| 9501 | SRO | Saudi Railways Organization | | SA | VKM |
| 9502 | SROA | SCHROEDER MOVING SYSTEMS OF MILWAUK | | | SCAC4 |
| 9503 | SROB | SANCHEZ RODRIGUEZ, BENJAMIN | | | SCAC4 |
| 9504 | SROC | STAR ROUTE CARRIERS, INC | | | SCAC1 |
| 9505 | SROD | STITES, RONALD | | | SCAC4 |
| 9506 | SROF | SUPERSONIC OF FLORIDA | | | SCAC4 |
| 9507 | SROG | SUPERMARCH | | | SCAC4 |
| 9508 | SROI | STEPHENSON, ROBBY OIL CO INC | | | SCAC4 |
| 9509 | SROP | SIROPS MAPLE GROVE INC | | | SCAC4 |
| 9510 | SROS | SOUTHERN ROSE | | | SCAC4 |
| 9511 | SROT | SONORA TRUCKING | | | SCAC4 |
| 9512 | SROX | Savannah River Operations Office, Atomic Energy Commission | 7/1954-7/1965 | | NAKINA |
| 9513 | SROX | U.S. Atomic Energy Commission, Savannah River Operations Office | 10/1966 | | NAKINA |
| 9514 | SROX | Savannah River Operations Office, Atomic Energy Commission | 4/1970-1/1975 | | NAKINA |
| 9515 | SROX | United States Energy Research and Development Administration, Savannah River Operations Office | added 4/1975; eliminated 1/1978 | | NAKINA |
| 9516 | SROX | U.S. Department of Energy, Savannah River Operations Office | added 1/1978; 1/1980; eliminated 1/1991 | | NAKINA |
| 9517 | SROX | U.S. Department of Energy, Savannah River Operations | 7/2005 (not listed) | | NAKINA |
| 9518 | SROX | Savannah River Operations Office, Atomic Energy Commission | 10/57-7/65 | | NRHS |
| 9519 | SROX | U.S. Atomic Energy Commission, Savannah River Operations Office | Oct-66 | | NRHS |
| 9520 | SROX | Savannah River Operations Office, Atomic Energy Commission | 4/70-1/75 | | NRHS |
| 9521 | SROX | United States Energy Research and Development Administration, Savannah River Operations Office | added 4/75; eliminated 1/78 | | NRHS |
| 9522 | SROX | U.S. Department of Energy, Savannah River Operations Office | added 1/78; 1/80; eliminated 1/91 | | NRHS |
| 9523 | SROX | *SHERADON RAIL OPERATIONS, INC. | | | PWRC |
| 9524 | SROX | +U.S. DEPT. OF ENERGY, SAVANNAH RIVER OPERATIONS | | | PWRC |
| 9525 | SROX | United States Department of Energy Savannah River Operations Office | | | RSRV |
| 9526 | SROX | US DEPARTMENT OF ENERGY SAVANNAH RI | | | SCAC4 |
| 9527 | SROX | U.S. Department of Energy, Savannah River Operations Office | | USA | TRAFFIC |
| 9528 | SROY | SUMMIT ROYAL TRANSPORT LTD | | | SCAC4 |
| 9529 | SRP | Bereitschaftpolizei Rheinland-Pfalz | Callsign: Sperber, | D | AVCODES |
| 9530 | SRP | Polizeihubschrafterstaffel Rheinland-Pfalz | | | ICAO1 |
| 9531 | SRP | Scandic Rail Partners ApS | 2006 - | DK | jernbanen.dk |
| 9532 | SRP | SALT RIVER PROJECT | | | PWRC |
| 9533 | SRP | Safe Handling Rail | | | RSRV |
| 9534 | SRP | Scandic Rail Partners ApS | 2006 - | DK | TRAFFIC |
| 9535 | SRPA | SERVICIO PUBLICO FEDERAL | | | SCAC4 |
| 9536 | SRPB | SHARP LOGISTICS INC | | | SCAC4 |
| 9537 | SRPC | SIERRA PACIFIC EXPRESS | | | SCAC4 |
| 9538 | SRPH | SMITH, RALPH COMPANY | | | SCAC4 |
| 9539 | SRPJ | SOUTHERN ARC TRANSPORTATION LLC | | | SCAC4 |
| 9540 | SRPK | SHARP EXPRESS | | | SCAC4 |
| 9541 | SRPQ | STAR TRANSPORT | | | SCAC4 |
| 9542 | SRPS | Scottish Railway Preservation Society | | UK | VKM |
| 9543 | SRPT | STARK PROPERTIES | | | SCAC4 |
| 9544 | SRPU | SARP INTERMODAL HIZMETLERI AS | | TR | BIC |
| 9545 | SRPV | SHARP TRANSIT | | | SCAC4 |
| 9546 | SRPW | SHARPLESS, M TRUCKING | | | SCAC4 |
| 9547 | SRPX | Rhinelander Division, St. Regis Paper Co. | added 1/1968; 4/1970-1/1975 | | NAKINA |
| 9548 | SRPX | Salt River Project Agricultural Improvement and Power District | added 7/1978; 1/1980; eliminated 10/1989; 1/1994-7/2005 (not listed) | | NAKINA |
| 9549 | SRPX | Rhinelander Division, St. Regis Paper Co. | added 1/68; 4/70-1/75 | | NRHS |
| 9550 | SRPX | Salt River Project Agricultural Improvement and Power District | added 7/78; 1/80; eliminated 10/89; 1/94-7/2000 | | NRHS |
