A question about a speeding problem

So just this morning I woke up to land my flight after a overnight trip from San Jose. I was coming into EGLL around 6,000 feet when I started racking up violations. It said my speed was over 250 kts while below 10,000 feet. I looked at my speed and it said I was at 280 kts. The only problem is that my speed that I set for autopilot was 180 kts. Why would my plane be at 280 kts while the speed I set for autopilot was 180 kts. I racked up 5 violations trying to fix the problem and managed to do it but now I can’t access the expert server.

Aircraft Boeing 777 200ER

What was your VS? If you were descending fast, it’s hard for the aircraft to slow down, so use speed brakes or flaps to slow down.

The 777 is known to be a “slippery” aircraft in a decent. Meaning, it likes flies through the air without much drag I’ve found that anything greater than -1800fpm will result in an increase in airspeed even if power is at idle.

To counter this “slippery” affect, I’d suggest using flight spoilers and some flaps within reason.

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My vs was around - 1800 so I understand now. I did counter this problem by lowering my VS thanks for the help

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Best to maintain max v/s of -1500 under 10.000 feet to avoid violations.

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I find the 777 slows down or goes down, but it won’t do both.

Bear in mind the only thing the auto throttle can do to reduced speed to what you set is bring the thrust down to idle, but if you are descending at a rate higher than around 1200fpm in the 777 even with the thrust at idle you gain speed.

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yes I learnt from bitter personal experince that these Triple 7’s dont like to slow down ! A trick that I have picked up (from @Heavydriver and @Yuan_Tugo who are proffesional dirvers, thanks gents) is too start your desecent early enough in order to slow down in time! I tend to use the “FL/3” rule and add about 20nm to that when calulating a TOD. As aprt of my planning I do a “step descent” so level off at about FL120 in order make sure I have slowed down below 250kts when dropping below 10,000ft.

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David has a good technique, generally I start my descent at 190nm away roughly. I set the alt to 11,000ft and descend at around 1400-1600vs then once my speed is at 220 knots IAS I then go down below 10,000. It works well and you don’t have to worry about over speed violations.

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Keep 250 and plan a v/s of 1000-1200 feet for descent and you will be fine. 220 might be very slow if you are let’s say 50NM out and you are number 1.

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