How many miles out is the MSA good to?

• A. 25 miles
• B. 30 miles
• C. 50 miles
• D. 75 miles

Answer: (A)

MSA shows the altitude you should stay at to stay clear of obstacles within a defined area around a navigation aid. On IFR charts, the Minimum Safe Altitude is laid out as a circle around a VOR (or other navaid) with a radius of 25 nautical miles. Within that 25 NM ring, you’re guaranteed obstacle clearance (usually 1000 feet over terrain in non-mountainous areas, more in mountainous terrain). So when the question asks how far out the MSA is good to, the standard answer is 25 nautical miles. If you’re thinking in statute miles, 25 NM is roughly 28.8 statute miles, but chart references use nautical miles, and the closest option shown is 25.