| 1901 | RCUG | RC TRUCKING | | | SCAC4 |
| 1902 | RCUR | ROLTIME COURIER SERVICES INC | | | SCAC3 |
| 1903 | RCUS | R.L. SOLUTIONS, LLC | | | SCAC4 |
| 1904 | RCV | Aerocanarias de Venezuela, S.A. | Callsign: Aerocanarias, | YV | AVCODES |
| 1905 | RCV | Airclub Aviator, LLC | Callsign: Strimer, | RUS | AVCODES |
| 1906 | RCVC | ROLANDO CONTAINER SERVICES INC | | | SCAC4 |
| 1907 | RCVG | RELIANCE MOVING & STORAGE | | | SCAC3 |
| 1908 | RCVG | RELIANCE MOVING & STORAGE | | | SCAC4 |
| 1909 | RCVL | RED CLAY VALLEY RWY EQUIP & LEASING CO. | | | PWRC |
| 1910 | RCVL | RECOVERY LOGISTICS INC | | | SCAC4 |
| 1911 | RCVN | ROSE CITY VAN & STORAGE | | | SCAC3 |
| 1912 | RCVS | RIVER CITY VAN & STORAGE | | | SCAC3 |
| 1913 | RCW | Rail Cargo Wagon - Austria GmbH | | AT | VKM |
| 1914 | RCWH | ROSE CITY WHOLESALE (1987) INC | | | SCAC3 |
| 1915 | RCWO | ROCKWOOD INDUSTRIES INC | | | SCAC4 |
| 1916 | RCWT | RIVER CITY TRANSPORTATION CORP | | | SCAC3 |
| 1917 | RCWT | RANCHERS WELDING LTD | | | SCAC4 |
| 1918 | RCWX | Royster Co. | added 10/1968; 4/1970-1/1975; eliminated 10/1976 | | NAKINA |
| 1919 | RCWX | F.S. Royster Guano Co. | added 10/1959; 4/1961-10/1966; eliminated 10/1968 | | NAKINA |
| 1920 | RCWX | F.S. Royster Guano Co. | 4/1938-10/1957 | | NAKINA |
| 1921 | RCWX | Royster Chemical Works | eliminated 10/1959 | | NAKINA |
| 1922 | RCWX | Royster Chemical Works | Apr-38 | | NRHS |
| 1923 | RCWX | F.S. Royster Guano Co. | 1/52-10/57 | | NRHS |
| 1924 | RCWX | Royster Chemical Works | eliminated 10/59 | | NRHS |
| 1925 | RCWX | F.S. Royster Guano Co. | added 10/59; 4/61-10/66; eliminated 10/68 | | NRHS |
| 1926 | RCWX | Royster Co. | added 10/68; 4/70-1/75 | | NRHS |
| 1927 | RCWX | ROYSTER CO. [ROYSTER CHEMICAL WORKS; F. S. ROYSTER GUANO CO.] | | | PWRC |
| 1928 | RCWX | ROYSTER GUANO CO, F S | | | SCAC3 |
| 1929 | RCWZ | UP [(REAZ) CHICAGO & NORTH WESTERN TRANS CO] | | | PWRC |
| 1930 | RCWZ | Union Pacific Railroad | | | RSRV |
| 1931 | RCWZ | UNION PACIFIC RAILROAD COMPANY | | | SCAC4 |
| 1932 | RCX | Air Service Center Srl | Callsign: Service Center, | I | AVCODES |
| 1933 | RCX | Republic Express Airlines | Callsign: Flag Ship, | USA | AVCODES |
| 1934 | RCX | Air Service Center | | | ICAO1 |
| 1935 | RCX | Republic Creosoting Co. | 7/1923-7/1937 | | NAKINA |
| 1936 | RCX | REPUBLIC CREOSOTING CO. | | | PWRC |
| 1937 | RCXD | RC TRANSPORT | | | SCAC4 |
| 1938 | RCXE | R C EXPRESS | | | SCAC4 |
| 1939 | RCXF | ROYAL CREST TRANSPORT LLC | | | SCAC4 |
| 1940 | RCXI | RIDGE CARRIERS INC | | | SCAC3 |
| 1941 | RCXI | RACKS EXPRESS INC | | | SCAC4 |
| 1942 | RCXL | RCA TRANSPORT LLC | | | SCAC4 |
| 1943 | RCXP | RICAL EXPRESS INC | | | SCAC3 |
| 1944 | RCXP | ROCKET XPRESS LLC | | | SCAC4 |
| 1945 | RCXQ | ROSE CITY EXPRESS INC | | | SCAC3 |
| 1946 | RCXT | R C TRANSPORTES | | | SCAC4 |
| 1947 | RCXU | R.C.C CONTAINERS BV | | NL | BIC |
| 1948 | RCXW | R & C TRANSPORT INC | | | SCAC4 |
| 1949 | RCY | Package Express, Inc. | Callsign: Race City, | USA | AVCODES |
| 1950 | RCY | Package Express | | | ICAO1 |
| 1951 | RCYA | RECYCLE AMERICA OF NORTH CALIFORNIA | | | SCAC4 |
| 1952 | RCYAF | Royal Ceylon Air Force | | CL | TRAFFIC |
| 1953 | RCYC | RECYCLERS TRANSPORT | | | SCAC3 |
