| 1 | SDU | Westair Commuter Airlines, Inc. / United Express | Designator OE recalled by IATA | USA | AVCODES |
| 2 | SDU | Westair Commuter Airlines, Inc. / United Express | IATA: OE, Designator OE recalled by IATA | USA | AVCODES |
| 3 | SDU | Sud Airlines | Callsign: Sud Lines, Ceased operations. | F | AVCODES |
| 4 | SDU | Dumont Aircraft Charter, LLC d/b/a Dumont Aviation | Callsign: Santos, | USA | AVCODES |
| 5 | SDU | Sud Airlines | | | ICAO1 |
| 6 | SDUC | SUPPLY DOCK CARRIERS INCORPORATED | | | SCAC4 |
| 7 | SDUE | SOUTHEAST ROAD BUILDERS INC | | | SCAC4 |
| 8 | SDUF | S E L MADURO (FLA) INC | | | SCAC4 |
| 9 | SDUG | SNEED TRUCKING | | | SCAC4 |
| 10 | SDUK | SANDHU S TRUCKING | | | SCAC4 |
| 11 | SDUP | STARDUST TRANSPORTATION LLC | | | SCAC4 |
| 12 | SDUS | SOUTHLAND ANGUS | | | SCAC4 |
| 13 | SDUT | STARDUST TRUCKING | | | SCAC4 |
