| 1901 | SCRZ | Squaw Creek Coal Company | | USA | TRAFFIC |
| 1902 | SCS | Charters (South African Non Schedules Airways (PTY) Ltd.) | Callsign: Southern Charters, | ZA | AVCODES |
| 1903 | SCS | South African Non Scheduled Airways | | | ICAO1 |
| 1904 | SCS | SQUAW CREEK SOUTHERN RAILROAD | | | PWRC |
| 1905 | SCS | SQUAW CREEK SOUTHERN RAILROAD | | | SCAC4 |
| 1906 | SCSA | STAINLESS STEEL ACCESSORIES MFG INC | | | SCAC4 |
| 1907 | SCSB | SUN COAST CARRIERS INC | | | SCAC4 |
| 1908 | SCSD | SHOWCASE INTERIORS INC | | | SCAC4 |
| 1909 | SCSE | Stagecoach Selkent | City: London | GB | TRAFFIC |
| 1910 | SCSF | SEACORE SEAFOOD INC | | | SCAC4 |
| 1911 | SCSI | SOUTHERN CHRISTIAN TRANSPORTATION I | | | SCAC4 |
| 1912 | SCSK | STEWART CONNECTOR SYSTEMS DE MEXICO | | | SCAC4 |
| 1913 | SCSO | STRATTON COMMUNITY STORE | | | SCAC4 |
| 1914 | SCSR | SECURITY STORAGE & MOVING SERVICE O | | | SCAC4 |
| 1915 | SCST | Seaboard Transportation Co., a Wholly Owned Subsidiary of the Seaboard Coast Line R.R. Co. | 1/1994-7/2005 | | NAKINA |
| 1916 | SCST | Seaboard Transportation Co., a Wholly Owned Subsidiary of the Seaboard Coast Line R.R. Co. | 1/94-7/2000 | | NRHS |
| 1917 | SCST | SEABOARD TRANSPORTATION COMPANY {SEABOARD COAST LINE RAILROAD} | | | PWRC |
| 1918 | SCST | Seaboard Transportation (CSX Transportation) | | | RSRV |
| 1919 | SCST | SUN COAST CARRIERS INC | | | SCAC4 |
| 1920 | SCSU | CARU CONTAINERS BV | | NL | BIC |
| 1921 | SCSU | CIE FLUVIALE ET MARITIME DE TRANSPO | | | SCAC3 |
| 1922 | SCSU | CIE FLUVIALE ET MARITIME DE TRANSPO | | | SCAC4 |
| 1923 | SCSV | SPORTS CAR SHOP | | | SCAC4 |
| 1924 | SCSX | The CIT Group/Capital Finance, Inc. | added 10/1998; 7/2000-7/2005 | | NAKINA |
| 1925 | SCSX | The CIT Group/Capital Finance, Inc. | added 10/98; 7/2000 | | NRHS |
| 1926 | SCSX | *SILVER CREEK & STEPHENSON RAILROAD | | | PWRC |
| 1927 | SCSX | *GEORGIA POWER (SOUTHERN COMPANY SERVICES) | | | PWRC |
| 1928 | SCSX | +THE CIT GROUP/CAPITAL FINANCE, INC. | | | PWRC |
| 1929 | SCSX | Southern Company Services (CIT Group) | | | RSRV |
| 1930 | SCSX | CIT GROUP/CAPITAL FINANCE INC, THE | | | SCAC4 |
| 1931 | SCSY | SICOM SYSTEMS LTD | | | SCAC4 |
| 1932 | SCSZ | TRANSPORT INTERNATIONAL POOL INC | | | SCAC4 |
| 1933 | SCT | Saab-Aircraft AB | Callsign: Saab-Craft, Name changed from Saab-Scania AS | S | AVCODES |
| 1934 | SCT | Saab-Scania AS | Callsign: Saab-Craft, Name changed to Saab-Aircraft AB | S | AVCODES |
| 1935 | SCT | SAAB-Aircraft | | | ICAO1 |
| 1936 | SCT | Sioux City Terminal Ry. | 1/1975-7/2005 | | NAKINA |
| 1937 | SCT | Sioux City Terminal Ry. | 1/75-7/2000 | | NRHS |
| 1938 | SCT | *SOUTH CENTRAL TENNESSEE RAILROAD | | | PWRC |
| 1939 | SCT | +SIOUX CITY TERMINAL RAILWAY | | | PWRC |
| 1940 | SCT | Sioux City Terminal Railway | | | RSRV |
| 1941 | SCT | Specialized Container Transport | | AUS | TRAFFIC |
| 1942 | SCTA | SCOTT TRANSPORTATION INC | | | SCAC4 |
| 1943 | SCTB | SADDLE CREEK TRANSPORTATION INC (BR | | | SCAC4 |
| 1944 | SCTC | Societá Cusiana Trasporti Costruzioni (Gossano) | | I | TRAFFIC |
| 1945 | SCTD | Sheffield Corporation Transport Department | | GB | TRAFFIC |
| 1946 | SCTE | SCOTT ENTERPRISES | | | SCAC4 |
| 1947 | SCTI | SUPER CONTAINER TRANSPORT INC | | | SCAC4 |
| 1948 | SCTL | STANS CHAPERONE/SHUTTLE SERVICE | | | SCAC4 |
