Aircraft speed not reducing

I was travelling from VIDP ( DELHI ) to OMDB ( DUBAI ) using B777-300ER , during my descent my speed was not reducing even though spoilers were in flight…(1500fpm)
What could be the reasons and solution ?

3 Likes

I’m not a professional or anything but it could be your descending to fast and also from what I know the 777 is hard to slow down

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Thats a big plane to slow down. Sometims you need to do step descents to slow down.

  • Reduce speed
  • Spoilers on
  • Descend to 15k
  • Level off and keep spoilers and speed reduced to slow down more.
    Repeat as needed.

Many will level off at 11k to slow down more before going below 10k. It just takes some practice.

11 Likes

IRL it’s a slippery beast! Trying to descend at 1500 fpm and slow down generally isn’t going to happen, even with the spoilers out.

When you need to slow down reduce your rate of descent to around 300fm, pull the spoilers, wait until you get the airspeed you desire then increase the rate of descent and retract the spoilers. Always anticipate your speed profile.

Pitch up, slow down, pitch down, speed up.

Keep it simple!

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From what I know, if you need it, you can raise the speedbrake 100% isn’t that correct? Even with that it wouldn’t slow down?

Not if you are trying to descend too fast no.

The aircraft weighs up to 200T+ on landing, that would need a massive speed brake surface to slow it down in a 1500fpm descent.

To slow down you must reduce your rate of descent. 2-300 fpm with speed brake will give you a very good decel profile.

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From my experience with the 77W, you need to start descending 150nm out. You can descend fairly rapidly at higher altitudes and reduce/maintain your airspeed, but lower down it gets really difficult to slow down so you need to have plenty of distance left to travel to be able to control your descent properly at 1000fpm or less. Treat this plane very differently from others in that regard and you’ll be fine, and of course once you get close enough to the airport and slow enough you can start using the flaps and gear to help it stay at the right speed.

The 772 can also be a bit of a speed demon on descent, but not to the same extent.

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@Chris_S has it right. It’s takes more advanced planing than all the other planes. Some of my additional thoughts are.

If you’re flying at a slower airspeed you’ll get more decent for the same distance travled. So level of and slow down as much as you dare. :)

You can deploy landing gear safely at under 250KIAS probably faster. You’ll have to look it up. They may provide even more drag than the speed brakes. Thais would be noisy in the cabin so it’s not a great for a commercial flight.

With the 777s you slow faster with a higher angle of attack. When you lower flaps and bring your angle of attack down you’ll actually not be slowing as well as with out the use of flaps. I’m sure it doesn’t work this way on a real plane but with the 777s if you want to decend faster wait to lower your flaps. Be warned… I’d hand fly it the auto pilot won’t like the high angle of attack. (Weirdly enough it’s a little more efficient at cruise with a little flaps to improve the angle of attack)

I’m very resourceful because I often don’t plan ahead well. Lol.

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but before this…it used to descend quickly at reasonable speed , today only I’m experiencing this situation

but before this…it used to descend quickly at reasonable speed , today only I’m experiencing this situation

Try what @Chris_S said descend to 15k or 11k then reduce speed and then descend again.

I’m
Not sure buddy. I just tried it on solo. From FL180 and 280KIAS I can decent at 1500 feet per minute keeping about the same airspeed. If very light you do speed up a bit if you’re close to max landing weight you slow a bit. Spoilers alone are more than enough to compsate. You may have been going too fast or too slow.

If they’ve flight programmed it correctly you will not slow down with 1500fpm and full speed brake. At best you won’t accelerate.

Obviously depending upon your weight but landing at 180T 1500fpm is too quick to slow down.

One or the other.

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It’s like flying a brick most of the time! 🤣

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