| 401 | QKWI | QUICKWAY CARRIERS INC | | | SCAC4 |
| 402 | QKWP | QUICKWAY TRANSPORTATION INC | | | SCAC4 |
| 403 | QKWQ | QWIK-WAY MOTOR SERVICE CORP | | | SCAC3 |
| 404 | QKWT | QUICKWAY TRANSPORTATION | | | SCAC3 |
| 405 | QKWT | QUICKWAY TRANSPORTATION | | | SCAC4 |
| 406 | QKWY | QUICKWAY COURIER | | | SCAC3 |
| 407 | QKXT | QUIKX TRANSX LTD | | | SCAC3 |
| 408 | QKXT | QUIK X TRANSPORTATION (US) INC | | | SCAC4 |
| 409 | QL | Air Lesotho (Pty) Ltd. | ICAO: LAI, Callsign: Lesotair, Designator QL recalled by IATA. Name changed from Lesotho Airways Corporation | LS | AVCODES |
| 410 | QL | Air Gulf Falcon PTY Ltd. | ICAO: GLN, Callsign: Gulfalcon, Ceased operations. Designator QL recalled by IATA | SD | AVCODES |
| 411 | QL | Lesotho Airways Corporation | ICAO: LAI, Callsign: Lesotair, Name changed to Air Lesotho (Pty) Ltd. | LS | AVCODES |
| 412 | QL | Serendib Express (Pvt) Ltd. | ICAO: RNL, Callsign: Serendib, Name changed to Aero Lanka (Pvt) Ltd. | CL | AVCODES |
| 413 | QL | Aero Lanka (Pvt) Limited | ICAO: RLN, Callsign: Serendib, Designator QL reinstated by IATA. Name changed from Serendib Express. Name changed from Serendib Express (Pvt) Ltd. | CL | AVCODES |
| 414 | QL | Linea Aerea de Servicio Ejecutivo Regional, C.A. (LASER) | ICAO: LER, Callsign: Laser, Name changed to Linea Aerea de Servicio Ejecutivo Regional, C.A. d/b/a Laser. Founded in 1993. Commenced operations in 1994. | YV | AVCODES |
| 415 | QL | Linea Aerea de Servicio Ejecutivo Regional, C.A. d/b/a Laser | ICAO: LER, Callsign: Laser, IATA Prefix: 782, Name changed from Linea Aerea de Servicio Ejecutivo Regional, C.A. (LASER). Founded in 1993. Commenced operations in 1994. | YV | AVCODES |
| 416 | QL&P | The Quebec Ry. Light & Power Co. | 8/1920-7/1936 | | NAKINA |
| 417 | QL&P | QUEBEC RWY. LIGHT & POWER CO. | | | PWRC |
| 418 | QLA | Aviation Quebec Labrador LTEE | IATA: QC, Callsign: Quebec Labrador, Designator QC recalled by IATA. IATA designator changed from JT* | CDN | AVCODES |
| 419 | QLA | Aviation Quebec Labrador LTEE | IATA: JT, Callsign: Quebec Labrador, IATA designator changed to QC | CDN | AVCODES |
| 420 | QLA | Aviation Quebec Labrador LTEE | Callsign: Quebec Labrador, Designator QC recalled by IATA. IATA designator changed from JT* | CDN | AVCODES |
| 421 | QLA | Aviation Quebec Labrador | | | ICAO1 |
| 422 | QLBS | QUALITY BUS SERVICE INC | | | SCAC4 |
| 423 | QLCS | QUALITY CONTAINER SERVICE INC | | | SCAC3 |
| 424 | QLEI | Q LINE EXPRESSWAY INC | | | SCAC4 |
| 425 | QLES | QUALITY ENTERPRISE TRUCKING LTD | | | SCAC4 |
| 426 | QLFI | QUALIFIED TRUCK LINES INC | | | SCAC3 |
| 427 | QLGD | QUADRA LOGISTICS GROUP LTD | | | SCAC4 |
| 428 | QLGI | QUANTA LOGISTICS INC | | | SCAC4 |
| 429 | QLGL | QUALITY LOGISTICS LLC | | | SCAC4 |
| 430 | QLIC | QUEST LINER INC | | | SCAC4 |
| 431 | QLIN | QUALITY INTERMODAL DELIVERY SERVICE | | | SCAC4 |
| 432 | QLIQ | QUALITY MOVING & STORAGE | | | SCAC3 |
| 433 | QLIS | QUINCY LOGISTICS INC | | | SCAC4 |
| 434 | QLIT | QUALITY TRUCKING | | | SCAC3 |
| 435 | QLIT | QUALITY ENGINEERED HOMES LTD | | | SCAC4 |
| 436 | QLK | Qantaslink | Callsign: Q Link, | AUS | AVCODES |
| 437 | QLLA | QUANTUM LOGISTICS LLC | | | SCAC4 |
| 438 | QLLD | QUICKLAND LLC | | | SCAC4 |
| 439 | QLLI | QUALITY LOGISTICS | | | SCAC4 |
| 440 | QLLO | QINGDAO LINKWORLD LOGISTICS CO LTD | | | SCAC4 |
| 441 | QLLX | Quality Leasing & Logistics Co. d/b/a QUALLCO | added 7/2006; eliminated 10/2007( | | NAKINA |
| 442 | QLLX | QUALITY LEASING & LOGISTICS CO. a/k/a QUALLCO | | | PWRC |
| 443 | QLLX | QUALITY LEASING & LOGISTICS A/K/A Q | | | SCAC4 |