| 1949 | SCTM | SUNCOAST TRANSPORTATION INC | | | SCAC4 |
| 1950 | SCTN | SMITH, CHARLES TRUCKING INCORPORATE | | | SCAC4 |
| 1951 | SCTR | South Central Tennessee R.R. Co., Inc. | added 10/1978; added 10/1979; 1/1980-1/1994; eliminated 10/1994 | | NAKINA |
| 1952 | SCTR | South Central Tennessee R.R. Corp. | added 10/1994; 7/2000; eliminated 4/2001 | | NAKINA |
| 1953 | SCTR | SCTRR, LLC | added 4/2000; 7/2005 | | NAKINA |
| 1954 | SCTR | South Central Tennessee R.R. Co., Inc. | added 10/78; 1/80-1/94; eliminated 10/94 | | NRHS |
| 1955 | SCTR | South Central Tennessee R.R. Corp. | added 10/94; 7/2000; eliminated 4/2001 | | NRHS |
| 1956 | SCTR | SCTRR, LLC | added 4/2000 | | NRHS |
| 1957 | SCTR | SCTRR, LLC [SOUTH CENTRAL TENNESSEE RAILROAD CORPORATION] | | | PWRC |
| 1958 | SCTR | South Central Tennessee Railroad | | | RSRV |
| 1959 | SCTR | SCTRR LLC | | | SCAC4 |
| 1960 | SCTS | S & C TRANSPORTATION | | | SCAC4 |
| 1961 | SCTT | SCOTT TRUCK SYSTEMS INC | | | SCAC4 |
| 1962 | SCTU | SOUTH COAST LOGISTICS LTD T/A SOUTH COAST | | IRL | BIC |
| 1963 | SCTU | SHIRLSTAR CONTAINER TRANSPORT LTD. | | | PWRC |
| 1964 | SCTU | Shirlstar Container Transport Limited | | | RSRV |
| 1965 | SCTU | SOUTHCOAST TRANSPORT | | | SCAC4 |
| 1966 | SCTV | SEACOAST TRANSPORTATION SERVICE INC | | | SCAC4 |
| 1967 | SCTW | SCOTT-WILLIAMS INC | | | SCAC4 |
| 1968 | SCTX | Steel Cities Chemical Co. | 8/1920-7/1932 | | NAKINA |
| 1969 | SCTX | STEEL CITIES CHEMICAL CO. | | | PWRC |
| 1970 | SCTY | SOUTHERN CHRISTIAN TRANSPORTATION I | | | SCAC4 |
| 1971 | SCU | Air Scorpio | Callsign: Scorpio Univers, | BG | AVCODES |
| 1972 | SCU | Spartan Education, LLC d/b/a Spartan College of Aeronautics and Technology | Callsign: Skelly, | USA | AVCODES |
| 1973 | SCU | Air Scorpio | | | ICAO1 |
| 1974 | SCU | RETIRED 04-22-93 ATP | | | PWRC |
| 1975 | SCU | S AND J COMMUTER BUS SERVICE INC | | | SCAC4 |
| 1976 | SCUA | SUCDEN AMERICAS CORPORATION | | | SCAC4 |
| 1977 | SCUB | SO-CAL EXPRESS | | | SCAC4 |
| 1978 | SCUC | S C K TRUCKING | | | SCAC4 |
| 1979 | SCUE | STONECUTTER TRUCKING COMPANY | | | SCAC1 |
| 1980 | SCUE | S C P P RIBERENA ISLAS UNIDAS S C D | | | SCAC4 |
| 1981 | SCUH | SCHUMACHER TRUCKING CORPORATION | | | SCAC1 |
| 1982 | SCUH | SCHUMACHE | | | SCAC4 |
| 1983 | SCUI | STAR CANOPUS-SPECIAL MARITIME ENTER | | | SCAC4 |
| 1984 | SCUM | SCHUMM TRANSPORT | | | SCAC4 |
| 1985 | SCUN | SCULLION TRUCKING CO | | | SCAC4 |
| 1986 | SCUO | SALAD COSMO USA CORP | | | SCAC4 |
| 1987 | SCUQ | SOUTH COAST LOGISTICS INC | | | SCAC4 |
| 1988 | SCUR | SECURED REFRIGERATED TRANSPORT INC | | | SCAC4 |
| 1989 | SCUT | STRUCTURE INC | | | SCAC4 |
| 1990 | SCUU | LIANYUNGANG SUPREME BUILDING PRODUC | | | SCAC4 |
| 1991 | SCUV | STAT COURIER SERVICE | | | SCAC4 |
| 1992 | SCUW | SUPERIOR CUT AND SEW | | | SCAC4 |
| 1993 | SCV | Servicios Aereos Del Centro. S.A. de C.V. | Callsign: Sacsa, | MEX | AVCODES |
| 1994 | SCV | Servicios Aereos Del Centro | | | ICAO1 |
| 1995 | SCVC | SASCO MOTORSPORTS DEVELOPMENTS INC | | | SCAC4 |
| 1996 | SCVD | SHOWCASE VAN LINES | | | SCAC4 |
| 1997 | SCVE | S T C SERVICES | | | SCAC4 |
| 1998 | SCVH | SERVICIOS LOGISTICOS VEA | | | SCAC4 |
| 1999 | SCVI | SCHRYER VIOLIN WORKSHOP INC | | | SCAC4 |
| 2000 | SCVJ | SCM DIVICION TRANSPORTE SA DE CV | | | SCAC4 |
