| 1 | UC | LADECO Cargo, S.A. | ICAO: LDC, Callsign: Ladeco Cargo, IATA Prefix: 527, Designator UC recalled by IATA | RCH | AVCODES |
| 2 | UC | Ladeco S.A. d/b/a Ladeco Airlines | ICAO: LCO, Callsign: Ladeco, IATA Prefix: 145, Name changed to LANExpress 01 November 2001. | RCH | AVCODES |
| 3 | UC | Ladeco S.A. d/b/a LANExpress | ICAO: LCO, Callsign: Ladeco, IATA Prefix: 145, Name changed from Ladeco S.A. d/b/a Ladeco Airlines | RCH | AVCODES |
| 4 | UC | Linea Aerea del Cobre Ltda. (LADECO) | ICAO: UCO, Callsign: Ladeco, | RCH | AVCODES |
| 5 | UC | LAN Cargo S.A. d/b/a LATAM Cargo Chile | ICAO: LCO, IATA Prefix: 527, Name changed from LAN Cargo S.A. w.e.f. 05 May 2016. | RCH | AVCODES |
| 6 | UCA | Champlain Enterprises, LLC. t/a CommutAir | IATA: C5, Callsign: Commutair, IATA Prefix: 841, Name changed from Commutair (US Airways Express) | USA | AVCODES |
| 7 | UCA | Commutair / US Airways Express | Callsign: Commutair, Name changed to Champlain Enterprises Inc. | USA | AVCODES |
| 8 | UCA | CommutAir | IATA: C5 | | ICAO1 |
| 9 | UCAG | UNITED CARGO LINES | | | SCAC4 |
| 10 | UCAL | UTI CRAF AGENT | | | SCAC4 |
| 11 | UCAR | UPSTATE AIR CARGO | | | SCAC4 |
| 12 | UCAT | USA CARTERET LLC | | | SCAC4 |
| 13 | UCAU | UCA CONTAINERS AG | | | PWRC |
| 14 | UCAU | UCA Containers AG | | | RSRV |
| 15 | UCAU | UNITED ARAB SHIPPING CO SAG | | | SCAC4 |
| 16 | UCAW | UNI-CHARTERING A/S | | | SCAC4 |
| 17 | UCB | United Caribbean Airlines B.V. | IATA: 4J, Callsign: Eagle Eye, Name changed to United Caribbean Airlines B.V. d/b/a JetAir Caribbean. | CUR | AVCODES |
| 18 | UCB | United Caribbean Airlines B.V. d/b/a JetAir Caribbean | IATA: 4J, Callsign: Eagle Eye, Name changed to Jetair Caribbean B.V. ICAO Designator changed to JRC. Name changed from United Caribbean Airlines B.V. | CUR | AVCODES |
| 19 | UCBC | UNION CITY BODY CO | | | SCAC4 |
| 20 | UCBX | United Carbon Co., Inc. | 7/1935-4/1961; eliminated 10/1963 | | NAKINA |
| 21 | UCBX | United Carbon Co. | added 10/1963; 7/1965-10/1966; eliminated 1/1969 | | NAKINA |
| 22 | UCBX | Ashland Chemical Co., Division of Ashland Oil & Refining Co., Carbon Black & Synthetic Rubber Division | added 1/1969; 4/1970; eliminated 4/1971 | | NAKINA |
| 23 | UCBX | Ashland Chemical Co., Division of Ashland Oil Inc., Carbon Black & Synthetic Rubber Division | added 4/1971; eliminated 7/1971 | | NAKINA |
| 24 | UCBX | Ashland Chemical Co., Division of Ashland Oil Inc. | added 7/1971; 1/1975; eliminated 1/1976 | | NAKINA |
| 25 | UCBX | United Carbon Co., Inc. | 4/38-10/66; eliminated 1/69 | | NRHS |
| 26 | UCBX | Ashland Chemical Co., Division of Ashland Oil & Refining Co., Carbon Black & Synthetic Rubber Division | added 1/69; 4/70; eliminated 4/71 | | NRHS |
