| 1 | QO | Aeromexpress S.A. de C.V. | ICAO: MPX, Callsign: Aeromexpress, IATA Prefix: 976, | MEX | AVCODES |
| 2 | QO | Origin Pacific Airways Limited | ICAO: OGN, Callsign: Origin, Founded in 1996. Commenced operatins in April 1997. Ceased passenger operations on 10 August 2006 and cargo operation on 15 September 2006. Placed into Receivership on 15 September 2006. | NZ | AVCODES |
| 3 | QO | British Airways RTZ | IATA designator changed to 5R*. Computer Reservation System | GB | AVCODES |
| 4 | QO | Air Maroochy Airlines | | AUS | AVCODES |
| 5 | QO | Malmo Aviation AB | ICAO: SCW, Callsign: Scanwings, IATA designator changed top 6E | S | AVCODES |
| 6 | QO | Quikjet Cargo Airlines Pvt. Ltd. | ICAO: FQA, IATA Prefix: 723, | IND | AVCODES |
| 7 | QO | Quikjet Cargo Airlines Pvt. Ltd. d/b/a Quikjet Airlines | ICAO: FQA, IATA Prefix: 915, | IND | AVCODES |
| 8 | QOCK | GE RAIL SERVICES | | | PWRC |
| 9 | QOCX | Quaker Oats Co. | 1/1994-7/2005 | | NAKINA |
| 10 | QOCX | General Electric Railcar Services Corp. | added 1/1984 | | NAKINA |
| 11 | QOCX | North American Car Co. | added 4/1971; 1/1975-1/1980; eliminated 1/1984 | | NAKINA |
| 12 | QOCX | North American Car Co. | added 4/71; 1/75-1/80 | | NRHS |
| 13 | QOCX | Quaker Oats Co. | 1/94-7/2000 | | NRHS |
| 14 | QOCX | *GENERAL ELECTRIC RAILCAR SERVICES CORP. [NORTH AMERICAN CAR CO.] | | | PWRC |
| 15 | QOCX | +QUAKER OATS COMPANY | | | PWRC |
| 16 | QOCX | GE Rail Services | | | RSRV |
| 17 | QOCX | QUAKER OATS COMPANY | | | SCAC4 |
| 18 | QOHX | Quaker Oats Co. | added 10/1980; 1/1994-7/2005 | | NAKINA |
| 19 | QOHX | Quaker Oats Co. | added 10/80; 1/94-7/2000 | | NRHS |
| 20 | QOHX | (QOCX) QUAKER OATS COMPANY | | | PWRC |
| 21 | QOHX | Quaker Oats | | | RSRV |
| 22 | QOHX | QUAKER OATS COMPANY | | | SCAC4 |
| 23 | QOOS | QUEBEC ONE ONE SIX SIX EIGHT | | | SCAC4 |
| 24 | QOPX | General Electric Rail Services Corp. | added 1/2000; 7/2000-7/2005 | | NAKINA |
| 25 | QOPX | General Electric Railcar Services Corp. | added 1/1988; 1/1994; eliminated 1/2000 | | NAKINA |
| 26 | QOPX | General Electric Railcar Services Corp. | added 1/88; 1/94; eliminated 1/2000 | | NRHS |
| 27 | QOPX | General Electric Rail Services Corp. | added 1/2000; 7/2000 | | NRHS |
| 28 | QOPX | (NATX) GENERAL ELECTRIC RAIL SERVICES CORPORATION | | | PWRC |
| 29 | QOPX | General Electric Rail Services Corporation | | | RSRV |
| 30 | QOPX | GENERAL ELECTRIC RAILCAR SERVICES C | | | SCAC4 |
| 31 | QOTX | Great Lakes Chemical Corp., Specialty Chemicals | added 10/1995; 7/2000-7/2005; added 10/2007 | | NAKINA |
| 32 | QOTX | QO Chemicals, Inc. | added 10/1984; 1/1994; eliminated 10/1995 | | NAKINA |
| 33 | QOTX | The Quaker Oats Co. | 8/1920-7/1923 | | NAKINA |
| 34 | QOTX | Quaker Oats Co.-Chemicals Division | added 10/1980; eliminated 10/1984 | | NAKINA |
| 35 | QOTX | Quaker Oats Co.-Chemicals Division | added 10/80; eliminated 10/84 | | NRHS |
| 36 | QOTX | QO Chemicals, Inc. | added 10/84; 1/94; eliminated 10/95 | | NRHS |
| 37 | QOTX | Great Lakes Chemical Corp., Specialty Chemicals | added 10/95; 7/2000 | | NRHS |
| 38 | QOTX | *QUAKER OATS COMPANY, CHEMICALS DIV. (QO CHEMICALS, INC.) | | | PWRC |
| 39 | QOTX | +GREAT LAKES CHEMICAL CORPORATION, SPECIALTY CHEMICALS | | | PWRC |
| 40 | QOTX | Quaker Oats Chemicals Division | | | RSRV |
| 41 | QOTX | QO CHEMICALS, INC. | | | SCAC4 |
| 42 | QOVX | Quaker Oil & Tank Co. | 7/1923 | | NAKINA |
| 43 | QOVX | QUAKER OIL & TANK CO. | | | PWRC |
