| 6001 | LOWX | Lion Oil Division of Tosco Corp. | added 10/1978; eliminated 7/1979 | | NAKINA |
| 6002 | LOWX | Lion Oil Co., subsidiary of Tosco Corp. | eliminated 10/1978 | | NAKINA |
| 6003 | LOWX | Lion Oil Co., subsidiary of the Oil Shale Corp. | added 7/1976 | | NAKINA |
| 6004 | LOWX | Lion Oil Co., subsidiary of the Oil Shale Corp. | added 7/76 | | NRHS |
| 6005 | LOWX | Lion Oil Co., subsidiary of Tosco Corp. | eliminated 10/78 | | NRHS |
| 6006 | LOWX | Lion Oil Division of Tosco Corp. | added 10/78; eliminated 7/79 | | NRHS |
| 6007 | LOWX | Tosco Corp. | added 7/79; 1/80; eliminated 4/87 | | NRHS |
| 6008 | LOWX | TOSCO CORP. [LION OIL CO.] | | | PWRC |
| 6009 | LOWX | Tosco Corporation | | | RSRV |
| 6010 | LOWY | LOWYS EXPRESS, INC | | | SCAC3 |
| 6011 | LOWY | LOWYS EXPRESS INC | | | SCAC4 |
| 6012 | LOX | flyRICH LLC | Callsign: Lox Jet, | USA | AVCODES |
| 6013 | LOXC | LOMAX CONSOLIDATORS | | | SCAC3 |
| 6014 | LOXC | LOGISTIXS CARGO | | | SCAC4 |
| 6015 | LOXI | LOGENIX INTERNATIONAL LLC | | | SCAC4 |
| 6016 | LOXL | LOG EX SOLUTIONS INC | | | SCAC4 |
| 6017 | LOXT | LOXTERCAMP TRANSPORT INC | | | SCAC3 |
| 6018 | LOXU | STRATOLAUNCH, LLC | | USA | BIC |
| 6019 | LOY | Loyd's Aviation Group Ltd. | Callsign: Loyds, | PL | AVCODES |
| 6020 | LOYC | LOYALIST CITY TOWING LTD | | | SCAC4 |
| 6021 | LOYH | LOYALTY SHIPPING S A REPUBLIC OF PA | | | SCAC4 |
| 6022 | LOYI | LLOYD INTERNATIONAL | | | SCAC3 |
| 6023 | LOYO | LOYOLA TRUCKING INC | | | SCAC3 |
| 6024 | LOYP | LOYALTY TRANSPORT LTD | | | SCAC4 |
| 6025 | LOYR | LANOWAY, ROBERT | | | SCAC4 |
| 6026 | LOYT | LOYD TRUCK LINES INC | | | SCAC3 |
| 6027 | LOYT | LOYD, JIM TRANSPORT CO INC | | | SCAC4 |
| 6028 | LOYU | COMPANIA DE NAVEGACAO LLOYD BRASILE | | | SCAC3 |
| 6029 | LOZN | LOZANO FUENTES, CARLOS JAVIER | | | SCAC4 |
| 6030 | LOZP | LOZANO, PAUL P & SONS TRUCKING | | | SCAC3 |
| 6031 | LOZR | LOZIER OIL COMPANY INC | | | SCAC4 |
| 6032 | LOZS | LOPEZ RODRIGUEZ, SANDRO H | | | SCAC4 |
| 6033 | LP | Lan Peru, S.A. | ICAO: LPE, Callsign: Patagonia, IATA Prefix: 544, Name changed to Lan Peru, S.A. d/b/a LATAM Airlines Peru w.e.f. 05 May 2016. Changed from Air Patagonia - Linea Aerea Del Sur S.A. ICAO changed from PTG | PE | AVCODES |
| 6034 | LP | Linea Aerea Del Sur, S.A. | ICAO: PTG, Changed to Lan Peru S.A. ICAO changed to LPE | PE | AVCODES |
