| 1 | 6K | Asian Spirit, Inc. | ICAO: RIT, Callsign: Asian Spirit, Established in 1995. Commenced operations in April 1996. Name changed to Zest Airways w.e.f. 30 September 2008. Designator 6K reinstated by IATA | RP | AVCODES |
| 2 | 6K | Keewatin Air Ltd. | ICAO: KEW, Callsign: Blizzard, IATA designator changed to FK*. Founded in 1998. in 1998. | CDN | AVCODES |
| 3 | 6K | Inter Express Hava Tasimacilik A.S. | ICAO: INX, Callsign: Inter-Euro, Founded on 17 December 1999. Ceased operations on 18 November 2008. | TR | AVCODES |
| 4 | 6K | Kyrgyz Trans Avia Ltd. Airline | ICAO: KTC, Ceased operations. | KS | AVCODES |
| 5 | 6K | Sky King, Inc. | ICAO: SGB, Callsign: Songbird, Operations resumed on 22 December 2014. Founded in July 1990. Ceased operation on 26 January 2014. Designator F3* recalled by IATA | USA | AVCODES |
| 6 | 6K | Songbird Airways, Inc. | ICAO: SGB, Callsign: Songbird, Name changed from Sky King, Inc in June 2015. | USA | AVCODES |
