| 1 | UCS | United Carriers Systems, Inc. | Callsign: United Carriers, | USA | AVCODES |
| 2 | UCS | United Carriers Systems | | | ICAO1 |
| 3 | UCSB | UNILOG CARGO SA | | | SCAC4 |
| 4 | UCSN | UNITED CARGO SERVICES INC | | | SCAC4 |
| 5 | UCSS | UNIBRIK CUSTOM SERVICES LTD | | | SCAC4 |
| 6 | UCSU | UNIVERSAL CONTAINER SERVICES LIMITED | | GB | BIC |
| 7 | UCSX | Union Camp Corp. | added 10/1988; 1/1994-7/2000; eliminated 4/2002 | | NAKINA |
| 8 | UCSX | International Paper Co. | added 4/2002; 7/2005 | | NAKINA |
| 9 | UCSX | Union Camp Corp. | added 10/88; 1/94-7/2000 | | NRHS |
| 10 | UCSX | INTERNATIONAL PAPER CO. [UNION CAMP CORPORATION] | | | PWRC |
| 11 | UCSX | Union Camp Corporation | | | RSRV |
| 12 | UCSX | INTERNATIONAL PAPER COMPANY | | | SCAC4 |
