| 1 | CT | Air Sofia | ICAO: SFB, Callsign: Air Sofia, IATA Prefix: 551, Closed down by Bulgarian Authorites on 05 March 2007. | BG | AVCODES |
| 2 | CT | Northwestern Air Lease Ltd. | ICAO: PLR, Callsign: Polaris, IATA Desigantor changed to J3 | CDN | AVCODES |
| 3 | CT | Air One Cityliner S.p.A. | ICAO: CYL, Callsign: Cityliner, Name changed to Alitalia Cityliner S.p.A. w.e.f. 20 April 2011. Founded June 2006 | I | AVCODES |
| 4 | CT | Alitalia Cityliner S.p.A. | ICAO: CYL, Callsign: Cityliner, Name changed from Air One Cityliner S.p.A. w.e.f. 20 April 2011. | I | AVCODES |
| 5 | CT | Air Atlanta Europe Limited | ICAO: AAE, Callsign: Euroviking, IATA Prefix: 317, Established on 09 December 2020. | M | AVCODES |
| 6 | CT | City of Columbia d/b/a Columbia Terminal | added 1/1988; eliminated 7/1989; added 1/1988; 1/1994-7/2005 | | NAKINA |
| 7 | CT | City of Columbia d/b/a Columbia Terminal | added 1/88; eliminated 7/89; added 1/88; 1/94-7/2000 | | NRHS |
| 8 | CT | CITY OF COLUMBIA D/B/A COLUMBIA TERMINAL RAILROAD CO. | | | PWRC |
| 9 | CT | Columbia Terminal | | | RSRV |
| 10 | CT | COLUMBIA TERMINAL | | | SCAC4 |
| 11 | CT | Central Trains Ltd. | 1999: standard gauge, electrified at 25kV 50Hz | GB | TRAFFIC |
| 12 | CT | Central Trains | | UK | VKM |
| 13 | CT&S | Cairo, Truman & Southern R.R. Co. | 7/1923-7/1932 | | NAKINA |
| 14 | CT&S | Cairo, Truman & Southern R.R. Co. | 23-Jul | | NRHS |
| 15 | CT&S | CAIRO, TRUMAN & SOUTHERN RAILROAD CO. | | | PWRC |
| 16 | CTA | Compagnie de Transport Aerien (CTA) | Callsign: CTA, Merged with Balair w.e.f. 01 January 1993. Desigantor RU recalled by IATA | CH | AVCODES |
| 17 | CTA | Trans Caribe, S.A. de C.V. | Callsign: Caribe-Trans, | MEX | AVCODES |
| 18 | CTA | Aero Charter and Transport | Callsign: Char-Tran, | USA | AVCODES |
| 19 | CTA | Compagnie de Transport Aerien (CTA) | IATA: RU, Callsign: CTA, Desigantor RU recalled by IATA | CH | AVCODES |
| 20 | CTA | Aero Charter and Transport | | | ICAO1 |
| 21 | CTA | CHICAGO TRANSIT AUTHORITY | | | PWRC |
| 22 | CTA | CONTINENTAL AIR TRANSPORT CO INC | | | SCAC4 |
| 23 | CTA | Chicago Transit Authority | | USA | TRAFFIC |
| 24 | CTAB | CHITTAMO TRUCK LINES | | | SCAC3 |
| 25 | CTAC | CONTRANS | | | SCAC3 |
| 26 | CTAD | COURT, ARTHUR DESIGNS INC | | | SCAC3 |
| 27 | CTAE | CONNER TRAFFIC ASSOCIATION INC | | | SCAC3 |
| 28 | CTAF | CONNECTICUT AIR FREIGHT INC | | | SCAC3 |
| 29 | CTAG | CORNERSTONE TRANSPORTATION, INC | | | SCAC3 |
| 30 | CTAI | CITY TRANSFER INC | | | SCAC3 |
| 31 | CTAK | COMMERCIAL TRUCK & CRANE | | | SCAC3 |
| 32 | CTAL | CONTINENTAL ATLANTIC LINES INC | | | SCAC3 |
| 33 | CTAN | C2C TRANSPORTATION SERVICES INC | | | SCAC4 |
| 34 | CTAO | COTA TRANSFER & STORAGE | | | SCAC3 |
| 35 | CTAP | COMMERCIAL TRUCK COMPANY (US) INC | | | SCAC3 |
| 36 | CTAP | CROSS COUNTRY TOURS INC | | | SCAC4 |
| 37 | CTAQ | CAROLINA TANK LINES INC | | | SCAC3 |
| 38 | CTAQ | CAROLINA TANK LINES INC | | | SCAC4 |
| 39 | CTAS | CROWLEY TRANSPORTATION SERVICE LLC | | | SCAC4 |
| 40 | CTAT | CONTRACT TRANSPORT INC | | | SCAC3 |
| 41 | CTAT | CONTRACT TRANSPORT INC | | | SCAC4 |
| 42 | CTAU | COOLTAINER NEW ZEALAND LIMITED | | NZ | BIC |
| 43 | CTAU | COOLTAINER SERVICES, LTD | | | SCAC3 |
| 44 | CTAU | OWENS REFRIGERATED FREIGHT LTD | | | SCAC4 |
| 45 | CTAV | CODE THREE AVIATION INC | | | SCAC3 |
| 46 | CTAV | CBC/RADIO-CANADA SOCIETE RADIO CANA | | | SCAC4 |
| 47 | CTAW | CATAWBA TRUCKING CO, INC | | | SCAC3 |
