What is the specified altitude below which descent must not be made without visual reference?

The specified altitude below which descent must not be made without visual reference is referred to as Minimum Descent Altitude (MDA). This is a critical concept in aviation safety, particularly during instrument approaches. MDA is established during an instrument approach procedure and indicates the lowest altitude to which a pilot can descend without having visual reference to the runway or landing area.

If a pilot reaches the MDA and does not have visual reference, they are required to execute a missed approach, as continuing to descend could lead to unsafe situations, including a potential loss of control or terrain collision. This altitude ensures that the pilot has adequate time and space to safely navigate and, if necessary, to transition to a missed approach.

In contrast, Decision Altitude (DA), while also relevant to approaches, specifically pertains to precision approaches where a decision must be made at that altitude—whether to continue to land or go around based on visual confirmation. Landing Decision Altitude is another term that may be used interchangeably with Decision Altitude in some contexts, primarily during precision approaches. The Defined Point of Landing Altitude does not represent a standard defined term within aviation regulations or practices.