Definition
On a precision instrument approach, the specified height above the runway touchdown zone at which the pilot must decide to either continue the approach to land or execute a missed approach. The decision is based on whether the required visual references for the intended runway are distinctly visible and identifiable. DH is referenced to the height above touchdown (HAT) and is read from the radio altimeter or barometric altimeter as specified on the approach chart.
Plain English
On certain instrument approaches, this is the exact height above the runway where the pilot must look up and decide: can I see the runway clearly enough to land, or do I have to climb away and try again? If the runway isn't visible at that height, the pilot must go around.
Context Anchor
Seen on instrument approach procedures, especially precision approaches such as an ILS, where the pilot is descending toward the runway using cockpit instruments.
Derivation
The name describes itself directly: the height at which a decision is made. Worth noting that 'height' here is deliberate — it means height above the runway touchdown zone, not altitude above sea level. That distinction matters on the approach chart.
Why Pilots Care
It is the last safe opportunity to confirm landing conditions before committing to touchdown or initiating a missed approach.
Intuition Check
Do not read “decision” as a flexible judgment point where the pilot can keep easing lower to take another look. At decision height, the required visual references are either there and adequate, or the pilot must go missed.
Example Sentence 1
Approaching the DH of 200 feet, the pilot saw the approach lights and continued to land.
Example Sentence 2
With no runway visible at decision height, the crew executed the missed approach procedure.