| 48 | CTAX | Coast to Coast Leasing, Inc. | added 4/1969; 4/1970-1/1975; eliminated 7/1977 | | NAKINA |
| 49 | CTAX | Shippers' Car Line Corp. (Service Tank Car Co.) | 1/1941-1/1943 | | NAKINA |
| 50 | CTAX | Service Tank Car Co. | 7/1937-4/1938 | | NAKINA |
| 51 | CTAX | Continental Tank Car Co. | 7/1923-7/1935 | | NAKINA |
| 52 | CTAX | Continental Tank Car Co. | Apr-38 | | NRHS |
| 53 | CTAX | Coast to Coast Leasing, Inc. | added 4/69; 4/70-1/75; eliminated 7/77 | | NRHS |
| 54 | CTAX | *SHIPPERS' CAR LINE CORP [SERVICE TANK CAR CO.; CONTINENTAL TANK CAR CO.] | | | PWRC |
| 55 | CTAX | *COAST TO COAST LEASING, INC. | | | PWRC |
| 56 | CTAY | COURTESY AND YELLOW CABS | | | SCAC3 |
| 57 | CTB | City Bird | IATA: H2, Callsign: Dream Flight, Ceased operations on 04 October 2001. Designator H2* reinstated by IATA | B | AVCODES |
| 58 | CTB | City Bird | IATA: H2, Callsign: Dream Flight, Designator H2* recalled by IATA | B | AVCODES |
| 59 | CTB | Thomas Cook Airlines Balearics S.L. | IATA: H5, Callsign: Sunnyheart, Established in October 2017. Ceased operations on 31 January 2021 | E | AVCODES |
| 60 | CTB | Compagnie Transport de Bourges | | F | TRAFFIC |
| 61 | CTB | Captrain Belgium NV | | BE | VKM |
| 62 | CTBA | CORONADO TRANSPORT INC | | | SCAC3 |
| 63 | CTBA | C2C TRANSPORTATION INC | | | SCAC4 |
| 64 | CTBB | COMPLETE TRUCK BROKERAGE INC | | | SCAC3 |
| 65 | CTBC | CALE TRANSPORT INC | | | SCAC3 |
| 66 | CTBE | COLONIAL TRANSIT INC | | | SCAC3 |
| 67 | CTBE | CARIBBEAN TRANSPORT EXPRESS INC | | | SCAC4 |
| 68 | CTBF | CHRISTIAN TRANSPORTATION | | | SCAC3 |
| 69 | CTBG | CONDOR TRANSPORT INC | | | SCAC3 |
| 70 | CTBH | CAROLINA TRUCK BROKERS INC | | | SCAC3 |
| 71 | CTBH | CLAYTON LOGISTICS LLC | | | SCAC4 |
| 72 | CTBI | CHRISTIAN TRANSPORT INC | | | SCAC3 |
| 73 | CTBI | CTB TRANSPORTATION INC | | | SCAC4 |
| 74 | CTBK | CONTINENTAL TRUCK BROKERS INC | | | SCAC4 |
| 75 | CTBM | CHAMPION PRODUCTS | | | SCAC4 |
| 76 | CTBN | CONTE TRANSPORTATION CO | | | SCAC3 |
| 77 | CTBO | CONTACT TRUCKING CORP | | | SCAC3 |
| 78 | CTBO | CJT LOGISTICS INC | | | SCAC4 |
| 79 | CTBP | COLONIAL TAXI CO | | | SCAC3 |
| 80 | CTBP | CARTERS TRUCKING & BLACKTOPPING INC | | | SCAC4 |
| 81 | CTBQ | CITY BONDED MESSENGER & TRUCKING SE | | | SCAC3 |
| 82 | CTBQ | CASTILLO TRANSPORT | | | SCAC4 |
| 83 | CTBR | CHRISTENSEN BROS TRUCKING INCORPORA | | | SCAC3 |
| 84 | CTBR | COAST TO COAST AUTO/MARINE TRANSPOR | | | SCAC4 |
| 85 | CTBS | C T SOUTHERN INC | | | SCAC3 |
| 86 | CTBT | C T B TRUCKING INC | | | SCAC3 |
| 87 | CTBT | CTB TRUCK BROKERAGE INC | | | SCAC4 |
| 88 | CTBU | CONTAINER TRADER LTD. | | BG | BIC |
| 89 | CTBV | CUSTOM TRANSPORT, INC | | | SCAC3 |
| 90 | CTBV | CUSTOM TRANSPORT INC | | | SCAC4 |
| 91 | CTBW | CAROLINA TRANSPORT OF BURGAW INC | | | SCAC4 |
| 92 | CTBY | CHELATCHIE TRUCKING INC | | | SCAC3 |
| 93 | CTBY | CRYSTAL CLEAR FREIGHT INC | | | SCAC4 |
| 94 | CTC | Corporacion Ejecutiva de Transporte Aereo, S.A. de C.V. | Callsign: Corp Ejecutiva, | MEX | AVCODES |
| 95 | CTC | C T C Air, S.A. | IATA: MW, Callsign: CTC, Designator MW recalled by IATA | E | AVCODES |
| 96 | CTC | CENTER FOR TRANSPORTATION | | | PWRC |
| 97 | CTC | CTC (Compagnie de Transports de Céréales | | FR | VKM |
| 98 | CTCA | CTC TRANSPORTATION INC | | | SCAC3 |
| 99 | CTCA | COLUMBIA TECHNOLOGIES LLC | | | SCAC4 |
| 100 | CTCC | COASTAL CAROLINA CARRIERS INC | | | SCAC3 |
