| 1 | CO | Continental Air Lines, Inc. | ICAO: COA, Callsign: Continental, IATA Prefix: 005, Name changed to Continental Airlines, Inc. | USA | AVCODES |
| 2 | CO | Continental Airlines, Inc. | ICAO: COA, Callsign: Continental, IATA Prefix: 005, Merged into United Airlines UA/UAL. Name changed from Continental Air Lines, Inc. | USA | AVCODES |
| 3 | CO | Cobaltair Limited t/a Cobaltair | ICAO: FCB, Callsign: New Age, ICAO callsign changed to Apollo. | CY | AVCODES |
| 4 | CO | Cobaltair Limited t/a Cobaltair | ICAO: FCB, Callsign: Apollo, Ceased operations on 18 October 2018. Entered voluntary liquidation on 19 December 2018. ICAO callsign changed from New Age. | CY | AVCODES |
| 5 | CO | North-Western Cargo International Airlines Co., Ltd. | ICAO: CNW, Callsign: Tang, IATA Prefix: 966, Established in 2016. | PRC | AVCODES |
| 6 | CO | CSX Transportation, Inc. | added 10/1987; 1/1994-7/2005 | | NAKINA |
| 7 | CO | Chesapeake & Ohio Ry. Co. | 1/1975-1/1980; eliminated 10/1987 | | NAKINA |
| 8 | CO | Chesapeake & Ohio Ry. Co. | 1/75-1/80; eliminated 10/87 | | NRHS |
| 9 | CO | CSX Transportation, Inc. | added 10/87; 1/94-7/2000 | | NRHS |
| 10 | CO | CSX TRANSPORTATION [CHESAPEAKE & OHIO RWY] | | | PWRC |
| 11 | CO | Chesapeake and Ohio Railway (CSX Transportation) | | | RSRV |
| 12 | CO | CHESAPEAKE AND OHIO RAILROAD COMPAN | | | SCAC4 |
| 13 | CO | Chesapeake & Ohio | | USA | TRAFFIC |
| 14 | CO | CEMOS Ostrava, a.s. | | CZ | VKM |
| 15 | CO&P | Chicago, Ottawa & Peoria Ry. (Illinois Traction, Inc.—Illinois Valley Division) | 7/1923 | | NAKINA |
| 16 | CO&P | Chicago, Ottawa & Peoria Ry. (Illinois Traction, Inc.--Illinois Valley Division) | 23-Jul | | NRHS |
| 17 | CO&P | CHICAGO OTTAWA & PEORIA RWY (ILLINOIS TRACTION, INC, ILLINOIS VALLEY DIV.) | | | PWRC |
| 18 | COA | Continental Air Lines, Inc. | IATA: CO, Callsign: Continental, IATA Prefix: 005, Name changed to Continental Airlines, Inc. | USA | AVCODES |
| 19 | COA | Continental Airlines, Inc. | IATA: CO, Callsign: Continental, IATA Prefix: 005, Merged into United Airlines UA/UAL. Name changed from Continental Air Lines, Inc. | USA | AVCODES |
| 20 | COA | Continental Airlines | IATA: CO | | ICAO1 |
| 21 | COA | Central Ry. Co. of Arkansas | 8/1920-7/1930 | | NAKINA |
| 22 | COA | Central Ry. Co. of Arkansas | 23-Jul | | NRHS |
| 23 | COA | CENTRAL RWY. CO. OF ARKANSAS | | | PWRC |
| 24 | COA | Continental Airlines | | USA | TRAFFIC |
| 25 | COAA | COASTAL TOWING & TRANSPORTATION CO, | | | SCAC3 |
| 26 | COAA | COASTAL EXPRESS INC | | | SCAC4 |
| 27 | COAB | COASTAL INC | | | SCAC3 |
| 28 | COAB | COASTAL INC | | | SCAC4 |
| 29 | COAC | COMBINED ATLANTIC CARRIERS | | | SCAC3 |
| 30 | COAC | COMBINED ATLANTIC CARRIERS | | | SCAC4 |
| 31 | COAC | Coast Cities | | US-NJ | TRAFFIC |
| 32 | COAD | COASTOL FIBERS INC | | | SCAC3 |
| 33 | COAF | COAST FREIGHT LINE | | | SCAC3 |
| 34 | COAF | Colombian Aerospace Force | Real: FAC, Fuerza Aeroespacial Colombiana | CO | TRAFFIC |
| 35 | COAG | COASTAL TRUCKING COMPANY | | | SCAC3 |
| 36 | COAH | COAST NURSERIES INC | | | SCAC4 |
| 37 | COAI | COASTAL MOVING COMPANY INC | | | SCAC3 |
| 38 | COAI | COASTAL MOVING COMPANY INC | | | SCAC4 |
| 39 | COAJ | COLUMBIA BASIN SPREADERS INC | | | SCAC4 |
| 40 | COAK | COAN TRANSPORTATION INC | | | SCAC4 |
| 41 | COAL | COALE TRUCK TRANSPORT INC | | | SCAC3 |
| 42 | COAL | CASCADE OIL CO | | | SCAC4 |
| 43 | COAL | Czech Coal services | | CZ | VKM |
