| 1 | UL | SriLankan Airlines Limited | ICAO: ALK, Callsign: Srilankan, IATA Prefix: 603, Formerly Air Lanka Limited. | CL | AVCODES |
| 2 | UL | Air Lanka Limited | ICAO: ALK, Callsign: Air Lanka, IATA Prefix: 603, Name changed to Srilankan during 1998. IATA designator changed from UJ | CL | AVCODES |
| 3 | UL | Lansa S.r.l. | | HN | AVCODES |
| 4 | ULA | Ultraair, LLC | Callsign: Ultrajet, | USA | AVCODES |
| 5 | ULA | Zuliana de Aviacion .C.A. | IATA: OD, Callsign: Zuliana, Designator OD recalled by IATA | YV | AVCODES |
| 6 | ULAC | ULTRA AIR CARGO INC | | | SCAC4 |
| 7 | ULB | Ulba | Callsign: Uskam, | KZ | AVCODES |
| 8 | ULC | Airlanka Cargo Limited | Callsign: Airlanka Cargo, | CL | AVCODES |
| 9 | ULC | Albinati Aviation Ltd. | Callsign: Albi, | M | AVCODES |
| 10 | ULCE | U L C EXPRESS | | | SCAC4 |
| 11 | ULCH | ULCH TRANSPORT LIMITED | | | SCAC4 |
| 12 | ULCN | USA LOGISTIX CORPORATION | | | SCAC4 |
| 13 | ULCU | UNICO LOGISTICS CO LTD | | ROK | BIC |
| 14 | ULCU | UNICO LOGISTICS | | | SCAC4 |
| 15 | ULCW | UNICO LOGISTICS CO LTD | | | SCAC4 |
| 16 | ULCX | Unit Load Car Corp. | added 7/1959; 4/1961-4/1970; eliminated 10/1974 | | NAKINA |
| 17 | ULCX | Unit Load Car Corp. | added 7/59; 4/61-4/70; eliminated 10/74 | | NRHS |
| 18 | ULCX | UNIT LOAD CAR CORP. | | | PWRC |
| 19 | ULCZ | ULRIZH CEMENT CO. | | | PWRC |
| 20 | ULE | Leisure International Airways Limited. | IATA: MV, | GB | AVCODES |
| 21 | ULG | U Airlines Co. Ltd. | IATA: YL, Founded April 2012. IATA desinator YL recalled. | T | AVCODES |
| 22 | ULG | U Airlines Co. Ltd. | Founded April 2012. IATA desinator YL recalled. | T | AVCODES |
| 23 | ULGI | UNITED LOGISTICS GROUP INC | | | SCAC4 |
| 24 | ULGN | UNITED LOGISTICS GROUP INC | | | SCAC4 |
| 25 | ULGP | UNITED LETTERLOCK GROUP INC | | | SCAC4 |
| 26 | ULGT | UNITED LOGISTICS INC | | | SCAC4 |
| 27 | ULGU | Universal Lng Solution | | | RSRV |
| 28 | ULGW | UNIVERSAL LOGISTICS GROUP WEST INC | | | SCAC4 |
| 29 | ULH | Ultimate Heli (Pty) Ltd | Callsign: Ultimate Heli, | ZA | AVCODES |
| 30 | ULIG | URBAN LOGISTICS INC | | | SCAC4 |
| 31 | ULII | ULTIMATE LOGISTICS INC | | | SCAC4 |
| 32 | ULIO | U & US LOGISTICS INC. | | | SCAC4 |
| 33 | ULIQ | UNI-LINK INC | | | SCAC4 |
| 34 | ULIR | UTI LOGISTIC INC | | | SCAC4 |
| 35 | ULIW | UNLIMITED WAREHOUSING, INC | | | SCAC1 |
| 36 | ULLB | UNLIMITED LOGISTICS LLC | | | SCAC4 |
