| 1 | IIC | Inter Island Air Charter | Callsign: Inter Air, | BS | AVCODES |
| 2 | IICL | ITS INTERNATIONAL CONTAINER LINES I | | | SCAC4 |
| 3 | IICU | IWATANI CORPORATION | | J | BIC |
| 4 | IICU | IWATANI INTERNATIONAL CORPORATION | | | SCAC4 |
| 5 | IICX | Interlake Iron Corp. | 4/1938-4/1961; eliminated 7/1965 (reporting marks changed to ISCX) | | NAKINA |
| 6 | IICX | Interlake Iron Corp. (Toledo Furnace Plant) | 7/1932-7/1937 | | NAKINA |
| 7 | IICX | Interlake Iron Corp. (Toledo Furnace Plant) | Apr-38 | | NRHS |
| 8 | IICX | Interlake Iron Corp. | 1/52-4/61; eliminated 7/65 (reporting marks changed to ISCX) | | NRHS |
| 9 | IICX | INTERLAKE IRON CORP. (MERK CHANGED TO ISCX 7-95) | | | PWRC |
| 10 | IICZ | CANADIAN NATIONAL RWY [ILLINOIS CENTRAL GULF RAILROAD; ILLINOIS CENTRAL RR] | | | PWRC |
| 11 | IICZ | Illinois Central Railroad (Canadian National Railway) | | | RSRV |
