Instrument Flight
Glossary
Military Operations Area (MOA): An airspace area established for the purpose of segregating certain
military training activities from airspace containing IFR aircraft. Nonparticipating IFR traffic may be
cleared through an active MOA if ATC can provide adequate IFR separation.
Minimum Descent Altitude (MDA): The lowest altitude, expressed in feet MSL, to which descent is
authorized on final approach or during a circling-to-land maneuver in the execution of a published non-
precision approach procedure.
Minimum Enroute Altitude (MEA): The altitude established between NAVAIDs or reporting points on
airways, air routes, or advisory routes that meets obstruction clearance requirements and assures
acceptable NAVAID signal reception.
Minimum Fuel: Indicates that the aircraft’s fuel supply has reached a state that, upon reaching the
destination, the pilot can accept little or no delay. This advisory does not reflect an emergency situation
but merely indicates an emergency situation is possible should any undue delay occur.
Minimum Safe Altitude (MSA): An altitude, expressed in 100-ft increments, providing 1,000 ft of
clearance over all obstructions/terrain within a 25-mile radius of the NAVAID on which the instrument
approach is centered.
Minimum Vectoring Altitude (MVA): The lowest MSL altitude at which an IFR aircraft will be vectored
by a radar controller, except as otherwise authorized for radar approaches, departures, and missed
approaches.
Missed Approach: A maneuver conducted by a pilot when an instrument approach cannot be completed
to a landing.
Missed Approach Point (MAP): A point on an instrument approach at which you must execute missed
approach procedures if you have not established the visual references required for landing.
MOA: See Military Operations Area.
MSA: See Minimum Safe Altitude.
N
Navigational Aid (NAVAID): An electronic device that provides position data to an aircraft.
Non-Precision Approach: A standard instrument approach where no electronic glideslope is provided,
e.g., VOR, TACAN, or ASR approaches.
P
PAR: Precision approach radar.
Penetration: That portion of a published high altitude terminal instrument approach that prescribes the
descent path from the fix on which the procedure is based to a fix or altitude from which an approach to
the airport is made.
Planimetric Course Line: A course line that is drawn through the TACAN, waypoint, or waypoint offset
symbol. Course intercept angle and deviation are shown by the relationship of the Planimetric course line
to the aircraft symbol.
Platform: Defined as 5,000 ft AGL and comes from carrier operations. Point at which speed brakes are
retracted and rate of descent is reduced to 2,000 fpm while maintaining 250 KIAS on a carrier-controlled
approach.
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