| 1 | SLT | Salert Air Charters And Relief Services | Callsign: Salcharters, | EAK | AVCODES |
| 2 | SLT | Starlight Airline STP, S.A. | IATA: QA, Callsign: Starlight Cargo, IATA Prefix: 321, | STP | AVCODES |
| 3 | SLT | Saltair Ltd. | Callsign: Saltair, | GB | AVCODES |
| 4 | SLTA | STEEL TRANSPORT INC | | | SCAC4 |
| 5 | SLTA | Singapore Land Transport Authority | City: Singapore | SGP | TRAFFIC |
| 6 | SLTE | SALTO ENTERPRISES INC | | | SCAC4 |
| 7 | SLTF | SHOWA LINE, LTD. | | | PWRC |
| 8 | SLTF | SLATER TRANSFER AND STORAGE INC | | | SCAC4 |
| 9 | SLTJ | S & L TRUCKING INC | | | SCAC4 |
| 10 | SLTL | SPARTA-LaCROSSE TRUCK LINES, INC | | | SCAC1 |
| 11 | SLTO | STARLINER TRANSPORT (1981) LTD | | | SCAC4 |
| 12 | SLTP | S & L TRANSPORTATION LLC | | | SCAC4 |
| 13 | SLTQ | SLT ENR | | | SCAC4 |
| 14 | SLTR | SLATER, M. C | | | SCAC1 |
| 15 | SLTR | SLATER, M C, INC | | | SCAC4 |
| 16 | SLTS | Silverlink Train Services | | UK | VKM |
| 17 | SLTT | SCOTLAND TRANSPORTATION LLC | | | SCAC4 |
| 18 | SLTU | SCM LINES TRANSPORTES MARITIMOS | | P | BIC |
| 19 | SLTU | SCM LINES TRANSPORTES MARITIMOS | | | SCAC4 |
| 20 | SLTU | Slovenské tunely, a.s. | | SK | VKM |
| 21 | SLTV | SELECT VAN & STORAGE INC | | | SCAC4 |
| 22 | SLTW | SLT EXPRESS WAY INC | | | SCAC4 |
| 23 | SLTX | Slade Transport, Inc. | added 7/1974; 1/1975-1/1980; eliminated 4/1987 | | NAKINA |
| 24 | SLTX | Slade Transport, Inc. | added 7/74; 1/75-1/80; eliminated 4/87 | | NRHS |
| 25 | SLTX | SLADE TRANSPORT INC. | | | PWRC |
| 26 | SLTX | Slade Transport | | | RSRV |
| 27 | SLTX | SEEGERS LIMITED | | | SCAC4 |
