| 1 | L&A | Louisiana & Arkansas Ry. (Co.) | 8/1920-10/1966 | | NAKINA |
| 2 | L&A | Louisiana & Arkansas Ry. | 4/38-10/66 | | NRHS |
| 3 | L&A | LOUISIANA & ARKANSAS RWY. CO. | | | PWRC |
| 4 | L&C | Lancaster & Chester Ry. Co. | 8/1920-7/1936 | | NAKINA |
| 5 | L&C | LANCASTER & CHESTER RWY. CO. | | | PWRC |
| 6 | L&HJ | Landskrona & Helsingborg Järnvägar | 1865 - 1940 | S | svenska-lok.se |
| 7 | L&HR | The Lehigh & Hudson River Ry. Co. | 7/1923-7/1936 | | NAKINA |
| 8 | L&HR | NORFOLK SOUTHERN [CONSOLIDATED RAIL CORP.; LEHIGH & HUDSON RIVER RY] | | | PWRC |
| 9 | L&HS | Louisville, Henderson & St. Louis Ry. Co. | Apr-38 | | NRHS |
| 10 | L&N | Louisville & Nashville R.R. (Co.) | 7/1923-10/1966 | | NAKINA |
| 11 | L&N | Louisville & Nashville R.R. | 4/38-10/66 | | NRHS |
| 12 | L&N | LOUISVILLE & NASHVILLE RAILROAD CO. | | | PWRC |
| 13 | L&NE | CONSOLIDATED RAIL CORP. [LEHIGH & NEW ENGLAND RR] | | | PWRC |
| 14 | L&W | Läger&Wöstenhöfer GmbH & CO KG | Berlin | D | privat-bahn.de |
| 15 | L&WD | Louisville and Wadley R.R. Co. (Wrightsville and Tennille R.R. Co.) | 7/1923-7/1936 | | NAKINA |
| 16 | L&WD | WRIGHTSVILLE & TENNILLE RAILROAD CO. [LOUISVILLE & WADLEY RAILROAD CO.] | | | PWRC |
| 17 | L&WV | Lackawanna & Wyoming Valley Ry. Co. | 10/1966 | | NAKINA |
| 18 | L&WV | Lackawanna & Wyoming Valley Ry. | 10/1957-7/1965 | | NAKINA |
| 19 | L&WV | Lackawanna & Wyoming Valley R.R. (Co.) | 8/1920-7/1954 | | NAKINA |
| 20 | L&WV | Lackawanna & Wyoming Valley Ry. | 1/52-7/65 | | NRHS |
| 21 | L&WV | Lackawanna & Wyoming Valley Ry. Co. | Oct-66 | | NRHS |
| 22 | L&WV | LACKAWANNA & WYOMING VALLEY RAILROAD CO. | | | PWRC |
| 23 | L0 | Reliant Air Charter, Inc. | ICAO: RLI, Callsign: Reliant, Designator L0 recalled by IATA. | USA | AVCODES |
| 24 | L1 | Lufthansa Systems Group GmbH | Computer Reservations Systems (CRS) | D | AVCODES |
| 25 | L1 | E-Savtravel | Computer Reservations Systems (CRS) | PE | AVCODES |
| 26 | L1 | Airlliance LLC | | CDN | AVCODES |
| 27 | L2 | Lynden Air Cargo, LLC | ICAO: LYC, Callsign: Lynden, IATA Prefix: 344, | USA | AVCODES |
| 28 | L2 | London Flight Centre (Stansted) Ltd. d/b/a Love Air | ICAO: LOV, Callsign: Loveair, IATA desigantor changed to 4J | GB | AVCODES |
| 29 | L2 | Djibouti Airlines | ICAO: DJB, IATA designator changed from MG*. IATA designator changed from DY / ICAO designator chan ged from DJU | DJI | AVCODES |
| 30 | L3 | Air Ketchum, Idaho, Inc. | | USA | AVCODES |
| 31 | L3 | DHL de Guatemala, S.A. | ICAO: JOS, IATA Prefix: 947, IATA designator changed from Z8* | GCA | AVCODES |
| 32 | L3 | LTU Billa Lufttransport Unternehmen GmbH | ICAO: LTO, Callsign: Billatransport, | A | AVCODES |
| 33 | L3 | Lynx Aviation, Inc. | ICAO: SSX, Callsign: Shasta, Subsidiary of Republic Airways Holdings, Inc. ICAO designator changed from SHA | USA | AVCODES |
| 34 | L4 | Lauda Air S.p.A. | ICAO: LDI, Callsign: Lauda Italy, IATA Prefix: 372, | I | AVCODES |
| 35 | L4 | Max Aviation Inc. | ICAO: MAX, Callsign: Max-Aviation, Designator L4* recalled by IATA | CDN | AVCODES |
| 36 | L4 | Wings of Lebanon S.a.l. | ICAO: WLB, Designator L4 recalled by IATA | RL | AVCODES |
