| 1 | DUC | Aircompany Duncan Ltd. | Callsign: Duncan, Ceased operations. | UA | AVCODES |
| 2 | DUC | Class Aviation | Callsign: Richat, | RIM | AVCODES |
| 3 | DUCD | DONOVANS USED CARS | | | SCAC4 |
| 4 | DUCH | DUFFY CRANE AND HAULING | | | SCAC4 |
| 5 | DUCP | DUNCAN, P L TRUCKING INC | | | SCAC4 |
| 6 | DUCR | DUTTON, C R TRANSPORTATION LLC | | | SCAC4 |
| 7 | DUCU | DUTCH ANTILLEAN CONTAINER LEASING LTD | | CY | BIC |
| 8 | DUCU | DUTCH ANTILLEAN CONTAINER LEASING N | | | SCAC4 |
| 9 | DUCX | Du Pont Canada Inc. | 1/1994-7/2005 (not listed) | | NAKINA |
| 10 | DUCX | Ducktown Tank Line Co. | 7/1930-7/1935 | | NAKINA |
| 11 | DUCX | Du Pont Canada Inc. | 1/94-7/2000 | | NRHS |
| 12 | DUCX | *DUCKTOWN TANK LINE INC. | | | PWRC |
| 13 | DUCX | +DU PONT CANADA INC. | | | PWRC |
| 14 | DUCX | Du Pont Canada | | | RSRV |
| 15 | DUCX | DU PONT CANADA INC. | | | SCAC4 |
