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seagull · September 24th, 2004, 02:27

If no VDP is published, most pilots like to find the point that would give them a nominal 300'/mile descent path from the MDA. Dividing the MDH by 300 would give an approx distance from the touchdown point in miles. The 1000' downfield would be met by the delay in your reaction time, so not something to worry about, just subtract if from the end of the runway. How you determine that point would depend on what type of approach, what equipment you had, etc.

Having said all that, if a VDP has not been established, then there is NO guarantee that you do not have obstacles between the MDA and the runway that project into the nominal path. There is no requirement on a non-precision to ensure that it is obstacle free, so unless it's also served by an ILS, you are taking a bit of a chance during the visual segment. A "roll you own" VDP can work, but you have to be very careful with it for that reason.

September 24th, 2004, 02:27	#2
seagull Old Skool Join Date: Sep 2001 Posts: 2,044	Re: How to calculate a VDP? If no VDP is published, most pilots like to find the point that would give them a nominal 300'/mile descent path from the MDA. Dividing the MDH by 300 would give an approx distance from the touchdown point in miles. The 1000' downfield would be met by the delay in your reaction time, so not something to worry about, just subtract if from the end of the runway. How you determine that point would depend on what type of approach, what equipment you had, etc. Having said all that, if a VDP has not been established, then there is NO guarantee that you do not have obstacles between the MDA and the runway that project into the nominal path. There is no requirement on a non-precision to ensure that it is obstacle free, so unless it's also served by an ILS, you are taking a bit of a chance during the visual segment. A "roll you own" VDP can work, but you have to be very careful with it for that reason.