DA/DH

DA (Decision Altitude) and DH (Decision Height) refer to the specified altitude or height during a precision approach at which a missed approach must be initiated if the required visual references for the runway have not been established.

• DA: Referenced to mean sea level (MSL)
• DH: Referenced to the runway threshold elevation

Typical values: CAT I ILS = 200 ft DH, CAT II = 100 ft DH, CAT IIIA = 50 ft DH or none. The pilot must decide at this point — no further descent is permitted without visual contact.