| 1 | CLS | Challenge Air Luftverkehrs GmbH | Callsign: Airisto, AOC revokedduring June 2018. | D | AVCODES |
| 2 | CLS | Club Air | IATA: JA, Callsign: Irish Club, | IRL | AVCODES |
| 3 | CLS | Challenge Air Transport | | | ICAO1 |
| 4 | CLSA | CLASSIC TRANSPORT INC | | | SCAC4 |
| 5 | CLSB | CUSTOM LOGISTICS SERVICES & TRANSPO | | | SCAC4 |
| 6 | CLSC | CLASSIC TRANSPORT INC | | | SCAC3 |
| 7 | CLSC | CARLSON TRUCKING | | | SCAC4 |
| 8 | CLSD | CLASSIC MOVING & STORAGE INC | | | SCAC3 |
| 9 | CLSF | CLASI-TOFC | | | SCAC3 |
| 10 | CLSF | COULTERS FURNITURE | | | SCAC4 |
| 11 | CLSF | Classfer S.R.L | | RO | TRAFFIC |
| 12 | CLSG | CLEAR SPRINGS TROUT COMPANY | | | SCAC3 |
| 13 | CLSG | CARLOS TRUCKING INC | | | SCAC4 |
| 14 | CLSH | COLUMBUS & SOUTHERN OHIO ELECTRIC C | | | SCAC3 |
| 15 | CLSH | CLASSIC CARRIERS INC | | | SCAC4 |
| 16 | CLSI | CALKINS, LES TRUCKING INC | | | SCAC3 |
| 17 | CLSI | CONTINENTAL LOGISTIC SERVICE INC | | | SCAC4 |
| 18 | CLSJ | CLARK, STEVEN J | | | SCAC3 |
| 19 | CLSJ | CORNELIUS LEASING SYSTEMS INC | | | SCAC4 |
| 20 | CLSL | Columbia & Silver Creek R.R. Co. | added 7/1982; eliminated 4/1989; added 1/1990; eliminated 10/1991; 1/1994-7/2005 | | NAKINA |
| 21 | CLSL | Columbia & Silver Creek R.R. Co. | added 7/82; eliminated 4/89; added 1/90; eliminated 10/91; 1/94-7/2000 | | NRHS |
| 22 | CLSL | COLUMBIA & SILVER CREEK RAILROAD COMPANY | | | PWRC |
| 23 | CLSL | COLUMBIA AND SILVER CREEK RR | | | PWRC |
| 24 | CLSL | Columbia and Silver Creek Railroad | | | RSRV |
| 25 | CLSL | COLUMBIA & SILVER CREEK RAILROAD CO | | | SCAC3 |
| 26 | CLSL | COLUMBIA & SILVER CREEK RAILROAD CO | | | SCAC4 |
| 27 | CLSM | CALWAY SYSTEMS INC | | | SCAC3 |
| 28 | CLSM | CLISHAM OIL CO | | | SCAC4 |
| 29 | CLSQ | CLASSIC LIMOUSINE SERVICE INC | | | SCAC3 |
| 30 | CLSQ | C L S EXPRESS INC | | | SCAC4 |
| 31 | CLST | CARLSON TRANSPORT, INC | | | SCAC3 |
| 32 | CLSU | CARAVEL LOGISTICS PRIVATE LIMITED | | IND | BIC |
| 33 | CLSU | CONTAINER LEASING SERVICES | | | SCAC3 |
| 34 | CLSU | CARAVEL SHIPPING SERVICES PRIVATE L | | | SCAC4 |
| 35 | CLSV | CARLS TOWING & REPAIR | | | SCAC3 |
| 36 | CLSW | COLUMBIA STORAGE WAREHOUSE COMPANY | | | SCAC3 |
| 37 | CLSX | Cargill Inc. — Salt Division | added 1/1991; 1/1994-7/2005 | | NAKINA |
| 38 | CLSX | Monitor Sugar Division of Robert Gage Coal Co. | 4/1938 | | NAKINA |
| 39 | CLSX | Monitor Sugar Co. | 7/1937 | | NAKINA |
| 40 | CLSX | Columbia Sugar Co. (Monitor Sugar Co.) | 7/1935 | | NAKINA |
| 41 | CLSX | Columbia Sugar Co. | 8/1920-7/1932 | | NAKINA |
| 42 | CLSX | Cargill Inc. -- Salt Division | added 1/91; 1/94-7/2000 | | NRHS |
| 43 | CLSX | Columbia Sugar Co. (Monitor Sugar, Division of Robert Gage Coal Co.) | Apr-38 | | NRHS |
| 44 | CLSX | *MONITOR SUGAR DIV. ROBERT GAGE COAL CO. [COLUMBIA SUGAR CO.] | | | PWRC |
| 45 | CLSX | +CARGILL INC., SALT DIVISION | | | PWRC |
| 46 | CLSX | Cargill Salt Division | | | RSRV |
| 47 | CLSX | CARGILL INC (SALT DIVISION) | | | SCAC4 |
| 48 | CLSY | CARLISLE LIMOUSINE SERVICE | | | SCAC3 |
| 49 | CLSY | CLEARDECK SYSTEMS LTD | | | SCAC4 |
