HOW DO I USE A VDP?

What is a VDP?

VDP stands for Visual Descent Point. It is a defined point on a straight-in, non-precision approach from which a normal descent from the MDA to the runway touchdown point may be commenced, as long as you have the required visual reference. If a VDP is available, it will be indicated by a bold letter "v" on the profile view portion of the approach chart.

What is the purpose of a VDP?

The VDP enhances flight safety by encouraging pilots to fly more stabilized approaches during the final portion of non-precision approaches. Upon reaching the VDP at the MDA, the pilot has a few options:

Option 1: Continue normal descent to landing, if visual with runway (ideal situation).
Option 2: Continue flying at or above MDA until the missed approach point.
Option 3: Commence missed approach at VDP (though it is not required).

Option 1 - In an ideal scenario, the pilot is visual with the runway at the VDP and MDA. From there, a normal descent (typically on a 3° glideslope) to landing can be made. This is the best case scenario and what we would call a "stabilized approach".

Option 2 - When a pilot elects to take this option (i.e. continue flying approach at MDA while not visual with the runway), safety margins are reduced. Referencing the sample approach above, imagine that the runway only becomes visual at 0.5nm, while the pilot is accurately maintaining the MDA (480 ft in this case). That would equate to more than twice the steepness of a normal approach. At that point, the pilot has to make a split-second decision on whether to descent for landing, or initiate a missed approach. A pilot who chooses to attempt the landing may end up with an excessively steep approach, a high approach speed or eat up a significant amount of runway before touching down - all of which may contribute to an unsafe landing in weather conditions that are probably less than ideal.

Option 3 - Making use of the VDP to take this option (i.e. commence missed approach) is often a more prudent course of action as it can help pilots to avoid making a bad decision in a high-stress, high-workload situation. Imagine a pilot who has been flying in bad weather, perhaps coming in to land at his home base after a long flight. When he sees the runway, there will be a strong temptation to come in for the landing, even if though the aircraft may be at an excessively steep approach angle. This is the situation we are hoping to avoid through the use of the VDP.

What if no VDP is published on the chart?

If a non-precision approach chart does not show a VDP, it likely means that there is terrain or obstacles within the visual segment of the approach. In such instances, the pilot may still determine a VDP using this rule of thumb: Height Above Touchdown (HAT) or Minimum Descent Height (MDH), divided by 300 (for a 3° glideslope). That would provide the location of the VDP in relation to the touchdown point, and aid in the execution of a stabilized approach. However, the pilot must ensure that there is sufficient visibility to see and avoid obstacles or terrain all the way to landing.


(Refer to AIM 5-4-5 for more information)