| 1 | GTA | GT Aviation | Callsign: GeeTee Avia, | GB | AVCODES |
| 2 | GTA | Gitanair | IATA: VG, Callsign: Gitanair, | I | AVCODES |
| 3 | GTA | City Airways Company Limited dba City Airways | IATA: E8, Callsign: City Airways, Commenced operations in September 2012. Suspended operations on 13 February 2016. | T | AVCODES |
| 4 | GTA | Grand Trunk Western R.R. Inc. | 1/1994-7/2005 | | NAKINA |
| 5 | GTA | Grand Trunk Western R.R. Co. | 1/1975-1/1980; eliminated 1/1983 | | NAKINA |
| 6 | GTA | Grand Trunk Western R.R. Co. | 1/75-1/80; eliminated 1/83 | | NRHS |
| 7 | GTA | Grand Trunk Western R.R. Inc. | 1/94-7/2000 | | NRHS |
| 8 | GTA | CANADIAN NATIONAL [GRAND TRUNK WESTERN] | | | PWRC |
| 9 | GTA | Grand Trunk Western (Canadian National Railway) | | | RSRV |
| 10 | GTAE | GTL ENTERPRISES INC | | | SCAC4 |
| 11 | GTAG | GABRIELS TOWING AND TRUCKING | | | SCAC4 |
| 12 | GTAH | GATES MANUFACTURING | | | SCAC4 |
| 13 | GTAL | GREAT AMERICAN LINES INC | | | SCAC4 |
| 14 | GTAN | GREAT TRANSPORTATION ENTERPRISE INC | | | SCAC4 |
| 15 | GTAO | GASEL TRANSPORTATION LINES INC | | | SCAC4 |
| 16 | GTAP | GANECA TRANSPORT (DIVISION OF TFI T | | | SCAC4 |
| 17 | GTAQ | GOGI TRUCKING INC | | | SCAC4 |
| 18 | GTAS | GUR-ISH TRUCKING LTD | | | SCAC4 |
| 19 | GTAT | GOGON TRANSPORT | | | SCAC4 |
| 20 | GTAU | GALLIKER TRANSPORT AG | | CH | BIC |
| 21 | GTAU | GALLIKER TRANSPORT AG | | | SCAC4 |
| 22 | GTAU | Greentrains | | AUS | TRAFFIC |
| 23 | GTAV | G T TRANSPORTATION SERVICES INC | | | SCAC4 |
| 24 | GTAW | GRANITE TOWN FARMS LTD | | | SCAC4 |
| 25 | GTAX | CHS Inc. | added 4/2007 | | NAKINA |
| 26 | GTAX | Cenex Harvest States Cooperatives | eliminated 4/2007 | | NAKINA |
| 27 | GTAX | Harvest States Cooperatives | added 1/1984; 1/1994-7/2000; eliminated 10/2000; 7/2005 (not listed) | | NAKINA |
| 28 | GTAX | Grain Terminal Association | added 7/1979; 1/1980; eliminated 1/1984 | | NAKINA |
| 29 | GTAX | Grain Terminal Association | added 7/79; 1/80 | | NRHS |
| 30 | GTAX | Harvest States Cooperatives | 1/94-7/2000; eliminated 10/2000 | | NRHS |
| 31 | GTAX | CHS, INC. [CENEX HARVEST STATES COOPERATIVES; GRAIN TERMINAL ASSOCIATION] | | | PWRC |
| 32 | GTAX | Harvest States Cooperative | | | RSRV |
| 33 | GTAX | CHS INC | | | SCAC4 |
| 34 | GTAX | Grain Terminal Association | | USA | TRAFFIC |