| 1 | UT | Air Orient | ICAO: ORT, Callsign: Air Orient, Desigantor UT recalled by IATA. Name changed from Air Charter Asia | F | AVCODES |
| 2 | UT | Air Charter Asia | ICAO: ORT, Name changed to Air Orient | F | AVCODES |
| 3 | UT | Utair Aviation Joint-Stock Company | ICAO: TMN, Callsign: Tjumavi, IATA Prefix: 298, IATA desigantor changed from P2. ICAO desigantor changed to UTA. Name changed from Tyumenavyatrans Aviation Joint-Stock Company. Name changed from Joint Stock Air Carrier Company Tjumenaviatrans | RUS | AVCODES |
| 4 | UT | Utair Aviation Joint-Stock Company | ICAO: UTA, Callsign: Tjumavi, IATA Prefix: 298, IATA desigantor changed from P2. ICAO desigantor changed from TMN. Name changed from Tyumenavyatrans Aviation Joint-Stock Company. Name changed from Joint Stock Air Carrier Company Tjumenaviatrans | RUS | AVCODES |
| 5 | UT | Union Terminal Ry. of St. Joseph, MO | 1/1941-1/1950 | | NAKINA |
| 6 | UT | Union Terminal Ry. Co. | 1/1952-4/1970 | | NAKINA |
| 7 | UT | Union Terminal Ry. Co. (of St. Joseph, MO) | 1/1975 | | NAKINA |
| 8 | UT | Missouri Pacific System | eliminated 1/1979 | | NAKINA |
| 9 | UT | Union Terminal Ry. Co. | 1/52-4/70 | | NRHS |
| 10 | UT | Union Terminal Ry. Co. (of St. Joseph, MO) | Jan-75 | | NRHS |
| 11 | UT | Missouri Pacific System | eliminated 1/79 | | NRHS |
| 12 | UT | MISSOURI PACIFIC SYSTEM [UNION TERMINAL RY (ST. JOSEPH, MO)] | | | PWRC |
| 13 | UTA | Utair Aviation Joint-Stock Company | IATA: UT, Callsign: Tjumavi, IATA Prefix: 298, IATA desigantor changed from P2. ICAO desigantor changed from TMN. Name changed from Tyumenavyatrans Aviation Joint-Stock Company. Name changed from Joint Stock Air Carrier Company Tjumenaviatrans | RUS | AVCODES |
| 14 | UTA | UTair Aviation | IATA: UT | | ICAO1 |
| 15 | UTA | Utah Transport Authority | City: Salt Lake City | USA | TRAFFIC |
| 16 | UTAA | UNDERDOG TRUCKING LLC | | | SCAC4 |
| 17 | UTAH | Utah Ry. Co. | 10/1957-7/2005 | | NAKINA |
| 18 | UTAH | Utah Ry. Co. | 10/57-7/2000 | | NRHS |
| 19 | UTAH | UTAH RAILWAY COMPANY | | | PWRC |
| 20 | UTAH | Utah Railway | | | RSRV |
| 21 | UTAH | Utah Railway Company | | USA | TRAFFIC |
| 22 | UTAI | UTAH TRAILWAYS | | | SCAC4 |
| 23 | UTAR | UNINATIONS CORPORATION | | | SCAC4 |
| 24 | UTAU | {LIMITED LIABILITY COMPANY "UTK HIMALYANS"};ZIPCODE=36008 | | UA | BIC |
| 25 | UTAW | U W FREIGHT LINE, INC | | | SCAC1 |
| 26 | UTAX | United Transportation, Inc. | added 7/1972; 1/1975-1/1980; eliminated 7/1985 | | NAKINA |
| 27 | UTAX | United Transportation, Inc. | 1/75-1/80 | | NRHS |
| 28 | UTAX | *UNITED TRANSPORTATION, INC. | | | PWRC |
| 29 | UTAX | *UTAH TRANSIT AUTHORITY | | | PWRC |
| 30 | UTAX | United Transportation (Utah Transit Authority) | | | RSRV |
| 31 | UTBI | USA TRUCK | | | SCAC4 |
| 32 | UTBT | UNITY TRUCKING BOAT TRANSPORTATION | | | SCAC4 |
| 33 | UTBX | Union Tank Car Co. | 1/1975; added 4/1975; 1/1980-1/1994 | | NAKINA |
| 34 | UTBX | Union Tank Car Co. | 1/75; added 4/75; 1/80-1/94 | | NRHS |
| 35 | UTBX | (UTCX) UNION TANK CAR CO. | | | PWRC |
| 36 | UTBX | Union Tank Car | | | RSRV |
| 37 | UTCB | UTE CAB CO | | | SCAC4 |
| 38 | UTCC | UTC | | | SCAC4 |
| 39 | UTCI | UNITED TRANSPORT INC | | | SCAC4 |
| 40 | UTCJ | UNIQUE TRANSPORT CORPORATION | | | SCAC4 |
