# When to reduce speed during descent?

Hello,

Whenever I’m flying, usually with an 787-10, my cruising speed is around M0.83.
Then, I’m slowing down to 265kts to descent from 36,000ft to 15,000ft, etc:

• 36,000ft > 15,000ft at 265kts.
• 15,000ft > 10,000ft at 250kts.
• 10,000ft > 8,000ft at 230kts.
• 8,000ft > 6,000ft at 200kts.
• 6,000ft > 4,000ft at 180kts.
• 4,000ft > 0ft at Landing Speed.

I would like to have, if you don’t mind, your point of view on those speeds.
Am I too fast/slow somewhere? Are those attributions (the speed value I’m attributing to the altitudes intervals) “realistic”?

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With the 787-10, I would reccomend a cruising speed of between m.85 - m.89, but it looks good otherwise

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I personally slow down a bit for my initial descent, then I slow down to 230 or 240 knots before descending below 10000 obviously, then I slow down to approach speed about 5 miles before hitting the cone.

For your descent profile I think that your initial descent could be a tad faster but it’s all in the personal opinion :)

@Oli_H I think you are mistaken, 787 cruises between .83 - .85

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I agree with all of it, however I get to my landing speed around 2,500 feet agl, but at that point it’s personal preference

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No I’ve always cruised in it at around m. 87 for the -10, .85 for -9 and. 84 for -8. @Mcg states that he/she is in the -10 variant

That doesn’t make it right…

Credits to Wikipedia:
“Its cruising airspeed is Mach 0.85,[185] equivalent to 561 mph (903 km/h; 487 kn) at typical cruise altitudes.”

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I can confirm that cruising speed for the 787-9 is M. 85 but like i said, we are talking about the 787-10 which is a little faster then the other variants

If you look at the very bottom of the article where a table of all of the variants specifications are listed, speed is merged into one cell, and across all variants it says:

“Cruise: Mach 0.85 (488 kn; 903 km/h)”

If you have further questions please message me.

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Alright then, let’s stop arguing

Only suggestion I have is 280kts 36000-15000ft :)

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This is what I use thanks to @Swiss:

Whenever I descend, i typically slow down to 430-440kts GS. (270kts KIAS in typical wind conditions) I would then wait for it to slow down and at around 14000ft MSL, I lower the speed to 250 kts KIAS.

The way I see it if there is enough fuel why not go as fast as possible (within over speed limits). Unless you are trying to do a ultra realistic flight.

Normally, I won’t slow my speed until I’m at FL150. Then, I’ll slow to 280 IAS until about FL110 - FL120 (depends on my descent rate). From there I keep my speed between 245 IAS and 225 IAS until I reach my intended airspace. Then I slow to approach speed.

Or (and this is what I recommend), use approach charts (STARs) to gauge what altitude and speed you should be at. If you’re going for realism, then this is my best suggestion.

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Any links/website you recommend in order to view those charts?

For American Airports, use flightaware.com, and for other airports, I use skyvector.com. Of course, you can always just google ([airport ICAO] STARs/Charts).

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Not the best guide there…

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Don’t shot the messanger.

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I’m usually 280-320 until about 12k, then I slow to 240 until about 20nm out. Then gradually decrease speed until about 5nm out. There isn’t a set value for descent speed. It can vary depending on other air traffic, descent profile, etc…

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I think that’s a pretty good decent! Of course, due to personal preference, some may have different views on this, but I think that’s a good decent profile.

Honestly, that sorta ruins the overall feel of the flight (for me at least).
Also, that isn’t being ultra-realistic, that’s simply realistic 😀

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