| 1 | GRT | Gabon-Air-Transport | | G | AVCODES |
| 2 | GRT | Gabon-Air-Transport | | | ICAO1 |
| 3 | GRT | Grampian Regional Transport | | GB | TRAFFIC |
| 4 | GRTA | GARRED TRANSPORT INC | | | SCAC4 |
| 5 | GRTC | Greater Richmond Transit Company | City: Richmond (VA) | USA | TRAFFIC |
| 6 | GRTE | GROUND AIR TRANSFER OF CLEVELAND, INC | | | SCAC1 |
| 7 | GRTK | GRINE TRUCKING INC | | | SCAC4 |
| 8 | GRTL | GREAT LAKES TRANSPORTATION LLC | | | SCAC4 |
| 9 | GRTN | GREAT NORTHERN | | | SCAC4 |
| 10 | GRTO | GARCIA TRANSPORTES | | | SCAC4 |
| 11 | GRTP | GRT TRANSFER SA DE CV | | | SCAC4 |
| 12 | GRTQ | GAREM TRANSPORTES | | | SCAC4 |
| 13 | GRTR | GREAT RIVER RAILROAD | | | PWRC |
| 14 | GRTR | GRT TRANSPORTATION LLC | | | SCAC4 |
| 15 | GRTT | GROENDYKE TRANSPORT, INC | | | SCAC4 |
| 16 | GRTU | HULDA MARITIME INTERNATIONAL CONTAINER | | HK | BIC |
| 17 | GRTV | GARRISON, R. E., TRUCKING INC | | | SCAC1 |
| 18 | GRTV | GARRISON, R E TRUCKING INC | | | SCAC4 |
| 19 | GRTX | Savage-Tolk Energy Services | added 4/2001; eliminated 7/2005; 7/2005 (not listed) | | NAKINA |
| 20 | GRTX | Wheelabrator Coal Services Co. | added 4/1994; 7/2000; eliminated 4/2001 | | NAKINA |
| 21 | GRTX | Wheelabrator Coal Services Co. | added 4/94; 7/2000; eliminated 4/2001 | | NRHS |
| 22 | GRTX | Savage-Tolk Energy Services | added 4/2001 | | NRHS |
| 23 | GRTX | SAVAGE-TOLK ENERGY SERVICES (WCSX) [WHEELABRATOR COAL SERVICES] | | | PWRC |
| 24 | GRTX | Savage-Tolk Energy Services | | | RSRV |
| 25 | GRTX | SAVAGE-TOLK ENERGY SERVICES | | | SCAC4 |
