| 1 | HQ | HMY Airways, Inc. | ICAO: HMY, Callsign: Harmony, Name changed to HMY Airways, Inc. d/b/a Harmony Airways | CDN | AVCODES |
| 2 | HQ | Business Express Airlines, Inc. | ICAO: GAA, Callsign: Bizex, Ceased operations on 03 December 2000. Name changed from Atlantic Air | USA | AVCODES |
| 3 | HQ | Hawker Siddeley Aviation Ltd. | Callsign: Hawkair, | GB | AVCODES |
| 4 | HQ | British Aerospace Plc | ICAO: BAE, Callsign: BAE, Designator HQ recalled by IATA. Name changed to BAE Systems | GB | AVCODES |
| 5 | HQ | HMY Airways, Inc. d/b/a Harmony Airways | ICAO: HMY, Callsign: Harmony, Founded in 2002. Ceased operationon 09 April 2007. Name changed from HMY Airways, Inc. | CDN | AVCODES |
| 6 | HQ | Thomas Cook Airline Belgium N.V. | ICAO: TCW, Callsign: Thomas Cook, Name changed to VLM Airlines N.V. IATA designator changed from FQ* | B | AVCODES |
| 7 | HQ | VLM Airlines N.V. | ICAO: TCW, Callsign: Phoenix, Name changed from Thomas Cook Airline Belgium N.V. IATA designator changed from FQ* | B | AVCODES |
| 8 | HQ | Sino-Lac Air | Designator HQ recalled by IATA | TL | AVCODES |
| 9 | HQ | Compass Cargo Airlines Ltd. | ICAO: ADZ, Callsign: Migrator, Name changed from Avio Delta Ltd. | BG | AVCODES |
| 10 | HQA | Quick Air-Trans Ltd. | Callsign: Willy Trans, | H | AVCODES |
| 11 | HQCN | HIGH QUALITY CONTAINERS TRANSPORT I | | | SCAC4 |
| 12 | HQFT | HOLMES Q S T INC | | | SCAC4 |
| 13 | HQID | HORIZON INTERNATIONAL DISTRIBUTORS | | | SCAC4 |
| 14 | HQLQ | HYBRID LOGISTICS SOLUTIONS INC | | | SCAC4 |
| 15 | HQLT | HART, L T INC | | | SCAC4 |
| 16 | HQMT | HQ MARINE TRANSPORT INC | | | SCAC4 |
| 17 | HQO | Avinor AS | | N | AVCODES |
| 18 | HQO | Avinor | | | ICAO1 |
| 19 | HQOI | HICKMAN OIL & ICE CO INC | | | SCAC4 |
| 20 | HQPC | HOOD PETROLEUM CO INC | | | SCAC4 |
| 21 | HQSL | HEAVYQUIP SALES LTD | | | SCAC4 |
| 22 | HQTA | HORN, QUINCE TRANSPORT | | | SCAC4 |
| 23 | HQTL | HANNIBAL-QUINCY TRUCK LINES | | | PWRC |
| 24 | HQUC | HYDRO-QUEBEC | | | SCAC4 |
