| U2 | EZY | Easyjet | |
| U3 | URA | 713 | Uralinteravia |
| U3 | AIA | Avies | |
| U4 | PMT | PMTair | |
| U6 | SVR | 262 | Ural Airlines |
| U8 | RNV | 669 | Armavia |
| UA | UAL | 016 | United Airlines Cargo |
| UC | LCO | 145 | LAN Cargo |
| UD | FST | 726 | Fast Air Carrier |
| UD | HER | 848 | Hex´Air |
| UF | SRO | Saro Airlines | |
| UF | UKM | 828 | UM Air |
| UG | TUI | 150 | Tuninter |
| UI | ECA | 475 | Eurocypria Airlines |
| UK | UKA | 130 | KLCuk |
| UK | BUZ | Buzz | |
| UL | ALK | 603 | Srilankan Airlines |
| UM | AZW | 168 | Air Zimbabwe |
| UN | TSO | 670 | Transaero Airlines |
| UO | HKE | Hong Kong Express Airways | |
| UP | BHS | 111 | Bahamasair |
| UQ | OCM | O´Connor Mt Gambier´s Airline | |
| UR | BIH | British International Helicopters | |
| US | CHQ | 363 | Chautauqua Airlines Inc (USAir Express) |
| US | USA | 037 | US Airways |
| UT | TMN | UT Air | |
| UU | REU | 760 | Air Austral |
| UW | PAG | 711 | Perimeter Airlines (Inland) Ltd |
| UX | AEA | 996 | Air Europa |
| UY | UYC | 604 | Cameroon Airlines |
| UZ | ARZ | Air Resorts Airlines | |
| UZ | TIS | 246 | Tesis Aviation Enterprise |