On 4 Jan 2005 23:15:59 -0800, wrote:

Make sure you do not descend out of the MDA towards a landing, even
with the ry in sight, unless you have reached the VDP if one is
published, or reached your own (calculated) VDP if one is not
published.

Calculate your own VDP as follows:
Take the HAT, and divide by 10. ie, if HAT = 400, HAT/10 = 40
Set the time from the FAF to the MAP into your timer, such that it
will count down to and reach 0 at the MAP.
Your VDP is when the timer shows HAT/10 seconds left. ie, HAT = 400,
HAT/10 = 40; do NOT descend out of the MDA until the timer reads :40 or
less.


Remember that the headwind component to be included in this
calculation for groundspeed is the cosine of the wind angle
multiplied by the velocity of the wind in knots, (multiplied by
5280/6200 if you are measuring your airspeed in MPH).