MSA stands for which altitude term?

• A. Mean Safe Altitude
• B. Maximum Safe Altitude
• C. Mean Sea Altitude
• D. Minimum Safe Altitude

Answer: (D)

MSA refers to the minimum safe altitude. This is the lowest altitude you can fly within a defined area around a navigation aid that guarantees obstacle clearance from terrain and obstacles. Typically this area is a certain radius around the VOR or other navaid, and the altitude provides at least 1000 feet of clearance in flat terrain (2000 feet in mountainous areas). This safety margin lets you descend or proceed with confidence on approaches or while navigating near the navaid, even if visibility is poor. Other terms like mean safe altitude, maximum safe altitude, or mean sea altitude aren’t standard aviation terms for this purpose, while mean sea level is simply a reference datum. The correct concept is minimum safe altitude.