| 1 | DU | Hemus Air | ICAO: HMS, Callsign: Hemus Air, IATA Prefix: 748, Merged into Bulgaria Air FB/LZB in 2010 | BG | AVCODES |
| 2 | DU | Roland Air Flugverkehrs und Vertriebsgesellschaft mbH | ICAO: ROA, Callsign: Roland Air, | D | AVCODES |
| 3 | DU | Air Commerz Fluggesellschaft mbH | Callsign: Aircomor, | D | AVCODES |
| 4 | DU | Chess Wing Ltd. | ICAO: DUA, Callsign: Checkmate, | GB | AVCODES |
| 5 | DU | Norwegian Long Haul AS | ICAO: NLH, Callsign: Norstar, Designator DU recalled by IATA. | N | AVCODES |
| 6 | DU | Sky Jet M.G. Inc. | Commenced Operations on 01 August 2007. IATA Designator changed from Q9* | CDN | AVCODES |
| 7 | DU | DAYTON UNION RAILWAY COMPANY | | | PWRC |
| 8 | DU | Duisburger Verkehrsgesellschaft AG | Real: DVG | D | TRAFFIC |
| 9 | DUA | Chess Wing Ltd. | IATA: DU, Callsign: Checkmate, | GB | AVCODES |
| 10 | DUA | Dushanbe Air | Callsign: Dushanbe Air, | TJ | AVCODES |
| 11 | DUA | Dualogis GmbH | | DE | VKM |
| 12 | DUAC | DUCKERINGS TRANSPORT LTD | | | SCAC4 |
| 13 | DUAK | DUAL TRUCK LINE | | | SCAC4 |
| 14 | DUAQ | DOCKTOR FREIGHT SOLUTIONS CORP | | | SCAC4 |
| 15 | DUAR | DUPUIS AND SONS SAWDUST INC | | | SCAC4 |
| 16 | DUAS | DOUBLE A ENTERPRISE INC | | | SCAC4 |
| 17 | DUAT | DUECK BROTHERS TRUCKING LTD | | | SCAC4 |
| 18 | DUB | Dubai Air Wing / Royal Flight | Callsign: Dubai, | UAE | AVCODES |
| 19 | DUB | Dubai Airwing | | | ICAO1 |
| 20 | DUBC | DOUBLE R LLC | | | SCAC4 |
| 21 | DUBF | DAUPHINAIS, LEO | | | SCAC4 |
| 22 | DUBH | DUBUQUE HARDWOODS INC | | | SCAC4 |
| 23 | DUBL | DUGAN TRUCK LINE LLC | | | SCAC4 |
| 24 | DUBL | Dublin Bus | City: Dublin, It is a subsidiary of Córas Iompair Éireann. | IRL | TRAFFIC |
| 25 | DUBT | DOUBLE T TRUCKING INC | | | SCAC4 |
| 26 | DUBU | CHIEF DIKE UDENSI IFEGWU | | | SCAC3 |
| 27 | DUC | Aircompany Duncan Ltd. | Callsign: Duncan, Ceased operations. | UA | AVCODES |
| 28 | DUC | Class Aviation | Callsign: Richat, | RIM | AVCODES |
| 29 | DUCD | DONOVANS USED CARS | | | SCAC4 |
| 30 | DUCH | DUFFY CRANE AND HAULING | | | SCAC4 |
| 31 | DUCP | DUNCAN, P L TRUCKING INC | | | SCAC4 |
| 32 | DUCR | DUTTON, C R TRANSPORTATION LLC | | | SCAC4 |
| 33 | DUCU | DUTCH ANTILLEAN CONTAINER LEASING LTD | | CY | BIC |
| 34 | DUCU | DUTCH ANTILLEAN CONTAINER LEASING N | | | SCAC4 |
| 35 | DUCX | Du Pont Canada Inc. | 1/1994-7/2005 (not listed) | | NAKINA |
| 36 | DUCX | Ducktown Tank Line Co. | 7/1930-7/1935 | | NAKINA |
| 37 | DUCX | Du Pont Canada Inc. | 1/94-7/2000 | | NRHS |
| 38 | DUCX | *DUCKTOWN TANK LINE INC. | | | PWRC |
| 39 | DUCX | +DU PONT CANADA INC. | | | PWRC |
| 40 | DUCX | Du Pont Canada | | | RSRV |
| 41 | DUCX | DU PONT CANADA INC. | | | SCAC4 |
| 42 | DUD | Dehn & Dehn Eisenbahn-Transportlogistik | | DE | VKM |
| 43 | DUDB | DOUBLE D DISTRIBUTION INC | | | SCAC4 |
| 44 | DUDO | DUPONT, DONALD | | | SCAC4 |
| 45 | DUDS | DUDLEY, S L TRANSPORTATION INC | | | SCAC4 |
| 46 | DUDT | DULUTH, UNION DEPOT & TRANSFER COMPANY | | | PWRC |
