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Air Asia Indonesia Lost Contact from Surabaya to Singapore

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Air Asia Indonesia Lost Contact from Surabaya to Singapore

Old 3rd Feb 2015, 18:06
  #2981 (permalink)  
 
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Bob

Well in a stalled condition the first consideration in recovery action is to "unload the wings". As most airline flying is S & L, "lowering the nose" would go a long way to achieving this, in most scenarios.

I do stand to be corrected, as the day I stop learning, for me is the day to give up..
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Old 3rd Feb 2015, 18:12
  #2982 (permalink)  
 
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Physicus, don't throw insults if you're not going to get it all right - adding power at high altitude is always going to be a gradual affair as the engines respond slowly up there. They also have relatively little thrust in the cruise due to the low air density, so aggressively firewalling the thrust levers from a high alt stall is not going to be the source of control issues and will be easily overcome by elevator pressure, especially if you remember to trim. Low speed and low altitude and yes, it is a major issue.

Last edited by Aluminium shuffler; 3rd Feb 2015 at 20:50. Reason: typo
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Old 3rd Feb 2015, 18:16
  #2983 (permalink)  
 
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As most airline flying is S & L, "lowering the nose" would go a long way to achieving this, in most scenarios.
SOP,

But that is precisely the point - you want a recovery technique which is going to work every time!
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Old 3rd Feb 2015, 18:29
  #2984 (permalink)  
 
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Air Asia Indonesia Lost Contact from Surabaya to Singapore

Originally Posted by AfricanSkies View Post
Equipment failure should not cause a stall, whichever way you look at it.
Noone says it did. Pilot's actions appear to have done.

Originally Posted by AfricanSkies View Post
And in the event that the aircraft enters a stall, it should be recoverable.
You are confused. The aircraft is recoverable, be it with difficulty. As long as the crew follow the right steps.

You would be wise to study some Boeing crashes re. stalling and crew confusion. Turkish 1951, Asiana 214. Your Airbus argument is flawed.
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Old 3rd Feb 2015, 18:51
  #2985 (permalink)  
 
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Colgan Air was not an Airbus or a Boeing. It was a turboprop.
The common factor is the pilot hauling back on the stick in response to a stall.

Please note that we do not have any clear evidence that this is the case here but it is looking rather likely - only the final report will tell.

Why would any trained pilot be so bl**dy stupid ?

Something wierd is happening, this can only be explained by some kind of psychological reaction to the unexpected.

More automation to stop pilots crashing is probably not the solution, maybe we could filter out pilots suseptible to this reaction by putting everyone into into unpredictable and varied extreme stresses in the simulator and adding a stall at random. Anyone who fails is obviously made of the "wrong stuff" and should not be a pilot.

Any other suggestions ?.
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Old 3rd Feb 2015, 19:01
  #2986 (permalink)  
 
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SOP monkey

SOP monkey: "I do stand to be corrected, as the day I stop learning, for me is the day to give up.."

I wish there was more evidence of this attitude in posts, and second the request for more civility. I don't see where being huffy has helped any post.

Certainty that one is right when events later show one was wrong enter into a lot of accidents.
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Old 3rd Feb 2015, 19:22
  #2987 (permalink)  
 
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I think D P Davies in his classic book "Handling the Big Jets" (written in the 1960s but still has some great guidance) states that the probability of an actual stall in commercial operations was one in ten million (or was it one million - would have to check?) but the probability of a stall warning was much higher at one in 100,000.

Obviously it is important that pilots know how to recover from a stall but far better to prevent the aircraft from stalling in the first place. Notwithstanding stall warning systems this requires a knowledge of the a/c performance and also correct monitoring of vital parameters such as pitch attitude, airspeed, power etc.

If you see ten degrees or more pitch up at cruising altitudes in a swept wing jet transport you better start making a correction before you get a stall warning.

Even before an a/c stalls and/or the stall warner operates (assuming from level flight or thereabouts) the first warning signs are low and reducing airspeed, high nose attitude and reduced control effectiveness.
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Old 3rd Feb 2015, 19:36
  #2988 (permalink)  
 
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One thing I dislike about the Brand A use of a verbal "STALL, STALL" (instead of a stick shaker) is that humans have a tendency to filter out aural inputs when concentrating or highly stressed. Meaning the STALL warning may not even be heard when it's most needed.
Problem is, I'm not convinced that a stick shaker is much better - I can think of at least two Brand B crashes where the pilot pulled back in response to an erroneous overspeed indication and stalled, then apparently dismissed the stick shaker as 'Mach buffet' due to the perceived overspeed.
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Old 3rd Feb 2015, 19:41
  #2989 (permalink)  
 
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reduced control effectiveness.
In normal law not in an FBW Airbus.
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Old 3rd Feb 2015, 19:49
  #2990 (permalink)  
 
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silverstrata;

The accepted definition of the "deep stall" or "super stall" is that of Davies', which refers solely to the blanked T-tail designs.
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Old 3rd Feb 2015, 19:49
  #2991 (permalink)  
 
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Australapithicus:

Silversrata....just...no.

Sorry, Austra, why?
Your statement as it stands is tantamount to an ad-hominem, and I don't like abuse. Please explain yourself further.
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Old 3rd Feb 2015, 19:50
  #2992 (permalink)  
 
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In normal law not in an FBW Airbus.
Icepack, quite!
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Old 3rd Feb 2015, 19:52
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Or even easier, just have an auto power reduction as the aircraft hits the stall. Pull the power off, and I bet the nose will drop just like a C152.
Ummm... whilst your conclusion might be true, I am not so sure how well it would work with, say, a Stall Warning on takeoff?

