| 1 | QS | Travel Service, a.s. | ICAO: TVS, Callsign: Skytravel, Name changed to Smartwings, a.s. w.e.f. 10 December 2018. Designator QS reinstated by IATA | CZ | AVCODES |
| 2 | QS | Travel Service, a.s. | ICAO: TVS, Callsign: Skytravel, Designator QS recalled by IATA | CZ | AVCODES |
| 3 | QS | African Safari Airways Ltd. | ICAO: QSC, Callsign: Zebra, Ceased operations. Designator QS recalled by IATA | EAK | AVCODES |
| 4 | QS | Smartwings, a.s. | ICAO: TVS, Callsign: Skytravel, Name changed from Travel Service, a.s. w.e.f. 10 December 2018. Designator QS reinstated by IATA | CZ | AVCODES |
| 5 | QSBA | QUE SABROSA | | | SCAC4 |
| 6 | QSC | African Safari Airways Ltd. | IATA: QS, Callsign: Zebra, Ceased operations. Designator QS recalled by IATA | EAK | AVCODES |
| 7 | QSC | African Safari Airways | IATA: QS | | ICAO1 |
| 8 | QSC | Queens Surface Corp. | City: New York | US-NY | TRAFFIC |
| 9 | QSCP | QUAKER SALES CORP | | | SCAC4 |
| 10 | QSDS | QUICKWAY SPECIAL DELIVERY SERVICE | | | SCAC3 |
| 11 | QSDV | QUICKSILVER DELIVERY INC | | | SCAC3 |
| 12 | QSEC | QUICK SHIP ELECTRONICS | | | SCAC4 |
| 13 | QSEP | QUICKSILVER EXPRESS COURIER OF GEOR | | | SCAC3 |
| 14 | QSGL | QUICK SAND & GRAVEL LLC | | | SCAC4 |
| 15 | QSIN | QUICK SHOT INC | | | SCAC3 |
| 16 | QSLG | QUICK STAR LOGISTICS | | | SCAC4 |
| 17 | QSM | Qeshm Air | IATA: QB, Callsign: Qeshm Air, IATA Prefix: 237, ICAO Designator changed from IRQ. | IR | AVCODES |
| 18 | QSMO | QUALITY SERVICES MOVING | | | SCAC4 |
| 19 | QSMX | Quaker State Corp. | added 10/1987; 1/1994; eliminated 10/1994; 7/2000-7/2005 (not listed) | | NAKINA |
| 20 | QSMX | Quaker State Oil Refining Corp. | 4/1938-1/1980; eliminated 10/1987 | | NAKINA |
| 21 | QSMX | Quaker State Oil Refining Co. | 7/1930-7/1937 | | NAKINA |
| 22 | QSMX | Quaker State Oil Refining Corp. | 4/38-1/80; eliminated 10/87 | | NRHS |
| 23 | QSMX | Quaker State Corp. | added 10/87; 1/94; eliminated 10/94; 7/2000 | | NRHS |
| 24 | QSMX | QUAKER STATE OIL REFINING CORPORATION | | | PWRC |
| 25 | QSMX | Quaker State Oil Refining Corporation | | | RSRV |
| 26 | QSMX | QUAKER STATE OIL REFINING CORP | | | SCAC3 |
| 27 | QSOC | QUALITY STATE OIL CO INC | | | SCAC4 |
| 28 | QSOX | Quaker State Oil Refining Corporation | | | RSRV |
| 29 | QSPS | QUALITY STAR PRODUCTS LTD | | | SCAC4 |
| 30 | QSR | SR Jet Co. Ltd. | Callsign: Sparkle Roll, | RCH | AVCODES |
| 31 | QSR | Bangor and Aroostook Rd. Co. | added 4/2001; 7/2005 | | NAKINA |
| 32 | QSR | Quebec Southern Ry. | added 4/1997; 7/2000; eliminated 4/2001; eliminated 4/2002 | | NAKINA |
| 33 | QSR | Quebec Southern Ry. | added 4/97; 7/2000; eliminated 4/2001 | | NRHS |
| 34 | QSR | Bangor and Aroostook Rd. Co. | added 4/2001 | | NRHS |
| 35 | QSR | BANGOR & AROOSTOCK RR CO. [QUEBEC SOUTHERN RAILWAY] | | | PWRC |
| 36 | QSR | Bangor and Aroostook Railroad (Montreal, Maine & Atlantic) | | | RSRV |
| 37 | QSR | Quebec Southern Railway | | CDN | TRAFFIC |
| 38 | QSRZ | QUALITY SERVICE RAIL CAR REPAIR | | | PWRC |
| 39 | QSST | Q S STORAGE & TRANSFER COMPANY | | | SCAC3 |
| 40 | QSSU | PT. INDONESIA TSINGSHAN STAINLESS STEEL | | RI | BIC |
| 41 | QSTE | QST EXPRESS INC | | | SCAC3 |
| 42 | QSTG | QUEST GLOBAL INC | | | SCAC4 |
| 43 | QSTI | QUEST INDUSTRIES INC | | | SCAC4 |
| 44 | QSTK | QUICK SHOT TRUCKING INC | | | SCAC4 |
| 45 | QSTN | QUALITY SERVICES & TRANSFER INC | | | SCAC4 |
| 46 | QSTS | Q'S TRANSPORT | | | SCAC4 |
| 47 | QSTT | QUEST TRANSPORTATION | | | SCAC3 |
