Definition
The lowest published altitude on an airway, route segment, or other IFR route that guarantees both acceptable navigation signal coverage and required obstacle clearance between the two fixes that bound the segment.
Plain English
The lowest altitude you are allowed to fly on this leg of an IFR route. At or above this altitude, you are guaranteed to clear the terrain and obstacles below, and your navigation radios will receive a usable signal the whole way to the next fix.
Context Anchor
Seen on IFR en route charts along published route segments, especially when planning or flying an instrument route.
Derivation
‘En route’ comes from French, meaning ‘on the way.’ So MEA is literally the minimum altitude ‘on the way’ between two fixes — the floor for that leg of the journey.
Why Pilots Care
It lets pilots maintain safe IFR navigation while guaranteeing both obstacle clearance and reliable navigation signals.
Intuition Check
Do not read MEA as just the lowest comfortable altitude. It is the lowest published altitude for that route segment that satisfies both obstacle clearance and navigation signal coverage.
Example Sentence 1
The MEA on the airway segment from BOLER to KEMPR is 6,000 feet, so we filed for 8,000.
Example Sentence 2
The MEA on this segment is higher than the MOCA because we need reliable signal coverage the entire way.