| 1 | 4A | Aero Transporte S.A. (ATSA) | ICAO: AMP, Callsign: Atsa, IATA Prefix: 212, | PE | AVCODES |
| 2 | 4A | F.S. Air Service, Inc. | ICAO: EYE, Callsign: Sockeye, | USA | AVCODES |
| 3 | 4A | Ararat Airlines | ICAO: ARK, Callsign: Ararat Avia, Designator 4A recalled by IATA | AM | AVCODES |
| 4 | 4A | Air Kiribati Limited | ICAO: AKL, Callsign: Air Kiribati, Founded on 01 April 1995. | KIR | AVCODES |
| 5 | 4A | R B Airline UK Ltd/Aviana Airways Ltd operating as Royal Bengal Airlines | ICAO: RRY, Callsign: Royal Bengal, Founded in 2006. Commenced commercial operations on 31 January 2008. | BD | AVCODES |
| 6 | 4A | Air Go Airlines S.A. | ICAO: AGS, Callsign: Airgo Cargo, IATA Prefix: 454, Commenced operations in September 2008. Ceased operations in October 2011. | GR | AVCODES |
| 7 | 4A | Aerodynamics, Inc. | ICAO: DYN, Callsign: Aerodynamics, Designator changed from 8N*. Name changed to Aerodynamics, Inc. d/b/a Great Lakes Jet Express. Name changed from Aero Dynamics, Inc. ICAO callsign from Aero Dynamic. IATA designator changed from Y7*. | USA | AVCODES |
| 8 | 4B | Olson Air Service, Inc. | | USA | AVCODES |
| 9 | 4B | Olson & Sons Inc d/b/a Olson Air Service | | USA | AVCODES |
| 10 | 4B | Aviastar-Tu Co. Ltd | ICAO: TUP, Callsign: Tupolevair, IATA Prefix: 210, | RUS | AVCODES |
| 11 | 4B | MC Aviation Corp d/b/a Boutique Air, Inc. | Name changed to Boutique Air, Inc. | USA | AVCODES |
| 12 | 4B | Perimeter Aviation Ltd. | ICAO: PAG, Callsign: Perimeter, Designator 4B recalled by IATA | CDN | AVCODES |
| 13 | 4B | Boutique Air, Inc. | ICAO: BTQ, Callsign: Boutique, Name changed from MC Aviation Corp d/b/a Boutique Air, Inc. | USA | AVCODES |
| 14 | 4C | Aerovias de Integration Regional d/b/a LATAM Airlines Colombia | {`ICAO: ARE, Callsign: LAN Colombia, Name changed from Aires S.A. Aerovias de Integracion Regional S.A.) d/b/a LAN Colombia w.e.f. 05 May 2016.`};SRCKEY=AVCODES | CO | |
| 15 | 4C | Aires, Aerovias de Integracion Regional, S.A. | ICAO: ARE, Callsign: Aires, Name changed to LAN Colombia w.e.f. 03 December 2001. | CO | AVCODES |
| 16 | 4C | Tashkent Aircraft Production Corporation | ICAO: CTP, Callsign: Cortas, IATA designator changed from PQ* | UZ | AVCODES |
| 17 | 4C | Click Airways | ICAO: CGK, Callsign: Click Air, Ceased operations. | KS | AVCODES |
| 18 | 4C | {`Aires S.A. Aerovias de Integracion Regional S.A.) d/b/a LAN Colombia`};ZIPCODE= | ICAO: ARE, Callsign: LAN Colombia, Name changed to Aerovias de Integration Regional d/b/a LATAM Airlines Colombia w.e.f. 05 May 2016. Name changed from Aires, Aerovias de Integracion Regional, S.A. w.e.f. 03 December 2011. | CO | AVCODES |
| 19 | 4D | Egypt Air Holding Company d/b/a Air Sinai | ICAO: ASD, Callsign: Air Sinai, IATA Prefix: 903, Designator 4D recalled by IATA. | ET | AVCODES |
| 20 | 4D | Aerro Direkt S.r.l. | ICAO: DIR, Callsign: Direkt Wings, | RO | AVCODES |
| 21 | 4D | Egypt Air Holding Company d/b/a Air Sinai | ICAO: ASD, Callsign: Air Sinai, Name chanegd to Air Sphinx. IATA Accounting and Prefix code recalled. | ET | AVCODES |
| 22 | 4E | Bidzy Ta Hot Aana Native Corporation t/a Tanana Air Service | ICAO: TNR, Callsign: Tan Air, IATA Designator changed to Z3. | USA | AVCODES |
| 23 | 4E | Stabo Air Limited | ICAO: SBO, Callsign: Stabair, IATA Prefix: 242, | Z | AVCODES |
