ence in frequency between the AM carrier signal and
the modulation signal.
(2) Least Significant Bit
LSD Least Significant Digit
LSI Large Scale Integration
LSK Line Select Key
LTP Left Top Plug. Identifies the plug on the rear connec-
tor of an avionics unit.
Lubber Line A fixed line placed on an indicator to indicate the
front-to-rear axis of the aircraft.
LV Lower Sideband Voice
LVDT Linear Voltage Differential Transducer (used with air-
craft control surface servos)
LVLCH Level Change
LVPS Low Voltage Power Supply
M
m Meter m/s Meter per Second MAC Medium Access Controller Mach Number Mach number is the ratio of the true airspeed to the
speed of sound at a particular flight condition. It is the chief criterion of airflow pattern and is usually represented by the free-stream steady-state value.
Mag Magnetic
Magnetic The bearing with respect to magnetic north.
Bearing
Magnetic The direction north as determined by the earth’s mag
North netic field. The reference direction for measurement
of magnetic directions.
MAMS Military Airspace Management System
MAR Managed Arrival Reservoir
Marker A transmitter operating at 75 MHz that provides iden
Beacon tification of a particular position along an airway or
on the approach to an instrument runway. The mark
er beacon is continuously tone-modulated by a 400-
Hz,a 1300-Hz or a 3000-Hz tone. Marker beacons
along an instrument runway provide along-course
(range) guidance and designate when an aircraft
should be at a certain altitude if the aircraft is follow
ing the glidepath.
MASPS Minimum Aviation System Performance Standards
MAT Maintenance Access Terminal
MAWP Missed Approached Waypoint
MB Marker Beacon
MBE Multiple Bit Error
MC Master Change
MCB Microwave Circuit Board
MCC Maintenance Control Computer
MCDP Maintenance Control Display Panel
MCDU Multifunctional Control Display Unit
MCN Manufacturing Control Number
MCP (1) Maintenance Control Panel
(2) Mode Control Panel
MCT Max Continuous Thrust
MCU (1) Modular Concept Unit (approximately 1/8-ATR,
Airline Transport Rack)
(2) Multifunction Concept Unit
MD11 Boeing Model 11 Aircraft (formerly McDonnell
Douglas)
MD90 Boeing Model 90 Aircraft (formerly McDonnell
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