Expert: David Bidwell - 8/10/2007

Question
Why do some approach plates have visual decent points and some don't?

Answer
Hi Kyle,
I think that the best way to answer your question is to clarify just what a VDP is.
Visual descent points (VDPs) provide pilots with a reference for the optimal location to begin descent from the MDA, based on the designed vertical descent angle (VDA) for the approach procedure, assuming required visual references are available. Approaches without VDPs have not been assessed for terrain clearance below the MDA, and may not provide a clear vertical path to the runway at the normally expected descent angle. Therefore, pilots must be especially vigilant when descending below the MDA at locations without VDPs. This does not necessarily prevent flying the normal angle; it only means that obstacle clearance in the visual segment could be less and greater care should be exercised in looking for obstacles in the visual segment. Use of visual glide slope indicator (VGSI) systems can aid the pilot in determining if the aircraft is in a position to make the descent from the MDA. However, when the visibility is close to minimums, the VGSI may not be visible at the start descent point for a "normal" glidepath, due to its location down the runway. VDP's are intended to provide additional guidance where they are implemented. Pilots not equipped to receive the VDP (DME) should fly the procedure as though no VDP has been provided.
Hope this helps,
Dave