| 1 | ARM | Aeromarket Express | Callsign: Amex, | E | AVCODES |
| 2 | ARM | Armadillo Airways Helicopters | Callsign: Heli Shuttle, | USA | AVCODES |
| 3 | ARM | Sky One | Callsign: Sunsky, Name changed to Megaviation Srl | MD | AVCODES |
| 4 | ARM | Megaviation Srl | Callsign: Sunsky, Name changed from Sky One. | MD | AVCODES |
| 5 | ARM | Aeromarket Express | | | ICAO1 |
| 6 | ARM | Armenian Railway CJSC | | AM | VKM |
| 7 | ARMA | ARMETTA TRUCKING INC | | | SCAC4 |
| 8 | ARMC | ARCADIAN MOTOR CARRIERS | | | SCAC3 |
| 9 | ARMC | ARIES MARINE CORP | | | SCAC4 |
| 10 | ARMD | Arnaud Railway | | | RSRV |
| 11 | ARMD | Arnaud Railway | | USA | TRAFFIC |
| 12 | ARME | ARM TRANSPORT | | | SCAC4 |
| 13 | ARMEX | Przedsiębiorstwo Inżynieryjno-Budowlane ARMEX Sp. z o.o | | PL | VKM |
| 14 | ARMF | AIR MATES TRUCKING CO | | | SCAC3 |
| 15 | ARMF | ARMAFER S.r.l. | | IT | VKM |
| 16 | ARMG | ARNOLD MOTOR SERVICE | | | SCAC3 |
| 17 | ARMH | Union Pacific R.R. Co. | added 4/1997; 7/2000-7/2005 | | NAKINA |
| 18 | ARMH | Missouri Pacific System | 1/1994; eliminated 4/1997 | | NAKINA |
| 19 | ARMH | Doniphan, Kensett & Searcy Ry. | added 1/1976; 1/1980 | | NAKINA |
| 20 | ARMH | Texas-New Mexico Ry. Co. | added 7/1975; eliminated 1/1976 | | NAKINA |
| 21 | ARMH | Missouri Pacific R.R. Co. | added 1/1975; 1/1975; eliminated 7/1975 | | NAKINA |
| 22 | ARMH | Missouri Pacific R.R. Co. | added 1/75; 1/75; eliminated 7/75 | | NRHS |
| 23 | ARMH | Texas-New Mexico Ry. Co. | added 7/75 | | NRHS |
| 24 | ARMH | Doniphan, Kensett & Searcy Ry. | Jan-80 | | NRHS |
| 25 | ARMH | Missouri Pacific System | 1/94; eliminated 4/97 | | NRHS |
| 26 | ARMH | Union Pacific R.R. Co. | added 4/97; 7/2000 | | NRHS |
| 27 | ARMH | UP [(DKS) MISSOURI PACIFIC (LEASED THROUGH ART FROM MILLER BREWING)] | | | PWRC |
| 28 | ARMH | Missouri Pacific Railroad (Union Pacific Railroad) | | | RSRV |
| 29 | ARMH | AVAIL RESOURCE MANAGEMENT INC | | | SCAC4 |
| 30 | ARMI | AURORA MOVING & STORAGE | | | SCAC3 |
| 31 | ARMI | ARMSTRONG, B & B TRUCKING LTD | | | SCAC4 |
| 32 | ARMJ | ARAMBEL, JOHN TRUCKING | | | SCAC3 |
| 33 | ARMK | ARMORED TRANSPORT OF CALIFORNIA INC | | | SCAC3 |
| 34 | ARML | ARROW MOVING & STORAGE CO | | | SCAC3 |
| 35 | ARMN | Union Pacific R.R. Co. | 7/2000-7/2005 | | NAKINA |
| 36 | ARMN | Missouri Pacific System | 1/1994; eliminated 4/1997 | | NAKINA |
