Definition
The lowest published altitude on an RNAV (area navigation) route segment that guarantees both adequate obstacle clearance and acceptable navigation signal reception or RNAV system performance for the entire segment between the two fixes that bound it. On high-altitude charts, an RNAV Route MEA is identified by the route designator with the prefix Q (e.g., Q-145) and is shown alongside other charted altitudes for the segment.
Plain English
The lowest altitude you are allowed to fly on a particular RNAV (GPS-based) route segment. At or above this altitude, you are guaranteed to clear terrain and obstacles and to have reliable navigation along that segment.
Context Anchor
Seen on IFR en route charts beside published RNAV route segments, including high-altitude en route charts.
Derivation
RNAV stands for area navigation, meaning navigation along any desired path rather than only between ground-based stations. MEA combines 'minimum,' 'en route' (from French, meaning 'on the way'), and 'altitude.' Together the term means: the floor altitude for travelling along an RNAV route.
Why Pilots Care
Sets the floor for safe IFR operations on RNAV routes, directly affecting route selection, fuel planning, and terrain avoidance.
Intuition Check
Do not read “minimum” as “best” or “normal.” It means the lowest published altitude for that RNAV route segment; higher altitudes may still be assigned or chosen. Also, it applies to a published RNAV route segment, not to any direct path a pilot creates in the navigator.
Example Sentence 1
Cleveland Center cleared us to climb to the RNAV Route MEA before joining Q-145.
Example Sentence 2
The chart showed a higher RNAV Route MEA on the alternate airway, so we stayed on the primary route.