Definition
The lowest altitude, expressed in feet above mean sea level (MSL), to which a pilot is authorized to descend during a non-precision instrument approach when no electronic glideslope is provided. The aircraft may not descend below this altitude unless the required visual references for the runway are in sight and the aircraft is in a position to land using normal maneuvers.
Plain English
On an instrument approach without a glideslope, this is the lowest you are allowed to go until you can actually see the runway environment. If you cannot see it by then, you stay at that altitude and fly the missed approach.
Context Anchor
Seen on instrument approach charts and briefed before starting an approach in low visibility.
Derivation
From Latin minimus (smallest) and descendere (to climb down). The phrase together names the smallest altitude to which descent is permitted. Knowing the literal meaning helps reinforce that this is a hard floor, not a target.
Why Pilots Care
Reaching MDA without visual contact with the runway requires an immediate missed approach, directly affecting safety and landing decisions.
Grounding Statement
Picture descending through cloud toward an airport: the minimum descent altitude is the floor you must not pass unless you can see enough outside to land safely.
Intuition Check
Do not treat minimum descent altitude as a goal to descend through. It is a lower limit: you may go down to it, but not below it until the landing requirements are met.
Example Sentence 1
The crew leveled off at the minimum descent altitude and, with the runway environment in sight, continued the approach to land.
Example Sentence 2
Because the airport remained obscured at the minimum descent altitude, the crew executed the published missed approach procedure.