| 1 | SLS | Aeroservicios Ejecutivos Sinaloenses, S.A. | Callsign: Sinaloenses, | MEX | AVCODES |
| 2 | SLS | Servicios Aereos Slainte, S.A. de C.V. | Callsign: Servicios Slainte, | MEX | AVCODES |
| 3 | SLS | Super Legacy XP Ltd. | Callsign: Power Blade, | RSM | AVCODES |
| 4 | SLS | Servicios Aereos Slainte | | | ICAO1 |
| 5 | SLS | Sea-Land Service, Inc. | 1/1975 | | NAKINA |
| 6 | SLS | Sea-Land Service, Inc. | Jan-75 | | NRHS |
| 7 | SLS | SEA-LAND SERVICE INC | | | SCAC4 |
| 8 | SLSA | SWITCH LUZ S A | | | SCAC4 |
| 9 | SLSC | SILVER LAKE SHIPPING COMPANY SA | | | SCAC4 |
| 10 | SLSD | SEALAND SPECIALIZED CARRIERS LTD | | | SCAC4 |
| 11 | SLSE | Swift Live Stock Transportation (General American Transportation Corp.) | 7/1935 | | NAKINA |
| 12 | SLSE | SEA-LAND FREIGHT SERVICE, INC | | | SCAC1 |
| 13 | SLSF | St. Louis-San Francisco Ry. Co. | 7/1923-1/1980; eliminated 1/1981; 7/2000 | | NAKINA |
| 14 | SLSF | Burlington Northern Inc. | added 1/1981; eliminated 7/1981 | | NAKINA |
| 15 | SLSF | Burlington Northern R.R. Co. | added 7/1981; 1/1994; eliminated 4/2005 | | NAKINA |
| 16 | SLSF | BNSF Ry. Co. | added 4/2005; 7/2005 | | NAKINA |
| 17 | SLSF | St. Louis-San Francisco Ry. Co. | 4/38-1/80; eliminated 1/81; 7/2000 | | NRHS |
| 18 | SLSF | Burlington Northern Inc. | added 1/81; eliminated 7/81 | | NRHS |
| 19 | SLSF | Burlington Northern R.R. Co. | added 7/81; 1/94 | | NRHS |
| 20 | SLSF | BNSF RWY. CO. [BURLINGTON NORTHERN RAILROAD CO.; ST. LOUIS-SAN FRANCISCO RWY. (FRISCO)] | | | PWRC |
| 21 | SLSF | St. Louis–San Francisco Railway (BNSF Railway) | | | RSRV |
| 22 | SLSF | Saint Louis - San Francisco Railway Company (Frisco) | | USA | TRAFFIC |
| 23 | SLSG | STAR TRANSPORTATION, INC. | | | SCAC1 |
| 24 | SLSG | STAR TRANSPORTATION INC | | | SCAC4 |
| 25 | SLSH | SINO-LINE SHIPPING LIMITED | | | SCAC4 |
| 26 | SLSI | SEA LION SHIPPING | | | SCAC4 |
| 27 | SLSN | SAL-SON TRUCKING CO INC | | | SCAC4 |
| 28 | SLSO | SHOWA LINE, LTD. | | | PWRC |
| 29 | SLSO | SOWLE, SIDNEY & SON INC | | | SCAC4 |
| 30 | SLSP | STEALTH TRANSPORTATION INC | | | SCAC4 |
| 31 | SLSP | Slovenská letecká spolocnost | | SK | TRAFFIC |
| 32 | SLSR | SILICONE TECHNOLOGIES S DE R L | | | SCAC4 |
| 33 | SLST | Swift Live Stock Transportation (General American Transportation Corp.) | 7/1935 | | NAKINA |
| 34 | SLST | ST. LOUIS STEAM TRAIN ASSOCIATION | | | PWRC |
| 35 | SLSU | SPINNAKER LEASING CORPORATION | | USA | BIC |
| 36 | SLSU | Spinnaker Leasing Corporation | | | RSRV |
| 37 | SLSU | SPINNAKER LEASING CORPORATION | | | SCAC4 |
| 38 | SLSV | STATES LOGISTICS SERVICES INC | | | SCAC4 |
| 39 | SLSW | SC LINE S A | | | SCAC4 |
| 40 | SLSX | Swift Live Stock Express (General American Transportation Corp.) (previously S.L.S.E. and S.L.S.T.) | added 11/1934; 7/1935 | | NAKINA |
| 41 | SLSX | General American Transportation Corp. | 7/1937-7/1965 | | NAKINA |
| 42 | SLSX | Swift Live Stock Express (General American Transportation Corp.) | 10/1966; eliminated 1/1970 | | NAKINA |
| 43 | SLSX | Swift Live Stock Express (General American Transportation Corp.) | Apr-38 | | NRHS |
| 44 | SLSX | General American Transportation Corp. | 1/52-7/65 | | NRHS |
| 45 | SLSX | Swift Live Stock Express (General American Transportation Corp.) | 10/66; eliminated 1/70 | | NRHS |
| 46 | SLSX | SWIFT LIVE STOCK EXPRESS (GATC) | | | PWRC |
| 47 | SLSY | SAHEL LINE S R L | | | SCAC4 |