What does MEA (minimum enroute altitude) protect, and why is it important?

• A. It guarantees obstacle clearance only at sector boundaries.
• B. It is the minimum altitude for flight above sea level.
• C. It determines the maximum allowable altitude on a given route.
• D. It guarantees obstacle clearance and reliable reception of navigation aids along a route; used for safe enroute navigation.

Answer: (D)

MEA is the lowest altitude you can fly on an enroute segment that guarantees two things: you have enough clearance above terrain and obstacles, and you can reliably receive the navigation signals needed to follow the airway. This dual protection is what makes MEA essential for safe enroute IFR flight. If you drop below MEA, you risk hitting obstacles or losing confidence in your navigation cues, since you might not be able to identify or track the route accurately. The MEA isn’t simply about being above sea level or about a maximum altitude; it’s about maintaining obstacle clearance and dependable nav aid reception along the route. For contrast, MOCA also protects obstacle clearance but guarantees navigation reception only within 100 miles of a VOR, whereas MEA ensures nav guidance along the route more broadly.