| 1 | UA | United Airlines | USA | TRAFFIC | |
| 2 | UAA | University Air Squadron | ICAO1 | ||
| 3 | UAAF | UNITED AIR LINES INC (AIR CODE UA) | SCAC4 | ||
| 4 | UAAI | UNITED ARAB AGENCIES INC | SCAC4 | ||
| 5 | UAAR | UNRAU, AARON | SCAC4 | ||
| 6 | UAAX | American Acid Co. | 8/1920-7/1923 | NAKINA | |
| 7 | UAAX | AMERICAN ACID CO. | PWRC | ||
| 8 | UAB | United Arabian Airlines | ICAO1 | ||
| 9 | UABP | UAB Panevezio autobusu parkas | City: Panevezys | LT | TRAFFIC |
| 10 | UABS | UNITED ABACO SHIPPING | SCAC4 | ||
| 11 | UAC | United Air Charters | ICAO1 | ||
| 12 | UAC | UNITED AIRCRAFT CORP. | PWRC | ||
| 13 | UACB | UNIVERSAL AM-CAN LTD (BROKERAGE DIV | SCAC4 | ||
| 14 | UACL | UNIVERSAL AM-CAN, LTD | SCAC1 | ||
| 15 | UACL | UNIVERSAL AM-CAN LTD | SCAC4 | ||
| 16 | UACS | UNIVERSAL AM-CAN US | SCAC4 | ||
| 17 | UACU | UNITED ARAB SHIPPERS | PWRC | ||
| 18 | UACU | United Arab Shipping | RSRV | ||
| 19 | UACU | UNITED ARAB SHIPPING CO SAG | SCAC4 | ||
| 20 | UACW | UNITED ARAB CHEMICAL CARRIERS LIMIT | SCAC4 | ||
| 21 | UACX | Universal Atlas Cement Co. | 7/1932; 1/1941-1/1952; eliminated 4/1953 | NAKINA | |
| 22 | UACX | Universal Atlas Cement Division of U.S. Steel Corp. | eliminated 7/1965 | NAKINA | |
| 23 | UACX | Universal Atlas Cement Co. | Jan-52 | NRHS | |
| 24 | UACX | Universal Atlas Cement Division of U.S. Steel Corp. | eliminated 7/65 | NRHS | |
| 25 | UACX | UNIVERSAL ATLAS CEMENT DIV., U.S. STEEL CORP. | PWRC | ||
| 26 | UAD | University Air Squadron | ICAO1 | ||
| 27 | UAE | Emirates Airline | IATA: EK | ICAO1 | |
| 28 | UAE | Emirates | UAE | TRAFFIC | |
| 29 | UAEA | United Aram Emirates Army | UAE | TRAFFIC | |
| 30 | UAEU | UNITED ARAB SHIPPING CO (S.A.G.) | PWRC | ||
| 31 | UAEU | United Arab Shipping | RSRV | ||
| 32 | UAEU | UNITED ARAB SHIPPING CO SAG | SCAC4 | ||
| 33 | UAF | United Arab Emirates Air Force | ICAO1 | ||
| 34 | UAG | Afra Airlines | ICAO1 | ||
| 35 | UAH | University Air Squadron | ICAO1 | ||
| 36 | UAI | Union Africaine des Transports | ICAO1 | ||
| 37 | UAIN | UTILITY AVIATION, INC. | SCAC4 | ||
| 38 | UAIX | United Asphalts, Inc. | added 10/1992; 1/1994-7/2005; eliminated 1/2007 | NAKINA | |
| 39 | UAIX | United Asphalts, Inc. | added 10/92; 1/94-7/2000 | NRHS | |
| 40 | UAIX | UNITED ASPHALTS, INC. | PWRC | ||
| 41 | UAIX | United Asphalts | RSRV | ||
| 42 | UAIX | UNITED ASPHALTS, INC. | SCAC4 | ||
| 43 | UAJ | University Air Squadron | ICAO1 | ||
| 44 | UAK | Kiev Aviation Plant | ICAO1 | ||
| 45 | UAL | United Airlines | IATA: UA | ICAO1 | |
| 46 | UALC | UNIVERSAL AFRICA LINES N V (N A) | SCAC4 | ||
| 47 | UALG | UNITED AMERICAN LOGISTICS INC | SCAC4 | ||
| 48 | UALL | UA LLC | SCAC4 | ||
| 49 | UALS | UAL UNIVERSAL AFRICA LINES N V (N A | SCAC4 | ||
| 50 | UAME | URIAS ARELLANES, MARIA ELENA | SCAC4 | ||
