8/15/19  Pilot/Controller Glossary  ridge of a sharp bluff area. As the air hits the upwind  side of the range, it starts to climb, thus creating what  is generally a smooth updraft which turns into a  turbulent downdraft as the air passes the crest of the  ridge. Mountain waves can cause significant  fluctuations in airspeed and altitude with or without  associated turbulence.  (Refer to AIM.)  MOVEMENT AREA- The runways, taxiways, and  other areas of an airport/heliport which are utilized  for taxiing/hover taxiing, air taxiing, takeoff, and  landing of aircraft, exclusive of loading ramps and  parking areas. At those airports/heliports with a  tower, specific approval for entry onto the movement  area must be obtained from ATC.  (See ICAO term MOVEMENT AREA.)  MOVEMENT AREA [ICAO]- That part of an  aerodrome to be used for the takeoff, landing and  taxiing of aircraft, consisting of the maneuvering area  and the apron(s).  MOVING TARGET INDICATOR- An electronic  device which will permit radar scope presentation  only from targets which are in motion. A partial  remedy for ground clutter.  MULTICOM- A mobile service not open to public  correspondence used to provide communications  essential to conduct the activities being performed by  or directed from private aircraft.  MULTIPLE RUNWAYS- The utilization of a  dedicated arrival runway(s) for departures and a  dedicated departure runway(s) for arrivals when  feasible to reduce delays and enhance capacity.  MRA- MSA- MSAW- MTI- MTR- (See MINIMUM RECEPTION ALTITUDE.)  (See MINIMUM SAFE ALTITUDE.)  (See MINIMUM SAFE ALTITUDE WARNING.)  (See MOVING TARGET INDICATOR.)  (See MILITARY TRAINING ROUTES.)  MVA- (See MINIMUM VECTORING ALTITUDE.)  PCG M-6 