The concept of VDP

Visual descent point

A concept related to the missed approach point is the Visual Descent Point, or VDP. This is a point on the MDA of a non-precision approach profile, from where the aircraft would be able to continue its descent to the runway threshold while maintaining a standard 3° descent angle. 

The concept of VDP was developed by the FAA to allow pilots to decide to initiate a missed approach even prior to reaching the MAP, in a situation where the runway or its environment is not visible at a 'normal' descent angle. 

Conversely, if the runway is visible at the VDP, the pilot may continue, following a standard descent angle to the runway. The VDP is always farther from the runway threshold than the MAP.

The following is the U.S. FAA's official definition of VDP:

"A defined point on the final approach course of a non precision straight-in approach procedure from which normal descent from the MDA to the runway touchdown point may be commenced, provided the approach threshold of that runway, or approach lights, or other markings identifiable with the approach end of that runway are clearly visible to the pilot."