| 1 | OTT | OTT Airlines Co., Ltd. | IATA: JF, Callsign: OTT Airlines, Subsidiary of China Eastern Airlines. Planned to operate Comac C919 and ARJ21. | PRC | AVCODES |
| 2 | OTT | Ottumwa Terminal R.R. Co. | added 1/1988; eliminated 7/1990; 1/1994-7/2005 | | NAKINA |
| 3 | OTT | Ottumwa Terminal R.R. Co. | added 1/88; eliminated 7/90; 1/94-7/2000 | | NRHS |
| 4 | OTT | OTTUMWA TERMINAL RAILROAD COMPANY | | | PWRC |
| 5 | OTT | Ottumwa Terminal Railroad | | | RSRV |
| 6 | OTT | OTTUMWA TERMINAL RAILROAD CO | | | SCAC4 |
| 7 | OTT1 | TEST CARRIER | | | SCAC3 |
| 8 | OTTA | OTT TRUCKING INC | | | SCAC4 |
| 9 | OTTC | OCEAN TRAILER TRANSPORT | | | PWRC |
| 10 | OTTC | OTTO CANDIES LLC | | | SCAC4 |
| 11 | OTTD | OTTO, J W DRAYAGE | | | SCAC3 |
| 12 | OTTD | ONE TWO THREE (123) DELIVERY INC | | | SCAC4 |
| 13 | OTTE | OTTE, CLYDE W | | | SCAC3 |
| 14 | OTTF | ON TIME TRUCKING INC | | | SCAC4 |
| 15 | OTTG | OTT TRUCKING | | | SCAC3 |
| 16 | OTTH | ONE THREE THREE TWO SIX EIGHT EIGHT | | | SCAC4 |
| 17 | OTTI | O T P TRANSPORT INC | | | SCAC4 |
| 18 | OTTJ | OTT, JIM TRUCKING INC | | | SCAC3 |
| 19 | OTTK | OTT, TED TRUCKING | | | SCAC3 |
| 20 | OTTK | ORTEGA TRUCKING | | | SCAC4 |
| 21 | OTTL | OTTEN TRUCK LINE | | | SCAC3 |
| 22 | OTTM | ON TIME TRUCKERS INC | | | SCAC4 |
| 23 | OTTN | ONE TWO THREE (123) TRANSPORT INC | | | SCAC4 |
| 24 | OTTO | OTTO | | | SCAC3 |
| 25 | OTTO | ONE THREE THREE FOUR ONE NINE FOUR | | | SCAC4 |
| 26 | OTTO | Technischer Handel Otto Rentschler | | DE | VKM |
| 27 | OTTP | OTT PLASTICS EXPRESS INC | | | SCAC3 |
| 28 | OTTQ | OTT, LAVERNE E INC | | | SCAC3 |
| 29 | OTTQ | OTTO TRANSPORTATION LLC | | | SCAC4 |
| 30 | OTTR | OTT, ROLAND | | | SCAC3 |
| 31 | OTTS | O T T TRANSPORTATION SERVICE | | | SCAC3 |
| 32 | OTTS | ONE THREE THREE SEVEN ZERO THREE (1 | | | SCAC4 |
| 33 | OTTT | OTTAWA TRAVEL CENTENNIAL TOWERS | | | SCAC3 |
| 34 | OTTU | OTTEVANGER MILLING ENGINEERS | | NL | BIC |
| 35 | OTTW | OTTAWAY MOTOR EXPRESS | | | SCAC3 |
| 36 | OTTW | OTTAWAY MOTOR EXPRESS LTD | | | SCAC4 |
| 37 | OTTX | TTX Co. | added 1/1992; 1/1994-7/2005 | | NAKINA |
| 38 | OTTX | Trailer Train Co. | 7/1965 (not listed); added 10/1965; 10/1968-1/1980; eliminated 1/1992 | | NAKINA |
| 39 | OTTX | Trailer Train Co. | 7/1965; added 10/1965; 10/1966 | | NAKINA |
| 40 | OTTX | Trailer Train Co. (FMS flats specially equipped to provide for loading of agricultural equipment) | 10/1968 | | NAKINA |
| 41 | OTTX | Trailer Train Co. (flat cars equipped with 64 chains, with snubbers, each secured to movable and retractable tie-down winches in 4 longitudinal channels, for transporting agricultural equipment) | 4/1970-1/1980 | | NAKINA |
| 42 | OTTX | Trailer Train Co./TTX Co. (flat cars equipped with 48 chains, with snubbers, each secured to movable and retractable tie-down winches in 4 longitudinal channels; for transporting agricultural equipment) | 7/1985-1/1994 | | NAKINA |
| 43 | OTTX | TTX Co. (flat cars equipped with 48 chains, with snubbers, each secured to movable and retractable tie-down winches in 4 longitudinal channels; for transporting agricultural equipment, equipped with end of car cush.) | 7/2000 | | NAKINA |
| 44 | OTTX | Trailer Train Co. | 7/65; added 10/65; 10/66 | | NRHS |
| 45 | OTTX | Trailer Train Co. (FMS flats specially equipped to provide for loading of agricultural equipment) | Oct-68 | | NRHS |
| 46 | OTTX | Trailer Train Co. | Apr-70 | | NRHS |
| 47 | OTTX | Trailer Train Co. (flat cars equipped with 64 chains, with snubbers, each secured to movable and retractable tie-down winches in four longitudinal channels, for transporting agricultural equipment) | 1/75-1/80 | | NRHS |
| 48 | OTTX | Trailer Train Co. | eliminated 1/92 | | NRHS |
| 49 | OTTX | TTX Co. | added 1/92 | | NRHS |
| 50 | OTTX | TTX Co. (flat cars equipped with 48 chains, with snubbers, each secured to movable and retractable tie-down winches in 4 longitudinal channels; for transporting agricultural equipment) | Jan-94 | | NRHS |
| 51 | OTTX | TTX Co. (flat cars equipped with 48 chains, with snubbers, each secured to movable and retractable tie-down winches in 4 longitudinal channels; for transporting agricultural equipment, equipped with end of car cush.) | Jul-00 | | NRHS |
| 52 | OTTX | TTX COMPANY | | | PWRC |
| 53 | OTTX | Trailer Train (TTX Corporation) | | | RSRV |
| 54 | OTTX | TTX COMPANY | | | SCAC4 |
