Calculate Top of Descent - XC Flight Planning (Private Pilot Lesson 14o)

Explanation of how to calculate the top of descent for the cross country flight plan.

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[BostonClipper]

Another way is to plan a 3 degree descent using trig. Two constants are all we need. For top of decent 318. For rate of descent 5.3.

Top of descent. 5, 500 - 1, 200 = 4, 300 4, 300 / 318 = 13.5 nm
Rate of descent uses ground speed but we can also assume calm winds aloft. 120 x 5.3 = 636 fpm.

Because 318 and 5.3 are constants creating a simple lookup table eliminates all the math. For simple GA aircraft only a dozen incremented values are needed. This method makes it VERY easy to ballpark distance and rate.
Top Of Descent
1, 000 - 3.1
2, 000 - 6.3
3, 000 - 9.4
4, 000 - 12.6
Etc

Rate of Descent
60 - 318
70 - 372
80 - 425
90 - 478
Etc

Or use the common rule of thumb of 3 and 5.
4, 300 use 4.3 x 3 = 12.3 nm
120 x 5 = 600 fpm
You descend a little late and flat however.

[ActioJjunky]

You didn’t finish explaining anything what’s the point if you won’t finish

[TheAvGeeKsOfficeAvinashbandaru]

You’re awesome thank you, your videos helps me a lot I reside in canada and use your tips and tricks to make my life easier

[snowman]

You've really helped me a lot during my ppl. My question is we're you've thought of IFR lessons too?

[scottpiette]

That was one great question you just answered for me thank you very much....

[willhibbardii]

Good lesson Cyndy. Thank you for posting these!