Sân bay quốc tế
| Airline Name | ICAO | IATA | Callsign | Country |
| U-Land Airlines | Taiwan | |||
| Uair | UE | Uruguay | ||
| Uganda Airlines | UGA | QU | Uganda | |
| UK International Airlines | UKI | KHALIQ | United Kingdom | |
| Ukraine International Airlines | AUI | PS | Ukraine | |
| Ukrainian Government | Ukraine | |||
| Ultimate Jetcharters | United States | |||
| UM Air - Ukrainian-Mediterranean Airlines | UKM | UF | Ukraine | |
| Unex - Universal Express Linhas Aereas | UNX | Brazil | ||
| UNI Airways | UIA | B7 | Taiwan | |
| Uni-Top Airlines | UW | China | ||
| Unibanco | Brazil | |||
| Unifly | UFL | Equatorial Guinea | ||
| Unifly Express | IP | Italy | ||
| United Airlines | UAL | UA | UNITED | United States |
| United Airways | 4H | Bangladesh | ||
| United Arab Emirates Air Force | UAF | United Arab Emirates | ||
| United Arab Emirates Government | United Arab Emirates | |||
| United Aviation | United States | |||
| United Eagle Airlines | UEA | EU | UNITED EAGLE | China |
| United Express | BLR | DH | United States | |
| United Feeder Service (United Express) | UFS | U2 | FEEDER-FLIGHT | United States |
| United Nations | UNO | Unknown | ||
| United Parcel Service (UPS) | UPS | 5X | United States | |
| Universair | UNA | UN | Spain | |
| Universal Airlines | UVG | UW | GUYANA JET | Guyana |
| Universal Airlines | Spain | |||
| Ural Airlines | SVR | U6 | SVERDLOVSK AIR | Russian Federation |
| US Airways | AWE | US | CACTUS | United States |
| US Navy | United States | |||
| USA 3000 | GWY | U5 | United States | |
| USA Jet Airlines | JUS | U7 | United States | |
| USAfrica Airways | USF | United States | ||
| USAir | USA | US | US AIR | United States |
| USAL Ltd. | United States | |||
| UTA | UTA | UT | UTA | France |
| UTAir Aviation | TMN | P2 | TYUMAVI | Russian Federation |
| Uzbekistan Airways | UZB | HY | Uzbekistan |