| 37 | ULLC | UNIMARK LLC | | | SCAC4 |
| 38 | ULLM | ULLMAN OIL INC | | | SCAC4 |
| 39 | ULLQ | US LOGISTICS LLC | | | SCAC4 |
| 40 | ULLV | USCS LOGISTICS LLC | | | SCAC4 |
| 41 | ULM | Stadtwerke Ulm | Real: SWU, City: Ulm | D | TRAFFIC |
| 42 | ULMD | UNLIMITED TRUCKING INC | | | SCAC4 |
| 43 | ULMI | UNILOCK MICHIGAN INC | | | SCAC4 |
| 44 | ULMS | ULTIMATE SEAT COMPANY LTD, THE | | | SCAC4 |
| 45 | ULMU | ULTRAMARINE SERVICE CO | | | SCAC4 |
| 46 | ULNB | ULCH TRAILER SALES LTD | | | SCAC4 |
| 47 | ULOA | UNITRANS INTERNATIONAL INC | | | SCAC4 |
| 48 | ULOC | UNITED LOGISTICS | | | SCAC4 |
| 49 | ULOG | UNIVERSAL LOGISTICS | | | SCAC4 |
| 50 | ULOI | UNION LOGISTICS INC | | | SCAC4 |
| 51 | ULOS | UNLIMITED LOGISTICS | | | SCAC4 |
| 52 | ULOT | UNION LOGISTICS | | | SCAC4 |
| 53 | ULQL | UNIGLOBAL LOGISTICS LLC | | | SCAC4 |
| 54 | ULQW | US COURIER & LOGISTICS - SAN ANTONI | | | SCAC4 |
| 55 | ULR | Ultimate Airways (Pty) Ltd | Callsign: Viper, | ZA | AVCODES |
| 56 | ULRD | UNISHIPPERS | | | SCAC4 |
| 57 | ULRI | ULRICH, RALPH TRUCKING | | | SCAC4 |
| 58 | ULS | Carroll Air Service, Inc. | Callsign: Ulster, | USA | AVCODES |
| 59 | ULS | Ultra Air S.A.S. | IATA: U0, Callsign: Air Ultra, | CO | AVCODES |
| 60 | ULS | Carroll Air Service | | | ICAO1 |
| 61 | ULS | RETIRED 05-15-92 TP (0806) | | | PWRC |
| 62 | ULSE | ULS EXPRESS INC | | | SCAC4 |
| 63 | ULSH | UNLIMITED FREIGHT INC | | | SCAC4 |
| 64 | ULSQ | USA LOGISTICS SERVICES INC | | | SCAC4 |
| 65 | ULSU | UNITED LOGISTIC SERVICES JSC | | | SCAC4 |
| 66 | ULSV | UNIVERSAL LOGISTICS SERVICES INC | | | SCAC4 |
| 67 | ULT | Ultrair, Inc. | Callsign: Ultrair, | USA | AVCODES |
| 68 | ULT | Ultrair | | | ICAO1 |
| 69 | ULT | UppTaget - Upplands Läns Trafik AB | | S | TRAFFIC |
| 70 | ULTC | ULTRACUTS LTD | | | SCAC4 |
| 71 | ULTE | UNLIMITED TRANSPORTATION SERVICES | | | SCAC4 |
| 72 | ULTF | UNILIGHT LTD | | | SCAC4 |
| 73 | ULTG | ULTRAMAR LTD | | | SCAC4 |
| 74 | ULTL | ULTRA LOGISTICS INC | | | SCAC4 |
| 75 | ULTP | ULSTER TRANSPORT INC | | | SCAC4 |
| 76 | ULTS | U-LINE TRANSPORT | | | SCAC4 |
| 77 | ULTT | ULT TRANSPORTATION INC | | | SCAC4 |
| 78 | ULTU | ACE ENGINEERING CO LTD | | ROK | BIC |
| 79 | ULTU | ACE ENGINEERING & CO LTD | | | SCAC4 |
| 80 | ULUI | UNICO LOGISTICS USA INC | | | SCAC4 |
| 81 | ULUN | ULLOA LUNA, CELESTE AIDA | | | SCAC4 |
| 82 | ULXI | ULTRAEX INC | | | SCAC4 |
