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A320 Stall Video


FlyingMonkey

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Here's a video of an intentional stall in an Airbus A320.  I can't tell if this is an actual airplane or a simulator.  

 

https://www.youtube.com/watch?v=Tyg_qFbnnUU

 

Swept wing airplanes are notoriously slow to recover from a stalled condition.  In this case, in a gentle stall, recovery took NINE THOUSAND feet.  In the AF447 crash, the A320 was in a deep stall and descended from 39,000 feet to the water in less than two minutes.

 

Anybody with flight experience in airplanes with these type characteristics care to comment?  Wm.Ince?  I have a friend who flies a CRJ, and he told me that airplane is considered "unrecoverable" in the stall, though there are so many warnings, stick shaker, stick pusher, etc that getting it there would take some real effort.

 

 

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Here's a video of an intentional stall in an Airbus A320.  I can't tell if this is an actual airplane or a simulator.  

 

https://www.youtube.com/watch?v=Tyg_qFbnnUU

 

Swept wing airplanes are notoriously slow to recover from a stalled condition.  In this case, in a gentle stall, recovery took NINE THOUSAND feet.  In the AF447 crash, the A320 was in a deep stall and descended from 39,000 feet to the water in less than two minutes.

 

Anybody with flight experience in airplanes with these type characteristics care to comment?  Wm.Ince?  I have a friend who flies a CRJ, and he told me that airplane is considered "unrecoverable" in the stall, though there are so many warnings, stick shaker, stick pusher, etc that getting it there would take some real effort.

 

The crash you are talking about happened because the pilots kept trying to pick up the nose by pulling back on the control stick, instead of breaking the stall first.

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The crash you are talking about happened because the pilots kept trying to pick up the nose by pulling back on the control stick, instead of breaking the stall first.

 

It was actually a lot more complex than that.  

 

The two pilots were each doing opposite control inputs, and the flight control computer (FCC) averaged them together, essentially canceling them out.  This allowed the airplane to pitch into an ever-increasing AoA.  At one point the AoA was 47 degrees (!).

 

Once the AoA got above a certain limit, the Flight Data Computer (FDC) rejected the data as impossible (basically "you can't possibly be above 40 degrees AoA" -- that data must be wrong).  It then stopped using that data and the stall warnings ceased.  

 

Once in that mode, lowering the nose to break the stall lowered the AoA to more normal numbers the FDC could accerpt,  and the FDC then "woke up" to the more reasonable AoA  and generated a stall warning once again.  The result of all this was that when the crew pulled the nose into insanely high AoA, the stall warning would stop; if they lowered the nose to anywhere near normal AoA the stall warnings would start again.  Essentially the FDC was telling them to do *exactly* the opposite of what they needed to do to correct the problem.  So that's what they did.

 

And all of this was caused by the pitot heat failing on a single tube, causing erroneous airspeed info that allowed the initial stall.

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Thanks Bill.  I had forgotten that part.  In the AF447 situation, I recall that that faulty airspeed indication due to the iced pitot put the airplane into alternate law and allowed the AoA to get well above what would normally be possible.  I might have some of those details not 100% correct, and I'm certainly no expert and only know what I read.   :)

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It was actually a lot more complex than that.  

 

The two pilots were each doing opposite control inputs, and the flight control computer (FCC) averaged them together, essentially canceling them out.  This allowed the airplane to pitch into an ever-increasing AoA.  At one point the AoA was 47 degrees (!).

 

Once the AoA got above a certain limit, the Flight Data Computer (FDC) rejected the data as impossible (basically "you can't possibly be above 40 degrees AoA" -- that data must be wrong).  It then stopped using that data and the stall warnings ceased.  

 

Once in that mode, lowering the nose to break the stall lowered the AoA to more normal numbers the FDC could accerpt,  and the FDC then "woke up" to the more reasonable AoA  and generated a stall warning once again.  The result of all this was that when the crew pulled the nose into insanely high AoA, the stall warning would stop; if they lowered the nose to anywhere near normal AoA the stall warnings would start again.  Essentially the FDC was telling them to do *exactly* the opposite of what they needed to do to correct the problem.  So that's what they did.

 

And all of this was caused by the pitot heat failing on a single tube, causing erroneous airspeed info that allowed the initial stall.

What's worse, is that all three pilots forgot the most basic TLA that would have saved all those lives: PAC, or Power Attitude Configuration: a specific power setting, a specific pitch attitude, a specific aircraft config (flaps, gear) will virtually always get you a specific airspeed (net of any temp and humidity variations).  As long as you have basic pitch attitude reference, you need nothing else. It still amazes me that the pilot flying held that 330 in a full stall for 30,000+ feet. With all of the conflicting data, he should have ignored the frackin automation and flown the PAC numbers!!!! It blows me away that not one of them recognized how simple the fix would have been. Get the airplane straight and level then sort it out. They had the chance to do so and, frankly, blew it.

 

BTW, flying PAC applies to any airplane. For example, I've been shooting instrument approaches and know that flaps 0 and 4800 will basically nail 90KIAS. So, when I enter a hold, I don't have to concentrate on speed control, 3WT does it for me! Want a 500FPM decent from there? Pull 1000RPM off and down you go at 500FPM/90KIAS.

 

Go give PAC flying a try; it adds another dimension of fun to flying.

 

On other hand, if your M.O. is more "sounds right/looks right", more power to you!

 

:giggle-3307:

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