| 1 | HCY | Helios Airways Ltd | IATA: ZU, Callsign: Helios, Established on 23 September 1998. Commenced operations on 15 May 2000. Name changed to Ajet w.e.f. 14 March 2006. Helios Airways Ltd | CY | AVCODES |
| 2 | HCY | Helios Airways Ltd | IATA: ZU, Callsign: Helios, IATA designator changed to ZU | CY | AVCODES |
| 3 | HCY | Helios Airways | IATA: ZU | | ICAO1 |
| 4 | HCY | Hill City Ry. Co. | 7/1923 | | NAKINA |
| 5 | HCY | HILL CITY RWY. CO. | | | PWRC |
| 6 | HCYR | Horry County Ry. Co. | added 7/1985; eliminated 1/1988 | | NAKINA |
| 7 | HCYR | Horry County Ry. Co. | eliminated 1/88 | | NRHS |
| 8 | HCYR | HORRY COUNTY RAILWAY CO. | | | PWRC |
| 9 | HCYR | Horry County Railway | | | RSRV |
