| 401 | ROOH | ROSE TRANSPORT INC | | | SCAC4 |
| 402 | ROOL | ROGER, R T OIL CO INC | | | SCAC4 |
| 403 | ROOM | ROLL ON TRANSPORTATION COMPANY | | | SCAC4 |
| 404 | ROON | ROOSEN TRUCKING | | | SCAC4 |
| 405 | ROOR | ROORDA TRANSPORT CO | | | SCAC3 |
| 406 | ROOS | ROOSTER EXPRESS INC | | | SCAC3 |
| 407 | ROOS | ROOSTER CRUISER LLC | | | SCAC4 |
| 408 | ROOV | ROBERTSONS OVERLAND EXPRESS | | | SCAC3 |
| 409 | ROP | Royal Oman Police | | OM | AVCODES |
| 410 | ROP | Royal Oman Police | | | ICAO1 |
| 411 | ROP | RAIL OPERATIONS SRL | | RO | VKM |
| 412 | ROPA | RONSON TRANSPORTATION INC | | | SCAC3 |
| 413 | ROPAG | ROP Roth AG | | DE | VKM |
| 414 | ROPAN | EUROPAN PROD SA | | RO | VKM |
| 415 | ROPC | ROGERS PETRO-CHEM CO | | | SCAC3 |
| 416 | ROPE | ROMERO, PAT FEEDS AND SUPPLY | | | SCAC3 |
| 417 | ROPE | ROTATION POWER & EQUIPMENT | | | SCAC4 |
| 418 | ROPG | ROYAL PROCESSING CO INC | | | SCAC3 |
| 419 | ROPN | ROSE TRANSPORTATION INC | | | SCAC3 |
| 420 | ROPR | ROSE TRANSPORTATION INC | | | SCAC3 |
| 421 | ROPS | ROCAROL PARCEL SYSTEM | | | SCAC3 |
| 422 | ROPT | ROPPE TRANSPORTATION CORPORATION | | | SCAC3 |
| 423 | ROPX | Rail Operators, Inc. | added 7/1993; 1/1994; eliminated 4/1997; 7/2000 (not listed) | | NAKINA |
| 424 | ROPX | Rail Operators, Inc. | added 7/93; 1/94; eliminated 4/97; 7/2000 | | NRHS |
| 425 | ROPX | RAIL OPERATORS, INC. | | | PWRC |
| 426 | ROPX | Rail Operators | | | RSRV |
| 427 | ROQS | ROSES TRANSPORT INC | | | SCAC4 |
| 428 | ROQT | ROSS, R L EQUIPMENT | | | SCAC3 |
| 429 | ROR | Roraima Airways | Callsign: Roraima, | GUY | AVCODES |
| 430 | ROR | Roraima Airways | | | ICAO1 |
| 431 | ROR | Rockton & Rion Ry. | 1/1975-1/1980 | | NAKINA |
| 432 | ROR | Rockton & Rion Ry. | 1/75-1/80 | | NRHS |
| 433 | ROR | FORMERLY ROCKTON & RION RAILROAD | | | PWRC |
| 434 | ROR | ROCKTON & RION RAILWAY | | | SCAC4 |
| 435 | RORA | ROGER A LEASING LTD (DIV OF AIPA) | | | SCAC3 |
| 436 | RORB | ROMERO ORTEGA, RUBEN | | | SCAC4 |
| 437 | RORF | ROARING FORK FOUNDERS | | | SCAC3 |
| 438 | RORF | ROMERO ROBLES, FAUSTO | | | SCAC4 |
| 439 | RORG | ROANES RIGGING & TRANSFER CO INC | | | SCAC3 |
| 440 | RORI | ROTRA INC | | | SCAC3 |
| 441 | RORI | ROTRA LLC | | | SCAC4 |
| 442 | RORL | ROMAN, R TRUCK LEASING INC | | | SCAC3 |
| 443 | RORL | ROMAN, R TRUCK LEASING INC | | | SCAC4 |
| 444 | RORM | ROADRUNNER MOTOR LINES INC | | | SCAC3 |
| 445 | RORN | ROADRUNNER EXPRESS SERVICE | | | SCAC3 |
| 446 | RORO | RODCO TRANSPORTATION | | | SCAC3 |
| 447 | RORP | ROAD RUNNER EXPRESS | | | SCAC3 |
| 448 | RORR | ROPER TRUCKING SERVICE | | | SCAC3 |
| 449 | RORT | ROAD RAIL TRANSPORT LTD | | | SCAC3 |
| 450 | RORT | RO TRANSPORT | | | SCAC4 |
| 451 | RORU | Road Runner | Fleetname for some S.M.Coaches operations | GB | TRAFFIC |
| 452 | RORX | Radio Oil Refineries, Ltd. | 7/1937 (not listed); 4/1938-1/1952; eliminated 4/1953 | | NAKINA |