| 1954 | RCYG | RIVER CITY TRUCKING COMPANY | | | SCAC4 |
| 1955 | RCYI | RIVER CITY TRUCKING INC | | | SCAC4 |
| 1956 | RCYK | ROCKY MOUNTAIN LOGISTICS INC | | | SCAC4 |
| 1957 | RCYL | RECYCLE MINNESOTA RESOURCES | | | SCAC3 |
| 1958 | RCYL | RECYCLING MIAMI INC | | | SCAC4 |
| 1959 | RCYP | RIVER CITY TRANSPORT INC | | | SCAC3 |
| 1960 | RCYR | RIVER CITY TRANSPORT LLC | | | SCAC4 |
| 1961 | RCYS | RIVER CITY LOGISTICS INC | | | SCAC4 |
| 1962 | RCYT | RIVERCITY TRUCKING CO INC | | | SCAC3 |
| 1963 | RCYT | RCY TRUCKING | | | SCAC4 |
| 1964 | RCZ | RICHARDSON COMPANY | | | PWRC |
| 1965 | RCZR | ROSAS CHAVEZ, ROBERTO | | | SCAC4 |
| 1966 | RD | Alitalia Team | ICAO: NOV, Callsign: Alitalia Team, Merged into Alitalia w.e.f. 01 August 2002. | I | AVCODES |
| 1967 | RD | Alderney Air Ferries Ltd. / Metropolitan Airlines Ltd. | | GB | AVCODES |
| 1968 | RD | Avianova | ICAO: NOV, Callsign: Avianova, Merged into Alitalia Express during 1996. | I | AVCODES |
| 1969 | RD | Airlift International, Inc. | ICAO: AIR, Callsign: Airlift, Designator RD recalled by IATA | USA | AVCODES |
| 1970 | RD | Ryan International Airlines | ICAO: RYN, Callsign: Ryan International, Founded in 1972. Filed for Chapter 11 Bankrupcy protection on 06 March 2012. Ceased operations on 11 January 2013. IATA Designator changed from 1I | USA | AVCODES |
| 1971 | RD | Small Planet Airlines Co., Ltd. | ICAO: LKH, Callsign: Skyplanet, Founded in October 2017. Ceased operations on 09 November 2018. | K | AVCODES |
| 1972 | RD | Easycharter LLC | ICAO: LOL, Callsign: Easy Charter, IATA Prefix: 311, | GE | AVCODES |
| 1973 | RD | LogicPaq Btd, s.r.l. d/b/a Sky Cana | ICAO: SNA, Callsign: Cana, IATA Prefix: 440, | DOM | AVCODES |
| 1974 | RDA | T K Travel Limited | Callsign: Reward, | WAG | AVCODES |
| 1975 | RDA | Redair Gambia Limited | Callsign: Redair Gambia, | WAG | AVCODES |
| 1976 | RDA | Reid Airways, Inc. | Callsign: Reid-Air, | USA | AVCODES |
| 1977 | RDA | Rada Airlines LLC | Callsign: Rada, | BY | AVCODES |
| 1978 | RDA | Royal Danish Army | | DK | TRAFFIC |
| 1979 | RDAA | R & D DISTRIBUTING LTD | | | SCAC4 |
| 1980 | RDAB | RANDALL BOAT MOVING | | | SCAC3 |
| 1981 | RDAB | R D T EXPRESS INC | | | SCAC4 |
| 1982 | RDAD | RED ARROW DELIVERY SERVICE CO INC | | | SCAC3 |
| 1983 | RDAD | RED ARROW DELIVERY SERVICE CO INC | | | SCAC4 |
| 1984 | RDAF | ROADAIR FEEDER SERVICE LTD | | | SCAC3 |
| 1985 | RDAF | Royal Dutch Air Force | | DK | TRAFFIC |
| 1986 | RDAG | RIDEAU RECOGNITION SOLUTIONS INC | | | SCAC4 |
| 1987 | RDAH | RADABAUGH TRUCKING INC | | | SCAC4 |
| 1988 | RDAK | REED, DENNIS A | | | SCAC4 |
| 1989 | RDAL | RANDAL TEXTRON | | | SCAC3 |
| 1990 | RDAM | ROAD AMERICA | | | SCAC3 |
| 1991 | RDAM | ROAD MACHINERY CO | | | SCAC4 |
| 1992 | RDAO | R & D AUTO TRANSPORT | | | SCAC4 |
| 1993 | RDAP | REIDPATH, DALE | | | SCAC4 |
| 1994 | RDAR | RAND-AIR DIST INC | | | SCAC3 |
| 1995 | RDAT | REDLANDS TRANSPORT INC | | | SCAC4 |
| 1996 | RDAV | RED DRAGON TRANSPORTATION INC | | | SCAC4 |
| 1997 | RDAY | RYANDAY PRODUCTS INC | | | SCAC4 |
| 1998 | RDB | Ordabasy | Callsign: Orda, | KZ | AVCODES |
| 1999 | RDBB | R D B TRUCKING | | | SCAC3 |
| 2000 | RDBB | R & D SERVICES INC | | | SCAC4 |
