| 1 | MCS | Macedonian Airlines | Callsign: Macair, Founded in 1998. Ceased operations in 2003. | GR | AVCODES |
| 2 | MCS | MCS AeroCarga de Mexico, S.A. de C.V. | IATA: T8, Callsign: Carmex, IATA Prefix: 137, Name changed to TUM AeroCarga de Mexico, S.A. de C.V. w.e.f. 01 August 2018. | MEX | AVCODES |
| 3 | MCS | TUM AeroCarga de Mexico, S.A. de C.V. | IATA: T8, Callsign: Carmex, IATA Prefix: 137, IATA designator changed to T2*. Name changed from MCS AeroCarga de Mexico, S.A. de C.V. w.e.f. 01 August 2018. | MEX | AVCODES |
| 4 | MCS | TUM AeroCarga de Mexico, S.A. de C.V. | IATA: T2, Callsign: Carmex, IATA Prefix: 137, IATA designator changed from T8. Name changed from MCS AeroCarga de Mexico, S.A. de C.V. w.e.f. 01 August 2018. | MEX | AVCODES |
| 5 | MCS | Macedonian Airlines | | | ICAO1 |
| 6 | MCS | MYERS COACH LINES INC | | | SCAC4 |
| 7 | MCSA | Moscow, Camden & San Augustine R.R. | 1/1975; added 7/1979; 1/1980; 1/1994; eliminated 1/2000; 7/2000-7/2005; added 10/2005; eliminated 7/2007 | | NAKINA |
| 8 | MCSA | Moscow, Camden & San Augustine R.R. | 1/75; added 7/79; 1/80; 1/94; eliminated 1/2000; 7/2000 | | NRHS |
| 9 | MCSA | MOSCOW, CAMDEN & SAN AUGUSTINE RAILROAD | | | PWRC |
| 10 | MCSA | Moscow, Camden and San Augustine Railroad | | | RSRV |
| 11 | MCSA | Moscow, Camden and San Augustine Railroad | | USA | TRAFFIC |
| 12 | MCSE | MACS OYSTERS LTD | | | SCAC4 |
| 13 | MCSG | MARK CROUSE TRUCKING INC | | | SCAC4 |
| 14 | MCSH | MCSHEE | | | SCAC4 |
| 15 | MCSI | MACSI LINES | | | SCAC1 |
| 16 | MCSI | MCSHANE MOVING & STORAGE INC | | | SCAC4 |
| 17 | MCSJ | MARINE CONTAINER SERVICES INC | | | SCAC4 |
| 18 | MCSM | MACS MARITIME CARRIER SHIPPING GMBH | | | SCAC4 |
| 19 | MCSN | MONTAGUE COLD STORAGE INC | | | SCAC4 |
| 20 | MCSO | MACTAVISH & SONS TRANSPORT INC | | | SCAC4 |
| 21 | MCSP | MAC SPORTS LTD | | | SCAC4 |
| 22 | MCSR | MITSUBISHI CORPORATION LT INC | | | SCAC4 |
| 23 | MCSS | MCS CARGO SYSTEMS, INC | | | SCAC1 |
| 24 | MCST | MACGREGOR CRANE SERVICE LIMITED | | | SCAC4 |
| 25 | MCSU | CHINA OCEAN SHIPPING COMPANY | | | PWRC |
| 26 | MCSU | China Ocean Shipping | | | RSRV |
| 27 | MCSU | MAERSK CONTAINER SERVICES BENELUX ( | | | SCAC4 |
| 28 | MCSV | MASTER CRAFT SERVICES INC | | | SCAC4 |
| 29 | MCSX | Mells Cargo Supply, Inc. | 1/1994 (not listed) | | NAKINA |
| 30 | MCSX | Malvern Cold Storage Co. (American Refrigerator Transit Co.) | 7/1935 | | NAKINA |
| 31 | MCSX | Mells Cargo Supply, Inc. | Jan-94 | | NRHS |
| 32 | MCSX | MELLS CARGO SUPPLY, INC. | | | PWRC |
| 33 | MCSZ | MEDITERRANEA | | | SCAC4 |