| 9551 | SRPX | *RHINELANDER DIV., ST. REGIS PAPER CO. | | | PWRC |
| 9552 | SRPX | *SALT RIVER PROJECT, AGRICULTURAL IMPROVEMENT & POWER DISTRICT | | | PWRC |
| 9553 | SRPX | Salt River Project Agricultural Improvement and Power District | | | RSRV |
| 9554 | SRPX | SALT RIVER PROJECT, AGRI.IMPRVMT & | | | SCAC4 |
| 9555 | SRPY | STARS & STRIPES TRANSPORT | | | SCAC4 |
| 9556 | SRPZ | SAVANNAH RIVER PLANT | | | PWRC |
| 9557 | SRQ | Seair Incorporated | Callsign: Seair, Name changed to South East Asian Airlines | RP | AVCODES |
| 9558 | SRQ | South East Asian Airlines (SEAIR) International, Inc. | IATA: DG, Callsign: Seair, Name changed to Tigerair Philippines. Name changed from Seair Incorporated | RP | AVCODES |
| 9559 | SRQ | Tigerair Philippines | IATA: DG, Callsign: Seair, Name changed from South East Asian Airlines (SEAIR) International, Inc. Name changed from Seair Incorporated | RP | AVCODES |
| 9560 | SRQ | Cebgo Inc. d/b/a Cebgo | IATA: DG, Callsign: Blue Jay, Name changed from Tigerair Philippines | RP | AVCODES |
| 9561 | SRQ | South East Asian Airlines | IATA: DG | | ICAO1 |
| 9562 | SRQB | SHEWOKIS, ROBERT FUELS INC | | | SCAC4 |
| 9563 | SRQG | STAR LOGISTICS | | | SCAC4 |
| 9564 | SRQK | SUNRISE TRUCKING | | | SCAC4 |
| 9565 | SRQL | S & R LOGISTICS | | | SCAC4 |
| 9566 | SRQP | SHELL RIVER TRANSPORT INC | | | SCAC4 |
| 9567 | SRQS | STRAC LOGISTICS LLC | | | SCAC4 |
| 9568 | SRR | Star Air A/S | IATA: S6, Callsign: Whitestar, IATA designator changed to DJ*. | DK | AVCODES |
| 9569 | SRR | Star Air A/S | IATA: DJ, Callsign: Whitestar, IATA Prefix: 763, AOC transferred to Maersk Air Cargo A/S w.e.f. 05/06/2022. IATA designator changed from S6*. | DK | AVCODES |
| 9570 | SRR | Maersk Air Cargo A/S | IATA: DJ, Callsign: Whitestar, IATA Prefix: 763, AOC transferred from Star Air A/S w.e.f. 05/06/2022. IATA designator changed from S6*. | DK | AVCODES |
| 9571 | SRR | Star Air | | | ICAO1 |
| 9572 | SRR | STARR TRANSIT CO INC | | | SCAC4 |
| 9573 | SRR | Sendai Rinkai Railway | | J | TRAFFIC |
| 9574 | SRRA | SIERRA COURIER | | | SCAC4 |
| 9575 | SRRC | SIERRA RAILROAD CO. | | | PWRC |
| 9576 | SRRD | SERVICIOS RAPIDOS TREBOL SA DE CV | | | SCAC4 |
| 9577 | SRRF | STAR FREIGHT SYSTEMS INC | | | SCAC4 |
| 9578 | SRRH | SHERRER, TODD | | | SCAC4 |
| 9579 | SRRK | STARR TRUCKING CORP | | | SCAC4 |
| 9580 | SRRL | SERRALTA HERNANDEZ, CARLOS | | | SCAC4 |
| 9581 | SRRN | STARRS TRANSPORTATION | | | SCAC4 |
| 9582 | SRRQ | SINGING RIVER RADIATOR SERVICE | | | SCAC4 |
| 9583 | SRRW | SHORELAND RACING | | | SCAC4 |
| 9584 | SRRX | Star Refining & Producing Co. | 7/1923; 7/1935; 7/1937-4/1938 (not listed) | | NAKINA |
| 9585 | SRRX | Star R.R. Equipment | added 1/1971; 1/1975-1/1980; eliminated 7/1992; 1/1994-7/2005 (not listed) | | NAKINA |
| 9586 | SRRX | Star R.R. Equipment | added 1/71; 1/75-1/80; eliminated 7/92; 1/94-7/2000 | | NRHS |
| 9587 | SRRX | *SANDY RIVER & RANGELEY LAKES RAILROAD | | | PWRC |
| 9588 | SRRX | +STAR RAILROAD EQUIPMENT CO | | | PWRC |
| 9589 | SRRX | Star Railroad Equipment | | | RSRV |
| 9590 | SRRX | STAR RAILROAD EQUIPMENT CO | | | SCAC4 |
| 9591 | SRS | Selkirk Remote Sensing Ltd. | Callsign: Photo Charlie, | CDN | AVCODES |
| 9592 | SRS | Southern Sky Airlines | IATA: IH, Callsign: Sky South, Subsidary of SCAT Airlines. | KZ | AVCODES |
| 9593 | SRS | Selkirk Remote Sensing | | | ICAO1 |
| 9594 | SRS | SRS Railservice GmbH | Krumbach (SRS = Scherer Rail Service) | D | privat-bahn.de |
| 9595 | SRS | Süddeutsche Railservice GmbH | Kaiserslautern | D | privat-bahn.de |
| 9596 | SRS | SPERRY RAIL SERVICE | | | PWRC |
| 9597 | SRS | Sperry Rail Service | | USA | TRAFFIC |
| 9598 | SRS | SRS Rail Servis GmbH | | DE | VKM |
| 9599 | SRSEU | Sperry Rail | | UK | VKM |
| 9600 | SRSF | SARSFIELD TRANSPORT INC | | | SCAC4 |