| 37 | L4 | Linea Turistica Aereotuy Lta, C.A. | ICAO: TUY, Callsign: Aereotuy, IATA Prefix: 445, Ceased operations on 30 July 2018. IATA designator changed from LD. | YV | AVCODES |
| 38 | L4 | Legacy Air Co., Ltd. | ICAO: LGC, Callsign: Legacy Air, Founded in 2009 | T | AVCODES |
| 39 | L4 | Air Service Liege (A.S.L.) N.V. | ICAO: BNJ, Callsign: Jet Belgium, Founded in 1997. Merged into ASL Group. | B | AVCODES |
| 40 | L4 | Grupo LASA S.r.l. d/b/a LASA Líneas Aéreas | | RA | AVCODES |
| 41 | L4 | The Landline Company | Railway Service | USA | AVCODES |
| 42 | L480 | BROWN DISTRIBUTION CENTERS | | | SCAC3 |
| 43 | L5 | Helikopter Service A/S | ICAO: HKS, Callsign: Helibus, Name changed to CHC Helikopter Service AS | N | AVCODES |
| 44 | L5 | Lufttransport A/S | ICAO: LTR, Callsign: Luft Transport, Designator L5* recalled by IATA | N | AVCODES |
| 45 | L5 | Atlantique Air Assistance | ICAO: TLB, Callsign: Triple-A, Founded in 1989. Ceased operations in October 2017. | F | AVCODES |
| 46 | L5 | CHC Helikopter Service AS | ICAO: HKS, Callsign: Helibus, Designator L5 recalled by IATA. Name changed from Helikopter Service A/S | N | AVCODES |
| 47 | L5 | Red Air S.r.l. | ICAO: REA, Callsign: Red Dominicana, IATA Prefix: 377, | DOM | AVCODES |
| 48 | L6 | Air Maldives Limited | ICAO: AMI, Callsign: Air Maldives, IATA Prefix: 900, Founded on 01 October 1974. Ceased operations during 2000. | MV | AVCODES |
| 49 | L6 | Servicios Aereos Ejecutivos Saereo, S.A. | ICAO: SRO, Callsign: Saereo, IATA Prefix: 532, IATA designator changed to MZ | EC | AVCODES |
| 50 | L6 | Tbilaviamsheni | ICAO: VNZ, Callsign: Tbilavia, | GE | AVCODES |
| 51 | L6 | Mauritanian Airlines International | ICAO: MAI, IATA Prefix: 495, Founded December 2010. Name changed to Mauritania Airlines. | RIM | AVCODES |
| 52 | L6 | Mauritania Airlines | ICAO: MAI, IATA Prefix: 495, Founded December 2010. Name changed from Mauritanian Airlines International. | RIM | AVCODES |
| 53 | L7 | Laoag International Airlines | ICAO: LPN, Callsign: Laoag Air, Ceased operations in 2006 | RP | AVCODES |
| 54 | L7 | Linea Aerea SAPSA Chile, S.A. | ICAO: LNP, Callsign: Sapsa, Designator L7* recalled by IATA | RCH | AVCODES |
| 55 | L7 | Lineas Aereas Carguera de Colombia S.A. | ICAO: LAE, Callsign: Lanco, IATA Prefix: 985, Name changed to Lineas Aereas Carguera de Colombia S.A. d/b/a LATAM Cargo Colombia | CO | AVCODES |
| 56 | L7 | Lineas Aereas Carguera de Colombia S.A. d/b/a LATAM Cargo Colombia | ICAO: LAE, Callsign: Lanco, IATA Prefix: 985, Name changed from Lineas Aereas Carguera de Colombia S.A. | CO | AVCODES |
| 57 | L8 | Laparkan Airways, Inc. | IATA Prefix: 959, IATA designator changed to LE | GUY | AVCODES |
| 58 | L8 | Leisure Air | ICAO: LWD, Callsign: Leisure World, Founded in 1992. Ceased operations in February 1995. | USA | AVCODES |
| 59 | L8 | Novosibirsk Airlines | ICAO: NLB, Voluntary Surrender of IATA prefix | RUS | AVCODES |
| 60 | L8 | Air Luxor GB, Lda | ICAO: LXG, Callsign: Luxor Gulf, Ceased | GW | AVCODES |
| 61 | L8 | International Air Cargo | Designator L8 recalled by IATA | KWT | AVCODES |
| 62 | L8 | Afric Aviation | ICAO: EKG, | G | AVCODES |
| 63 | L8 | Lynden Air Cargo PNG Ltd. | ICAO: LYB, Callsign: Highlands, Designator L8* recalled by IATA. | PNG | AVCODES |
