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VDP Visual Descent Point

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sinair

New member
Joined
Nov 26, 2001
Posts
3
Ok, I can't remember for the life of me how to determine a vdp. Please remind me. All help would be appreciated. Thanks,
Sin
 
VDP

Go to the "rules of thumb" section of this website (link at bottom of screen). There is a very detailed way of figuring out VDP there.

Mark
 
Sinair,

Probably the easiest is the old 300' per NM.

Example:

TDZE: 560

MDA: 1010

1010-560 = 450

450/300 = VDP of 1.5 NM

Of course you can save a little time and math by looking on the Jepps for the parenthetical number next to MDA, which of course is the AGL and divide it by 300 to give you the VDP. All this is based on the standard 3 deg. GS.
 
Also, if the missed approach is based on time then the following applies: (HAT) multiplied by 10% = the amount of time in seconds subtracted from your MAP timing to arrive at the VDP.
 
This may be commons sense, but if you are able to use DME on any approach whether it is an on-field or off-field navaid, convert your VDP into DME. Then you simply wait for the DME that you calculated to arrive. After that point, its missed approach time or circle-to-land time.

If there is no DME to use on the approach then 10% of your MDH gives you the time to go to MAP. In other words, if you have an MDH of 500 ft AGL, then 50 seconds prior to the MAP is your VDP. Always try to use the count-down method.

Good Luck!
 
Thanks guys, I always learned the HAT/GS otherwise known as gus wears a hat. I just couldn't remember the whole formula.
Sin
 
If you determine you have to circle to land....(past the VDP) and you are below circling minimums what do you do? (legally) Climb?
Thanks
 
If you know you need to circle to land prior to starting the approach, you are flying to higher minimums that allow such a maneuver. If you break out and are not in a position to land on the intended runway at straight in minimums, then you go missed approach. Thats why its called a "missed approach point", not a "this is the last instance you can land point".
 

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