| 1 | T4 | Hellas Jet S.A. | ICAO: HEJ, Callsign: Hellas Jet, IATA Designator changed to HJ. Subsidary of Cyprus Airways | GR | AVCODES |
| 2 | T4 | Rhoades Aviation, Inc. d/b/a transair | ICAO: RDS, Callsign: Rhoades Express, Operates transair Boeing 737 fleet. | USA | AVCODES |
| 3 | T4 | Transeast Airlines Ltd. | ICAO: TRL, Callsign: Lattrans, | LV | AVCODES |
| 4 | T4 | TRIP Linhas Aéreas | ICAO: TIB, Callsign: Trip, IATA designator changed to T4 | BR | AVCODES |
| 5 | T4 | TRIP Linhas Aéreas | ICAO: TIB, Callsign: Trip, IATA Prefix: 661, Founded in 1998. Merged in Azul Brazilian Airlines on 06 May 2014. IATA designator changed from T4* | BR | AVCODES |
| 6 | T4 | Topre Corporation | Computer Reservation System | J | AVCODES |
