What is the term for the specified altitude at which a missed approach must be initiated during a 3D instrument approach?

The term for the specified altitude at which a missed approach must be initiated during a 3D instrument approach is known as "Decision Height." This is a critical point in an instrument approach where the pilot must decide whether to continue to the runway or execute a missed approach based on the visibility and whether the required visual reference to proceed to landing has been established.

At Decision Height, if the required visual references are not visible, the pilot is mandated to initiate the missed approach procedure to ensure safety and compliance with aviation regulations. This altitude is specifically determined for each approach based on the aircraft's performance, the approach's design, and relevant weather conditions.

The other terms listed, such as "Approach Height," "Reproach Height," and "Reference Height," do not specifically refer to the point of decision-making for a missed approach during an instrument approach, and thus are not recognized as standard terminology in aviation.