Limit load factor.  Amount of stress, or load factor, that an  aircraft can withstand before structural damage or failure  occurs.  Maneuvering speed (V$_{A}$).  The maximum speed where full,  abrupt control movement can be used without overstressing  the airframe.  Load factor.  The ratio of the load supported by the airplane’s  wings to the actual weight of the aircraft and its contents.  Also referred to as G-loading.  Manifold pressure (MP).  The absolute pressure of the fuel/ air mixture within the intake manifold, usually indicated in  inches of mercury.  Longitudinal axis.  An imaginary line through an aircraft  from nose to tail, passing through its center of gravity. The  longitudinal axis is also called the roll axis of the aircraft.  Movement of the ailerons rotates an airplane about its  longitudinal axis.  Maximum allowable takeoff power.  The maximum power  an engine is allowed to develop for a limited period of time;  usually about one minute.  Maximum landing weight.  The greatest weight that an  airplane normally is allowed to have at landing.  Longitudinal stability (pitching).  Stability about the lateral  axis. A desirable characteristic of an airplane whereby it tends  to return to its trimmed angle of attack after displacement.  Maximum ramp weight.  The total weight of a loaded  aircraft, including all fuel. It is greater than the takeoff  weight due to the fuel that will be burned during the taxi  and runup operations. Ramp weight may also be referred to  as taxi weight.  Mach.  Speed relative to the speed of sound. Mach 1 is the  speed of sound.  Maximum takeoff weight.  The maximum allowable weight  for takeoff.  Mach buffet.  Airflow separation behind a shock-wave  pressure barrier caused by airflow over flight surfaces  exceeding the speed of sound.  Mach compensating device.  A device to alert the pilot  of inadvertent excursions beyond its certified maximum  operating speed.  Maximum weight.  The maximum authorized weight of  the aircraft and all of its equipment as specified in the Type  Certificate Data Sheets (TCDS) for the aircraft.  Maximum zero fuel weight (GAMA).  The maximum  weight, exclusive of usable fuel.  Mach critical.  The Mach speed at which some portion of the  airflow over the wing first equals Mach 1.0. This is also the  speed at which a shock wave first appears on the airplane.  Minimum controllable airspeed.  An airspeed at which any  further increase in angle of attack, increase in load factor,  or reduction in power, would result in an immediate stall.  Mach tuck.  A condition that can occur when operating a  swept-wing airplane in the transonic speed range. A shock  wave could form in the root portion of the wing and cause  the air behind it to separate. This shock-induced separation  causes the center of pressure to move aft. This, combined  with the increasing amount of nose down force at higher  speeds to maintain left flight, causes the nose to “tuck.” If  not corrected, the airplane could enter a steep, sometimes  unrecoverable dive.  Minimum drag speed (L/D$_{MAX}$).  The point on the total  drag curve where the lift-to-drag ratio is the greatest. At this  speed, total drag is minimized.  Mixture.  The ratio of fuel to air entering the engine’s  cylinders.  M$_{MO}$.  Maximum operating speed expressed in terms of a  decimal of Mach speed.  Magnetic compass.  A device for determining direction  measured from magnetic north.  Moment arm.  The distance from a datum to the applied  force.  Main gear.  The wheels of an aircraft’s landing gear that  supports the major part of the aircraft’s weight.  Moment index (or index).  A moment divided by a constant  such as 100, 1,000, or 10,000. The purpose of using a moment  index is to simplify weight and balance computations of  airplanes where heavy items and long arms result in large,  unmanageable numbers.  Maneuverability.  Ability of an aircraft to change directions  along a flightpath and withstand the stresses imposed upon it.  G-11 M