| 1 | AU | Cielos del Sur S.A. d/b/a Austral Lineas Aereas S.A. | ICAO: AUT, Callsign: Austral, IATA Prefix: 143, Merged into Aerolineas Argentinas w.e.f. 30 November 2020. Name changed from Austral Lineas Aereas. | RA | AVCODES |
| 2 | AU | Austral Lineas Aereas | ICAO: AUT, Callsign: Austral, IATA Prefix: 143, Name changed to Cielos del Sur S.A. d/b/a Austral Lineas Aereas S.A. Name changed from Compania Argentina de Transortes Aereos S.A.C. eI. - Austral | RA | AVCODES |
| 3 | AU | Canada Jetlines Operations Ltd | ICAO: CJL, Callsign: Jetbus, Vancouver based planned Ultra Low Cost Carrier. Planned startup 17 December 2019. 49% owned by Jet Metal Corporation (US). Planned startup with two A320 from SmartLynx. | CDN | AVCODES |
| 4 | AUA | Austrian Airlines | IATA: OS, Callsign: Austrian, IATA Prefix: 257, Name changed to Austrian Airlines, Osterreichische Luftverkehrs AG d/b/a/ Austrian | A | AVCODES |
| 5 | AUA | Austrian Airlines, Osterreichische Luftverkehrs AG d/b/a/ Austrian | IATA: OS, Callsign: Austrian, IATA Prefix: 257, Name changed to Austrian Airlines AG d/b/a/ Austrian. Name changed from Austrian Airlines | A | AVCODES |
| 6 | AUA | Austrian Airlines AG d/b/a/ Austrian | IATA: OS, Callsign: Austrian, IATA Prefix: 257, Name changed from Austrian Airlines, Osterreichische Luftverkehrs AG d/b/a/ Austrian | A | AVCODES |
| 7 | AUA | Austrian Airlines | IATA: OS | | ICAO1 |
| 8 | AUA | Austrian Airlines | | A | TRAFFIC |
| 9 | AUAA | AUSTIN, A A TRUCKING | | | SCAC4 |
| 10 | AUAB | AROUND AND ABOUT TOURS | | | SCAC3 |
| 11 | AUAB | AUGEN OPTICOS S A DE C V | | | SCAC4 |
| 12 | AUAC | AUTO AIR CARGO COMPANY | | | SCAC4 |
| 13 | AUAD | AURORA DISTRIBUTING CO INC | | | SCAC3 |
| 14 | AUAE | AURORA AREA EXPRESS, INC | | | SCAC3 |
| 15 | AUAE | AURORA AREA EXPRESS INC | | | SCAC4 |
| 16 | AUAF | AUTOMATIC AIR FREIGHT | | | SCAC3 |
| 17 | AUAG | AUTOCON OF ATLANTA INC | | | SCAC3 |
| 18 | AUAG | AULT TRUCKING | | | SCAC4 |
| 19 | AUAH | AUTO SALVAGE AUCTION INC | | | SCAC4 |
| 20 | AUAI | AUSTIN, CHARLES LTD | | | SCAC4 |
| 21 | AUAO | AAA UNITED AUTO TRANSPORT | | | SCAC4 |
| 22 | AUAP | ACURA TRANSPORTATION | | | SCAC3 |
| 23 | AUAR | AUSTIN AREA TERMINAL RAILROAD | | | PWRC |
| 24 | AUAR | Austin Area Terminal Railroad | | | RSRV |
| 25 | AUAR | Austin Area Terminal Railroad | | USA | TRAFFIC |
| 26 | AUAS | ACU TRANSPORT CO LTD | | | SCAC4 |
| 27 | AUAT | AUGUSTA TRUCKING COMPANY | | | SCAC3 |
| 28 | AUAW | AAA TRAVEL AGENCY | | | SCAC3 |
| 29 | AUB | Augsburg Airways GmbH | IATA: IQ, Callsign: Augsburg Air, IATA Prefix: 614, Ceased operations on 31 October 2013. Founded in 1980 as Interot Airways. | D | AVCODES |
| 30 | AUB | Augsburg Airways | IATA: IQ | | ICAO1 |
| 31 | AUBA | AUTOBAHN FREIGHT LINES LTD | | | SCAC4 |
| 32 | AUBC | AUTOBUS CARON & LAURIN LTD | | | SCAC3 |
| 33 | AUBF | AUTOTRANSPORTES HERMANOS DIAZ | | | SCAC4 |
| 34 | AUBG | AUTOBRIDGE | | | SCAC3 |
| 35 | AUBH | AUTOBUS COUTURE & CAHILL INC | | | SCAC3 |
| 36 | AUBI | AUTOBUS INTER-CITY (1986) ENR | | | SCAC3 |
| 37 | AUBI | AUTO BARN INC, THE | | | SCAC4 |
| 38 | AUBK | AUBURN TRUCKING CO INC | | | SCAC3 |
| 39 | AUBL | AUTOBUS L P R INC | | | SCAC3 |
| 40 | AUBN | AUBURNDALE COMPANY INC | | | SCAC3 |
| 41 | AUBO | AUDUBON-CESCO CORP | | | SCAC4 |
| 42 | AUBP | AUTOMOBILE TRANSPORT INC | | | SCAC3 |
| 43 | AUBR | AUBURN EXPRESS SERVICE | | | SCAC3 |
| 44 | AUBS | AUTO BUSES DE HUMACAO INC | | | SCAC3 |
| 45 | AUBT | AUBURN TRANSPORT INC | | | SCAC3 |
| 46 | AUBX | U.S. Plastic Lumber Ltd. | 7/2005 (not listed) | | NAKINA |
