Definition
The lowest published altitude between two navigation fixes on an airway or route segment that guarantees both acceptable navigation signal coverage and required obstacle clearance for that segment.
Plain English
The lowest altitude you're allowed to fly along a given stretch of an airway. Fly it or higher, and you're guaranteed to clear the terrain and still pick up the navigation signals you need.
Context Anchor
You see MEA on instrument en route charts, usually along an airway or published route segment between named navigation points.
Derivation
‘En-route’ comes from the French for ‘on the way’ — the part of the flight between departure and arrival. So Minimum En-route Altitude is simply the lowest altitude you can fly while ‘on the way’ along that route.
Why Pilots Care
Flying below the MEA risks loss of navigation signals or terrain conflict on IFR routes.
Intuition Check
Do not read “minimum” as “lowest altitude that might work.” MEA means the lowest published altitude that has been checked for both obstacle clearance and navigation signal coverage on that route segment.
Example Sentence 1
The MEA on this segment of V23 is 7,000 feet, so we'll plan to cruise at 9,000.
Example Sentence 2
We climbed to the published MEA to maintain continuous VOR reception.