Minimum reception altitude

Minimum reception altitude (MRA). The lowest altitude at which an airway intersection can be determined.

Minimum reception altitude
S
Standard Instrument Departure
Standard Terminal Arrival Route ...

MRA--Minimum reception altitude is lowest at which an intersection can be determined.
MEA--Minimum en route altitude is lowest altitude between navaids that gives both obstacle clearance and signal coverage.

See also: Navigation, Clearance, Obstacle, Flight, Altitude