| 51 | UAR | Aerostar Airlines | ICAO1 | ||
| 52 | UASC | UNITED ARAB SHIPPING COMPANY | SCAC1 | ||
| 53 | UASI | UPS SCS (ASIA) LIMITED | SCAC4 | ||
| 54 | UASU | UNITED ARAB SHIPPING COMPANY | PWRC | ||
| 55 | UASU | United Arab Shipping | RSRV | ||
| 56 | UASU | UNITED ARAB SHIPPING CO SAG | SCAC4 | ||
| 57 | UASV | UTKILEN AS | SCAC4 | ||
| 58 | UASW | UNIFIED AIRCRAFT SERVICES INC | SCAC4 | ||
| 59 | UASX | United Alloy Steel Corp. | 7/1923 | NAKINA | |
| 60 | UASX | UNITED ALLOY STEEL CORP. | PWRC | ||
| 61 | UASZ | UNITED ARAB SHIPPERS | PWRC | ||
| 62 | UASZ | United Arab Shipping | RSRV | ||
| 63 | UASZ | UNITED ARAB SHIPPERS | SCAC4 | ||
| 64 | UATA | UA AUTO TRANSPORT INC | SCAC4 | ||
| 65 | UATN | UA TRANSPORTATION | SCAC4 | ||
| 66 | UAUS | UNITED AUTOSPORTS USA LLC | SCAC4 | ||
| 67 | UAWX | Union Acid Works, Inc. (Standard Wholesale Phosphate & Acid Works, Inc.) | 7/1930-7/1935 | NAKINA | |
| 68 | UAWX | Standard Wholesale Phosphate & Acid Works, Inc. | 7/1937-4/1947 | NAKINA | |
| 69 | UAWX | Mathieson Chemical Corp. | 1/1950 (not listed) | NAKINA | |
| 70 | UAWX | Union Acid Works, Inc. (Standard Wholesale Phosphate & Acid Works, Inc.) | Apr-38 | NRHS | |
| 71 | UAWX | *STANDARD WHOLESALE PHOSPHATE & ACID WORKS, INC. [UNION ACID WORKS, INC.] | PWRC | ||
| 72 | UAWX | *MATHIESON CHEMICAL CORP. | PWRC | ||
| 73 | UB | UNION BELT OF DETROIT | PWRC | ||
| 74 | UBA | Myanma Airways | IATA: UB | ICAO1 | |
| 75 | UBAI | URBANO INTERNATIONAL INC | SCAC4 | ||
| 76 | UBB | Usedomer Bäderbahn GmbH | Heringsdorf | D | privat-bahn.de |
| 77 | UBB | Usedomer Bäder-Bahn | D | TRAFFIC | |
| 78 | UBB | Usedomer Bäder-Bahn | DE | VKM | |
| 79 | UBBU | U B C LTD | SCAC4 | ||
| 80 | UBCA | UNITED BULK CARRIERS (USA) | SCAC4 | ||
| 81 | UBCI | UNITED BULK CARRIERS INTERNATIONAL | SCAC4 | ||
| 82 | UBCL | USA BOUQUET COMPANY LLC | SCAC4 | ||
| 83 | UBCM | UNITED BULK CARRIERS INTERNATIONAL | SCAC4 | ||
| 84 | UBCU | UNITED FRUIT CO. | PWRC | ||
| 85 | UBCU | United Fruit | RSRV | ||
| 86 | UBCU | CHIQUITA BRANDS (GREAT WHITE FLEET) | SCAC1 | ||
| 87 | UBCU | UNITED FRUIT CO (CHIQUITA BRANDS IN | SCAC4 | ||
| 88 | UBDI | UB DISTRIBUTORS LLC | SCAC4 | ||
| 89 | UBEI | US BLUE EXPRESS INC | SCAC4 | ||
| 90 | UBEX | United Bio Energy Ingredients, LLC | 7/2005 (not listed) | NAKINA | |
| 91 | UBEX | UNITED BIO ENERGY INGREDIENTS, LLC | PWRC | ||
| 92 | UBFL | UNITED - BUCKINGHAM FRT LINES | PWRC | ||
| 93 | UBFS | URBAN FREIGHT SERVICES | SCAC4 | ||
| 94 | UBKI | UB TRUCKING INC | SCAC4 | ||
| 95 | UBLA | UNIQUE BROKERAGE & LOGISTICS INC | SCAC4 | ||
| 96 | UBLG | USA BORDER LOGISTICS LLC | SCAC4 | ||
| 97 | UBLT | UNIBILT TRANSPORT INC | SCAC4 | ||
| 98 | UBMU | UNITED BALTIC CORP. LTD. | PWRC | ||
| 99 | UBMU | United Baltic Corporation Limited | RSRV | ||
| 100 | UBRG | UTS BROKERAGE | SCAC4 |