| 47 | AUBX | US PLASTIC LUMBER LTD. | | | PWRC |
| 48 | AUBX | US Plastic Lumber | | | RSRV |
| 49 | AUC | Aero Marine Consulting Pty Ltd. d/b/a Transaustralian Air Express Pty. Ltd. | IATA: HW, Callsign: Auscargo, IATA designator HW* recalled by IATA | AUS | AVCODES |
| 50 | AUC | A.D.T. (Aviation) Ltd. | Callsign: Auctions, Formerly British Car Auctions (Aviation) Ltd. Merged into Air Hanson during 1990 | GB | AVCODES |
| 51 | AUC | Austrian Airtransport (Osterreiechische Flugbetriebsgesellschaft mbH.) | IATA: OB, Callsign: Aircharter, ICAO callsign changed to Austrain Aircharter. Charter subsidary of Austrian Airlines | A | AVCODES |
| 52 | AUC | Austrian Airtransport (Osterreiechische Flugbetriebsgesellschaft mbH.) | IATA: OB, Callsign: Austrian charter, ICAO callsign changed from Aircharter. Charter subsidary of Austrian Airlines | A | AVCODES |
| 53 | AUC | Aero Marine Consulting Pty Ltd. d/b/a Transaustralian Air Express Pty. Ltd. | Callsign: Auscargo, IATA designator HW* recalled by IATA | AUS | AVCODES |
| 54 | AUC | Transaustralian Air Express | | | ICAO1 |
| 55 | AUCA | AUTO CUSTOM CARPETS INC | | | SCAC3 |
| 56 | AUCA | AURAND TRUCKING INC | | | SCAC4 |
| 57 | AUCB | AUTOMOBILE CLUB OF MICHIGAN | | | SCAC3 |
| 58 | AUCC | AUTHORIZED CARRIER CORPORATION | | | SCAC3 |
| 59 | AUCD | AUTOCON INC | | | SCAC3 |
| 60 | AUCE | AUTO CARRIERS INC | | | SCAC3 |
| 61 | AUCE | AULT FARMS | | | SCAC4 |
| 62 | AUCF | AUTO CARRIER EXPRESS INC | | | SCAC4 |
| 63 | AUCH | ACCU CHEM CONVERSION INC | | | SCAC4 |
| 64 | AUCH | Auch Inter-Borough Transit Co | City: Philadelphia | US-PA | TRAFFIC |
| 65 | AUCJ | AUTOCAR INC | | | SCAC4 |
| 66 | AUCK | AUSTIN TRUCKING | | | SCAC4 |
| 67 | AUCK | Auckland Transport | Real: AT, City: Auckland | AUS | TRAFFIC |
| 68 | AUCL | AUCLAIR TRANSPORTATION INC | | | PWRC |
| 69 | AUCL | AUCLAIR TRANSPORTATION, INC | | | SCAC3 |
| 70 | AUCM | AUSTIN CATTLE COMPANY | | | SCAC3 |
| 71 | AUCN | AUCTION TRANSPORT, INC | | | SCAC3 |
| 72 | AUCO | AURORA CARTAGE CO | | | SCAC3 |
| 73 | AUCP | AUSMUS CORPORATION | | | SCAC3 |
| 74 | AUCP | AUSMUS CORPORATION | | | SCAC4 |
| 75 | AUCQ | AUTHORITY CHRISTIAN TRANSPORTATION | | | SCAC4 |
| 76 | AUCR | AUTO CARRIERS INC | | | SCAC3 |
| 77 | AUCR | AUTOMATED TRANSPORTATION LLC | | | SCAC4 |
| 78 | AUCS | ACCUCAST | | | SCAC4 |
| 79 | AUCT | AURORA CARGO TRANSFER CORP | | | SCAC3 |
| 80 | AUCU | INTA MODAL SL | | | SCAC4 |
| 81 | AUCV | AUTO CONVOY CO | | | SCAC3 |
| 82 | AUCV | AUTO EXPRESS ORIENTE SA DE CV | | | SCAC4 |
| 83 | AUCX | AUTO-TRAIN CORPORATION | | | PWRC |
| 84 | AUCX | AUTOCOM RAIL SERVICES S DE RL DE DV | | | SCAC4 |
| 85 | AUCY | AUSTIN CODY EXPRESS | | | SCAC3 |
| 86 | AUCY | AUTOMATIC COATING LIMITED | | | SCAC4 |
| 87 | AUD | Audi Air, Inc. | Callsign: Audi Air, | USA | AVCODES |
| 88 | AUD | TransNorthern Airways, LLC. | Callsign: Genie, | USA | AVCODES |
| 89 | AUD | Audi Air, Inc. | | | ICAO1 |
| 90 | AUDC | AUDACIOUS INC | | | SCAC4 |
| 91 | AUDE | AUXILIAR DE TRANSPORTES MARITIMOS S | | | SCAC3 |
| 92 | AUDF | AUDUBON FORWARDING INC | | | SCAC3 |
| 93 | AUDG | AUSTIN DRAYING COMPANY | | | SCAC3 |
| 94 | AUDI | Audi | | D | TRAFFIC |
| 95 | AUDM | AUDUBON MOVING & STORAGE INC | | | SCAC3 |
| 96 | AUDM | AUDUBON MOVING & STORAGE LLC | | | SCAC4 |
| 97 | AUDN | AUDNEL AMERICA | | | SCAC3 |
| 98 | AUDN | AUDNEL AMERICA INTERNATIONAL INC. | | | SCAC4 |
| 99 | AUDO | AUDIO ASSOCIATES | | | SCAC4 |
| 100 | AUDP | AUTO DEALERS TRANSPORT | | | SCAC3 |