| 453 | RORX | Radio Oil Refineries, Ltd. | 4/38-1/52 | | NRHS |
| 454 | RORX | *RADIO OIL REFINERIES, LTD. | | | PWRC |
| 455 | RORX | +RED OAK RAIL TRANSPORT, LLC | | | PWRC |
| 456 | RORY | ROUTH, RAY & SONS INC | | | SCAC3 |
| 457 | RORZ | ROBINSON RUN | | | PWRC |
| 458 | ROS | Rossair Europe B.V. | Callsign: Catcher, | NL | AVCODES |
| 459 | ROS | ATS-Aviation Transport Services (ATS-Servicii de Transport Aerian) | Callsign: Romas, | RO | AVCODES |
| 460 | ROS | F.A.S. Rhodos Pilots Academy | Callsign: Lindos Air, | GR | AVCODES |
| 461 | ROS | Rossair Europe | | | ICAO1 |
| 462 | ROSA | RENOWN CO SA, PANAMA REP OF PANAMA | | | SCAC3 |
| 463 | ROSA | ROSALYN TANKER CORPORATION | | | SCAC4 |
| 464 | ROSB | ROSENBAUM CARREON, RENE | | | SCAC4 |
| 465 | ROSC | RODINO SHIPPING COMPANY LIMITED | | | SCAC4 |
| 466 | ROSD | ROSS TRANSPORT CO INC | | | SCAC3 |
| 467 | ROSE | ROSENBERGER ENTERPRISES INC | | | SCAC3 |
| 468 | ROSE | ROSE INTERNATIONAL INC | | | SCAC4 |
| 469 | ROSG | ROAD SERVICE GARAGE | | | SCAC3 |
| 470 | ROSI | ROSEVILLE MOTOR EXPRESS, INC | | | SCAC3 |
| 471 | ROSI | ROSEVILLE MOTOR EXPRESS INC | | | SCAC4 |
| 472 | ROSL | ROSEVELT, JAMES L | | | SCAC3 |
| 473 | ROSL | ROSE LOGISTICS INC | | | SCAC4 |
| 474 | ROSM | ROSE, WILLIAM GARY | | | SCAC3 |
| 475 | ROSM | RESORTES K-L DE MEXICO SA DE CV | | | SCAC4 |
| 476 | ROSO | ROSALIUS, CURTIS H | | | SCAC3 |
| 477 | ROSO | ROSARIO E N E | | | SCAC4 |
| 478 | ROSP | ROSEMAN, E, COMPANY | | | SCAC3 |
| 479 | ROSQ | ROSAS TRANSPORTATION & EQUIPMENT LE | | | SCAC3 |
| 480 | ROSQ | ROSSER TRUCKING | | | SCAC4 |
| 481 | ROSR | ROSS, ROY TRUCKING COMPANY | | | SCAC3 |
| 482 | ROSS | ROSS TRANSPORTATION | | | SCAC3 |
| 483 | ROSS | RANGER OILFIELD SERVICES | | | SCAC4 |
| 484 | ROST | ROBLIN STEEL | | | PWRC |
| 485 | ROSU | ROOS SPEDITION GMBH | | D | BIC |
| 486 | ROSU | ROOS SPEDITION GMBH | | | SCAC4 |
| 487 | ROSV | ROSES TRANSPORTATION | | | SCAC4 |
| 488 | ROSX | Ross and Company, Inc. | 7/1935 | | NAKINA |
| 489 | ROSY | ROSE-WAY INC | | | SCAC3 |
| 490 | ROSY | ROBINSON OIL SUPPLY & TRANSPORT INC | | | SCAC4 |
| 491 | ROSZ | ROSS TRUCKING LLC | | | SCAC4 |
| 492 | ROT | Compnia Nationala de Transporturi Aeriene Romane TAROM S.A. | IATA: RO, Callsign: Tarom, IATA Prefix: 281, Name changed from TAROM - Romanian Air Transport. | RO | AVCODES |
| 493 | ROT | Tarom | IATA: RO | | ICAO1 |
| 494 | ROT | RAIL OR TRAIL CORP. | | | PWRC |
| 495 | ROT | Rotterdamse Elektrische Tram | Real: RET, City: Rotterdam | NL | TRAFFIC |
| 496 | ROTA | ROOT, A L, TRANSPORTATION, INC | | | SCAC3 |
| 497 | ROTA | TAROM - Transporturile Aeriene Române | Real: ROT | RO | TRAFFIC |
| 498 | ROTB | ROSSI, THEODORE TRUCKING CO, INC | | | SCAC3 |
| 499 | ROTC | ROSE TRUCKING CORP | | | SCAC4 |
| 500 | ROTD | ROTENBERGER, DAVID M | | | SCAC3 |
