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0 votes
asked by (50 points)
I fly X-Plane 10 regularly, and whenever I descend into an airport, I either go miles past it, or I am way too early. So, how many miles should I be away from the airport to start descending and what should my vertical speed be?

1 Answer

0 votes
answered by (1.8k points)
You can try this:
Crusing Altitude - Target Altitude= Amount of ft to descend
Amount of feet to descend x 0.003 = 33000ft x 0.003 = 99 miles away from the airport
commented by (50 points)
So, what would my Vertical speed be?
commented by (1.8k points)
Vertical speed (ft/min) = Descent rate (%) x Ground speed (knots)

Example: Ground speed is 110kt, and descent rate is standard 5.2% (we can take 5%). Vertical speed = 5 x 110 = 550ft/min.

You should remember that ground speed in some aircraft is not known because the wind is not known and it can change during descent if this speed is not maintained constant.
commented by (50 points)
Ok, I'll try these methods. Thank you for the help!
commented by (15 points)
Altitude to lose multiplied by 3 then drop the zeros.  
FL330 down to 12,000= 21kft x 3 = 63miles.  Can add five miles for t/d start and level off.

How fast to descend?  Again, simple:  Grounds speeddivided by 2 add a zero.  
400kts grndsp = 2000ft/m VSI.   ( can use IAS, if needed, just recheck your math every so often to verify your descent).