| 301 | ROL | Aeroel Airways Ltd. | Callsign: Aeroel, | IL | AVCODES |
| 302 | ROL | Aeroel Airways | | | ICAO1 |
| 303 | ROLA | ROWLAND DRAYAGE CORPORATION | | | SCAC3 |
| 304 | ROLB | ROLLET BROS LOGISTICS | | | SCAC4 |
| 305 | ROLD | ROULAND TRUCKING SERVICE | | | SCAC3 |
| 306 | ROLD | ROLLET BROS TRUCKING CO INC | | | SCAC4 |
| 307 | ROLF | ROLFE RACING INC | | | SCAC4 |
| 308 | ROLI | ROLLING STONE CARTAGE INC | | | SCAC3 |
| 309 | ROLI | ROLLING STONE CARTAGE INC | | | SCAC4 |
| 310 | ROLJ | ROLLMAN, J & SON, INC | | | SCAC3 |
| 311 | ROLJ | ROLLMAN, J AND SON INC | | | SCAC4 |
| 312 | ROLK | ROLCO TRAILERS INC | | | SCAC4 |
| 313 | ROLL | ROLL-OFFS TRUCKING INC | | | SCAC4 |
| 314 | ROLM | ROLLINS MOVING AND STORAGE, INC | | | SCAC3 |
| 315 | ROLM | ROLLINS MOVING AND STORAGE, INC | | | SCAC4 |
| 316 | ROLMA | Rolmafer | | CH | VKM |
| 317 | ROLN | ROLAND TRUCKING COMPANY | | | SCAC3 |
| 318 | ROLO | R O L I SYSTEMS INC | | | SCAC3 |
| 319 | ROLO | RO-LOU TRANSPORT LTEE | | | SCAC4 |
| 320 | ROLP | ROLAND LEASING CORP | | | SCAC3 |
| 321 | ROLP | ROLAND LEASING CORP | | | SCAC4 |
| 322 | ROLQ | ROLLINS TERMINALS INC | | | SCAC3 |
| 323 | ROLS | ROSEN LIVESTOCK | | | SCAC3 |
| 324 | ROLU | RO-LO PACIFIC LINE | | | PWRC |
| 325 | ROLU | Ro-Lo Pacific Line | | | RSRV |
| 326 | ROLU | RO-LO PACIFIC LINE | | | SCAC3 |
| 327 | ROLU | ROLLTAINER | | | SCAC4 |
| 328 | ROLV | ROUSSLANG TRANSFER | | | SCAC3 |
| 329 | ROLX | Empire Railcar Corp. | 7/2005 (not listed) | | NAKINA |
| 330 | ROLX | Robson Leather Co., Ltd. | added 7/1960; 4/1961-4/1970; eliminated 7/1970 | | NAKINA |
| 331 | ROLX | Royal Manufacturing Co. of Duquesne | 1/1945-4/1947 | | NAKINA |
| 332 | ROLX | Robson Leather Co., Ltd. | added 7/60; 4/61-4/70; eliminated 7/70 | | NRHS |
| 333 | ROLX | *ROYAL MANUFACTURING CO. OF DUQUESNE | | | PWRC |
| 334 | ROLX | *ROBSON LEATHER CO., LTD. | | | PWRC |
| 335 | ROLX | +EMPIRE RAILCAR CORP. | | | PWRC |
| 336 | ROLX | ROBSON LEATHER CO LTD | | | SCAC3 |
| 337 | ROLX | EMPIRE RAILCAR CORPORATION | | | SCAC4 |
| 338 | ROLY | ROLLEY MOVING & STORAGE INC | | | SCAC3 |
| 339 | ROLY | ROLYS TRUCKING INC | | | SCAC4 |
| 340 | ROM | Aeromar C. Por. A. | IATA: BQ, Callsign: Bravo Quebec, IATA Prefix: 926, Name changed to Aeromar Airlines | DOM | AVCODES |
| 341 | ROM | Aeromar Airlines | IATA: BQ, Callsign: Bravo Quebec, IATA Prefix: 926, Name changed from Aeromar C. Por. A. | DOM | AVCODES |
| 342 | ROM | Encompass Aviation, LLC | IATA: LC, Callsign: Rome, Ceased operations during 2018. | USA | AVCODES |
| 343 | ROM | Aeromar | IATA: BQ | | ICAO1 |
| 344 | ROMAG | RAAN - SUCURSALA ROMAG TERMO | | RO | VKM |
| 345 | ROMB | ROBERTS MOTOR SERVICE CO | | | SCAC3 |
| 346 | ROMDS | M&D SEA FARERS SRL | | RO | VKM |
| 347 | ROMG | ROME'N SONS CARTAGE, INC | | | SCAC3 |
| 348 | ROMG | ROMERO GONZALEZ, ANGEL | | | SCAC4 |
| 349 | ROMI | RO-MAC | | | SCAC3 |
| 350 | ROML | ROBERTS MOTOR LINES, INC | | | SCAC3 |
| 351 | ROMN | ROMANS MOTOR FREIGHT, INC | | | SCAC3 |
| 352 | ROMN | ROMANS MOTOR FREIGHT INC | | | SCAC4 |