| 444 | QLMS | QUALITY MOVERS OF MISSISSIPPI INC | | | SCAC3 |
| 445 | QLMX | Qilico Ltd. c/o SC Capital Corp. | added 10/1994; eliminated 10/1997 | | NAKINA |
| 446 | QLMX | Qilico Ltd. c/o SC Capital Corp. | added 10/94; eliminated 10/97 | | NRHS |
| 447 | QLMX | QILICO LIMITED (SC CAPITAL CORP.) | | | PWRC |
| 448 | QLOG | QUALITY LOGISTICS INC | | | SCAC4 |
| 449 | QLP | Quebec Ry. Light & Power Co. | 4/1938-4/1970 | | NAKINA |
| 450 | QLP | Quebec Ry. Light & Power Co. | 4/38-4/70 | | NRHS |
| 451 | QLP | (CNR) QUEBEC RY. LIGHT & POWER CO. | | | PWRC |
| 452 | QLSC | QUALITY ENTERPRISES USA CORPORATION | | | SCAC4 |
| 453 | QLSI | QUALITY LOGISTICS SYSTEMS INC | | | SCAC4 |
| 454 | QLSN | QUALITY LOGISTICS SERVICES INC | | | SCAC4 |
| 455 | QLSX | General American Transportation Corp. | 7/1937-1/1945 | | NAKINA |
| 456 | QLSX | Quaker City Live Stock Express (General American Tank Car Corp.) | 7/1935 | | NAKINA |
| 457 | QLSX | Quaker City Live Stock Express | 7/1930-7/1932 | | NAKINA |
| 458 | QLSX | Quaker City Live Stock Express (General American Transportation Corp.) | Apr-38 | | NRHS |
| 459 | QLSX | QUAKER CITY LIVE STOCK EXPRESS (GENERAL AMERICAN TRANSPORTATION CORP.) | | | PWRC |
| 460 | QLTA | QUALITY TRANSPORT (A DIV OF AMERICA | | | SCAC3 |
| 461 | QLTC | QUALITY TRANSPORT COMPANY | | | SCAC4 |
| 462 | QLTF | QUALITY FREIGHT TRANSPORTATION | | | SCAC3 |
| 463 | QLTL | QUALITY LOGISTICS INCORPORATED | | | SCAC4 |
| 464 | QLTN | QUALITY TRANSPORT INC | | | SCAC3 |
| 465 | QLTN | QUALITY TRANSPORTATION | | | SCAC4 |
| 466 | QLTO | QUALITY TRANSPORT INC | | | SCAC4 |
| 467 | QLTP | QUALITY TRANSPORTATION | | | SCAC4 |
| 468 | QLTR | QUALITY TRANSPORTATION | | | SCAC3 |
| 469 | QLTV | QUALITY TRANSPORT SA DE CV | | | SCAC4 |
| 470 | QLTY | QUALITY TRANSPORTATION CONSULTANTS | | | SCAC3 |
| 471 | QLTY | QUALITY EXPRESS USA INC | | | SCAC4 |
| 472 | QLYC | QUALITY CARRIERRS INC | | | SCAC3 |
| 473 | QLYC | QUALITY CARRIERS INC | | | SCAC4 |
| 474 | QLYD | QUALITY DISTRIBUTION, INC | | | SCAC3 |
| 475 | QLYD | QUALITY DISTRIBUTION INC | | | SCAC4 |
| 476 | QLYR | QUALITY TRUCKING INC | | | SCAC4 |
| 477 | QLYT | QUALITY TRANSPORT INC | | | SCAC4 |
| 478 | QM | Air Malawi Limited | ICAO: AML, Callsign: Malawi, IATA Prefix: 167, Founded on 01 September 1967. Ceased operations during February 2013. Designator QM reinstated by IATA | MW | AVCODES |
| 479 | QM | Monacair | | MC | AVCODES |
| 480 | QM&S | Quebec, Montreal & Southern Ry. Co. | 7/1923 | | NAKINA |
| 481 | QM&S | CANADIAN NATIONAL RWYS. [QUEBEC, MONTREAL & SOUTHERN RWY. CO.] | | | PWRC |
| 482 | QMAS | QUALITY MOVING & STORAGE INC | | | SCAC3 |
| 483 | QMBC | QUIMBY COMPANY | | | SCAC3 |
| 484 | QMBY | QUIMBY TRUCKING INC | | | SCAC3 |
| 485 | QMBY | QUAM, MARTIN BARRY | | | SCAC4 |
| 486 | QMEI | QUALITY MOVERS EAST INC | | | SCAC3 |
| 487 | QMGS | QUALITY MOVING SERVICE INC | | | SCAC3 |
| 488 | QMHC | QUALITY MOBILE HOME CONTRACTING | | | SCAC3 |
| 489 | QMHS | QUALITY MOBILE HOME TRANSPORT | | | SCAC3 |
| 490 | QMIC | QUANTUM METALS INC | | | SCAC4 |
| 491 | QMKL | QUINDEN MARKETING LTD | | | SCAC4 |
| 492 | QMLD | QUALITY MOLD 2000 | | | SCAC4 |
| 493 | QMLI | QUANTUM LOGISTICS INC | | | SCAC4 |
| 494 | QMLS | QUINTANA, MANUEL S | | | SCAC3 |
| 495 | QMLT | QUEEN MARITIME LTD | | | SCAC4 |
| 496 | QMMI | QUALITY MOVE MANAGEMENT INC | | | SCAC3 |
| 497 | QMMS | Q & M MOTORS | | | SCAC4 |
| 498 | QMMT | QMM TRANSPORT INC | | | SCAC4 |
| 499 | QMNS | QUINN MOVING AND STORAGE | | | SCAC3 |
| 500 | QMPL | QM PLASTICS | | | SCAC4 |