| 24 | 4E | British Airtours | Used to LGW-EWR route only | GB | AVCODES |
| 25 | 4F | Air City | ICAO: ECE, Name changed from Air-City. Railway Service | D | AVCODES |
| 26 | 4F | Air Nigeria plc | | WAN | AVCODES |
| 27 | 4F | Frontier Air Ltd. | | CDN | AVCODES |
| 28 | 4F | Freedom Airlines Express Ltd. | ICAO: FDT, Callsign: Freedom Eagle, ICAO callsign changed from Freedom Ero | EAK | AVCODES |
| 29 | 4F | Air City | ICAO code ECE recalled. Name changed from Air-City. Railway Service | D | AVCODES |
| 30 | 4G | Shenzhen Airlines | ICAO: CSZ, Callsign: Shenzhen Air, IATA designator to changed to ZH w.e.f. 04 March 2002. Designator 4G reinstated by IATA | PRC | AVCODES |
| 31 | 4G | Advance Leasing Company | IATA designator changed from BC* | USA | AVCODES |
| 32 | 4G | Gazpromavia Aviation Company Limited | ICAO: GZP, Callsign: Gazprom, Founded in 1995 | RUS | AVCODES |
| 33 | 4G | Georgian Air | Designator 4G* recalled by IATA | GE | AVCODES |
| 34 | 4H | Fly S.A. Linhas Aereas | ICAO: FLB, Callsign: Aereafly, | BR | AVCODES |
| 35 | 4H | Trans Pacific Air (Malaysia) SDN. BHD. | IATA designator changed from X5* | MAL | AVCODES |
| 36 | 4H | Albatros Airways | ICAO: LBW, IATA Prefix: 931, Ceased operations on 01 September 2006. | AL | AVCODES |
| 37 | 4H | United Airways Bangladesh Ltd | ICAO: UBD, Callsign: United Bangladesh, Founded in 2005. Commenced operations on 10 July 2007. Ceased operations on 06 March 2016. | BD | AVCODES |
| 38 | 4H | Hi Air Co., Ltd. | ICAO: HGG, Callsign: Hi Air, | ROK | AVCODES |
| 39 | 4I | Knighthawk Air Express Ltd. | ICAO: KNX, Callsign: Knight Flight, IATA Prefix: 699, Founded in December 1993. Ceased operations in 2005. | CDN | AVCODES |
| 40 | 4I | IHY Izmir Havayollari A.S. t/a iZair | ICAO: IZM, IATA Prefix: 597, Founded in April 2005. Merged into Pegasus Airlines by end 2018. | TR | AVCODES |
| 41 | 4J | Transaero Airlines | ICAO: TSO, IATA designator changed to UN | RUS | AVCODES |
| 42 | 4J | Nationwide Airlines (Zambia) Ltd. | ICAO: NWZ, Callsign: Zamnat, Designator 4J* reinstated by IATA. Founded in 1991 | Z | AVCODES |
| 43 | 4J | London Flight Centre (Stansted) Ltd. d/b/a Love Air | ICAO: LOV, Callsign: Loveair, Ceased operations during April 2000. IATA desigantor changed from L2 | GB | AVCODES |
| 44 | 4J | Aircompany Somon Air LLC | ICAO: SMR, Callsign: Somon Air, IATA designator changed to SZ. | TJ | AVCODES |
| 45 | 4J | United Caribbean Airlines B.V. | ICAO: UCB, Callsign: Eagle Eye, Name changed to United Caribbean Airlines B.V. d/b/a JetAir Caribbean. | CUR | AVCODES |
| 46 | 4J | Flydamas Airlines | ICAO: FDK, Callsign: Damavia, | SYR | AVCODES |
| 47 | 4J | Jetair Caribbean B.V. | ICAO: JRC, | CUR | AVCODES |
| 48 | 4J | United Caribbean Airlines B.V. d/b/a JetAir Caribbean | ICAO: UCB, Callsign: Eagle Eye, Name changed to Jetair Caribbean B.V. ICAO Designator changed to JRC. Name changed from United Caribbean Airlines B.V. | CUR | AVCODES |
| 49 | 4K | Kenn Borek Air Ltd. | ICAO: KBA, Callsign: Borek Air, Designator 4K recalled by IATA | CDN | AVCODES |
| 50 | 4K | Askari Aviation (Pvt) Ltd. | ICAO: AAS, Callsign: Al-ass, Name changed from M/S Askari Aviation Serivces (Pvt) Ltd. | PK | AVCODES |
