Maneuverability.  Ability of an aircraft to change directions  along a flight path and withstand the stresses imposed upon it.  Maneuvering speed (V$_{A}$).  The design maneuvering speed.  Operating at or below design maneuvering speed does not  provide structural protection against multiple full control  inputs in one axis or full control inputs in more than one  axis at the same time.  Manifold absolute pressure.  The absolute pressure of the  fuel/air mixture within the intake manifold, usually indicated  in inches of mercury.  MAP.  See missed approach point.  Margin identification.  The top and bottom areas on an  instrument approach chart that depict information about  the procedure, including airport location and procedure  identification.  Marker beacon.  A low-powered transmitter that directs its  signal upward in a small, fan-shaped pattern. Used along the  flight path when approaching an airport for landing, marker  beacons indicate both aurally and visually when the aircraft  is directly over the facility.  Mass.  The amount of matter in a body.  Maximum altitude.  An altitude depicted on an instrument  approach chart with overscored altitude value at which or  below aircraft are required to maintain altitude.  Maximum authorized altitude (MAA).  A published altitude  representing the maximum usable altitude or flight level for  an airspace structure or route segment.  Maximum landing weight.  The greatest weight that an  airplane normally is allowed to have at landing.  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.  Maximum takeoff weight.  The maximum allowable weight  for takeoff.  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.  Military operations area (MOA).  Airspace established for  the purpose of separating certain military training activities  from IFR traffic.  Mileage breakdown.  A fix indicating a course change  that appears on the chart as an “x” at a break between two  segments of a federal airway.  Microwave landing system (MLS).  A precision instrument  approach system operating in the microwave spectrum which  normally consists of an azimuth station, elevation station,  and precision distance measuring equipment.  Microburts.  A strong downdraft which normally occurs  over horizontal distances of 1 NM or less and vertical  distances of less than 1,000 feet. In spite of its small  horizontal scale, an intense microburst could induce  windspeeds greater than 100 knots and downdrafts as strong  as 6,000 feet per minute.  MB.  See magnetic bearing.  MCA.  See minimum crossing altitude.  MDA.  See minimum descent altitude.  MEA.  See minimum en route altitude.  Mean aerodynamic chord (MAC).  The average distance  from the leading edge to the trailing edge of the wing.  Mean sea level.  The average height of the surface of the  sea at a particular location for all stages of the tide over a  19-year period.  MEL.  See minimum equipment list.  Meridians.  Lines of longitude.  Mesophere.  A layer of the atmosphere directly above the  stratosphere.  METAR.  See Aviation Routine Weather Report.  MFD.  See multi-function display.  MH.  See magnetic heading.  MHz.  Megahertz.  G-19 