Which altitude is specifically intended to ensure obstacle clearance during en route flight?

• A. Minimum En Route Altitude
• B. Minimum Elevation Altitude
• C. Mean En Route Altitude
• D. Maximum En Route Altitude

Answer: (A)

Obstacle clearance along an IFR en route segment is ensured by the minimum en route altitude. This is the lowest published altitude between navigation fixes that guarantees safe clearance above terrain and man-made obstacles, while also typically allowing reliable navigation signal reception along the route. Because the question focuses on obstacle clearance during en route flight, this altitude is the best fit.

The other terms don’t apply here: mean en route altitude isn’t a standard designation for this purpose, maximum en route altitude refers to the top of the operational range rather than clearance, and minimum elevation altitude isn’t a recognized term used for en route obstacle protection. (For context, MOCA also ensures obstacle clearance but only within a certain distance of a VOR and doesn’t guarantee navigation reception beyond that.)