When should I descend?

So I have a quick question about descending. Should I descend before contacting the approach frequency, or should I remain at my cruise altitude and let the approach controller guide my descent? I know this may be a stupid question, but I just got to grade 3 and I’m flying expert server now, so I just want to know the proper procedure.

Edit: thanks guys for the support and help, but many of you have misunderstood the post. Maybe it is the title, or maybe you didn’t read the post, but I’m asking about the ATC part of descent, not the actual descent calculations and stuff. Still, thanks for trying to help.

Well since there is no centre and approach only handles planes under 18 000ft then yes you should start descending before contacting approach.


The approach controller is in charge of aircrafts FL180 and below, so you should descend first and contact approach when closer to the airport.


He’s asking about the atc part of descending…

Oh ok, thank you very much

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Thanks for the response, highly appreciated

A good way to find out, is to take your Cruise alt in ft - 3000. Multiply with 3, and add 10. That’ll be you’re Top of descend (where and how far out you should descend in NM)

The formula looks like this:

There’s other ways, but this is the most simple imo

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Start your descent normally following your flight plan.
I think you can contact the approach 60 miles from the airport and if not available the tower about 30 miles form it. if your cruising altitude is about 30000 feet you have to descend earlier

Oh yeah, I already saw a post about this rule, but thanks for the reply anyway!

You might find the app ‘VirtualHub’ useful for this as it includes a descent calculator within the app.

It is downloadable from IOS and Android I believe. It could be useful for future for you and it is easy to use.

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Usually, what I do is divide my altitude by three.


30,000 ft / 3 = 10,000

Start your descent 100 nmi out.

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I normally do a sort of step descent (credit to @jakevaz423). When I’m a certain time away from my destination (ETE: ALT/1,000), I descend at a rate of 1,000. I normally slow down to Mach .78, or 300 KTS airspeed (depending on aircraft). I normally descend to about 20,000. Then, I stay there until I’m ALT/1,000 away from my destination. So, in this case, until I’m 20 minutes away. Then, I finally descend to 10,100. So on and so forth, until I find the ILS.
Example: I’m at 36,000 FT. Going at Mach .80. Once I’m 36 minutes from my destination, I slow down to Mach .78 and then descend at a rate of -1,000 to 20,000 FT. Once I’m at 20,000 FT, I wait there until I’m 20 minutes away. By this time, I’m normally off of Mach. So, I speed up/down to 300-310 KTS. Then, I descend at a rate of -1,000. Then, when I reach 10,100, I wait until I’m 9 minutes out. Then, I slow down to 240-245 kts. Once I’m at 245 kts, I start descending at a rate of -1,000 again. And so on.

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