| 4401 | MJN | Royal Air Force of Oman | IATA: RS | | ICAO1 |
| 4402 | MJNB | MARATHON J&B | | | SCAC1 |
| 4403 | MJNK | MJN TRUCK LINES LTD | | | SCAC4 |
| 4404 | MJNS | MJN SERVICES INC | | | SCAC4 |
| 4405 | MJOA | MASSINO, JOSEPH | | | SCAC4 |
| 4406 | MJOB | MORRISSETTE, JIM OIL BURNER | | | SCAC4 |
| 4407 | MJOE | MASEWICH, JOEL | | | SCAC4 |
| 4408 | MJOM | MOHOLLAND, JOE INC | | | SCAC4 |
| 4409 | MJON | MAJOR OIL COMPANY INC | | | SCAC4 |
| 4410 | MJOR | MAJOR TRANSPORT INC | | | SCAC4 |
| 4411 | MJP | Air Majoro S.A. | Callsign: Air Majoro, | PE | AVCODES |
| 4412 | MJPB | MACHINERIE JEAN-PIERRE BENOIT INC | | | SCAC4 |
| 4413 | MJPL | MAY, JAMES PIPE & | | | SCAC4 |
| 4414 | MJPT | MILLER, JP TRUCKING LLC | | | SCAC4 |
| 4415 | MJQH | MJ QUARTER HORSES AND PAINTS | | | SCAC4 |
| 4416 | MJR | Midamerica Jet, Inc. | Callsign: Major, | USA | AVCODES |
| 4417 | MJR | Midamerica Jet | | | ICAO1 |
| 4418 | MJRB | MCKINNON, JAMES R TRUCKING LLC | | | SCAC4 |
| 4419 | MJRC | MOORE, JOHN R TRUCKING INC | | | SCAC4 |
| 4420 | MJRE | MJR ENTERPRISES LLC | | | SCAC4 |
| 4421 | MJRK | MARTINEZ, J R TRUCKING | | | SCAC4 |
| 4422 | MJRM | MJR MESSENGER INC | | | SCAC4 |
| 4423 | MJRO | MARTIN, J R TRANSPORT LLC | | | SCAC4 |
| 4424 | MJRQ | M J R HORSE TRANSPORTATION INC | | | SCAC4 |
| 4425 | MJRT | MAJOR TRANSPORTATION SERVICES INC | | | SCAC4 |
| 4426 | MJRX | Railway Service Contractors | added 10/2003; eliminated 1/2004; 7/2005 (not listed) | | NAKINA |
| 4427 | MJRX | RAILWAY SERVICE CONTRACTORS INC. | | | PWRC |
| 4428 | MJRX | M. Ryan Railway Service Contractors | | | RSRV |
| 4429 | MJRX | RAILWAY SERVICE CONTRACTORS INC | | | SCAC4 |
| 4430 | MJS | WWW-Bedarfsluftfahrts GmbH | Callsign: Medical Jet, Ceased operations. | A | AVCODES |
| 4431 | MJS | Air Charters Worldwide, Inc t/a My Jet Saver | Callsign: Jet Saver, Name changed from Air Charters Worldwide, Inc. ICAO designator changed from WFT. ICAO Callsign changed from World Flight. | USA | AVCODES |
| 4432 | MJSA | MJS AMERITRANS LOGISITICS INC | | | SCAC4 |
| 4433 | MJSH | MJS HOLDINGS LTD | | | SCAC4 |
| 4434 | MJSN | MILLER, JOSEPH & SON INC | | | SCAC4 |
| 4435 | MJSO | MAJESTIC OIL CO INC | | | SCAC4 |
| 4436 | MJSP | MJS TRANSPORTATION INC | | | SCAC4 |
| 4437 | MJSU | JOINT VENTURE MIXED COMPANY TEM | | | SCAC4 |
| 4438 | MJT | Mex-Jet, S.A. de C.V. | Callsign: Mejets, | MEX | AVCODES |
| 4439 | MJT | Madjet-Tranportes Aereos, S.A. | Callsign: Madjet, | P | AVCODES |
| 4440 | MJT | Mex-Jet | | | ICAO1 |
| 4441 | MJTE | MAJESTIC TANKERS CORPORATION | | | SCAC4 |
| 4442 | MJTF | MAJOR TRANSPORTATION SERVICES INC | | | SCAC4 |
| 4443 | MJTI | MUHLENKAMP | | | SCAC4 |
| 4444 | MJTL | MJ TRANSPORT LOGISTICS LLC | | | SCAC4 |
| 4445 | MJTO | M & J TRANSPORT SERVICES CORP | | | SCAC4 |
| 4446 | MJTP | MARCO & JOSE TRANSPORT | | | SCAC4 |
| 4447 | MJTS | MARJON TRANSPORTATION, INC | | | SCAC1 |
| 4448 | MJTS | MARJON TRANSPORTATION INC | | | SCAC4 |
| 4449 | MJTT | MIKE AND JOY TRANSPORTATION INC | | | SCAC4 |
| 4450 | MJTU | MAMMOET EUROPE BV | | NL | BIC |
| 4451 | MJTU | ALE HEAVYLIFT | | | SCAC4 |
