| 1 | WU | China Eastern Airlines Wuhan Co., Ltd. | ICAO: CWU, Callsign: Wuhan Air, Merged into China Eastern Airlines during 2003. | PRC | AVCODES |
| 2 | WU | Tikal Jets, S.A. | ICAO: TKC, Callsign: Tikal, IATA designator changed to WU. IATA designator previously changed from 2E*, Then from A5* | GCA | AVCODES |
| 3 | WU | Tikal Jets, S.A. | ICAO: TKC, Callsign: Tikal, Designator WU recalled by IATA. IATA designator changed from WU*. IATA designator previously changed from 2E*, Then from A5* | GCA | AVCODES |
| 4 | WU | Netherlands Airlines for European Commuter Services (Netherlands) | ICAO: NET, Callsign: Netherlines, IATA Desigantor changed from KJ | NL | AVCODES |
| 5 | WU | Wizz Air Ukraine, LLC | ICAO: WAU, Callsign: Wizzair Ukraine, Founded in 2008. Ceased operations on 20 April 2015. | UA | AVCODES |
| 6 | WU | Western Air Limited | ICAO: WST, Callsign: Western Bahamas, | BS | AVCODES |
| 7 | WU | Jetways Airlines Limited | ICAO: JWX, Callsign: Jetways, | EAK | AVCODES |
| 8 | WUA | Asian Express General Aviation Wuxi Co., Ltd. | IATA: YJ, Callsign: Yajie Air, | PRC | AVCODES |
| 9 | WUBN | WEISS TRUCKING CO INC | | | SCAC4 |
| 10 | WUCT | WEST UNION COMMUNITY FUELS & LUBRIC | | | SCAC4 |
| 11 | WUDX | Western-United Dairy Co. | 1/1943-4/1947 | | NAKINA |
| 12 | WUDX | WESTERN-UNITED DAIRY CO. | | | PWRC |
| 13 | WUE | Wuerth Aviation | Callsign: Fasty, | D | AVCODES |
| 14 | WUE | Königlich Württembergische Staatseisenbahn | Real: K.W.St.E. | D | TRAFFIC |
| 15 | WUES | WUEST | | | SCAC4 |
| 16 | WUET | WUETHRICH TRANSPORTATION INC | | | SCAC4 |
| 17 | WUK | Wizz Air UK Limited | IATA: W9, Callsign: Wizz Go, | GB | AVCODES |
| 18 | WULI | WID-U LOGICS INC | | | SCAC4 |
| 19 | WUOL | WILLINGHAM OIL INC | | | SCAC4 |
| 20 | WUP | Wuppertaler Stadtwerke | Real: WSW, City: Wuppertal | D | TRAFFIC |
| 21 | WUPZ | WERNER ENTERPRISES | | | SCAC4 |
| 22 | WURQ | WURTH BROTHERS INC | | | SCAC4 |
| 23 | WURR | Wallowa Union R.R. Authority | added 10/2003; 7/2005 | | NAKINA |
| 24 | WURR | WALLOWA UNION RAILROAD AUTHORITY | | | PWRC |
| 25 | WURR | WALLOWA UNION RAILROAD AUTHORITY | | | SCAC4 |
| 26 | WUSA | WORLD LOGISTICS USA INC | | | SCAC4 |
| 27 | WUT | Wichita Union Terminal Ry., Co. | 1/1994-7/2005 | | NAKINA |
| 28 | WUT | Wichita Union Terminal Ry., Co. | 1/94-7/2000 | | NRHS |
| 29 | WUT | WICHITA UNION TERMINAL RWY.CO. | | | PWRC |
| 30 | WUT | Wichita Union Terminal Railway | | | RSRV |
| 31 | WUT | WICHITA UNION TERMINAL RAILWAY CO | | | SCAC4 |
| 32 | WUTQ | WILSON UTC INC | | | SCAC4 |
| 33 | WUTX | Western Union Telegraph Co. | 7/1937-4/1961 (not listed) | | NAKINA |
| 34 | WUTX | Western Union Telegraph Co. | 1/52-4/61 | | NRHS |
| 35 | WUTX | *WESTERN UNION TELEGRAPH CO. | | | PWRC |
| 36 | WUTX | *WASHINGTON UTILITIES & TRANSP. COMMN. (SCALE TEST CARS) | | | PWRC |
| 37 | WUTX | Washington Utilities and Transportation Commission | | | RSRV |
| 38 | WUTX | WASH UTILITIES & TRANSP COMM (SCALE | | | SCAC4 |
