Definition
The lowest published altitude on an RNAV (area navigation) airway or route segment that ensures both adequate obstacle clearance and acceptable navigation signal coverage for RNAV-equipped aircraft along that segment. It is depicted on en route charts with the suffix 'G' (for GNSS) next to the altitude value, indicating the route is based on GPS or other RNAV systems rather than ground-based navaids.
Plain English
The lowest height you are allowed to fly along an RNAV route, set so you stay safely above terrain and obstacles and your navigation system still works reliably along that leg.
Context Anchor
Seen on IFR en route charts and in instrument flight planning when choosing or checking altitudes for published RNAV route segments.
Derivation
RNAV stands for Area Navigation -- a method that lets aircraft fly any desired path, not just airways between ground stations. 'Minimum En Route Altitude' simply means the lowest altitude allowed while en route along that segment. Together: the lowest legal cruise altitude on an RNAV-defined route.
Why Pilots Care
It guarantees both navigation signal reception and terrain clearance on RNAV routes, directly affecting route usability and safety.
Intuition Check
Minimum does not mean recommended or comfortable; it means the lowest published altitude that still meets the required protection for that exact route segment. It also does not apply to nearby off-route flying.
Example Sentence 1
Cruising eastbound on the Q-route, the pilot leveled at the RNAV minimum en route altitude shown on the chart.
Example Sentence 2
The chart showed the RNAV Minimum En Route Altitude rising to 6,000 feet over the mountains.