Question

[Olendirk]

Hey guys!

with a ground speed of 540 kt and 12% slope what is my descend rate?

Thanks!

OD

[WX Man]

Groundspeed = 540kt = 9nm/min = 54720fpm
12% of 54720 = 6566fpm

You must be a tug pilot or a parachute drop pilot.

[Keith.Williams.]

You can cut the arithmetic a little by using

ROC = % x 1.0133 x TAS

It is actually the same method as used by WX Man, but some of the stages have been combined into the 1.0133.

The more 3s you put onto the end of the 1.0133, the more accurate will be your answer.

[Jinkster]

My method:

Convert percentage to degrees = (12/ 100) x 60 = 7.2deg

deg x 100 x groundspeed divide by 60

7.2 x 100 x 540 / 60 = 6480FPM