| 1 | UJ | Montair Aviation, Inc. | Designator UJ reinstated by IATA. Designator UJ recalled by IATA | CDN | AVCODES |
| 2 | UJ | State Airline Ukraine National Airlines | IATA designator changed to UR | UA | AVCODES |
| 3 | UJ | USA Jet Airlines, Inc. | ICAO: JUS, Callsign: Jet USA, Designator U7 recalled by IATA | USA | AVCODES |
| 4 | UJ | Uganda Air Limited | Callsign: Ugandajet, | EAU | AVCODES |
| 5 | UJ | Air Lanka Limited | ICAO: ALK, Callsign: Air Lanka, Commenced operations on 01 September 1979. IATA designator changed to UL | CL | AVCODES |
| 6 | UJ | Sun Freight Logistics Company Limited | ICAO: SFG, | T | AVCODES |
| 7 | UJ | Almasria Universal Airlines | ICAO: LMU, Callsign: Almasria, | ET | AVCODES |
| 8 | UJ | USA Jet Airlines, Inc. | ICAO: JUS, Callsign: Jet USA, Designator U7 recalled by IATA | USA | AVCODES |
| 9 | UJC | Ultimate Jetcharters, Inc. | IATA: UE, Callsign: Ultimate, Name changed to Ultimate Jetcharters LLC dba Ultimate Air Shuttle. IATA designator changed from UI. | USA | AVCODES |
| 10 | UJC | Ultimate Jetcharters, Inc. | IATA: UI, Callsign: Ultimate, IATA designator changed to UE. | USA | AVCODES |
| 11 | UJC | Ultimate Jetcharters LLC dba Ultimate Air Shuttle | IATA: UE, Callsign: Ultimate, Name changed from Ultimate Jetcharters, Inc. IATA designator changed from UI. | USA | AVCODES |
| 12 | UJEVE | Ulrich Joh. Evers GmbH & Co. KG | | DE | VKM |
| 13 | UJIL | US JESCO INTERNATIONAL LTD INC | | | SCAC4 |
| 14 | UJR | Universal Jet Rental de Mexico, S.A. de C.V. | Callsign: Universal Jet, | MEX | AVCODES |
| 15 | UJR | Universal Jet Rental de Mexico | | | ICAO1 |
| 16 | UJS | Eurojet Service | | RUS | AVCODES |
| 17 | UJSD | UNIFORMES JULIAN SA DE CV | | | SCAC4 |
| 18 | UJT | Universal Jet Aviation, Inc. | Callsign: Uni-jet, Name changed to Journey Aviation, LLC | USA | AVCODES |
| 19 | UJT | Universal Jet Aviation | | | ICAO1 |
| 20 | UJUI | UJU INC | | | SCAC4 |
| 21 | UJX | AtlasJet Ukraine | IATA: UH, Callsign: Atlas Ukraine, IATA Prefix: 500, Ceased operations. | UA | AVCODES |