| 27 | UCBX | Ashland Chemical Co., Division of Ashland Oil Inc., Carbon Black & Synthetic Rubber Division | added 4/71 | | NRHS |
| 28 | UCBX | Ashland Chemical Co., Division of Ashland Oil Inc. | Jan-75 | | NRHS |
| 29 | UCBX | ASHLAND CHEMICAL CO., CARBON BLACK & SYNTHETIC RUBBER DIV. [UNITED CARBON CO.] | | | PWRC |
| 30 | UCBZ | UNITED COOP OF BIGELOW | | | PWRC |
| 31 | UCC | Uganda Air Cargo | Callsign: Uganda Cargo, | EAU | AVCODES |
| 32 | UCC | Uganda Air Cargo | | | ICAO1 |
| 33 | UCC | UNION CARBIDE CORPORATION, CARBON PRODUCTS DIV. | | | PWRC |
| 34 | UCCB | US CARRIERS CORP | | | SCAC4 |
| 35 | UCCE | ULTIMATE CONTAINER CARRIER | | | SCAC4 |
| 36 | UCCP | US CARGO CORP | | | SCAC4 |
| 37 | UCCS | UPPER COLUMBIA CONFERENCE SDA | | | SCAC4 |
| 38 | UCCU | AMERICAN CYANAMID | | | PWRC |
| 39 | UCCU | American Cyanamid | | | RSRV |
| 40 | UCCX | Utah Copper Corp. | 7/1937 (not listed) | | NAKINA |
| 41 | UCCX | United Contracting Co. | 4/1947-4/1961 (not listed) | | NAKINA |
| 42 | UCCX | Union Carbide Canada Ltd. | added 10/1969; 4/1970-1/1980; eliminated 1/1985; 1/1994-7/2005 (not listed) | | NAKINA |
| 43 | UCCX | United Contracting Co. | 1/52-4/61 | | NRHS |
| 44 | UCCX | Union Carbide Canada Ltd. | added 10/69; 4/70-1/80; eliminated 1/85; 1/94-7/2000 | | NRHS |
| 45 | UCCX | *UTAH COPPER CORP. | | | PWRC |
| 46 | UCCX | *UNITED CONTRACTING CO. | | | PWRC |
| 47 | UCCX | +UNION CARBIDE CANADA, LTD. | | | PWRC |
| 48 | UCCX | Union Carbide Canada | | | RSRV |
| 49 | UCCX | UNION CARBIDE CORP. OF CANADA | | | SCAC4 |
| 50 | UCCZ | UNION CAMP CORP. | | | PWRC |
| 51 | UCDU | UNIVERSAL INC CONTAINERS TRADING LLC | | UAE | BIC |
| 52 | UCEA | USA CARRIER ENTERPRISES LLC | | | SCAC4 |
| 53 | UCEN | UNITED CARTAGE INC | | | SCAC4 |
| 54 | UCEX | Union Electric Co. | added 10/1980; eliminated 10/1984; 1/1994 (not listed); added 1/1997; eliminated 4/1997; 7/2000-7/2005 (not listed) | | NAKINA |
| 55 | UCEX | Union Electric Co. | added 10/80; eliminated 10/84; 1/94; added 1/97; eliminated 4/97; 7/2000 | | NRHS |
| 56 | UCEX | UNION ELECTRIC COMPANY | | | PWRC |
| 57 | UCEX | Union Electric | | | RSRV |
| 58 | UCEX | UNION ELECTRIC COMPANY | | | SCAC4 |
| 59 | UCFN | UNITED CALIFORNIA FREIGHT SOLUTIONS | | | SCAC4 |
| 60 | UCFX | Union Carbide Corp., Chemicals and Plastics Operations Division | added 4/1971; 1/1975; eliminated 1/1979 | | NAKINA |
| 61 | UCFX | Union Carbide Corp., Chemicals and Plastics Division | added 1/1979; 1/1980; eliminated 7/1980 | | NAKINA |
| 62 | UCFX | Union Carbide Corp. | added 7/1980; eliminated 10/1980 | | NAKINA |
| 63 | UCFX | Union Carbide Corp., Chemicals and Plastics Division | added 10/1980; eliminated 5/1983 | | NAKINA |
| 64 | UCFX | Union Carbide Corp. | added 5/1983; eliminated 1/1993 | | NAKINA |
