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CA1900 said:Here's what I use:
Thousands of Feet to Lose x 3 = NM from fix to start down
Groundspeed x 5 = Descent rate in fpm
For example: You're at 23,000. You're instructed to cross 30 miles this side of XXX at 11,000.
That means you have 12,000 feet to lose. Multiply by 3, you get 36 miles. (So in this example, you'd add 30 miles to THAT to get 66 miles out.)
You're doing 300 knots over the ground, multiply by 5 to get 1500 feet per minute. (Or, since I can do it faster, I multiply by 10, then cut it in half. Same end result. 300 x 10 = 3000, /2 = 1500.)
There you go. I'm sure there's more to it if you're flying something faster, but this works great in a turboprop.
CA1900 said:Here's what I use:
Thousands of Feet to Lose x 3 = NM from fix to start down
Groundspeed x 5 = Descent rate in fpm
minitour said:That's the way to go.
-mini
Yes. The formulas that have been bandied about are for figuring out things based on a nice comfortable 500 fpm descent (altitude to lose X 3) rate or a 3° glideslope (GS X 5).GravityHater said:Originally Posted by CA1900
Here's what I use:
Thousands of Feet to Lose x 3 = NM from fix to start down
Groundspeed x 5 = Descent rate in fpm
I think that only is useful if you are given a pd descent. Where YOU decide when the descent is going to start, no?
GravityHater said:And then fudge a little; go down a bit faster than planned, because your gs will rise as you point the nose down.