| 3401 | OSNL | OVERSEAS NAVIGATION LTD | | | SCAC3 |
| 3402 | OSNT | OWENSBY & SONS TRUCKING INC | | | SCAC3 |
| 3403 | OSNV | OPAL SEAS NAVIGATION LTD | | | SCAC3 |
| 3404 | OSNV | OPAL SEAS NAVIGATION LTD | | | SCAC4 |
| 3405 | OSNX | Osnabrook Farmers Cooperative Elevator | added 1/2008; eliminated 4/2008 | | NAKINA |
| 3406 | OSNX | OSNABROCK FARMERS COOPERATIVE ELEVATOR | | | PWRC |
| 3407 | OSNX | OSNABROCK FARMERS COOPERATIVE ELEVA | | | SCAC4 |
| 3408 | OSNY | OVERSEAS NEW YORK LLC | | | SCAC4 |
| 3409 | OSO | Artidoro Leal Cauntes (Aerosorno) | Callsign: Aerosorno, | RCH | AVCODES |
| 3410 | OSO | Aviapartner Limited Company | | RUS | AVCODES |
| 3411 | OSO | Aviapartner Limited Company | | | ICAO1 |
| 3412 | OSO | Ocilla Southern R.R. Co. | 7/1923 | | NAKINA |
| 3413 | OSO | OCILLA SOUTHERN RAILROAD CO. | | | PWRC |
| 3414 | OSOC | ORLAND SOIL CONTRACTORS INC | | | SCAC3 |
| 3415 | OSOC | OSO EXPRESS CORP | | | SCAC4 |
| 3416 | OSOF | ONE SIX ONE FOUR SIX FOUR (161464) | | | SCAC4 |
| 3417 | OSOI | ONE STOP OIL CO INC | | | SCAC3 |
| 3418 | OSOR | OSOW TRANSPORTATION LLC | | | SCAC4 |
| 3419 | OSOT | OLD SOUTH TRANSPORTATION MANAGEMENT | | | SCAC3 |
| 3420 | OSOW | ONE SIX ONE TWO FIVE TWO TWO (16125 | | | SCAC4 |
| 3421 | OSPD | ONE (1) SOURCE DESIGN LTD | | | SCAC4 |
| 3422 | OSPH | OVERSEAS PHILADELPHIA LLC | | | SCAC4 |
| 3423 | OSPL | OUTLOOK SHIPPING LTD | | | SCAC3 |
| 3424 | OSPL | OUTLOOK SHIPPING LTD | | | SCAC4 |
| 3425 | OSPU | OXIGENO SANTA CLARA SAC | | PE | BIC |
| 3426 | OSQC | ONTARIO SHIPPING CORP. | | | SCAC3 |
| 3427 | OSQF | ORIENT STAR CONSOLIDATING & FORWARD | | | SCAC3 |
| 3428 | OSQT | OLD SCHOOL TRUCKING LTD | | | SCAC4 |
| 3429 | OSR | OSR | Belongs to SNCB | F | TRAFFIC |
| 3430 | OSRB | OLSON, ROBERT TRUCKING | | | SCAC3 |
| 3431 | OSRC | ON-STAGE RENTALS INC | | | SCAC4 |
| 3432 | OSRK | OCHSNER TRUCKING | | | SCAC3 |
| 3433 | OSRM | OSTEGO READY MIX INC | | | SCAC3 |
| 3434 | OSRR | The Columbus & Ohio River R.R. Co. | added 10/1992 | | NAKINA |
| 3435 | OSRR | Ohio Southern R.R., Inc. | 1/1994-7/2005 | | NAKINA |
| 3436 | OSRR | Ohio R.R. System | eliminated 10/1992 | | NAKINA |
| 3437 | OSRR | Ohio Southern R.R., Inc. | added 10/1987 | | NAKINA |
| 3438 | OSRR | Ohio Southern R.R., Inc. | added 10/87 | | NRHS |
| 3439 | OSRR | Ohio R.R. System | eliminated 10/92 | | NRHS |
| 3440 | OSRR | The Columbus & Ohio River R.R. Co. | added 10/92 | | NRHS |
| 3441 | OSRR | Ohio Southern R.R., Inc. | 1/94-7/2000 | | NRHS |
| 3442 | OSRR | OHIO SOUTHERN RAILROAD INC. (COLUMBUS & OHIO RIVER RAILROAD CO.) | | | PWRC |
| 3443 | OSRR | Ohio Southern Railroad | | | RSRV |
| 3444 | OSRR | OHIO SOUTHERN RAILROAD CO | | | SCAC3 |
| 3445 | OSRR | OHIO SOUTHERN RAILROAD CO | | | SCAC4 |
| 3446 | OSRS | OVERLAND SHIPPERS & RECEIVERS ASSOC | | | SCAC3 |
| 3447 | OSRT | OSBORNE, RON TRUCKING INC | | | SCAC3 |
| 3448 | OSRU | SIEMENS ENERGY GLOBAL GMBH & CO. KG. | | D | BIC |
| 3449 | OSRX | Ontario Southland Inc. | 7/2005 (not listed) | | NAKINA |
| 3450 | OSRX | Ontario Southland Ry. Inc. | 7/2000 (not listed) | | NAKINA |
