Originally Posted by
Officer Kite
Altitude to descend x 3 gives distance to descend on a -3 deg path
Ground speed x 5 gives ROD necessary to stay on the -3 deg path
Say you need to descend 30,000ft and your GS is 400kts. So it's 30 x 3 = 90 miles needed
400 x 5 = -2000fpm ROD required to descend within the 90 miles.
Of course the altitude will need to have the necessary QNH adjustments to it for the calculated distance to be perfect.
I'm not so clever so complicated formula don't work, keeping it simple has so far!
There’s little point doing QNH adjustments when your basic formula is so coarse.