Definition
The lowest published altitude between radio fixes on an airway, route, or route segment that ensures acceptable navigation signal coverage and meets obstacle clearance requirements between those fixes.
Plain English
The lowest altitude you're allowed to fly along a published route, set so you'll stay clear of terrain and obstacles and still receive the navigation signals needed to follow the route.
Context Anchor
Seen on IFR en route charts and in instrument procedure discussions when deciding the minimum usable altitude for a published route segment.
Derivation
The name describes itself: 'minimum' (the floor), 'en route' (between airports, on an airway), 'altitude' (height above sea level). The phrase tells you exactly what it does.
Why Pilots Care
Ensures safe navigation signal reception and obstacle clearance on designated IFR routes, directly affecting route and altitude choices.
Intuition Check
Do not read MEA as just “minimum safe height.” It means the published minimum altitude that covers both obstacle clearance and navigation signal reception for that route segment.
Example Sentence 1
ATC cleared us to descend to the MEA of 8,000 feet on the next airway segment.
Example Sentence 2
After crossing the fix the MEA steps up to 7000 feet because of higher terrain ahead.