Which statement correctly differentiates MEA and MSA?

Which statement correctly differentiates MEA and MSA?

• A. MEA is the altitude for an en-route segment that provides adequate reception of navigational facilities and ATS communications
• B. MSA is the altitude that provides 1000 ft obstacle clearance within 50 NM of the leg
• C. MEA equals MSA
• D. MSA stands for Minimum Safe Altitude

Answer: (A)

The point being tested is how MEA and MSA differ in what they guarantee for flight planning and safety. MEA (Minimum Enroute Altitude) is the lowest altitude on an enroute segment that ensures two things: obstacle clearance along the route and reliable reception of navigation aids and ATC communications. In other words, it’s the altitude you can fly to maintain safe clearance and to be able to navigate and communicate properly while en route. MSA (Minimum Safe Altitude) serves a different purpose. It provides at least 1000 ft of obstacle clearance within a defined area around a navigation facility (typically within 25 nautical miles of the facility). It’s a safety figure for that area, helping you avoid terrain/obstacles in case you need to fly at a lower altitude there, but it does not guarantee navigation signal reception or ATC communications. So the best statement clarifies MEA as the enroute altitude that ensures adequate reception of navigational facilities and ATS communications, whereas MSA is the altitude that guarantees obstacle clearance within a surrounding sector (not about guarantee of nav/communications). The other options either get the distance wrong (not 50 NM), mix up what MSA guarantees, or mix up the acronyms.

The point being tested is how MEA and MSA differ in what they guarantee for flight planning and safety.

MEA (Minimum Enroute Altitude) is the lowest altitude on an enroute segment that ensures two things: obstacle clearance along the route and reliable reception of navigation aids and ATC communications. In other words, it’s the altitude you can fly to maintain safe clearance and to be able to navigate and communicate properly while en route.

MSA (Minimum Safe Altitude) serves a different purpose. It provides at least 1000 ft of obstacle clearance within a defined area around a navigation facility (typically within 25 nautical miles of the facility). It’s a safety figure for that area, helping you avoid terrain/obstacles in case you need to fly at a lower altitude there, but it does not guarantee navigation signal reception or ATC communications.

So the best statement clarifies MEA as the enroute altitude that ensures adequate reception of navigational facilities and ATS communications, whereas MSA is the altitude that guarantees obstacle clearance within a surrounding sector (not about guarantee of nav/communications). The other options either get the distance wrong (not 50 NM), mix up what MSA guarantees, or mix up the acronyms.