Descent Calculations

There is definitely a lot of ways to calculate and plan your descent and I have been playing for over a year and I just found the method that I find the most efficient for me and you just need some simple calculations

What you will need:

  • Your current altitude (MSL)
  • The elevation at your destination
  • Your groundspeed


FOR YOUR TOD (top of descent)

  • Take your altitude (ex: 33000ft)
  • Subtract your altitude by your destination airport elevation (ex: 33000 - 1269 = 31731)
  • Subtract this number by 3000 (ex: 31731 - 3000 = 28731)
  • Divide this number by 100 (ex: 28731 / 100 = about 287)
  • Divide this number by 3 (ex: 287 / 3 = about 96

So your TOD will be 96nm from the airport

FOR YOUR VS (vertical speed)

  • Take your groundspeed and multiply it by -5 (ex: 427 x -5 = -2135)

So your VS will be -2200fpm


Already there. Not sure if another topic of basically the same thing should exist or not.


MaxSez: Rule of Thumb, No Wiswheel, Calculator or pencil and paper it’s the 21 century! . Try this, the classic fix;



I tried months ago it but normally, the VS changes along with the descent which is impossible with this website.

1 Like

Nice! I have this bookmarked now.

1 Like

Also remember ground speed changes in time so you need to adjust V/S with same calculation

What’s with all the bold text

A quick and easy way to calculate the descent. I used these calculations, only I did not know what speed has to be used from the calculated nm and start with the descent.
My other question is, if I go to an altitude of 30,000ft, and I have to start descending at a vertical speed of -1,800, suppose, in my AP, what height should I configure? (3,500 for example)

This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.