| 51 | 4L | Air Astana | ICAO: AST, Callsign: Astanaline, ICAO designator changed to KZR. IATA Designator changed from LQ* | KZ | AVCODES |
| 52 | 4L | Deltacraft Oy | ICAO: DEC, Callsign: Deltacraft, Designator 4L* recalled by IATA | FIN | AVCODES |
| 53 | 4L | Lineas Aereas Suramericanas SA t/a LAS, S.A. | ICAO: LAU, Callsign: Suramericano, IATA Prefix: 174, | CO | AVCODES |
| 54 | 4L | Air Alma, Inc. | ICAO: AAJ, Callsign: Air Alma, Designator 4L recalled by IATA | CDN | AVCODES |
| 55 | 4L | Air Astana | ICAO: KZR, Callsign: Astanaline, IATA designator changed to KC w.e.f 29 October 2006. ICAO designator changed from AST. IATA Designator changed from LQ* | KZ | AVCODES |
| 56 | 4L | Euroline | ICAO: MJX, Name changed to Georgian International Airlines Ltd. | GE | AVCODES |
| 57 | 4L | Georgian International Airlines Ltd. | ICAO: GIL, Name changed from Euroline | GE | AVCODES |
| 58 | 4L | Palau National Airlines | ICAO: PNA, Callsign: Tropic Bird, IATA designator changed from 9P. ICAO Callsign changed from Sebus. | PAL | AVCODES |
| 59 | 4M | African Star Airways (PTY) Ltd. | ICAO: ASG, Callsign: African Star, | ZA | AVCODES |
| 60 | 4M | Island Air Limited | ICAO: IML, Callsign: Mal Air, Designator 4M recalled by IATA | FJI | AVCODES |
| 61 | 4M | Minskavia | ICAO: MEN, Callsign: Minsk, Designator 4M recalled by IATA | BY | AVCODES |
| 62 | 4M | Líneas Aéreas Nacionales de Navegación Dominicana, S.A (LAN Dominicana) | ICAO: LNC, Callsign: Lancana, | DOM | AVCODES |
| 63 | 4M | Aero 2000, S.A. | ICAO: DSM, Callsign: Aero Dosmil, Name change to Aero 2000, S.A. dba LAN Argentina | RA | AVCODES |
| 64 | 4M | Aero 2000, S.A. dba LAN Argentina | ICAO: DSM, Callsign: Aero Dosmil, Name changed to LAN Argentina. Name change from Aero 2000, S.A. | RA | AVCODES |
| 65 | 4M | LAN Argentina S.A. | ICAO: DSM, Callsign: Aero Dosmil, IATA Prefix: 469, Name changed from Aero 2000, S.A. d/b/a LAN Argentina w.e.f. 05 May 2016. Name change from Aero 2000, S.A. | RA | AVCODES |
| 66 | 4M | LAN Argentina S.A. d/b/a LATAM Airlines Argentina | ICAO: DSM, Callsign: Aero Dosmil, IATA Prefix: 469, Ceased operations on 17 June 2020. Name changed from Aero 2000, S.A. dba LAN Argentina and previously from Aero 2000, S.A. | RA | AVCODES |
| 67 | 4M | Mavi Gök Havacilik A.S. | ICAO: MGH, Callsign: Mavi, IATA Prefix: 734, Founded in March 2007. Commenced operations on 19/07/2022. | TR | AVCODES |
| 68 | 4N | Air North Charter | ICAO: ANT, Callsign: Air North, IATA Prefix: 287, Name changed to Air North Charter and Training Ltd. | CDN | AVCODES |
| 69 | 4N | Air North Charter and Training Ltd. t/a Air North | ICAO: ANT, Callsign: Air North, IATA Prefix: 287, Name changed from Air North Charter. | CDN | AVCODES |
| 70 | 4O | Ocean Airlines | ICAO: KMO, | COM | AVCODES |
| 71 | 4O | ABC Aerolineas, S.A. de C.V. | ICAO: AIJ, Callsign: ABC Aerolineas, IATA Prefix: 837, Ceased operations on 11 December 2020. Designator 4O* reinstated by IATA | MEX | AVCODES |
| 72 | 4O | Orbest Airlines, S.L. | ICAO: OBS, Callsign: Orbest, IATA desigantor changed to 6O. Subsidary of Iberworld, Spain. | P | AVCODES |
| 73 | 4P | Pacific East Asia Cargo Airlines, Inc. | ICAO: PEC, Callsign: Pac-East Cargo, Founded on 09 October 1990. | RP | AVCODES |