| 44 | COAM | COASTAL MOVING & STORAGE, INC | | | SCAC3 |
| 45 | COAN | CONTAINER TRANSPORT INC | | | SCAC3 |
| 46 | COAN | CANO GUEVARA, DIANA | | | SCAC4 |
| 47 | COAN | Argentine Naval Aviation | Comando de la Aviación Naval Argentina | RA | TRAFFIC |
| 48 | COAO | COLORADO CONSOLIDATORS CORP | | | SCAC3 |
| 49 | COAO | CORO AUTOTRANSPORTES | | | SCAC4 |
| 50 | COAQ | COASTAL CARTAGE CO | | | SCAC3 |
| 51 | COAR | COAST REFRIGERATED TRUCKING CO INC | | | SCAC3 |
| 52 | COAS | COASTAL SUPPLY CO INC | | | SCAC4 |
| 53 | COASTER | Coaster | | USA | TRAFFIC |
| 54 | COAT | COATES-NORRELL MOTOR EXPRESS INC | | | SCAC3 |
| 55 | COAT | COATES-NORRELL MOTOR EXPRESS INC | | | SCAC4 |
| 56 | COAV | CAHALAN OIL COMPANY | | | SCAC4 |
| 57 | COAW | COASTAL TOWING & LIGHTERAGE CORP | | | SCAC3 |
| 58 | COAW | COLANGELO, ADAM | | | SCAC4 |
| 59 | COAX | Trinity Rail Management, Inc. | added 7/1997; 7/2000-7/2005 | | NAKINA |
| 60 | COAX | Transcisco Leasing Co. | added 7/1994; eliminated 7/1997 | | NAKINA |
| 61 | COAX | Transcisco Leasing Co. | added 7/94; eliminated 7/97 | | NRHS |
| 62 | COAX | Trinity Rail Management, Inc. | added 7/97; 7/2000 | | NRHS |
| 63 | COAX | *(MCHX) TRANSCISCO LEASING COMPANY | | | PWRC |
| 64 | COAX | +TRINITY RAIL MANAGEMENT INC | | | PWRC |
| 65 | COAX | Trinity Rail Management | | | RSRV |
| 66 | COAX | TRINITY RAIL MANAGEMENT | | | SCAC4 |
| 67 | COAZ | COLUMBIA ALUMINUM | | | PWRC |
| 68 | COB | Platinum Air Charter Executive Limited | Callsign: Cobham, Ceased operations | GB | AVCODES |
| 69 | COB | Cobra Jet Aviation | Callsign: Cobra Jet, | ET | AVCODES |
| 70 | COBA | COBANE AIR FREIGHT & EXPRESS INC | | | SCAC3 |
| 71 | COBB | COBB AUTO | | | SCAC4 |
| 72 | COBC | County Bus and Coach | London Country North East was bought by AJS and Parkdale in April 1988, then divided into two chunks in January 1989. County Bus and Coach was at Hertford, Harlow and Grays. | GB | TRAFFIC |
| 73 | COBD | CANNING PRODUCE INC | | | SCAC4 |
| 74 | COBE | CONTRACT BEVERAGES INC | | | SCAC3 |
| 75 | COBE | COBRA EXPRESS INC | | | SCAC4 |
| 76 | COBF | COBB FROZEN TRANSPORT INC | | | SCAC3 |
| 77 | COBG | COLBERG TRANSPORTATION | | | SCAC3 |
| 78 | COBG | COMPOSITES ONE LLC | | | SCAC4 |
| 79 | COBH | CORBIN TRUCKING CO INC | | | SCAC3 |
| 80 | COBI | COLORADO BEEF CO | | | SCAC3 |
| 81 | COBJ | COBB, JOSEPH E | | | SCAC3 |
| 82 | COBL | COBLE TRANSFER & STORAGE CO | | | SCAC3 |
| 83 | COBL | CONALTA ENTERPRISES CORP | | | SCAC4 |
| 84 | COBM | COLUMBUS CONSOLIDATED METRO | | | SCAC3 |
| 85 | COBN | COB-ASH INC | | | SCAC4 |
| 86 | COBO | COASTAL BEND DELIVERY SERVICE | | | SCAC3 |
| 87 | COBP | COLUMBIA BASIN CONTAINER CORP | | | SCAC3 |
| 88 | COBQ | COLIA BROTHERS | | | SCAC3 |
| 89 | COBQ | COLD STAR FREIGHT SYSTEMS INC | | | SCAC4 |
| 90 | COBRA | Cobelfret Rail NV | | BE | VKM |
| 91 | COBS | COBB-VANTRESS INCORPORATED | | | SCAC4 |
| 92 | COBT | COMMODITY OCEAN TRANSPORT CORP | | | SCAC3 |
| 93 | COBU | SONANGOL PESQUISA & PRODUCAO SA | | ANG | BIC |
| 94 | COBU | CONTAINER BUSINESS INC | | | SCAC3 |
| 95 | COBU | ELF EXPLORATION ANGOLA | | | SCAC4 |
| 96 | COBV | COBAM, ANTWERP, BELGIUM | | | SCAC3 |
| 97 | COBV | COBELFRET BULK CARRIERS NV | | | SCAC4 |
| 98 | COBW | CCBCC OPERATIONS LLC | | | SCAC4 |
| 99 | COBX | Cobre Mining Co. | added 1/1997; eliminated 7/1999; 7/2000 (not listed) | | NAKINA |
| 100 | COBX | Cobre Mining Co., Inc. | eliminated 1/1997 | | NAKINA |
