Video: How to descend below 10000' without overspeeding

If this is a duplicate please just delete it.

In this example we descent from FL180 to below 10000’.

This is just one example, there are many ways to do it, but this just shows you how to make it in a smooth way. You have to work with your Speed, Vertical Speed and the Speed Brakes ( Spoilers ).
Always watch how your Aircraft is executing a command, in general, when you are flying level and start a descent while maintaining a selected SPD ( using Autothrottle ) your Aircraft will:

  • Reduce N1 as much as needed to not accelerate. Once the engines reached idle,
    the maximum the Autothrottle System can help you with losing SPD is reached.

If you are still accelerating, it is now on you to assist. There are a few possibilities:

  • Use the Spoilers. In modern Aircraft with a supercritical wing profile like the B777 or planes with a
    high aspect ratio wing design like the B787 it is nearly impossible to descent from Cruising ALT without use of the Spoilers/SPD Brakes, especially when ATC tells you: " Descent ALT/FLXXX , 2500 feet or more" ( This command does not excist in IF ), but when you are close to an Airport and too high the same situation can occure, you need to descent with a higher VS.

  • Work with your VS Reducing the VS will raise the nose of your aircraft and help you to reduce SPD

  • Set your selected SPD to a value below 250 kts. If you leave it at 250kts the autothrottle system will increase N1 when it reaches 250kts because it will assure just one thing: That you will not reach a SPD lower then what you selected. As the Autothrottle System is programmed like this it is very likely that it will use as much N1 OR MORE as needed to not become too slow. That can easily lead to a SPD greater then 250kts for a few seconds. Too long to not receive an overspeed warning in IF.

Just look the actions in the Video and the combination of using VS, Spoiler, SPD .

And as many said before : Stop your descent before you reached 10000’ and make sure you have a speed somewhere close but below 250 kts. That is one reason your friendly ATC Controller clears you most of the time first to 11000’ before instructing you " descent 9000’ ". To give you the time to prepare your aircraft for a further descent without overspeeding.

Hope this helps a little bit…

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Great info!

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I like this, I did learn something from it

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I m glad to hear this. Feel free to contact me at any time if there are still questions open.

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Now I was doing a flight into Honolulu the other day I got told by approach control to turn heading 300 I accidentally hit speed hold and when I hit it the second time even after I dropped the throttle to zero with flight spoilers out it took a steep angle of attack to get the aircraft slowed down in 777 causing me to get 4 violations in five minutes or less

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Much needed refresher! I feel like every 4th post i see now is is “Over speed violations for nothing. Please take them off. I was descending on autopilot while I was asleep. When I woke up two days later I had 6 violations and I’m Grade 1. There has to be a bug with the app!”

Thanks!

I don’t think the aircraft should be at a nose down pitch as this will make the “passengers” uncomfortable?

And if you can’t get your speed under in time then pull up and level out. And as a general thing I start reducing VS and speed starting at FL 130

Hi,

In order to descent after a straight and level flight we always follow the same sequence:

  1. Power ( reduce )
  2. Attitude
  3. Trim

Your Idea of a pitch close to 0 Degrees during descent indeed works- but not that well in a passenger jet, speaking of descent rates with vertical speeds between 1500’-2800’ per minute or more. You can achieve this while:

  • following your preferred method, pitch attitude near zero. But we will maybe not achieve the rate of descent needed leaving FL390 descending FL240 to be at level 25NM inbound whatever waypoint ( Because we had to wake up the, as always, friendly ATC Controller with this kindly reminder:
    “Airline XXX, request descent” :) )

  • Flying slow with a high angle of attack, which produces, up to a certain point, an amount of higher lift, but also leads to an increased frontal area and increased boundary layer thickness…the drag.

  • Reducing Power, lowering the nose, and then trim the aircraft so it descends with a steady rate of descent and angle of attack. Using a near-constant pitch angular velocity of approximately 3 °/sec. ( going from cruise to descent ) will barely be detected by the semicircular canals, the vestibular organs that measure the angular rotation of the head, means this rotation is normally not felt by the passengers. Additionally, the following applies:
    For a constant vertical / -speed ( descent or climb ), the lift is equal to the weight of the aircraft. Vertical acceleration only happens when the lift is less than the weight, so when we increase the rate of descent or decrease the rate of climb.
    Also when you lower the flaps of a low wing aircraft, the increased camber from the flap deflection produces lift primarily on the rear portion of the wing, producing a nose-down force until the speed is reduced to that amount that we gain again a constant rate of descent around 700-800 feet per minute during the final approach. This time with the nose up again.

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What I do for example is set my altitude to 10200ft. Has never let me down except when I forget to press ALT 😬

Is 200-220 a realistic decent speed for the 787-8 or 737

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