| 1601 | UR | Brintel Helicopters t/a British International Helicopters Ltd. | ICAO: BIH, Callsign: Lion, ICAO Callsign changed to Brintel | GB | AVCODES |
| 1602 | UR | Brintel Helicopters t/a British International Helicopters Ltd. | ICAO: BIH, Callsign: Brintel, Merged with Bond / New name Scotia Helicopter Service | GB | AVCODES |
| 1603 | UR | British Airways Helicopters Ltd. | ICAO: BIH, Renamed British International Helicopters Ltd. | GB | AVCODES |
| 1604 | UR | British International Helicopters Ltd. | ICAO: BIH, Callsign: Lion, IATA designator changed to BS* | GB | AVCODES |
| 1605 | UR | Transafricair | Callsign: Transafricair, | RWA | AVCODES |
| 1606 | UR | Aerosun International, Inc. | ICAO: ASI, Callsign: Aerosun, Designator UR recalled by IATA. Name changed from Red Carpet Airlines in September 1981. | USA | AVCODES |
| 1607 | UR | UTAir Express | ICAO: UTX, Callsign: UTAir-Express, IATA Prefix: 434, Ceased operations | RUS | AVCODES |
| 1608 | UR | Uganda National Airlines Company Limited d/b/a/ Uganda Airlines | ICAO: UGD, Callsign: Crested, | EAU | AVCODES |
| 1609 | URA | Aircompany Rosavia Ltd. | Callsign: Rosavia, | UA | AVCODES |
| 1610 | URA | Aircompany Rosavia | | | ICAO1 |
| 1611 | URBC | UGLY TRUCK / BEAUTIFUL SERVICE | | | SCAC4 |
| 1612 | URBS | URBAN EXPRESS | | | SCAC4 |
| 1613 | URC | United Railways Co. (Spokane, Portland & Seattle Ry.) | 7/1923-7/1936 | | NAKINA |
| 1614 | URC | United Railways Co. | 4/1938-1/1941 | | NAKINA |
| 1615 | URC | United Railways Co. | Apr-38 | | NRHS |
| 1616 | URC | UNITED RAILWAYS CO. 9SPOKANE, PORTLAND & SEATTLE RWY.) | | | PWRC |
| 1617 | URCS | UNITED RELOCATION SYSTEMS INC | | | SCAC4 |
| 1618 | URCX | United Refining Co. | 8/1920-4/1970; eliminated 7/1971 | | NAKINA |
| 1619 | URCX | United Refining Co. | 4/38-4/70 | | NRHS |
| 1620 | URCX | UNITED REFINING CO. | | | PWRC |
| 1621 | URDS | URS AUTO TRANSPORT DIVISION | | | SCAC4 |
| 1622 | URDX | United States Steel Corp., Resource Development Group | added 10/1980; eliminated 4/1985 | | NAKINA |
| 1623 | URDX | Arch of Kentucky, Inc. | added 4/1985; 1/1994; eliminated 4/1994; 7/2000-7/2005 (not listed) | | NAKINA |
| 1624 | URDX | United States Steel Corp., Resource Development Group | added 10/80; eliminated 4/85 | | NRHS |
| 1625 | URDX | Arch of Kentucky, Inc. | added 4/85; 1/94; eliminated 4/94; 7/2000 | | NRHS |
| 1626 | URDX | ARCH OF KENTUCKY, INC. {UNITED STATES STEEL CORP., RESOURCE DEVELOPMENT GROUP] | | | PWRC |
| 1627 | URDX | United States Steel | | | RSRV |
| 1628 | URDX | ARCH OF KENTUCKY, INC. | | | SCAC4 |
| 1629 | URE | Eureca srl | IATA: F4, Callsign: Eureca, Designator F4 recalled by IATA. Name changed from International Flying Services. ICAO designator changed from IFS | I | AVCODES |
| 1630 | UREG | USCA REFRIGERATED | | | SCAC4 |
| 1631 | URES | UNIVERSAL RELOCATION SYSTEMS INC | | | SCAC4 |
| 1632 | UREU | URENCO LTD | | D | BIC |
| 1633 | UREU | URENCO LTD | | | SCAC4 |
| 1634 | URF | Executive Flight Services | Callsign: Executive Express, | M | AVCODES |
| 1635 | URF | Surf Air | Callsign: Surfair, | USA | AVCODES |
| 1636 | URFU | EUROTRANS LOGISTICS LLC | | RUS | BIC |
| 1637 | URG | Air Urga | IATA: 3N, Callsign: Urga, IATA Prefix: 746, | UA | AVCODES |
| 1638 | URG | Air Urga | IATA: 3N | | ICAO1 |
| 1639 | URGX | UniCapital Rail Group | 7/2000 (not listed) | | NAKINA |
| 1640 | URGX | UniCapital Rail Group | Jul-00 | | NRHS |
| 1641 | URGX | UNICAPITAL RAIL GROUP | | | PWRC |
| 1642 | URGY | URUGUAY TRUCKING | | | SCAC4 |
| 1643 | URHC | UNIVERSAL ROAD HAUL CORP. | | | SCAC1 |
| 1644 | URHS | United Railroad Historical Society of New Jersey | | USA | TRAFFIC |
| 1645 | URHX | UNITED RAILWAY HISTORICAL SOCIETIES OF NEW JERSEY | | | PWRC |
| 1646 | URI | uSKY AIR | Callsign: Uri Air, | ROK | AVCODES |
| 1647 | URIM | UR IMAGE INC | | | SCAC4 |
| 1648 | URJ | Star Air Aviation (Private) Limited | IATA: 6S, Callsign: Starav, | PK | AVCODES |
| 1649 | URJ | Star Air | | | ICAO1 |