| 74 | 4P | Business Aviation | Designator 4P* recalled by IATA. Reinstated by IATA | ZRE | AVCODES |
| 75 | 4P | Transportes Aereos del Peru S.A. d/b/a Transperu S.A. | Designator 4P recalled by IATA | PE | AVCODES |
| 76 | 4P | Viking Airlines AB | ICAO: VIK, Callsign: Swedjet, IATA Prefix: 078, Founded in 2003. Commenced operations on 05 May 2003. Ceased operations on 18 October 2010. | S | AVCODES |
| 77 | 4P | Travel Air Limited | | PNG | AVCODES |
| 78 | 4P | Public Charters, Inc. d/b/a REGIONAL Sky | IATA designator changed from P1. Name changed from Aviation Technologies Inc. d/b/a PublicCharters.com | USA | AVCODES |
| 79 | 4Q | Aerolyon | ICAO: AEY, Callsign: Aerolyon, Name changed to L-Air | F | AVCODES |
| 80 | 4Q | Air Atlantique / Air Publicité | ICAO: APB, Callsign: Charente, Declared bankruprcy on 06 April 2004. Designator KI recalled by IATA | F | AVCODES |
| 81 | 4Q | L-Air Holdings | ICAO: AEY, Callsign: Aerolyon, Designator 4Q recalled by IATA. Name changed from Aerolyon | F | AVCODES |
| 82 | 4Q | Anderson Airlink (AC-Coach Ops, Inc.) | Railway Service | USA | AVCODES |
| 83 | 4Q | Safi Airways Ltd. | ICAO: SFW, Callsign: Safi Airways, Ceased operations during 2018. | AFG | AVCODES |
| 84 | 4Q | 25Only Aviation GmbH | ICAO: ONY, Callsign: Only Jet, | D | AVCODES |
| 85 | 4R | CJSC Royal Flight Airlines | {ICAO: ABG, Callsign: Royal Flight, IATA Designator changed to RL. Name changed from Joint Stock Company "Abakan-Avia" w.e.f. 11 July 2014.};SRCKEY=AVCODES | RUS | |
| 86 | 4R | Joint Stock Company "Abakan-Avia" | ICAO: ABG, Callsign: Abakan-Avia, Name changed to CJSC Royal Flight Airlines w.e.f. 11 July 2014. | RUS | AVCODES |
| 87 | 4R | Hamburg International Luftverkehirsgesellschaft mbH | ICAO: HHI, Callsign: Hamburg Jet, Ceased operations on 20 October 2010 and filed for Bankruptcy | D | AVCODES |
| 88 | 4R | Orient Eagle Airways | ICAO: OEG, Callsign: Orienteagle, Ceased operations | KZ | AVCODES |
| 89 | 4R | Northern Thunderbird Air Ltd. d/b/a N.T. Air | ICAO: NTA, Callsign: Thunderbird, Designator 4R recalled by IATA | CDN | AVCODES |
| 90 | 4R | Renfe Viajeros | IATA Designator changed to 4R. Railway Service | E | AVCODES |
| 91 | 4R | Star East Airline s.r.l. | ICAO: SEK, Callsign: East Rider, | RO | AVCODES |
| 92 | 4R | Renfe Viajeros Sociedad Mercantil Estatal SA | IATA Designator changed from 4R*. Railway Service | E | AVCODES |
| 93 | 4S | East West Travel Trade Links Ltd. d/b/a East West Airlines | Founded in 1991. | IND | AVCODES |
| 94 | 4S | Aero Hunduras, S.A. d/b/a Sol Air | ICAO: HON, Callsign: Aero Honduras, IATA Prefix: 377, Established in January 2002. Commenced operation on 12 July 2002. Ceased operations in 2005. | HN | AVCODES |
| 95 | 4S | Solar Cargo, C.A. | ICAO: OLC, Callsign: Solarcargo, IATA Prefix: 644, | YV | AVCODES |
| 96 | 4S | Finalair Congo | ICAO: FNC, Callsign: Finalair Congo, IATA Prefix: 122, | ZRE | AVCODES |
| 97 | 4S | Star Airways sh.p.k | ICAO: STB, | AL | AVCODES |
| 98 | 4S | F.A. Conner Airways, Inc. | | USA | AVCODES |
| 99 | 4T | TCH of Russian Airlines | ICAO: TCH, Callsign: Trans-Charter, Designator 4T recalled by IATA | RUS | AVCODES |
| 100 | 4T | Transwest Air Limited | Callsign: Athabaska, Formed by the merger of Air Sask and Athabaska Airways | CDN | AVCODES |