| 41 | UTCK | UNITED TRUCKING | | | SCAC4 |
| 42 | UTCL | UNICO TRANS CORP | | | SCAC4 |
| 43 | UTCM | UNITED TRUCKING CORP | | | SCAC4 |
| 44 | UTCO | Union Traction Co. | 7/1923-1/1941 | | NAKINA |
| 45 | UTCO | Union Traction Co. | Apr-38 | | NRHS |
| 46 | UTCO | UNION TRACTION CO. | | | PWRC |
| 47 | UTCO | UNDERGROUND TECHNOLOGIES INC | | | SCAC4 |
| 48 | UTCP | UTC PROJECTS INC | | | SCAC4 |
| 49 | UTCQ | UNITED TRANSIT COMPANY | | | SCAC1 |
| 50 | UTCQ | UNITED TRANSIT CO | | | SCAC4 |
| 51 | UTCR | UNITED TRANS CO OF R I | | | PWRC |
| 52 | UTCR | UNIWORLD TRUCKING CO | | | SCAC4 |
| 53 | UTCU | STOLT TANK CONTAINERS LEASING LTD | | BM | BIC |
| 54 | UTCU | STOLT TANK CONTAINERS INC. | | | PWRC |
| 55 | UTCU | Stolt Tank Containers | | | RSRV |
| 56 | UTCU | STOLT TANK CONTAINERS INC | | | SCAC4 |
| 57 | UTCV | U T C OVERSEAS INC | | | SCAC4 |
| 58 | UTCX | Union Tank Car Co. | 7/1930-7/2005 | | NAKINA |
| 59 | UTCX | Union Tank Car Co. | 4/38-7/2000 | | NRHS |
| 60 | UTCX | UNION TANK CAR CO | | | PWRC |
| 61 | UTCX | Union Tank Car | | | RSRV |
| 62 | UTCX | Union Tank Car Co. | | USA | TRAFFIC |
| 63 | UTD | United Air | Callsign: Uniform Echo, | ZA | AVCODES |
| 64 | UTD | UNION TERMINAL CO. (DALLAS, TX) | | | PWRC |
| 65 | UTDC | TRI-COUNTY COMMUTER RAIL AUTHORITY {UTDC TRANSIT SERVICES, INC.} | | | PWRC |
| 66 | UTEL | UTL TRANSPORTATION SERVICES (DIVISI | | | SCAC4 |
| 67 | UTEP | UTAH EXPRESS LLC | | | SCAC4 |
| 68 | UTEU | Unienergy Technologies | | | RSRV |
| 69 | UTEX | Przedsiębiorstwo Produkcyjno-Handlowe UTEX Sp. z o.o. | | PL | VKM |
| 70 | UTFS | UNION TRANSFER & STORAGE | | | SCAC4 |
| 71 | UTFW | UT FREIGHT FORWARDER CO LTD | | | SCAC4 |
| 72 | UTG | Union de Transportes Aereo de Guinea Ecuatorial | Callsign: Utage, | GQ | AVCODES |
| 73 | UTG | UTAGE | | | ICAO1 |
| 74 | UTGD | ULTIMATE TRUCK GEAR LTD | | | SCAC4 |
| 75 | UTH | UTair-Helicopter Services | Callsign: Utair Helicopters, | RUS | AVCODES |
| 76 | UTHZ | TRANSAMERICA LEASING INCORPORATED | | | PWRC |
| 77 | UTHZ | TAL International Inc | | | RSRV |
| 78 | UTHZ | TRANSAMERICA LEASING INC | | | SCAC4 |
| 79 | UTI | UPSTATE TRANSIT OF SARATOGA LLC | | | SCAC4 |
| 80 | UTI | Uzbekistan Railways - Узбекистон темир йуллари (УТИ) | | UZ | VKM |
| 81 | UTIB | UNION TRUCKING INC | | | SCAC4 |
| 82 | UTIC | UPDEGRAFF TRANSPORTATION INC | | | SCAC4 |
| 83 | UTID | UTAH-IDAHO FREIGHT SYSTEMS | | | SCAC1 |
| 84 | UTID | UTAH IDAHO FREIGHT SYSTEMS | | | SCAC4 |
| 85 | UTIF | US TRANSPORT INC | | | SCAC4 |
| 86 | UTIG | UNDERWOOD TRUCKING INC | | | SCAC4 |
| 87 | UTIH | UCS TRANSPORT INC | | | SCAC4 |
| 88 | UTIJ | USCS TRANSPORT INC | | | SCAC4 |
| 89 | UTIK | UNLIMITED TRUCKING INC | | | SCAC4 |
| 90 | UTIL | UNI-TRANS ILLINOIS CONSOLIDATED INC | | | SCAC4 |
| 91 | UTIL | Utility Lines | | USA | TRAFFIC |
| 92 | UTIM | UNLIMITED TRANSPORT INC | | | SCAC4 |
| 93 | UTIO | UNLIMITED TRANSPORTS INC | | | SCAC4 |
| 94 | UTIQ | UA TRANSPORT INC | | | SCAC4 |
| 95 | UTIR | UNITRANS INTERNATIONAL INC | | | SCAC4 |
| 96 | UTIU | UZBEKISTON TEMIR JOLLARI | | | SCAC4 |
| 97 | UTIV | URIE TRUCKING INC | | | SCAC4 |
| 98 | UTIW | UTI | | | SCAC4 |
| 99 | UTK | JSC, Irkutsk Aviation Industrail Association | Callsign: Irkut, | RUS | AVCODES |
| 100 | UTK | Unitranscom | | BG | VKM |