| 64 | L8 | Lulutai Airlines Limited | ICAO: TON, Callsign: Tonga, | TO | AVCODES |
| 65 | L9 | Air Mali, S.A. | ICAO: MLI, Callsign: Air Mali, IATA Prefix: 109, Suspended operations on 07 April 2003. Designator L9 reinstated by IATA | RMM | AVCODES |
| 66 | L9 | Air Logistics LLC | ICAO: ALG, Callsign: Airlog, Name changed to Bristow US, LLC | USA | AVCODES |
| 67 | L9 | Teamline Air Luftfahrt GmbH | ICAO: TLW, Callsign: Teamline, | A | AVCODES |
| 68 | L9 | Belle Air Europe s.r.l. | ICAO: BAL, Callsign: Belle Italy, Ceased operations on 25 November 2013. | I | AVCODES |
| 69 | L9 | Bristow US, LLC | ICAO: BTZ, Callsign: Bristow Group, | USA | AVCODES |
| 70 | L9 | Lumiwings S.A. | ICAO: LWI, Callsign: Lumi, Founded in 2015. Commenced operations during May 2018. | GR | AVCODES |
| 71 | LA | Linea Aerea Nacional-Chile S.A. Lan-Chile | ICAO: LAN, Callsign: LAN, IATA Prefix: 045, Name changed to LAN Airlines, S.A. | RCH | AVCODES |
| 72 | LA | LAN Airlines, S.A. | ICAO: LAN, Callsign: LAN, IATA Prefix: 045, Name changed to LATAM Airlines Group S.A. d/b/a LAN Airlines. Name changed from Linea Aerea Nacional-Chile S.A. Lan-Chile | RCH | AVCODES |
| 73 | LA | LATAM Airlines Chile | ICAO: LAN, Callsign: LAN, IATA Prefix: 045, Name changed from LAN Airlines, S.A. w.e.f. 05 May 2016. Name changed from LAN Airlines, S.A. previously from Linea Aerea Nacional-Chile S.A. Lan-Chile. | RCH | AVCODES |
| 74 | LA | The Kansas City Southern Ry. Co. | eliminated 1/1989; 1/1994-7/2005 | | NAKINA |
| 75 | LA | Louisana & Arkansas Ry. | 1/1975-1/1980 | | NAKINA |
| 76 | LA | Louisana & Arkansas Ry. | 1/75-1/80 | | NRHS |
| 77 | LA | The Kansas City Southern Ry. Co. | eliminated 1/89; 1/94-7/2000 | | NRHS |
| 78 | LA | KANSAS CITY SOUTHERN RAILWAY COMPANY [LOUISIANA & ARKANSAS RY] | | | PWRC |
| 79 | LA | Louisiana and Arkansas Railway (Kansas City Southern Railway) | | | RSRV |
| 80 | LA | LOUISIANA & ARKANSAS RAILWAY COMPAN | | | SCAC4 |
| 81 | LA | | | USA | TRAFFIC |
| 82 | LA&S | Lorain, Ashton & Southern R.R. | 8/1920-7/1923 | | NAKINA |
| 83 | LA&S | LORAIN, ASHTON & SOUTHERN RAILROAD | | | PWRC |
| 84 | LAA | Jamahirya Libyan Arab Airlines | IATA: LN, Callsign: Libair, Name changed to Libyan Airlines | LAR | AVCODES |
| 85 | LAA | Libyan Airlines | IATA: LN, Callsign: Libair, Name changed from Jamahirya Libyan Arab Airlines | LAR | AVCODES |
| 86 | LAA | Libyan Arab Airlines | IATA: LN | | ICAO1 |
| 87 | LAAAB | Lundstams Åkeri & Åkeri & Återvinning AB | | SE | VKM |
| 88 | LAAC | LAMB, ARTHUR C COMPANY | | | SCAC3 |
| 89 | LAAD | LAND-AIR DELIVERY INC | | | SCAC3 |
| 90 | LAAF | LONG AGO & FAR AWAY | | | SCAC4 |
| 91 | LAAF | Libyan Arab Armed Forces | | LAR | TRAFFIC |
| 92 | LAAJ | LACHMAR | | | SCAC3 |
| 93 | LAAM | L&L MOTOR FREIGHT, INC | | | SCAC3 |
| 94 | LAAM | LA CASA GRANDE | | | SCAC4 |
| 95 | LAAN | LAMARTIS INC | | | SCAC4 |
| 96 | LAAO | LATIN AMERICAS TRAVEL & TOURS | | | SCAC3 |
| 97 | LAAP | LOUISIANA ARMY AMMO PLANT | | | PWRC |
| 98 | LAAP | LATIN AMERICAN SHIPPING | | | SCAC3 |
| 99 | LAAP | LAMONTAGNE, JINNY | | | SCAC4 |
| 100 | LAAQ | LOS ANGELES AIR TRUCKING SERVICE | | | SCAC3 |