| 353 | ROMO | RODS PARCEL DELIVERY | | | SCAC3 |
| 354 | ROMPK | ROMPAK S.R.L. | | RO | VKM |
| 355 | ROMQ | ROME-ALBANY EXPRESS INC | | | SCAC3 |
| 356 | ROMQ | ROSELAND MANAGEMENT CO | | | SCAC4 |
| 357 | ROMR | ROAM TRANSPORT INC | | | SCAC4 |
| 358 | ROMT | ROBBINS MOTOR TRANSPORTATION INC | | | SCAC3 |
| 359 | ROMU | ROMOCEAN S.L. | | E | BIC |
| 360 | ROMW | ROMAR TERMINAL AND WAREHOUSE CO INC | | | SCAC3 |
| 361 | ROMX | Roy O. Martin Lumber Co., Inc. | added 10/1968; 4/1970; eliminated 1/1971 | | NAKINA |
| 362 | ROMX | Roy O. Martin Lumber Co., Inc. | added 10/68; 4/70; eliminated 1/71 | | NRHS |
| 363 | ROMX | ROY O. MARTIN LUMBER CO., INC. | | | PWRC |
| 364 | ROMY | ROOMSTORE INC | | | SCAC4 |
| 365 | RON | Air Nauru | IATA: ON, Callsign: Air Nauru, IATA Prefix: 123, Commenceds operation on 14 February 1970. Ceased operations on 18 December 2005. Relaunched as Nauru Air Corporation t/a Our Airline on 14 October 2006. Designator ON reinstated by IATA | NAU | AVCODES |
| 366 | RON | Nauru Air Corporation t/a Our Airline | IATA: ON, IATA Prefix: 123, Nauru Air Corporation t/a Nauru Airlines w.e.f. 01 August 2014. Name changed from Air Nauru on 14 October 2005. | NAU | AVCODES |
| 367 | RON | Nauru Air Corporation t/a Nauru Airlines | IATA: ON, IATA Prefix: 123, Name changed from Nauru Air Corporation t/a Our Airline w.e.f. 01 August 2014. | NAU | AVCODES |
| 368 | RON | Nauru Air Corporation | IATA: ON | | ICAO1 |
| 369 | RON | Our Airline | IATA: ON | | ICAO1 |
| 370 | RONA | RONTRA FREIGHT INC | | | SCAC4 |
| 371 | RONE | ROUNTREE TRUCKING COMPANY | | | SCAC3 |
| 372 | RONE | ROSENAU EQUIPMENT COMPANY INC | | | SCAC4 |
| 373 | RONE | Rail One S.p.A. | | IT | VKM |
| 374 | RONF | ROANE TRANSFER | | | SCAC3 |
| 375 | RONI | ROMANELLI & SON INC | | | SCAC4 |
| 376 | RONJ | ROGERS TRANSFER, INC | | | SCAC3 |
| 377 | RONK | RONNIES TRUCKING INC | | | SCAC4 |
| 378 | RONL | ROTRANSCO | | | SCAC3 |
| 379 | RONM | RONNOCO 1 INC | | | SCAC4 |
| 380 | RONN | RONE TRUCKING INC | | | SCAC3 |
| 381 | RONN | RONE TRUCKING INC | | | SCAC4 |
| 382 | RONO | RONS TOWING | | | SCAC3 |
| 383 | RONP | RONS PRODUCE INC | | | SCAC3 |
| 384 | RONP | ROLL ON TRANSPORTATION INC | | | SCAC4 |
| 385 | RONQ | RONEY DELIVERY SERVICE | | | SCAC3 |
| 386 | RONR | RONS TRANSPORT | | | SCAC3 |
| 387 | RONS | ROBERTS & SINGER | | | SCAC3 |
| 388 | RONS | ROBERTS & SINGER | | | SCAC4 |
| 389 | RONT | RONALDS TRAILER TRANSPORT | | | SCAC3 |
| 390 | RONU | RDON, INC. | | | SCAC3 |
| 391 | RONU | NAHSHOL TALLYING AND SUPERVISION | | | SCAC4 |
| 392 | RONW | ROWELL & WATSON CO INC | | | SCAC3 |
| 393 | RONX | MACQUARIE RAIL INC | | | SCAC4 |
| 394 | ROO | Aeroitalia | Callsign: Aeroitalia, | I | AVCODES |
| 395 | ROO | Aero Roa, S.A. de C.V. | Callsign: Aero Ria, | MEX | AVCODES |
| 396 | ROO | Aeroitalia | | | ICAO1 |
| 397 | ROOC | ROCO OIL COMPANY INC | | | SCAC3 |
| 398 | ROOC | ROCO OIL COMPANY INC | | | SCAC4 |
| 399 | ROOG | ROCCO-S TRUCKING INC | | | SCAC4 |
| 400 | ROOH | ROSE TRANSPORT INC | | | SCAC3 |
