| 1 | QL | Air Lesotho (Pty) Ltd. | ICAO: LAI, Callsign: Lesotair, Designator QL recalled by IATA. Name changed from Lesotho Airways Corporation | LS | AVCODES |
| 2 | QL | Air Gulf Falcon PTY Ltd. | ICAO: GLN, Callsign: Gulfalcon, Ceased operations. Designator QL recalled by IATA | SD | AVCODES |
| 3 | QL | Lesotho Airways Corporation | ICAO: LAI, Callsign: Lesotair, Name changed to Air Lesotho (Pty) Ltd. | LS | AVCODES |
| 4 | QL | Serendib Express (Pvt) Ltd. | ICAO: RNL, Callsign: Serendib, Name changed to Aero Lanka (Pvt) Ltd. | CL | AVCODES |
| 5 | 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 |
| 6 | 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 |
| 7 | 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 |
| 8 | QL&P | The Quebec Ry. Light & Power Co. | 8/1920-7/1936 | | NAKINA |
| 9 | QL&P | QUEBEC RWY. LIGHT & POWER CO. | | | PWRC |
| 10 | QLA | Aviation Quebec Labrador LTEE | IATA: QC, Callsign: Quebec Labrador, Designator QC recalled by IATA. IATA designator changed from JT* | CDN | AVCODES |
| 11 | QLA | Aviation Quebec Labrador LTEE | IATA: JT, Callsign: Quebec Labrador, IATA designator changed to QC | CDN | AVCODES |
| 12 | QLA | Aviation Quebec Labrador LTEE | Callsign: Quebec Labrador, Designator QC recalled by IATA. IATA designator changed from JT* | CDN | AVCODES |
| 13 | QLA | Aviation Quebec Labrador | | | ICAO1 |
| 14 | QLBS | QUALITY BUS SERVICE INC | | | SCAC4 |
| 15 | QLCS | QUALITY CONTAINER SERVICE INC | | | SCAC3 |
| 16 | QLEI | Q LINE EXPRESSWAY INC | | | SCAC4 |
| 17 | QLES | QUALITY ENTERPRISE TRUCKING LTD | | | SCAC4 |
| 18 | QLFI | QUALIFIED TRUCK LINES INC | | | SCAC3 |
| 19 | QLGD | QUADRA LOGISTICS GROUP LTD | | | SCAC4 |
| 20 | QLGI | QUANTA LOGISTICS INC | | | SCAC4 |
| 21 | QLGL | QUALITY LOGISTICS LLC | | | SCAC4 |
| 22 | QLIC | QUEST LINER INC | | | SCAC4 |
| 23 | QLIN | QUALITY INTERMODAL DELIVERY SERVICE | | | SCAC4 |
| 24 | QLIQ | QUALITY MOVING & STORAGE | | | SCAC3 |
| 25 | QLIS | QUINCY LOGISTICS INC | | | SCAC4 |
| 26 | QLIT | QUALITY TRUCKING | | | SCAC3 |
| 27 | QLIT | QUALITY ENGINEERED HOMES LTD | | | SCAC4 |
| 28 | QLK | Qantaslink | Callsign: Q Link, | AUS | AVCODES |
| 29 | QLLA | QUANTUM LOGISTICS LLC | | | SCAC4 |
| 30 | QLLD | QUICKLAND LLC | | | SCAC4 |
| 31 | QLLI | QUALITY LOGISTICS | | | SCAC4 |
| 32 | QLLO | QINGDAO LINKWORLD LOGISTICS CO LTD | | | SCAC4 |
| 33 | QLLX | Quality Leasing & Logistics Co. d/b/a QUALLCO | added 7/2006; eliminated 10/2007( | | NAKINA |
| 34 | QLLX | QUALITY LEASING & LOGISTICS CO. a/k/a QUALLCO | | | PWRC |
| 35 | QLLX | QUALITY LEASING & LOGISTICS A/K/A Q | | | SCAC4 |
| 36 | QLMS | QUALITY MOVERS OF MISSISSIPPI INC | | | SCAC3 |
| 37 | QLMX | Qilico Ltd. c/o SC Capital Corp. | added 10/1994; eliminated 10/1997 | | NAKINA |
| 38 | QLMX | Qilico Ltd. c/o SC Capital Corp. | added 10/94; eliminated 10/97 | | NRHS |
| 39 | QLMX | QILICO LIMITED (SC CAPITAL CORP.) | | | PWRC |
| 40 | QLOG | QUALITY LOGISTICS INC | | | SCAC4 |
| 41 | QLP | Quebec Ry. Light & Power Co. | 4/1938-4/1970 | | NAKINA |
| 42 | QLP | Quebec Ry. Light & Power Co. | 4/38-4/70 | | NRHS |
| 43 | QLP | (CNR) QUEBEC RY. LIGHT & POWER CO. | | | PWRC |
| 44 | QLSC | QUALITY ENTERPRISES USA CORPORATION | | | SCAC4 |
| 45 | QLSI | QUALITY LOGISTICS SYSTEMS INC | | | SCAC4 |
| 46 | QLSN | QUALITY LOGISTICS SERVICES INC | | | SCAC4 |
| 47 | QLSX | General American Transportation Corp. | 7/1937-1/1945 | | NAKINA |
| 48 | QLSX | Quaker City Live Stock Express (General American Tank Car Corp.) | 7/1935 | | NAKINA |
| 49 | QLSX | Quaker City Live Stock Express | 7/1930-7/1932 | | NAKINA |
| 50 | QLSX | Quaker City Live Stock Express (General American Transportation Corp.) | Apr-38 | | NRHS |
| 51 | QLSX | QUAKER CITY LIVE STOCK EXPRESS (GENERAL AMERICAN TRANSPORTATION CORP.) | | | PWRC |
| 52 | QLTA | QUALITY TRANSPORT (A DIV OF AMERICA | | | SCAC3 |
| 53 | QLTC | QUALITY TRANSPORT COMPANY | | | SCAC4 |
| 54 | QLTF | QUALITY FREIGHT TRANSPORTATION | | | SCAC3 |
| 55 | QLTL | QUALITY LOGISTICS INCORPORATED | | | SCAC4 |
| 56 | QLTN | QUALITY TRANSPORT INC | | | SCAC3 |
| 57 | QLTN | QUALITY TRANSPORTATION | | | SCAC4 |
| 58 | QLTO | QUALITY TRANSPORT INC | | | SCAC4 |
| 59 | QLTP | QUALITY TRANSPORTATION | | | SCAC4 |
| 60 | QLTR | QUALITY TRANSPORTATION | | | SCAC3 |
| 61 | QLTV | QUALITY TRANSPORT SA DE CV | | | SCAC4 |
| 62 | QLTY | QUALITY TRANSPORTATION CONSULTANTS | | | SCAC3 |
| 63 | QLTY | QUALITY EXPRESS USA INC | | | SCAC4 |
| 64 | QLYC | QUALITY CARRIERRS INC | | | SCAC3 |
| 65 | QLYC | QUALITY CARRIERS INC | | | SCAC4 |
| 66 | QLYD | QUALITY DISTRIBUTION, INC | | | SCAC3 |
| 67 | QLYD | QUALITY DISTRIBUTION INC | | | SCAC4 |
| 68 | QLYR | QUALITY TRUCKING INC | | | SCAC4 |
| 69 | QLYT | QUALITY TRANSPORT INC | | | SCAC4 |
