| 1 | QC | Aviation Quebec Labrador LTEE | ICAO: QLA, Callsign: Quebec Labrador, Designator QC recalled by IATA. IATA designator changed from JT* | CDN | AVCODES |
| 2 | QC | Air Zaire | ICAO: AZR, Callsign: Air Zaire, | ZAR | AVCODES |
| 3 | QC | Air Corridor | ICAO: CRD, Callsign: Air Corridor, Designator QC reinstated by IATA | MOC | AVCODES |
| 4 | QC | Canadian Pacific Ry. Co. | added 1/1997; 7/2000-7/2005 | | NAKINA |
| 5 | QC | CP Rail System (Canadian Pacific Ltd.) | added 7/1994; eliminated 1/1997 | | NAKINA |
| 6 | QC | Quebec Central Ry. (Co.) | 8/1920-10/1957; 1/1975; added 10/1979; 1/1980-1/1994; eliminated 7/1994 | | NAKINA |
| 7 | QC | Quebec Central Ry. | 4/38-10/57 | | NRHS |
| 8 | QC | Quebec Central Ry. Co. | 1/75-1/94; eliminated 7/94 | | NRHS |
| 9 | QC | CP Rail System (Canadian Pacific Ltd.) | added 7/94; eliminated 1/97 | | NRHS |
| 10 | QC | Canadian Pacific Ry. Co. | added 1/97; 7/2000 | | NRHS |
| 11 | QC | CP RAIL [QUEBEC CENTRAL RY] | | | PWRC |
| 12 | QC | Quebec Central Railway | | | RSRV |
| 13 | QC | Quebec Central Railway Company | | CDN | TRAFFIC |
| 14 | QCAF | QUEEN CITY AIR FREIGHT | | | SCAC3 |
| 15 | QCAF | QUEEN CITY AIR FREIGHT | | | SCAC4 |
| 16 | QCAI | Q CARRIERS INC | | | SCAC3 |
| 17 | QCBH | QCB SHIPPING | | | SCAC4 |
| 18 | QCC | Qwest Commuter Corporation | Callsign: Qwest Air, | USA | AVCODES |
| 19 | QCC | Qwest Commuter Corporation | | | ICAO1 |
| 20 | QCCC | QUICK/CARE CORPORATION | | | SCAC3 |
| 21 | QCCC | QUICKPICK.COM LLC | | | SCAC4 |
| 22 | QCCI | QUAKER CITY CHEMICALS INC | | | SCAC4 |
| 23 | QCCR | QUAL CON CONCRETE CONTRACTORS | | | SCAC4 |
| 24 | QCCX | General Electric Rail Services Corp. | added 10/2009 | | NAKINA |
| 25 | QCCX | Equistar Chemicals, LP | added 4/1998; 7/2000-7/2005; eliminated 10/2009 | | NAKINA |
| 26 | QCCX | Quantum Chemical Corp., USI Division | eliminated 4/1998 | | NAKINA |
| 27 | QCCX | Trancisco Leasing Co. | added 10/1996; eliminated 1/1997 | | NAKINA |
| 28 | QCCX | Quantum Chemical Corp. | added 1/1997 | | NAKINA |
| 29 | QCCX | Trancisco Leasing Co. | added 10/96; eliminated 1/97 | | NRHS |
| 30 | QCCX | Quantum Chemical Corp. | added 1/97 | | NRHS |
| 31 | QCCX | Quantum Chemical Corp., USI Division | eliminated 4/98 | | NRHS |
| 32 | QCCX | Equistar Chemicals, LP | added 4/98; 7/2000 | | NRHS |
| 33 | QCCX | EQUISTAR CHEMICALS LP [QUANTUM CHEMICAL CORP.] (TRANCISCO LEASING) | | | PWRC |
| 34 | QCCX | Quantum Chemical Corporation | | | RSRV |
| 35 | QCCX | EQUISTAR CHEMICALS LP | | | SCAC4 |
| 36 | QCDS | QUALITY COURIER & DELIVERY SERVICE | | | SCAC3 |
| 37 | QCEP | QUIVAS CARGO EXPRESS | | | SCAC4 |