| 4452 | MJTV | MJ TRANSPORTATION SERVICES | | | SCAC4 |
| 4453 | MJTY | M J TRANSPORT INC | | | SCAC4 |
| 4454 | MJUK | MJ TRUCKING | | | SCAC4 |
| 4455 | MJVU | (MERX) MERCO, A JOINT VENTURE | | | PWRC |
| 4456 | MJVU | Merco | | | RSRV |
| 4457 | MJWL | MOODY, JERRY WILLIS | | | SCAC4 |
| 4458 | MJWN | MJW INC | | | SCAC4 |
| 4459 | MJX | Euroline | IATA: 4L, Name changed to Georgian International Airlines Ltd. | GE | AVCODES |
| 4460 | MJXI | MAJOR TRANSPORTATION INC | | | SCAC4 |
| 4461 | MJXL | MOJO TRANSPORTATION LLC | | | SCAC4 |
| 4462 | MJXN | M J TRANSPORTATION | | | SCAC4 |
| 4463 | MJXP | M & J EXPEDITORS | | | SCAC4 |
| 4464 | MJXV | MAJESTIC TRANSPORTATION SERVICES | | | SCAC4 |
| 4465 | MK | Air Mauritius | ICAO: MAU, Callsign: Airmauritius, IATA Prefix: 239, | MUS | AVCODES |
| 4466 | MK&T | Missouri, Kansas & Texas Ry. (M. K. & T. Lines) | 8/1920 | | NAKINA |
| 4467 | MK&T | UNION PACIFIC RAILROAD CO. [MISSOURI PACIFIC; MISSOURI, KANSAS & TEXAS RWY.; M.K. & T. LINES] | | | PWRC |
| 4468 | MKA | MK Airlines Limited | IATA: 7G, Callsign: Kruger-Air, IATA Prefix: 513, Registered country changed from Ghana | GB | AVCODES |
| 4469 | MKA | MK Airlines Limited | IATA: 7G, Callsign: Kruger-Air, IATA Prefix: 513, Registered country changed to United Kingdom | GH | AVCODES |
| 4470 | MKA | MK Airlines Limited | Callsign: Kruger-Air, IATA Prefix: 513, Ceased Operation. Voluntarily surrendered AOC 09 April 2010. Registered country changed from Ghana | GB | AVCODES |
| 4471 | MKA | Moka Airways | Callsign: Moka Air, | YAR | AVCODES |
| 4472 | MKA | MK Airline | | | ICAO1 |
| 4473 | MKAA | MCKANN TRANSPORT LLC | | | SCAC4 |
| 4474 | MKAB | MACKS FARM & RV CENTER | | | SCAC4 |
| 4475 | MKAD | MC KINNIE TRUCKING LLC | | | SCAC4 |
| 4476 | MKAG | MILLER LIVESTOCK INC | | | SCAC4 |
| 4477 | MKAJ | MORRIS KREITZ AND SON INC | | | SCAC4 |
| 4478 | MKAK | MIKES AUTO TRANSPORT LLC | | | SCAC4 |
| 4479 | MKAT | MACKAT INC | | | SCAC4 |
| 4480 | MKAT | Przedsiębiorstwo Komunikacji Miejskiej Katowice | | PL | TRAFFIC |
| 4481 | MKAU | RWE NUCLEAR GMBH | | D | BIC |
| 4482 | MKAV | MKAT SERVICES LLC | | | SCAC4 |
| 4483 | MKAW | MIKES AUTO TRANSPORT | | | SCAC4 |
| 4484 | MKB | Mack Air | Callsign: Greentail, | BW | AVCODES |
| 4485 | MKB | AG Märkische Kleinbahn e.V. | Berlin | D | privat-bahn.de |
| 4486 | MKB | Mindener Kreisbahnen GmbH | Minden | D | privat-bahn.de |
| 4487 | MKB | Mindener Kreisbahnen GmbH | | D | TRAFFIC |
| 4488 | MKB | Mindener Kreisbahnen | | DE | VKM |
| 4489 | MKBB | MK TRANSPORT INC | | | SCAC4 |
| 4490 | MKBK | MINN-KAN BROKERAGE INC | | | SCAC4 |
| 4491 | MKC | Mak-Air | | MK | AVCODES |
| 4492 | MKC | McKeesport Connecting R.R. Co. | 1/1946-7/2005 | | NAKINA |
| 4493 | MKC | McKeesport Connecting R.R. Co. | 1/52-7/2000 | | NRHS |
| 4494 | MKC | MCKEESPORT CONNECTING RAILROAD CO. | | | PWRC |
| 4495 | MKC | McKeesport Connecting Railroad | | | RSRV |
| 4496 | MKCB | MUELLER TRUCKING COMPANY | | | SCAC4 |
| 4497 | MKCE | MKC ENTERPRISES INC | | | SCAC4 |
| 4498 | MKCG | MAK CARRIERS INC | | | SCAC4 |
| 4499 | MKCH | MK CARTAGE LTD | | | SCAC4 |
| 4500 | MKCL | MAVRAK COMPANY LLC | | | SCAC4 |
