Definition
A specified altitude in a precision approach or approach with vertical guidance at which the pilot must decide whether to continue the approach to landing or execute a missed approach. The decision must be made by the time the aircraft reaches this altitude, and it is referenced to mean sea level (MSL).
Plain English
On certain instrument approaches, this is the altitude at which the pilot has to make the call: keep going and land, or go around. It is read directly off the altimeter because it is measured from sea level.
Context Anchor
Seen on instrument approach charts, including RNAV approach charts, in the minimums section for approaches that provide vertical guidance.
Derivation
From Latin decidere, meaning 'to cut off' or 'determine' — the point at which a choice must be cut off and made. 'Altitude' comes from Latin altus, 'high.' Together: the height at which the decision can no longer be delayed.
Why Pilots Care
It prevents descent below a safe altitude without visual confirmation of the runway, reducing the risk of controlled flight into terrain in low visibility.
Grounding Statement
As the altimeter reaches DA, the pilot must already be ready to either continue visually to land or begin the missed approach.
Intuition Check
Do not treat decision altitude as a place to pause and think it over. The decision must be made and acted on at that altitude; also, DA is an altitude shown on the altimeter, not simply a height above the runway.
Example Sentence 1
Approaching DA on the ILS, the captain called 'minimums' and, with the runway in sight, continued to land.
Example Sentence 2
Reaching decision altitude with no runway in sight, the pilot immediately initiated the missed approach.