What does MSA stand for, and what is its typical radius?

The correct choice indicates that MSA stands for Minimum Safe Altitude, which is a critical concept in aviation, particularly concerning navigation and safety protocols. The Minimum Safe Altitude refers to the lowest altitude at which an aircraft can fly while ensuring safe clearance over obstacles in the vicinity, thereby reducing the risk of collisions with terrain or other hazards.

The specified radius of 25 nautical miles is typically associated with how air traffic management systems determine safe operational altitudes during approaches and departures from airports. This radius is important for ensuring that an aircraft remains at a safe elevation when flying near busy airspace and especially when dealing with potential obstructions.

In contrast, the other options present either incorrect definitions or incorrect altitude measurements typically associated with different aviation terms. These inaccuracies emphasize the importance of ensuring clarity in definitions and measurements within aviation contexts to maintain safety standards.