| 37 | ARMN | Missouri Pacific R.R. Co. | added 11/1973; 1/1975-1/1980 | | NAKINA |
| 38 | ARMN | Missouri Pacific R.R. Co. | added 11/73; 1/75-1/80 | | NRHS |
| 39 | ARMN | Missouri Pacific System | 1/94; eliminated 4/97 | | NRHS |
| 40 | ARMN | Union Pacific R.R. Co. | Jul-00 | | NRHS |
| 41 | ARMN | MISSOURI PACIFIC RAILROAD | | | PWRC |
| 42 | ARMN | UP [MISSOURI PACIFIC RAILROAD] | | | PWRC |
| 43 | ARMN | Missouri Pacific Railroad (Union Pacific Railroad) | | | RSRV |
| 44 | ARMN | ARCEMENT TRUCKING COMPANY | | | SCAC3 |
| 45 | ARMN | ARM TRANSPORTATION INC | | | SCAC4 |
| 46 | ARMN | Arriva Midland North | | GB | TRAFFIC |
| 47 | ARMO | ARMOLD TRANSFER & STORAGE COMPANY I | | | SCAC3 |
| 48 | ARMO | ARMENTA SOTO, BERNARDINO | | | SCAC4 |
| 49 | ARMP | ARMSTRONG, MERVYN E | | | SCAC3 |
| 50 | ARMQ | ARMORED MOTORS SERVICE | | | SCAC3 |
| 51 | ARMQ | ARCHITECTURAL METALCRAFT INDUSTRIES | | | SCAC4 |
| 52 | ARMR | ARMORED MOTOR SERVICE CORPORATION | | | SCAC3 |
| 53 | ARMR | ARMBRUSTER MOVING & STORAGE INC | | | SCAC4 |
| 54 | ARMR | Atlas Rhein main GmbH | | DE | VKM |
| 55 | ARMS | ARMSTRONG RELOCATION | | | SCAC4 |
| 56 | ARMT | ARMSTRONG TRANSFER AND STORAGE COMP | | | SCAC3 |
| 57 | ARMT | ARMSTRONG RELOCATION CO | | | SCAC4 |
| 58 | ARMU | ADAPTAINER LTD | | GB | BIC |
| 59 | ARMU | A.R.M.E.C. LTD | | | SCAC3 |
| 60 | ARMU | ADAPTAINER B V | | | SCAC4 |
| 61 | ARMV | AIR-RIDE MOVING & STORAGE INC | | | SCAC3 |
| 62 | ARMW | ARMASOL LINE | | | SCAC3 |
| 63 | ARMW | ARIADMAR LIMITED | | | SCAC4 |
| 64 | ARMX | American Rail & Marine Corp. | added 4/1984; eliminated 4/1987; 1/1994-7/2005 (not listed) | | NAKINA |
| 65 | ARMX | Armco Steel Corp. | 1/1952 (not listed); 7/1954-10/1957; eliminated 1/1959 | | NAKINA |
| 66 | ARMX | Armco Steel Corp. | 1/52-10/57; eliminated 1/59 | | NRHS |
| 67 | ARMX | American Rail & Marine Corp. | added 4/84; eliminated 4/87; 1/94-7/2000 | | NRHS |
| 68 | ARMX | *ARMCO STEEL CORP. (ELIMINATED 1/1959) | | | PWRC |
| 69 | ARMX | +AMERICAN RAIL & MARINE CORPORATION | | | PWRC |
| 70 | ARMX | American Rail and Marine Corporation | | | RSRV |
| 71 | ARMX | AMERICAN RAIL & MARINE CORPORATION | | | SCAC4 |
| 72 | ARMZ | ARMASAL LINE - AMERICAN RAIL & MARINE CORP. (ARMCO INDUSTRIES) | | | PWRC |
| 73 | ARMZ | Armasal Line | | | RSRV |
| 74 | ARMZ | ARMASAL LINE | | | SCAC4 |
