Definition
On a precision instrument approach, the specified height at which the pilot must decide whether to continue the approach to landing or execute a missed approach. Decision Height (DH) is referenced to height above the runway threshold or touchdown zone (measured by the radio altimeter), while Decision Altitude (DA) is referenced to mean sea level (read from the barometric altimeter). At this point, the required visual references for the runway must be in sight to continue; if not, the pilot must immediately go missed.
Plain English
It's the point during a precision approach where the pilot must look outside and decide: can I see enough of the runway to land, or do I need to go around? If the runway environment isn't visible at that point, the approach must be abandoned.
Context Anchor
Seen on instrument approach charts and used during approaches flown in clouds, low visibility, or other conditions where the runway may not be visible until late in the approach.
Derivation
Decision because that is the literal moment of commitment — land or go around. Altitude is measured from sea level; height is measured above a local reference (the runway). The two terms exist because different equipment measures the aircraft's vertical position differently: the barometric altimeter gives altitude above sea level, while a radio altimeter gives height above the ground directly below.
Why Pilots Care
Ensures pilots do not descend below a safe height without visual confirmation of the runway, preventing accidents in poor weather.
Grounding Statement
At DH, the aircraft is close enough to the ground that the pilot must have the runway area in sight before continuing down.
Intuition Check
DH is not a suggestion or a good place to start thinking about the decision. It is the published point where the decision must already be made: continue only if the required visual references are visible, otherwise go missed.
Example Sentence 1
At decision height, the runway lights came into view, so the captain continued the approach to landing.
Example Sentence 2
When the runway was not visible at DH the crew executed the missed approach without delay.