Minimum descent altitude (MDA) defines what?

• A. The altitude above the runway.
• B. The minimum descent altitude for precision approaches only.
• C. The lowest altitude to which descent is authorized on final approach for nonprecision approaches.
• D. The altitude of the final approach fix.

Answer: (C)

Minimum descent altitude is the lowest altitude to which you are authorized to descend on the final approach segment of a nonprecision approach. You descend to this altitude and level off there, staying at or above it until you have the runway environment in sight and can land safely. If you do not have the required visual references by the time you reach MDA, you must execute a missed approach. This concept applies specifically to nonprecision approaches; precision approaches use a decision altitude/height at which you must decide to land or go around. The MDA is published on the approach plate (typically in feet MSL) and is used to determine how low you can descend on the final approach while still maintaining adequate clearance until you can land.