| 6035 | LP | The Hawaii Express | ICAO: HEA, Ceased operations | USA | AVCODES |
| 6036 | LP | La Tur Airlines | ICAO: LPT, Callsign: Latur, Ceased operations | MEX | AVCODES |
| 6037 | LP | Société Air Alpes | ICAO: ALP, Merged into TAT | F | AVCODES |
| 6038 | LP | Lan Peru, S.A. d/b/a LATAM Airlines Peru | ICAO: LPE, Callsign: Lanperu, IATA Prefix: 544, Name changed from Lan Peru, S.A. w.e.f. 05 May 2016. Changed from Air Patagonia - Linea Aerea Del Sur S.A. ICAO changed from PTG | PE | AVCODES |
| 6039 | LP | Lincoln Pacific Railway | | | RSRV |
| 6040 | LPA | PAL Aerolineas, S.A. de C.V. | Callsign: Lineaspal, | MEX | AVCODES |
| 6041 | LPA | Air Large European Aviation Project t/a Air Leap | IATA: FL, Callsign: Leap, Ceased operation on 24 January 2022 and filed for reorganisation. | S | AVCODES |
| 6042 | LPA | Pal Aerolineas | | | ICAO1 |
| 6043 | LPAC | LES PRODUITS ALIMENTAIRES DURAN INC | | | SCAC4 |
| 6044 | LPAI | LES PRODUCTIONS ATLAN INC | | | SCAC4 |
| 6045 | LPAL | LA PALMITA | | | SCAC4 |
| 6046 | LPAM | LOPEZ, PEDRO ABRAHAM | | | SCAC4 |
| 6047 | LPAN | LOPEZ, ANTONIETA | | | SCAC4 |
| 6048 | LPAQ | LAUSIER, P A TRUCKING | | | SCAC3 |
| 6049 | LPAQ | L P A SERVICE | | | SCAC4 |
| 6050 | LPAR | LOGISTICS PARTNERS COMPANY | | | SCAC3 |
| 6051 | LPAS | LEP INTERNATIONAL PTY LTD | | | SCAC3 |
| 6052 | LPAX | The Lake Asphalt and Petroleum Co. of Pennsylvania | 7/1937-7/1965 (not listed) | | NAKINA |
| 6053 | LPAX | The Lake Asphalt and Petroleum Co. of Pennsylvania | 1/52-7/65 | | NRHS |
| 6054 | LPAX | LAKE ASPHALT & PETROLEUM CO. OF PENNSYLVANIA | | | PWRC |
| 6055 | LPB | The Louisiana & Pine Bluff Ry. Co. | 1/1975; eliminated 10/1979 | | NAKINA |
| 6056 | LPB | The Louisiana & Pine Bluff Ry. Co. | Jan-75 | | NRHS |
| 6057 | LPB | LOUISIANA & PINE BLUFF RWY.D CO. | | | PWRC |
| 6058 | LPB | Locarno - Ponte Brolla - Bignasco | | CH | TRAFFIC |
| 6059 | LPBC | LAMPE BLOCK COMPANY | | | SCAC3 |
| 6060 | LPBD | LOS PLEBES | | | SCAC4 |
| 6061 | LPBE | LEP INTERNATIONAL NV | | | SCAC3 |
| 6062 | LPBO | LOSINJSKA PLOVIDBA BRODARSTVO D O O | | | SCAC4 |
| 6063 | LPBR | LEP INTERNATINAL DO BRASIL LTDA | | | SCAC3 |
| 6064 | LPBR | LAUREL TRANSPORT | | | SCAC4 |
| 6065 | LPC | Alpine Aviation | Callsign: Apline Charter, | ZA | AVCODES |
| 6066 | LPC | Alpine Aviation (Pty) Ltd | Callsign: Netstar, | ZA | AVCODES |
