# Ideal descent point?

How do you know what V/S to have?

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Hey there Junior!

I strongly recommend you watch this video.

And use this a source:

As of VS: Use the link over here.

Happy flying! 👨‍✈️

Ace out! ✌️

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Here’s one it does TOD and your V/S

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This may sound weird but i start my descent 25 minutes out. It’s the same nautical miles because I always start at around the same time.

So once I’m 25 minutes out i start descending at -2000fpm. Once I hit below FL280 I slow my speed to 195 knots and change my descent rate to -800fpm to -1000fpm.

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I generally take an average descent profile of 3 degree. So i roughly add 3.5nm for every 1000ft i’ve to loose and add 20% to it for speed to loose and other stuff.
Works for me most of time. Sometimes on wide body i’ve to get my spoilers out but very rare. Hardly 1 out of 10 times. Rest 9 times i’m almost on my ideal approach.

Suppose cruise altitude fl350. Airport elevation 1100 ft.
Altitude to loose 34000ft.
34 x 3.5 119nm

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I think thats a good point. Look at this

i hope this wil be clear off for you.

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yes it does sound weird :)

descents are usually calculated as a function of distance remaining rather than time remaining. Also slowing to 195knts at FL280 and having such a slow rate of descent is odd - you shouldn’t be that slow until you get somewhere near the airport.

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its weird but it does work for me and i do feel confortable, im doing a flight and ill let you know the distance

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Don’t you want to learn how to do things properly?

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as of right now i just feel confortable doing it but its also over 100nm out so it is somewhat like how it should be

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i might try the actual way my next flight

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Okay, Thanks!!!

I will look for it !!! thanks for your tip!

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I believe it also depends on the altitude you are at.

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I didn’t actually figure it out. Credit goes to another forum member who made this method.

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You can calculate it with the TOD formula or gently wait for VNAV in 20.1 :D

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This is the TOD formula that I was taught in ground school flight training. Take the altitude you want to descend to and subtract that from your current altitude. Then divide that number by your descent rate. Multiply that number by your ground speed. And then divide by 60 since there are 60 minutes in an hour.

So for example. You’re cruising at 35,000ft going 475kts (GROUND speed) and want to descent to pattern altitude of 3,000ft. You want to do so at 1,500fpm. (You want to use a calculator)

So take 35,000 (current alt) - 3,000 (your pattern alt)

= 32,000 —> 32,000 / 1500 (vertical speed you want to descend at)

= 21.3 —> 21.3 x 475 (ground speed)

= 10117.5 —> 10117.5 / 60 (minutes in an hour)

= 168.6 — the exact amount of miles you want to start your descent. So that means once you’re 168 miles from your destination you can go ahead and start that descent down to 3,000ft.

Note: Don’t forget to multiply by your GROUND speed NOT Air speed.

Hopefully this helps. Let me know if you have questions!

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That was quite helpful thanks very much

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