| 1650 | URK | Turkestan | Callsign: Djuma, | KZ | AVCODES |
| 1651 | URLL | UNCLE RAYS LLC | | | SCAC4 |
| 1652 | URLO | URSA LOGISTICS | | | SCAC4 |
| 1653 | URMX | Union Refrigerator Transit Lines, a Division of the General American Transportation Corp. | 7/1965-10/1966 | | NAKINA |
| 1654 | URMX | Union Refrigerator Transit Lines | eliminated 7/1967 | | NAKINA |
| 1655 | URMX | Union Refrigerator Transit Lines, a Division of the General American Transportation Corp. | 7/65-10/66 | | NRHS |
| 1656 | URMX | Union Refrigerator Transit Lines | eliminated 7/67 | | NRHS |
| 1657 | URMX | *UNION REFRIGERATOR TRANSIT LINES, DIV. GENERAL AMERICAN TRANSPORTATION CORP. | | | PWRC |
| 1658 | URMX | +UNITRAC RAILROAD MATERIALS INC. | | | PWRC |
| 1659 | URMX | UNITRAC RAILROAD MATERIALS INCORPOR | | | SCAC4 |
| 1660 | URN | Turan Air Airline Company | IATA: 3T, Callsign: Turan, IATA Prefix: 359, Ceased operations in 2013. | AZ | AVCODES |
| 1661 | URN | Turan Air | IATA: 3T | | ICAO1 |
| 1662 | URO | Euroair Transport Ltd. | IATA: EZ, Callsign: Euroair, | GB | AVCODES |
| 1663 | URO | European Cargo Limited | IATA: PS, Callsign: Euro, IATA Prefix: 436, IATA designator changed to SE. | GB | AVCODES |
| 1664 | URO | European Cargo Limited | IATA: SE, Callsign: Euro, IATA Prefix: 436, IATA designator changed from PS*. | GB | AVCODES |
| 1665 | UROI | UNITED ROAD ONTARIO INC | | | SCAC4 |
| 1666 | UROS | URO SYSTEMS LLC | | | SCAC4 |
| 1667 | URP | ARP 410 Airlines | Callsign: Air-Arp, | UA | AVCODES |
| 1668 | URP | ARP 410 Airlines | | | ICAO1 |
| 1669 | URPL | ULTIMATE RECYCLED PLASTICS | | | SCAC4 |
| 1670 | URQR | URQUHART, RAY V | | | SCAC4 |
| 1671 | URR | Aurora Airlines | Callsign: Air Aurora, Founded in 2005. Ceased operations in 2009. | SLO | AVCODES |
| 1672 | URR | Aurora Airlines | | | ICAO1 |
| 1673 | URR | Union R.R. Co. (Pittsburgh, PA) | 1/1975-7/2005 | | NAKINA |
| 1674 | URR | Union R.R. Co. (Pittsburgh, PA) | 1/75-7/2000 | | NRHS |
| 1675 | URR | UNION RAILROAD CO. (PITTSBURGH, PA) | | | PWRC |
| 1676 | URR | Union Railroad Pittsburgh | | | RSRV |
| 1677 | URR | UNION RAILROAD COMPANY | | | SCAC4 |
| 1678 | URR | Union R.R. Co. (Pittsburgh, PA) | | USA | TRAFFIC |
| 1679 | URS | Air Company LLC Silk Road Cargo Business | IATA: S9, Callsign: Silk Cargo, IATA Prefix: 939, | UZ | AVCODES |
| 1680 | URSA | URSA SHIPPING | | | SCAC4 |
| 1681 | URSC | UNITED RAILWAY SUPPLY CO. | | | PWRC |
| 1682 | URSM | URS SMS LLC | | | SCAC4 |
| 1683 | URSO | URSO FUEL OIL CO | | | SCAC4 |
| 1684 | URST | UNIE VAN REDDING-EN SLEEPDIENS TOWA | | | SCAC4 |
| 1685 | URT | Avia-Urartu | Callsign: Urartu Air, | AM | AVCODES |
| 1686 | URTA | UNITED RIM TRANSPORT INC | | | SCAC4 |
| 1687 | URTB | URTRUCKBROKER | | | SCAC4 |
| 1688 | URTC | Union Refrigerator Transit Lines | a Division of the General American Transportation Corp. | USA | TRAFFIC |
| 1689 | URTCo. | Union Refrigerator Transit Co. | 7/1935 | | NAKINA |
| 1690 | URTS | URTRUCKSTUFF.COM LLC | | | SCAC4 |
| 1691 | URTT | URUAMERICA TRUCKING LLC | | | SCAC4 |
| 1692 | URTX | Union Refrigerator Transit Co. (previously U.R.T.Co.) | added 11/1934; 7/1935-4/1947 | | NAKINA |
| 1693 | URTX | Union Refrigerator Transit Lines, a Division of the General American Transportation Corp. | 1/1950-4/1970; eliminated 10/1971 | | NAKINA |
| 1694 | URTX | General American Transportation Corp., Freight Car Division | added 10/1971 | | NAKINA |
| 1695 | URTX | General American Transportation Corp. | 1/1975-1/1980; eliminated 10/1992 | | NAKINA |
| 1696 | URTX | Union Refrigerator Transit Lines, a Division of the General American Transportation Corp. | 4/38-4/70; eliminated 10/71 | | NRHS |
| 1697 | URTX | General American Transportation Corp., Freight Car Division | added 10/71 | | NRHS |
| 1698 | URTX | General American Transportation Corp. | 1/75-1/80; eliminated 10/92 | | NRHS |
| 1699 | URTX | (GATX) RETIRED 08-19-92 ATP (1631) [UNION REFRIGERATOR TRANSIT LINES] | | | PWRC |
| 1700 | URTX | Union Refrigerator Transit Lines (GATX) | | | RSRV |