| 65 | UCFX | Union Carbide Chemicals and Plastics Co., Inc. | added 1/1993; 1/1994; eliminated 1/1995; eliminated 4/1995 | | NAKINA |
| 66 | UCFX | Union Carbide Corp. | added 1/1995; added 4/1995; 7/2000-7/2005 | | NAKINA |
| 67 | UCFX | Union Carbide Corp., Chemicals and Plastics Operations Division | added 4/71; 1/75; eliminated 1/79 | | NRHS |
| 68 | UCFX | Union Carbide Corp., Chemicals and Plastics Division | added 1/79; 1/80; eliminated 7/80 | | NRHS |
| 69 | UCFX | Union Carbide Corp. | added 7/80; eliminated 10/80 | | NRHS |
| 70 | UCFX | Union Carbide Corp., Chemicals and Plastics Division | added 10/80; eliminated 5/83 | | NRHS |
| 71 | UCFX | Union Carbide Corp. | added 5/83; eliminated 1/93 | | NRHS |
| 72 | UCFX | Union Carbide Chemicals and Plastics Co., Inc. | added 1/93; 1/94; eliminated 1/95; eliminated 4/95 | | NRHS |
| 73 | UCFX | Union Carbide Corp. | added 1/95; added 4/95; 7/2000 | | NRHS |
| 74 | UCFX | UNION CARBIDE CORP., SUBSIDIARY OF THE DOW CHEMICAL CO. U.S.A. | | | PWRC |
| 75 | UCFX | Union Carbide Corporation | | | RSRV |
| 76 | UCFX | UNION CARBIDE CORPORATION (A SUBSID | | | SCAC4 |
| 77 | UCG | Uniworld Commercial Group, S.A. (Uniworld Air Cargo) | IATA: U7, Callsign: Uniworld, IATA Prefix: 399, | PA | AVCODES |
| 78 | UCGL | UNITED CONCRETE & GRAVEL LTD | | | SCAC4 |
| 79 | UCGO | UNICARGO TRANSPORT | | | SCAC4 |
| 80 | UCGU | UCGU CONTAINERS DI UCCELLINI VALTER | | | SCAC4 |
| 81 | UCH | US Airports Air Charter | Callsign: US Charter, | USA | AVCODES |
| 82 | UCH | US Airports Air Charter | | | ICAO1 |
| 83 | UCHL | UNLIMITED CHANNELS | | | SCAC4 |
| 84 | UCHN | UCHAN TRANSPORT (1987) LTD | | | SCAC4 |
| 85 | UCIA | UNION COMMERCIAL INCORPORATED | | | SCAC4 |
| 86 | UCIC | ULYSESS CARRIERS INC | | | SCAC4 |
| 87 | UCINA | TECHNOSTEEL LBR SRL | | RO | VKM |
| 88 | UCIQ | UNLIMITED CARRIER INC | | | SCAC4 |
| 89 | UCIR | Union County Industrial R.R. Co. | added 7/1996; 7/2000-7/2005 | | NAKINA |
| 90 | UCIR | Union County Industrial R.R. Co. | added 7/96; 7/2000 | | NRHS |
| 91 | UCIR | UNION COUNTY INDUSTRIAL RAILROAD CO. | | | PWRC |
| 92 | UCIR | Union County Industrial Railroad | | | RSRV |
| 93 | UCIR | UNION COUNTY INDUSTRIAL RAILROAD CO | | | SCAC4 |
| 94 | UCIS | UNIQUE CARRIERS INC | | | SCAC4 |
| 95 | UCIX | Unichema Chemicals, Inc. | added 1/1986; 1/1994; eliminated 4/1996 | | NAKINA |
| 96 | UCIX | Unichema Chemicals, Inc. | added 1/86; 1/94; eliminated 4/96 | | NRHS |
| 97 | UCIX | UNICHEMA CHEMICALS INC | | | PWRC |
| 98 | UCK | State Firefighting Service Of The Eastern Kazakhstan Region | Callsign: Galeta, | KZ | AVCODES |
| 99 | UCK | Air Division of the Eastern Kazakhstan Region | | | ICAO1 |
| 100 | UCKX | Union Coal & Coke Co. (Bethlehem Steel Co.) | 8/1920-7/1923 | | NAKINA |