| 38 | QCFL | QUIK CHEK FUELS | | | SCAC4 |
| 39 | QCGU | Quest Capital Group | | | RSRV |
| 40 | QCGU | QUEST CAPITAL GROUP LLC | | | SCAC4 |
| 41 | QCHM | QUALITY CRAFT HOMES | | | SCAC4 |
| 42 | QCIC | QUALITY CARTAGE INCORPORATED | | | SCAC3 |
| 43 | QCIN | QUALITY COURIER INC | | | SCAC3 |
| 44 | QCIY | QUEEN CITY INC | | | SCAC4 |
| 45 | QCL | Air Class Lineas Aereas (Aerovip Ltda) | IATA: QD, Callsign: Acla, Founded in 1996. Commenced operations in 1997. | ROU | AVCODES |
| 46 | QCL | AeroVIP S.A. (Air Class) | IATA: VZ, Callsign: Acla, IATA Prefix: 762, Founded in 1996. Commenced operations in 1997. Name changed to Air Express S.A. d/b/a Air Class Lineas Aereas. | ROU | AVCODES |
| 47 | QCL | Air Express S.A. d/b/a Air Class Lineas Aereas | IATA: VZ, Callsign: Acla, IATA Prefix: 762, Founded in 1996. Commenced operations in 1997. Name changed from AeroVIP S.A. (Air Class). | ROU | AVCODES |
| 48 | QCL | Air Class Lineas Aereas | IATA: QD | | ICAO1 |
| 49 | QCLH | QUAIL CREEK LIVESTOCK HAULING INC | | | SCAC4 |
| 50 | QCLI | QUALITY COACH LINES INC | | | SCAC3 |
| 51 | QCLL | QUICK COACH LINES LTD | | | SCAC3 |
| 52 | QCLL | QUICK COACH LINES LTD | | | SCAC4 |
| 53 | QCM | Quebec Cartier Mining Railway | | CDN | TRAFFIC |
| 54 | QCMF | QUINTE CANVAS MANUFACTURING | | | SCAC4 |
| 55 | QCMH | Q C MOBILE HOMES INC | | | SCAC3 |
| 56 | QCMS | QUEEN CITY MOVING & STORAGE CO | | | SCAC3 |
| 57 | QCR | Quebec Central Ry. Co. | 7/2005 | | NAKINA |
| 58 | QCR | QUEBEC CENTRAL RWY. CO. | | | PWRC |
| 59 | QCR | Quebec Central Railway | | | RSRV |
| 60 | QCR | QUEBEC CENTRAL RAILWAY COMPANY | | | SCAC4 |
| 61 | QCR | Quebec Central Rail | | CDN | TRAFFIC |
| 62 | QCRS | QUALITY OF CALIFORNIA RELOCATION SE | | | SCAC3 |
| 63 | QCSE | QUICK COURIER SERVICES | | | SCAC4 |
| 64 | QCSF | QUICK CSF INC | | | SCAC4 |
| 65 | QCSI | QUALITY CONTAINER SERVICES INC | | | SCAC3 |
| 66 | QCSI | QUALITY CONTAINER SERVICES INC | | | SCAC4 |
| 67 | QCSL | QUALITY CONSOLIDATORS LTD | | | SCAC3 |
| 68 | QCSV | QUALITY COURIER SERVICE | | | SCAC3 |
| 69 | QCSY | Q C SYSTEMS OF LANCASTER INC | | | SCAC3 |
| 70 | QCTA | QUARTER CIRCLE 13 TRANSPORTATION | | | SCAC4 |
| 71 | QCTD | QUALITY CONSTRUCTION (TRUCKING DIVI | | | SCAC4 |
| 72 | QCTH | QUETOP CORPORATION, THE | | | SCAC4 |
| 73 | QCTS | QUEEN CITY TRAFFIC SERVICE INC | | | SCAC3 |
| 74 | QCTY | QUEEN CITIES | | | SCAC3 |
| 75 | QCWC | QUEEN CITY WAREHOUSE CORP | | | SCAC3 |
| 76 | QCX | Quemahoning Coal Co. | 8/1920-7/1923 | | NAKINA |
| 77 | QCX | QUEMAHONING COAL CO. | | | PWRC |
| 78 | QCXU | QUALITY CARRIERS | | USA | BIC |
