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. 

## MRA- 

(See MINIMUM RECEPTION ALTITUDE.) 

## MSA- 

(See MINIMUM SAFE ALTITUDE.) 

## MSAW- 

(See MINIMUM SAFE ALTITUDE WARNING.) 

## MTI- 

(See MOVING TARGET INDICATOR.) 

## MTR- 

(See MILITARY TRAINING ROUTES.) 

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. 

## MVA- 

(See MINIMUM VECTORING ALTITUDE.) 

