| 1 | ATM | Airlines of Tasmania Pty Ltd. | IATA: FO, Callsign: Airtas, Designator IP recalled by IATA | AUS | AVCODES |
| 2 | ATM | Airlines of Tasmania Pty Ltd. | IATA: IP, Callsign: Airtas, Designator IP recalled by IATA. ICAO designator changed from XAL | AUS | AVCODES |
| 3 | ATM | Airlines Of Tasmania | IATA: FO | | ICAO1 |
| 4 | ATM | Azienda Trasporti Milanesi | City: Milano | I | TRAFFIC |
| 5 | ATMA | ATLAS MARINE SERVICES INC | | | SCAC3 |
| 6 | ATMA | AUTO TRANSPORTE AMAYA | | | SCAC4 |
| 7 | ATMB | | City: Bologna | I | TRAFFIC |
| 8 | ATMC | ATOMIC CARTAGE INC | | | SCAC3 |
| 9 | ATMC | A TIMELEIGH MOTORCAR | | | SCAC4 |
| 10 | ATMD | ACTION TRANSFER INC | | | SCAC3 |
| 11 | ATME | ATLANTIC MARITIME LINES | | | SCAC3 |
| 12 | ATME | ATHENA MARINE LTD | | | SCAC4 |
| 13 | ATME | Azienda Transporti di Messina | Real: ATM | I | TRAFFIC |
| 14 | ATMG | ALLSTATES MOVING INC | | | SCAC4 |
| 15 | ATMH | ATLANTIC DISTRIBUTION SERVICES INC | | | SCAC4 |
| 16 | ATMI | ATLAS MARINE | | | SCAC3 |
| 17 | ATMI | ATLAS MARINE INC | | | SCAC4 |
| 18 | ATMJ | A T MONITORS | | | SCAC4 |
| 19 | ATML | ATLANTA MOTOR LINES INC | | | SCAC3 |
| 20 | ATML | AUTO TRANSPORTES MELGOZA | | | SCAC4 |
| 21 | ATMM | AIR TRAFFIC MANAGEMENT INC | | | SCAC4 |
| 22 | ATMN | ALTMAN TRUCKING | | | SCAC3 |
| 23 | ATMN | ALL TIME TRANSPORT CORP | | | SCAC4 |
| 24 | ATMO | ATCHISON MOVING & STORAGE | | | SCAC3 |
| 25 | ATMO | ATMS MOVING SYSTEMS | | | SCAC4 |
| 26 | ATMP | ATLANTIC MOVERS | | | SCAC3 |
| 27 | ATMQ | A T M C INC | | | SCAC3 |
| 28 | ATMR | ATLAS MOTOR EXPRESS, INC | | | SCAC3 |
| 29 | ATMR | ATLAS MOTOR EXPRESS INC | | | SCAC4 |
| 30 | ATMS | ATLAS MOVING & STORAGE CO, INC | | | SCAC3 |
| 31 | ATMS | AUTOMSSA | | | SCAC4 |
| 32 | ATMT | ATLAS MOTOR EXPRESS, INCORPORATED | | | SCAC3 |
| 33 | ATMT | | City: Torino | I | TRAFFIC |
| 34 | ATMU | ATOM ULUSLARARASI NAKLİYAT VE LOJİSTİK HİZMETLERİ A.Ş. | | TR | BIC |
| 35 | ATMU | MTC ALFA-TRANS CO LTD | | | SCAC4 |
| 36 | ATMW | AMERICAN TRAILS TRANSPORTATION CO | | | SCAC3 |
| 37 | ATMX | U.S. Dept. of Energy, Albuquerque Operations Office | added 1/1978; 1/1980-1/1994; eliminated 10/1997; 7/2000-7/2005 (not listed) | | NAKINA |
| 38 | ATMX | U.S. Atomic Energy Commission, Albequerque Operations Office | 1/1975; eliminated 4/1975 | | NAKINA |
| 39 | ATMX | United States Energy Research and Development Administration, Albequerque Operations Office | added 4/1975; eliminated 1/1978 | | NAKINA |
| 40 | ATMX | U.S. Atomic Energy Commission, Albequerque Operations Office | 4/1970 | | NAKINA |
| 41 | ATMX | U.S. Atomic Energy Commission, Paducah, Kentucky | eliminated 4/1973 | | NAKINA |
| 42 | ATMX | U.S. Atomic Energy Commission | 4/1961; added 7/1961; added 1/1965; 7/1965; eliminated 7/1965; 10/1966; eliminated 1/1968 | | NAKINA |
| 43 | ATMX | U.S. Atomic Energy Commission | 1/1950-10/1957 | | NAKINA |
| 44 | ATMX | U.S. Atomic Energy Commission, care of Union Carbide Nuclear Co., Division of Union Carbide Corp. | added 4/1959 | | NAKINA |
| 45 | ATMX | U.S. Atomic Energy Commission | 1/52-4/61; added 1/65; 7/65; eliminated 7/65; 10/66; eliminated 1/68 | | NRHS |
| 46 | ATMX | U.S. Atomic Energy Commission, Albequerque Operations Office | Apr-70 | | NRHS |
| 47 | ATMX | U.S. Atomic Energy Commission, Paducah, Kentucky | eliminated 4/73 | | NRHS |
| 48 | ATMX | U.S. Atomic Energy Commission, Albequerque Operations Office | 1/75; eliminated 4/75 | | NRHS |
| 49 | ATMX | United States Energy Research and Development Administration, Albequerque Operations Office | added 4/75; eliminated 1/78 | | NRHS |
| 50 | ATMX | U.S. Dept. of Energy, Albuquerque Operations Office | added 1/78; 1/80-1/94; eliminated 10/97; 7/2000 | | NRHS |
| 51 | ATMX | *PENNSYLVANIA RAILWAY MUSEUM ASSOC. [ARDEN TROLLEY MUSEUM] | | | PWRC |
| 52 | ATMX | *U.S. ENERGY RESEARCH & DEVELOPMENT ADM. - ALBUQUERQUE OPERATIONS | | | PWRC |
| 53 | ATMX | United States Department of Energy Albuquerque Operations (Arcelor Mittal Montreal) | | | RSRV |
| 54 | ATMX | UNITED STATES ATOMIC ENERGY COMMISS | | | SCAC3 |
| 55 | ATMY | ATLAS MARINE COMPANY | | | SCAC3 |
| 56 | ATMZ | ATLLAS TIE MILL | | | PWRC |