One more thing about VDP
In addition to the previous explanation I gave you before I would like to add one more thing. Keep in mind that the VDP is not part of the FAR (Federal Aviation Regulations) and is not mentioned under part 91.175 (Descent below MDA). Basically there´re only 3 critirias that should met to legally descend below the MDA: 1) The flight visibilty (determined by the pilot) should not be less than the one prescribed in the approach procedure, 2) The pilot should be able to land the airplane on the runway using NORMAL maneuvers and normal rate of descent and, for part 121,135operations the pilot should be able to land on the Touch Down Zone (First 3,000 feet of the runway).3)At least one of 10 visual references mentioned in part91.175 are visible to the pilot, for example: The touch down zone markings,the runway lights, the threshold etc. Basically descending below MDA prior to reaching the VDP does not mean breaking the FARs but if you have the means of identifying the VDP (DME for example) it´s recommended not to leave the MDA prior to reaching the VDP since it provides you with a 3 degrees slope to the runway touch down zone i.e NORMAL RATE OF DESCENT FOR LANDING Hope I made things clearer.
