| 1 | C4 | Zimex Aviation Limited | ICAO: IMX, Callsign: Zimex, IATA designator changed from MF | CH | AVCODES |
| 2 | C4 | Airlines of Carriacou Limited | ICAO: COU, Designator C4 recalled by IATA | WG | AVCODES |
| 3 | C4 | Aerolineas Mesoamericanas, S.A. de C.V. d/b/a ALMA de Mexico | ICAO: MSO, Callsign: Alma, IATA Prefix: 665, Founded in 2005. Commenced operations on 12 June 2006. Ceased operations on 07 November 2008. | MEX | AVCODES |
| 4 | C4 | Conquest Air, Inc. | ICAO: QAI, Callsign: Chickpea, IATA Prefix: 340, | USA | AVCODES |
