| 1 | ALS | Air Alsie A/S | Callsign: Mermaid, ICAO designator changed to MMD | DK | AVCODES |
| 2 | ALS | Atlantis European Airways | IATA: TD, Callsign: Atlantis Liner, ICAO Designator changed to LUR. Designator TD reinstated by IATA | AM | AVCODES |
| 3 | ALS | Atlantis Airlines | IATA: 9V, Callsign: Atlantis-Lines, | SN | AVCODES |
| 4 | ALS | Chartair, Inc. | Callsign: Air Los Angeles, | USA | AVCODES |
| 5 | ALS | Aeralp | Callsign: Aeralp, | F | AVCODES |
| 6 | ALS | Alas del Sur C.A. | Callsign: Alasdelsur, Operations never started. | YV | AVCODES |
| 7 | ALS | Alton and Southern Ry. Co. | 1/1975-7/2005 | | NAKINA |
| 8 | ALS | (AL&S) Alton & Southern R.R. | 4/1970 | | NAKINA |
| 9 | ALS | (AL&S) Alton & Southern R.R. | Apr-70 | | NRHS |
| 10 | ALS | Alton and Southern Ry. Co. | 1/75-7/2000 | | NRHS |
| 11 | ALS | Alstom Lokomotiven Service | Stendal | D | privat-bahn.de |
| 12 | ALS | ALTON & SOUTHERN RAILWAY {MISSOURI PACIFIC RAILROAD} (UP) | | | PWRC |
| 13 | ALS | Alton and Southern Railroad (Alton and Southern Railway) | | | RSRV |
| 14 | ALS | (AL&S) Alton & Southern R.R. | | USA | TRAFFIC |
| 15 | ALS | ALSTOM Lokomotiven Service GmbH | | DE | VKM |
| 16 | ALSA | ALL-STAR TRANSPORTATION, INC | | | SCAC3 |
| 17 | ALSA | ALL STAR TRANSPORTATION INC | | | SCAC4 |
| 18 | ALSA | ALSA Rail | | E | TRAFFIC |
| 19 | ALSC | ALL SERVICE TRANSPORT INC | | | SCAC3 |
| 20 | ALSC | ALL SERVICE TRANSPORT | | | SCAC4 |
| 21 | ALSD | A LEASING INC | | | SCAC4 |
| 22 | ALSF | ALS TRUCKING | | | SCAC3 |
| 23 | ALSG | ALS GARAGE | | | SCAC3 |
| 24 | ALSH | ALICE SHIPPING LTD | | | SCAC3 |
| 25 | ALSH | ALLOCEANS SHIPPING COMPANY LIMITED | | | SCAC4 |
| 26 | ALSI | ALL STAR MOVING & STORAGE INC | | | SCAC3 |
| 27 | ALSJ | ALLSOPP, J F | | | SCAC3 |
| 28 | ALSJ | ALS CANADA LTD | | | SCAC4 |
| 29 | ALSK | ASTLES TRUCKING INC | | | SCAC4 |
| 30 | ALSK | ALPINESLOVAKIA, s.r.o. | | SK | VKM |
| 31 | ALSL | ALBERS, LAMONT L | | | SCAC3 |
| 32 | ALSM | ALLSTATES MOVING & STORAGE CO | | | SCAC3 |
| 33 | ALSM | ALSA | | | SCAC4 |
| 34 | ALSN | ALLSTATE CARTAGE INC | | | SCAC3 |
| 35 | ALSN | ALS TRANSPORT INC | | | SCAC4 |
| 36 | ALSO | ALL-STATE TRANSPORT | | | SCAC3 |
| 37 | ALSP | ALLSPEED TRANSPORTATION SERVICE, IN | | | SCAC3 |
| 38 | ALSP | ALPHA SERVICES INC | | | SCAC4 |
| 39 | ALSQ | ALS TOWING SERVICE | | | SCAC3 |
| 40 | ALSR | ALLSTAR MOVING & STORAGE INC | | | SCAC3 |
| 41 | ALSS | ALCOA STEAMSHIP CO INC | | | PWRC |
| 42 | ALSS | ALCOA STEAMSHIP CO., INC. | | | SCAC3 |
| 43 | ALSS | ALCOA STEAMSHIP CO., INC. | | | SCAC4 |
| 44 | ALST | ALLEGHENY LUDLUM STEEL | | | PWRC |
| 45 | ALSTOM | Alstom Lokomotiven Service GmbH | Real: ALS, In 2002 Alstom took over the DBAG Stendal works. ALS leases/hires locomotives to operators, mainly rebuilt DBAG class 202. | D | TRAFFIC |
| 46 | ALSU | AIR LIQUIDE GAS AB | | S | BIC |
| 47 | ALSU | ALFAX AB | | | SCAC3 |
| 48 | ALSU | AIR LIQUIDE GAS AB | | | SCAC4 |
| 49 | ALSV | ALS VAN LINE SERVICES INC | | | SCAC4 |
| 50 | ALSW | ALL TRANS SERVICES INC | | | SCAC4 |
| 51 | ALSX | Albis Canada, Inc. | added 7/1989; eliminated 4/1993; 1/1994 (not listed); added 10/1996; eliminated 4/97; 7/2000-7/2005 (not listed) | | NAKINA |
| 52 | ALSX | Atlantic Live Stock Express, Inc. | 7/1935-7/1937 | | NAKINA |
| 53 | ALSX | Albis Canada, Inc. | added 7/89; eliminated 4/93; 1/94; added 10/96; eliminated 4/97; 7/2000 | | NRHS |
| 54 | ALSX | *ATLANTIC LIVE STOCK EXPRESS, INC. | | | PWRC |
| 55 | ALSX | +ALBIS CANADA, INC. | | | PWRC |
| 56 | ALSX | Albis Canada | | | RSRV |
| 57 | ALSX | ALBIS CANADA, INC. | | | SCAC4 |
| 58 | ALSY | AMERICAN LEASING SYSTEMS LLC | | | SCAC4 |
