| 1 | RTT | Titan Aero Airlines, Closed Joint-Stock Company | Callsign: Rustitan, | RUS | AVCODES |
| 2 | RTT | RIVER TRAILS TRANSIT LINES INC | | | SCAC4 |
| 3 | RTT | RAILTRANSPORT s.r.o. | | CZ | VKM |
| 4 | RTTA | R T TRANSPORTATION INCORPORATED | | | SCAC3 |
| 5 | RTTC | REFINERS TRANSPORT & TERMINAL CORPO | | | SCAC3 |
| 6 | RTTD | R T TRANSPORT INC | | | SCAC3 |
| 7 | RTTE | RT&T ENTERPRISES INC | | | SCAC4 |
| 8 | RTTF | R & T TRANSPORT | | | SCAC3 |
| 9 | RTTH | RITTER TRUCKING | | | SCAC3 |
| 10 | RTTI | ROTTIER TRUCKING INC | | | SCAC3 |
| 11 | RTTJ | RTTJ TRANSPORTATION INC | | | SCAC3 |
| 12 | RTTK | R T TRUCKING INC | | | SCAC4 |
| 13 | RTTL | REUTER, TODD TRUCKING LLC | | | SCAC4 |
| 14 | RTTM | RYAN, TIM TRUCKING LLC | | | SCAC4 |
| 15 | RTTN | R T TRANSPORTATION | | | SCAC4 |
| 16 | RTTP | RITTER TRANSPORTATION | | | SCAC3 |
| 17 | RTTP | Rīgas Tramvaju un Trolejbusu Pārvalde | City: Riga | LV | TRAFFIC |
| 18 | RTTR | RTR TRANSPORTATION SERVICES | | | SCAC4 |
| 19 | RTTS | R T T S INC | | | SCAC4 |
| 20 | RTTT | RITTER TRUCKING | | | SCAC3 |
| 21 | RTTU | RASA TECHNOLOGY TAIWAN LTD | | RC | BIC |
| 22 | RTTU | RASA TECHNOLOGY TAIWAN LTD | | | SCAC4 |
| 23 | RTTV | ROYS TOW & TRANSPORT SERV | | | SCAC3 |
| 24 | RTTX | TTX Co. | added 1/1992; 1/1994-7/2005 | | NAKINA |
| 25 | RTTX | Trailer Train Co. | added 1/1961; 4/1961-1/1980; eliminated 7/1984; added 7/1986; eliminated 1/1992 | | NAKINA |
| 26 | RTTX | Rapid Transit Tank Car Line | 7/1923 | | NAKINA |
| 27 | RTTX | Trailer Train Co. (not defined) | added 1/1961; 4/1961 | | NAKINA |
| 28 | RTTX | Trailer Train Co. (FCS flat cars equipped with tri-level automobile carrying superstructures furnished by member railroads. Cars are not equipped with hitches and bridge plates) | 4/1963 | | NAKINA |
| 29 | RTTX | Trailer Train Co. (FA flat cars equipped with tri-level automobile carrying superstructures furnished by member railroads. Cars are not equipped with hitches and bridge plates) | 7/1965-10/1968 | | NAKINA |
| 30 | RTTX | Trailer Train Co. (flat cars, equipped with fixed tri-level auto racks furnished by participant railroads) | 4/1970-1/1980 | | NAKINA |
| 31 | RTTX | Trailer Train Co. | eliminated 7/1984 | | NAKINA |
| 32 | RTTX | Trailer Train Co. (standard deck, 3-hitch flat cars with non-collapsible hitches at the ends of the car and a collapsible hitch at the centre of the car, capable of carrying 3-28' trailers with kingpin spacing of 36"" or less, or any two trailers with 36"" kingpin spacing, whose overall combined length does not exceed 90' (i.e. 2-45', 1-42' & 1-48', 1-40' & 1-48', etc.), between lift-on/lift-off facilities only) | 7/1985 | | NAKINA |
| 33 | RTTX | Trailer Train Co./TTX Co. (89' and 360' TOFC cars. 89' cars (6 digit car numbers other than 165000 series) are standard deck, 3-hitch flatcars with non-collapsable hitches at the ends of the car and a collapsable hitch at the centre of the car, capable of carrying 3-28' trailers with kingpin spacing of 36"" or less, or any two trailers with 36"" kingpin spacing, whose overall combined length does not exceed 90' — i.e., 2-45', 1-42' & 1-48', 1-40' & 1-48', etc. — between lift-on/lift-off facilities only. 360 | added 7/1986; 10/1991-1/1992 | | NAKINA |
| 34 | RTTX | TTX Co. (89' and 178' TOFC Flat cars. 89' cars (6 digit car numbers other than 165000 series) are standard deck, 3-hitch flatcars with non-collapsable hitches at the ends of the car and a collapsable hitch at the centre of the car, capable of carrying 3-28' trailers with kingpin spacing of 36"" or less, or any two trailers with 36"" kingpin spacing, whose overall combined length does not exceed 90' — i.e., 2-45', 1-42' & 1-48', 1-40' & 1-48', etc. — between lift-on/lift-off facilities only. 178' cars (6 dig | 1/1994-7/2000 | | NAKINA |
| 35 | RTTX | Trailer Train Co. | 4/61-7/65 | | NRHS |
| 36 | RTTX | Trailer Train Co. (FA flat cars equipped with tri-level automobile carrying superstructures furnished by member railroads. Cars are not equipped with hitches and bridge plates) | 10/66-10/68 | | NRHS |
| 37 | RTTX | Trailer Train Co. | Apr-70 | | NRHS |
| 38 | RTTX | Trailer Train Co. (flat cars, equipped with fixed tri-level auto racks furnished by participant railroads) | 1/75-1/80 | | NRHS |
| 39 | RTTX | Trailer Train Co. | eliminated 7/84 | | NRHS |
| 40 | RTTX | Trailer Train Co. | added 7/86; eliminated 1/92 | | NRHS |
| 41 | RTTX | TTX Co. | added 1/92 | | NRHS |
| 42 | RTTX | TTX Co. (89' and 178' TOFC Flat cars. 89' cars (6 digit car numbers other than 165000 series) are standard deck, 3-hitch flatcars with non-collapsable hitches at the ends of the car and a collapsable hitch at the centre of the car, capable of carrying 3 28' trailers with kingpin spacing of 36" or less, or any two trailers with 36" kingpin spacing, whose overall combined length does not exceed 90' -- i.e., 2-45', 1-42' & 1-48', 1-40' & 1-48', etc. -- between lift on/lift off facilities only. 178' cars (6 dig | 1/94-7/2000 | | NRHS |
| 43 | RTTX | *RAPID TRANSIT TANK CAR LINE | | | PWRC |
| 44 | RTTX | +TTX COMPANY | | | PWRC |
| 45 | RTTX | TTX Corporation | | | RSRV |
| 46 | RTTX | TTX COMPANY | | | SCAC4 |
| 47 | RTTY | ROCKY TOP TRUCKING | | | SCAC4 |
| 48 | RTTZ | UP [(REAZ) RETIRED 04-06-93 ATP (ACI 2384)] | | | PWRC |
| 49 | RTTZ | Union Pacific Railroad | | | RSRV |
