LHP  Lightning HIRF Protection 
LIB  Left Inboard 
LISN  Line Impedance Stabilization Network 
LLP  Left Lower Plug. Identifies the plug on the rear con-nector of an avionics unit. 
LLWAS  Low-Level Wind Shear Alert System 
L/M  List of Materials 
LMM  Locator Middle Marker. An NDB that is co-located at the same site as the 75 MHz middle marker beacon. 
LMP  Left Middle Plug. Identifies the plug on the rear con-nector of an avionics unit. 
LMT  Local Mean Time 
LNA  Low Noise Amplifier 
LNAV  Lateral Navigation 
LOB  Left Outboard 
LOC  Localizer. The lateral guidance portion of an ILS sys-tem. 
Lock-On  The condition that exists when the DME receives reply pulses to at least 50 percent of the interroga-tions. Valid distance information is then available. 
LOM  Locator Outer Marker. An NDB that is co-located at the same site as the 75 MHz outer marker beacon. 
LON  Longitude 
LORAN  Long Range Navigation. A system using a ground facil-ity composed of a master station and a slave station. The airborne receiver computes the position of the aircraft by using two or more received master-slave pairs of signals. LORAN-A operates at 1850,1900 and 1950 kHz. LORAN-C operates at 100 kHz. LORAN A was replaced by LORAN C in 1980. 
LORAN C  Long Range Navigation System 
LOS  Line Of Sight 
LPC  Low Pressure Compressor 

LPT Low Pressure Turbine
LRA  (See RALT) 
LRM  Line Replaceable Module 
LRRA  (See RALT) 
LRU  Line Replaceable Unit 
LSB  (1) Lower Sideband. The lower sideband is the differ-