| 1 | SDR | Air Toronto | IATA: CS, Callsign: Soundair, Air Canada Connector | CDN | AVCODES |
| 2 | SDR | City Airline AB | IATA: CF, Callsign: Swedestar, IATA Prefix: 419, Ceased Operations and filed for bankruptcy 12 May 2012. | S | AVCODES |
| 3 | SDR | Soundair Express | Callsign: Soundiar, | CDN | AVCODES |
| 4 | SDR | Sundair GmbH | IATA: SR, Callsign: Sundair, Commenced operations on 27 September 2017. | D | AVCODES |
| 5 | SDR | City Airline | IATA: CF | | ICAO1 |
| 6 | SDR | Sudarec | | RO | TRAFFIC |
| 7 | SDRA | STRADER-FERRIS INTERNATIONAL LIMITE | | | SCAC4 |
| 8 | SDRA | Sundair | Real: SDR | D | TRAFFIC |
| 9 | SDRC | SISTEMA DE RIEGO EL DURAZNO | | | SCAC4 |
| 10 | SDRD | SANDER GEOPHYSICS LTD | | | SCAC4 |
| 11 | SDRE | SERVICE DE REMORQUAGE DIRECT INC | | | SCAC4 |
| 12 | SDRH | SMITH, D R TRUCKING INC | | | SCAC4 |
| 13 | SDRI | SISTEMA DE RIEGO PETERS SA DE CV | | | SCAC4 |
| 14 | SDRO | SUDDATH RELOCATION SYSTEMS OF ST PE | | | SCAC4 |
| 15 | SDRR | SOUTH DAKOTA RAILROAD AUTHORITY | | | PWRC |
| 16 | SDRS | SANDERS TRUCK TRANSPORTATION CO INC | | | SCAC4 |
| 17 | SDRT | SNADER, D L TRANSPORT INC | | | SCAC4 |
| 18 | SDRU | SIDRA DENIZCILIK VE TICARET A.S. | | TR | BIC |
| 19 | SDRV | SADDLE RIVER TRAILS INC | | | SCAC4 |
| 20 | SDRW | SANDERS, WILEY TRUCK LINES INC | | | SCAC4 |
| 21 | SDRX | Sinclair Refining Co. | 8/1920-7/1954; eliminated 1/1958 | | NAKINA |
| 22 | SDRX | Union Tank Car Co. | 10/1957; added 1/1958; 4/1961-4/1970; eliminated 7/1973 | | NAKINA |
| 23 | SDRX | Central Puget Sound Regional Transit Authority | 7/2000-7/2005 (not listed) | | NAKINA |
| 24 | SDRX | Sinclair Refining Co. | 4/38-1/52; eliminated 1/58 | | NRHS |
| 25 | SDRX | Union Tank Car Co. | 10/57; added 1/58; 4/61-4/70; eliminated 7/73 | | NRHS |
| 26 | SDRX | Central Puget Sound Regional Transit Authority | Jul-00 | | NRHS |
| 27 | SDRX | *SINCLAIR REFINING CO. (UNION TANK CAR CO.) | | | PWRC |
| 28 | SDRX | +CENTRAL PUGET SOUND REGIONAL TRANSIT AUTHORITY (SEATTLE) | | | PWRC |
| 29 | SDRX | Sounder Commuter Rail | | | RSRV |
| 30 | SDRX | CENTRAL PUGET SOUND REGIONAL TRANSI | | | SCAC4 |
| 31 | SDRX | Sinclair Refining Co. | | USA | TRAFFIC |