| 47 | DUDT | DUDLEYS TRANSCONTINENTAL MOVERS | | | SCAC4 |
| 48 | DUDU | AMIRAL GEMI VE DENIZ ACENTELIGI LTD | | | SCAC4 |
| 49 | DUEC | DUECE TRUCKING INC | | | SCAC4 |
| 50 | DUEE | DOWN UNDER ENTERPRISES | | | SCAC4 |
| 51 | DUFF | DUFFY, TOM COMPANY | | | SCAC4 |
| 52 | DUFM | DUFF, MICHAEL INC | | | SCAC4 |
| 53 | DUFR | DUFRESNE, CLAUDE | | | SCAC4 |
| 54 | DUFS | DUFERCO SHIPPING SA | | | SCAC4 |
| 55 | DUFX | Duffy & Sons, Inc. | 7/2005 (not listed) | | NAKINA |
| 56 | DUFX | Merchants Despatch Transportation Corp. | 1/1950-1/1952; eliminated 4/1954; 7/1954 | | NAKINA |
| 57 | DUFX | Merchants Despatch Transportation Corp. | 1/52; eliminated 4/54 | | NRHS |
| 58 | DUFX | *MERCHANTS DESPATCH TRANSPORTATION CORP. | | | PWRC |
| 59 | DUFX | +DUFFEY & SONS, INC. | | | PWRC |
| 60 | DUFX | Duffy and Sons | | | RSRV |
| 61 | DUFX | DUFFY & SONS | | | SCAC4 |
| 62 | DUFY | DUFRY AMERICA SERVICES INC | | | SCAC4 |
| 63 | DUG | Aerotecnica S.A. | Callsign: Atsaven, | YV | AVCODES |
| 64 | DUGC | DUGGAN, J C INC | | | SCAC4 |
| 65 | DUGN | USF DUGAN, INC | | | SCAC3 |
| 66 | DUGN | DUGAN TRUCK LINE INC (TNT DUGAN INC | | | SCAC4 |
| 67 | DUGS | DUGGAN'S TRUCKING, INC | | | SCAC1 |
| 68 | DUGS | DUGGANS TRUCKING INC | | | SCAC4 |
| 69 | DUGW | DURAND, GEORGE W | | | SCAC4 |
| 70 | DUGY | DUGUAY HAULAGE INC | | | SCAC4 |
| 71 | DUHA | Duhabex, Długosz & Długosz, s.j. | City: Chrzanów | PL | TRAFFIC |
| 72 | DUIC | DISPATCH USA INC | | | SCAC4 |
| 73 | DUIF | DUCKERINGS INTERNATIONAL FREIGHT SE | | | SCAC4 |
| 74 | DUIN | DSECARGONET USA INC | | | SCAC4 |
| 75 | DUIQ | DUTCH INDUSTRIES | | | SCAC4 |
| 76 | DUIS | duisport rail GmbH | Real: DPR | D | TRAFFIC |
| 77 | DUJT | DUFFY, JOHN T | | | SCAC4 |
| 78 | DUK | Ducair, S.A. | Callsign: Lion King, Ceased operations. | L | AVCODES |
| 79 | DUK | Ducair | | | ICAO1 |
| 80 | DUKA | DUCK'S AGRO LTD | | | SCAC4 |
| 81 | DUKB | DUNKEL BROS MACHINERY MOVING INC | | | SCAC4 |
| 82 | DUKD | DUKES, DAN TRUCKING INC | | | SCAC4 |
| 83 | DUKE | DUKE OIL COMPANY INC | | | SCAC4 |
| 84 | DUKG | DUDLEY TRUCKING | | | SCAC4 |
| 85 | DUKK | DUKE TRUCKING | | | SCAC4 |
| 86 | DUKL | DUKE TRUCKING LLC | | | SCAC4 |
| 87 | DUKOL | DUKOL Ostrava, s.r.o. | | CZ | VKM |
| 88 | DUKS | DUCKS TRUCKING INC | | | SCAC4 |
| 89 | DUKX | The Dupps Co. | added 11/1973; 1/1975-7/2000; eliminated 10/2003; 7/2005 (not listed) | | NAKINA |
| 90 | DUKX | Duke, Inc. | added 4/1967; 4/1970; eliminated 11/1973 | | NAKINA |
| 91 | DUKX | Duke, Inc. | added 4/67; 4/70 | | NRHS |
| 92 | DUKX | The Dupps Co. | 1/75-7/2000 | | NRHS |
| 93 | DUKX | DUPPS COMPANY [DUKE, INC.] | | | PWRC |
| 94 | DUKX | Dupps | | | RSRV |
| 95 | DUKX | DUPPS COMPANY | | | SCAC4 |
| 96 | DULA | DULAI, SANTOKH TRUCKING LTD | | | SCAC4 |
| 97 | DULD | DELLINGER UNLIMITED LLC | | | SCAC4 |
| 98 | DULI | DURA LOGISTICS INC | | | SCAC4 |
| 99 | DULK | DUAL TRUCKING INC | | | SCAC4 |
| 100 | DULQ | DELIVERIES UNLIMITED INC | | | SCAC4 |
