| 1 | GTW | Gateway Aviation | Callsign: Gateway, | Z | AVCODES |
| 2 | GTW | Multi-Aero, Inc. | Callsign: United States of America, ICAO designator changed to WBR. ICAO Callsign changed to Weber | USA | AVCODES |
| 3 | GTW | American Air Charter, Inc. | Callsign: United States of America, | USA | AVCODES |
| 4 | GTW | Grand Trunk Western R.R. Inc. | 1/1994-7/2005 | | NAKINA |
| 5 | GTW | Grand Trunk Western R.R. Co. | 4/1938-10/1966 & 1/1975-1/1980 | | NAKINA |
| 6 | GTW | Grand Trunk Western R.R. Co. | 4/38-10/66 & 1/75-1/80 | | NRHS |
| 7 | GTW | Grand Trunk Western R.R. Inc. | 1/94-7/2000 | | NRHS |
| 8 | GTW | CANADIAN NATIONAL RAILWAY [GRAND TRUNK WESTERN RAILROAD] | | | PWRC |
| 9 | GTW | Grand Trunk Western (Canadian National Railway) | | | RSRV |
| 10 | GTW | GRAND TRUNK WESTERN RAILROAD | | | SCAC4 |
| 11 | GTW | Grand Trunk Western Railroad | | CDN | TRAFFIC |
| 12 | GTWE | GEORGETOWN LOGISTICS FLINT RECYCLIN | | | SCAC4 |
| 13 | GTWF | GATEWAY FREIGHT SYSTEMS INC | | | SCAC4 |
| 14 | GTWG | G TWO (G2) LOGISTICS TRANSPORT INC | | | SCAC4 |
| 15 | GTWI | G TWO (2) EQUIPMENT | | | SCAC4 |
| 16 | GTWJ | GT WORLDWIDE TRANSPORT INC | | | SCAC4 |
| 17 | GTWL | GATEWAY LEASING INC | | | SCAC4 |
| 18 | GTWP | GO TWO (GO 2) TRANSPORTATION LLC | | | SCAC4 |
| 19 | GTWQ | Grand Trunk Western R.R. Inc. | added 7/1995; 7/2005 | | NAKINA |
| 20 | GTWQ | Grand Trunk Western R.R. Inc. | added 7/95; 7/2000 | | NRHS |
| 21 | GTWQ | CANADIAN NATIONAL RAILWAY [GRAND TRUNK WESTERN RAILROAD] | | | PWRC |
| 22 | GTWQ | Grand Trunk Western (Canadian National Railway) | | | RSRV |
| 23 | GTWQ | G T W | | | SCAC4 |
| 24 | GTWS | G TWO (G2) LOGISTICS LLC | | | SCAC4 |
| 25 | GTWV | GENTEL TOWING COMPANY | | | SCAC4 |
| 26 | GTWW | GATEWAY TOWING | | | SCAC4 |
