpress | | | ICAO1 |
| 683 | ICX | Industrial Chemicals Transit Co. | 1/1946-4/1947 | | NAKINA |
| 684 | ICX | INDUSTRIAL CHEMICALS TRANSIT CO. | | | PWRC |
| 685 | ICXI | INTEGRITY CARTAGE & EXPEDITED INC | | | SCAC4 |
| 686 | ICXN | ICT TRANSPORTATION INC | | | SCAC4 |
| 687 | ICXS | ILLINOIS - CALIFORNIA EXP | | | PWRC |
| 688 | ICXS | INLAND CONTAINER EXPRESS | | | SCAC4 |
| 689 | ICXT | INTERSTATE CARRIER XPRESS, INC | | | SCAC1 |
| 690 | ICXT | INTERSTATE CARRIER XPRESS | | | SCAC4 |
| 691 | ICXX | INDIANTOWN COGENERATION, LP | | | PWRC |
| 692 | ICXX | INDIANTOWN COGENERATION LP | | | SCAC4 |
| 693 | ICY | Intercity Air Sdn Bhd | Callsign: Intercity, | MAL | AVCODES |
| 694 | ICYS | INTERCITY SOLUTION INC | | | SCAC4 |
| 695 | ICZ | IPS COMPANY | | | PWRC |
| 696 | ICZL | INTERCHEZ LOGISTICS SYSTEMS INC | | | SCAC4 |
| 697 | ID | Normandie Aviation | ICAO: RNO, Callsign: Normandie, | F | AVCODES |
| 698 | ID | Intavia Ltd. | ICAO: FFL, Callsign: Aircargo, | GB | AVCODES |
| 699 | ID | Interlink Airlines (Pty) Ltd. | ICAO: ITK, Callsign: Interlink, IATA Prefix: 431, Designator ID restated by IATA | ZA | AVCODES |
| 700 | ID | Normandie Aviation | ICAO: RNO, Callsign: Normandie, | F | AVCODES |
