Instrument Flight
Glossary
Maximum Altitude (Instrument Approach): The MSL altitude above a geographical location which an
aircraft may not exceed during a portion of an instrument approach. The requirement for a maximum
altitude may be created by airspace separation criteria. On an approach plate, a maximum altitude is
depicted by a number with a line above it.
MDA: See Minimum Descent Altitude.
MEA: See Minimum Enroute Altitude.
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 ft 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-foot 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.
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