Definition
The lowest height, expressed in feet above a specified reference (typically the airport or runway threshold elevation), to which a pilot is authorized to descend on a non-precision instrument approach without acquiring the required visual references for the runway environment. Below MDH, descent is permitted only if the visual cues required by regulation are visible and the aircraft is in a position to land safely.
Plain English
The lowest you are allowed to descend on a non-precision approach unless you can actually see the runway or its required visual cues. If you reach that height and still cannot see what you need, you must level off and not go any lower.
Context Anchor
Seen in instrument approach procedures and instrument training, especially when discussing descent limits on approaches that do not give a full glidepath to the runway.
Derivation
Minimum means the lowest allowed. Descent refers to going down. Height, in aviation, specifically means distance above a chosen reference point on the ground (such as the airport), as opposed to altitude, which is measured from sea level. The term emphasizes that the value is referenced to the ground below, not to sea level.
Why Pilots Care
It sets the hard altitude limit that prevents descent into terrain or obstacles when the runway is still hidden by weather.
Grounding Statement
Think of MDH as the lowest safe height you are allowed to descend to while still relying mainly on instruments during that approach.
Intuition Check
Do not read “height” here as the same thing as altitude above sea level. MDH is measured above a specified local reference, such as an airport or runway reference point. “Minimum” does not mean you must descend to it; it means you must not go below it unless the required conditions are met.
Example Sentence 1
On the non-precision approach into the destination, the crew leveled off at the MDH and began searching for the runway lights.
Example Sentence 2
When the airport remained obscured at MDH, the crew immediately executed the published missed approach.