| 6067 | LPC | Alpine Aviation | | | ICAO1 |
| 6068 | LPC | LEHIGH PORTLAND CEMENT | | | PWRC |
| 6069 | LPCA | LE PROJET CARDBOARD BOX INC | | | SCAC4 |
| 6070 | LPCB | LOADPOWER OF COLUMBUS | | | SCAC3 |
| 6071 | LPCB | LOPEZ BARRAGAN, PAULO CESAR | | | SCAC4 |
| 6072 | LPCE | LEPCO ENTERPRISES INC | | | SCAC3 |
| 6073 | LPCE | LAKE NORMAN EXPEDITE INC | | | SCAC4 |
| 6074 | LPCK | L P TRUCKING | | | SCAC4 |
| 6075 | LPCL | LAREDO POWER CONTAINERS LLC | | | SCAC4 |
| 6076 | LPCM | L P CUSTOM MACHINING LTD | | | SCAC4 |
| 6077 | LPCN | LA PAZ COMPANIA BAVIERA S A | | | SCAC3 |
| 6078 | LPCN | LOLLY POP CHILDRENS WEAR CO | | | SCAC4 |
| 6079 | LPCO | LOUISIANA-PACIFIC CORPORATION | | | SCAC3 |
| 6080 | LPCR | LEELANAU TRANSIT COMPANY | | | PWRC |
| 6081 | LPCU | CATERPILLAR (NI) LTD | | GB | BIC |
| 6082 | LPCU | FG WILSON (ENGINEERING) LTD | | | SCAC4 |
| 6083 | LPCX | Lehigh Portland Cement Co. | 7/1935-10/1966; eliminated 1/1969 | | NAKINA |
| 6084 | LPCX | Lehigh Portland Cement Co. | 4/38-10/66; eliminated 1/69 | | NRHS |
| 6085 | LPCX | LEJIGH PORTLAND CEMENT CO. | | | PWRC |
| 6086 | LPCX | LEHIGH PORTLAND CEMENT CO | | | SCAC3 |
| 6087 | LPCZ | FLEXI-VAN LEASING INC | | | SCAC4 |
| 6088 | LPD | UK Royal / H.R.H. Duke of York | Callsign: Leopard, | GB | AVCODES |
| 6089 | LPD | UK Royal/HRH Duke of York | | | ICAO1 |
| 6090 | LPDA | LEPAGE, D A TRANSPORT LTD | | | SCAC4 |
| 6091 | LPDE | LASSEN GMBH | | | SCAC3 |
| 6092 | LPDM | LPD, INC | | | SCAC3 |
| 6093 | LPDP | LES PRODUITS DE PAPIER LAPACO LTEE | | | SCAC4 |
| 6094 | LPDS | LP INDUSTRIES | | | SCAC4 |
| 6095 | LPDT | LOGISTICS PLUS DISTRIBUTION TRANSPO | | | SCAC4 |
| 6096 | LPDY | LIQUID PETROLEUM DELIVERY | | | SCAC4 |
| 6097 | LPE | Lan Peru, S.A. | IATA: LP, Callsign: Patagonia, IATA Prefix: 544, Name changed to Lan Peru, S.A. d/b/a LATAM Airlines Peru w.e.f. 05 May 2016. Changed from Air Patagonia - Linea Aerea Del Sur S.A. ICAO changed from PTG | PE | AVCODES |
| 6098 | LPE | Lan Peru, S.A. d/b/a LATAM Airlines Peru | IATA: LP, Callsign: Lanperu, IATA Prefix: 544, Name changed from Lan Peru, S.A. w.e.f. 05 May 2016. Changed from Air Patagonia - Linea Aerea Del Sur S.A. ICAO changed from PTG | PE | AVCODES |
| 6099 | LPE | LAN Peru | IATA: LP | | ICAO1 |
| 6100 | LPEL | LACHAPELLE OIL & HEATING CO INC | | | SCAC4 |