| 3451 | OSRX | Oil State Refining Co. | 8/1920-7/1923 | | NAKINA |
| 3452 | OSRX | Ontario Southland Ry. Inc. | Jul-00 | | NRHS |
| 3453 | OSRX | *OIL STATE REFINING CO. | | | PWRC |
| 3454 | OSRX | +ONTARIO SOUTHLAND RAILWAY | | | PWRC |
| 3455 | OSRX | Ontario Southland Railway | | | RSRV |
| 3456 | OSRX | ONTARIO SOUTHLAND INC | | | SCAC4 |
| 3457 | OSS | Servicios Aereos Noticiosos, S.A. de C.V. | Callsign: Noticiosos, | MEX | AVCODES |
| 3458 | OSS | Servicios Aereos Noticiosos | | | ICAO1 |
| 3459 | OSSA | OLYMPIC STEAMSHIP AGENCIES, INC. | | | SCAC3 |
| 3460 | OSSB | ONE SEVEN SIX ZERO SIX ONE SIX | | | SCAC4 |
| 3461 | OSSG | ONE SEVEN SEVEN ZERO SIX NINE SEVEN | | | SCAC4 |
| 3462 | OSSK | ONE SEVEN SIX FIVE FOUR NINE FIVE ( | | | SCAC4 |
| 3463 | OSSL | OCEANSAFETY SHIPPING LTD | | | SCAC3 |
| 3464 | OSSM | ONE SEVEN SEVEN FOUR SIX ZERO ONE ( | | | SCAC4 |
| 3465 | OSSN | ONE SEVEN SIX FOUR TWO TWO TWO (176 | | | SCAC4 |
| 3466 | OSSO | ONE FIVE FOUR FIVE SIX SEVEN SIX (1 | | | SCAC4 |
| 3467 | OSSP | ONE SEVEN SEVEN FOUR FIVE TWO THREE | | | SCAC4 |
| 3468 | OSSQ | ONE SEVEN SEVEN SIX NINE FOUR FOUR | | | SCAC4 |
| 3469 | OSSR | Ministerstvo obrany SR | | SK | VKM |
| 3470 | OSSU | EUROVOS B.V. | | | PWRC |
| 3471 | OSSU | Eurovos B.V. | | | RSRV |
| 3472 | OSSU | DEN HARTOGH INTERMODAL BV | | | SCAC4 |
| 3473 | OSSV | OWENS SECURITY SERVICES INC | | | SCAC3 |
| 3474 | OSSV | ONE SIX SIX ZERO FIVE ONE THREE (16 | | | SCAC4 |
| 3475 | OSSY | OCCUPANT SAFETY SYSTEMS INC | | | SCAC3 |
| 3476 | OST | Alania, Leasing Airline | Callsign: Alania, Name changed to Airline Alania, Public Joint Stock Company | RUS | AVCODES |
| 3477 | OST | Airline Alania, Public Joint Stock Company | Callsign: Alania, Name changed from Alania, Leasing Airline | RUS | AVCODES |
| 3478 | OST | Ostermans Aero AB | Callsign: Osterman, | S | AVCODES |
| 3479 | OST | Oklahoma State University | Callsign: Ostate, | USA | AVCODES |
| 3480 | OST | Airline Alania | | | ICAO1 |
| 3481 | OST | LOK-OST | | DE | VKM |
| 3482 | OSTA | OLD STAR TRANSPORT INC | | | SCAC4 |
| 3483 | OSTB | ORIENTAL SHIPPING & TRADING S A | | | SCAC4 |
| 3484 | OSTC | OCEAN SHIPPING & TRANSPORT | | | SCAC3 |
| 3485 | OSTC | OSTAPEC, DANIEL | | | SCAC4 |
| 3486 | OSTD | OMNI SERVICE TRANSPORTATION LTD | | | SCAC3 |
| 3487 | OSTE | OSTEBOE MOTORWAY | | | SCAC3 |
| 3488 | OSTE | ONE SIX THREE EIGHT ZERO ZERO (1638 | | | SCAC4 |
| 3489 | OSTF | O S T TRUCKING | | | SCAC3 |
| 3490 | OSTF | ONE SEVEN THREE FIVE ZERO FOUR (173 | | | SCAC4 |
| 3491 | OSTG | OSBORN TRUCKING | | | SCAC3 |
| 3492 | OSTG | ONE SIX TWO FIVE FOUR FOUR THREE (1 | | | SCAC4 |
| 3493 | OSTI | ON-SITE TRUCKING CO | | | SCAC3 |
| 3494 | OSTI | ORIENT STAR TRANSPORT INTL LTD | | | SCAC4 |
| 3495 | OSTK | OLIVAS TRUCK | | | SCAC4 |
| 3496 | OSTL | ONE STOP LOGISTICS | | | SCAC4 |
| 3497 | OSTM | O S T TRUCKING CO INC | | | SCAC3 |
| 3498 | OSTN | O & S TRUCKING CO | | | SCAC3 |
| 3499 | OSTN | O & S TRUCKING INC | | | SCAC4 |
| 3500 | OSTO | O S T TRANSPORTATION | | | SCAC3 |