"Stall Warning on Takeoff" is an A320 Memory Drill, and taking the power off I cannot recall as part of the drill In fact, the complete opposite is the case

Had such a device been installed on AF447, the power would have reduced at the first hint of a stall, the nose would have dropped
Disagree - at the first hint of a stall, he just kept pulling back. As others have said, there is not much thrust / couple at cruise Altitude.

PS Does the A320 have a stick shaker, like the 737?
No.
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Old 3rd Feb 2015, 20:01
  #2994 (permalink)  
 
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The accepted definition of the "deep stall" or "super stall" is that of Davies', which refers solely to the blanked T-tail designs.
A deep stall is any stall that cannot be remedied with elevators.



For what it's worth. I fly Airbus, and it has NEVER been marketed or 'sold' to me as being un-stallable. Look at the damn attitude display and the speed !!!!
When it was identified in the 1960s that rear engined T-tail aircraft could enter a deep stall, stick pushers and shakers were added until it was almost impossible to enter that condition.

We now have a situation where underslung engined aircraft can also enter a deep stall, if the thrust remains at cruise or higher. And this applies to both Airbus and Boeing designs.

In normal law, an Airbus should never enter this state, but in alternate law it certainly can (as can Boeing twins). There is no reason why a stick pusher or a thrust reducer cannot be applied in these cases, where the aircraft is in alternate law. A thrust reduction at the point of stall, will lower the nose quite sharply (if the stick is neutral or forward of neutral) and make the exit of the stall relatively simple.
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Old 3rd Feb 2015, 20:03
  #2995 (permalink)  
 
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Physicus, don't throw insults if you're not going to get is all right - adding power at high altitude is always going to be a gradual affair as the engines respond slowly up there. They also have relatively little thrust in the cruise due to the low air density, so aggressively firewalling the thrust levers from a high alt stall is not going to be the source of control issues and will be easily overcome by elevator pressure, especially if you remember to trim. Low speed and low altitude and yes, it is a major issue.
Aluminium shuffler, while I agree with you regarding thrust at high altitude, how can the following post by silverstrata be explained?

Likewise the high altitude stalling was interesting too. With the engines at full chat (as commanded by the a/t) it was almost impossible to recover from the stall. And at cruise power, full forward control deflection was required. It was useful to learn that the standard light aircraft nod into a recoverable descent just did not happen, and the aircraft would just pancake down almost tail first - just as AF447 and this one did.
Is it a case of lack of sim fidelity or is elevator effectiveness reduced at high altitude by approximately the same amount as the available thrust is reduced?
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Old 3rd Feb 2015, 20:04
  #2996 (permalink)  
 
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Nigel the latest stall drill in the QRH states--


NOSE DOWN PITCH CONTROL APPLY
This will reduce angle of attack
Note:
In case of lack of pitch down authority, reducing thrust may be necessary.
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Old 3rd Feb 2015, 20:10
  #2997 (permalink)  
 
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Nigeldraft:

"Stall Warning on Takeoff" is an A320 Memory Drill, and taking the power off I cannot recall as part of the drill In fact, the complete opposite is the case

Agreed, but then so would a stick pusher be inconvenient at that point in the flight - but that did not stop stick pushers being added to aircraft. And the last stick pusher I had was quite forceful - ten kilos of push perhaps? Anyway, it was nearly capable of taking the stick out of your hands if you were relaxed.

Likewise the stick shaker which I had go off on rotation, that can be disconcerting too (especially on a 2,000m runway). Am I at the right speed?? Gets the ticker ticking.

Besides, it is not beyond the ken of Airbus engineers, to put a 2,000 ft altitude limitation on the proposed power-reduction-at-stall protocol.
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Old 3rd Feb 2015, 20:24
  #2998 (permalink)  
 
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Oakape:

Is it a case of lack of sim fidelity or is elevator effectiveness reduced at high altitude by approximately the same amount as the available thrust is reduced?
Two factors.

Firstly, this was a stalling demonstration in the sim, so the aircraft was very slow. We might have been back at .62 mach or so, or about 180 kts IAS at 39,000 ft. Remember that with underslung twins, the thrust can overpower the elevator at low altitudes. Yes, there is less thrust at altitude, but that thrust is still opposing the required elevator motion.

Secondly, it is not simply the lack of elevator authority, but the stick forces required (not Airbus). The force required to push the stick forward was surprisingly high and counter intuitive. Normally at altitude the stick is very sensitive, so the need to push with both hands was not usual for that altitude, and could be confusing.

And that is why we do these demonstrations in the sim.
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Old 3rd Feb 2015, 20:47
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Oakape, I have done the high altitude upset exercises several times in the 737 800 sim and not found any issue regarding flight control effectiveness. The force needed on the elevator will be large if trimmed nose up (for the reducing IAS prior to stall), but that is no different from at any altitude, but even without trimming, I didn't find any problem. I'm not a sportsman and never go to the gym, though I'm not a couch potato either - I just live an active lifestyle. So, a 5' waif may have trouble, but the average male pilot shouldn't have any issues. I can't speak for other types, though.
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Old 3rd Feb 2015, 20:59
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The Ancient Greek:

My guess at why several stalls have been maintained or exacerbated by pilots hauling back on the column/stick is that it is human nature when scared to grab and pull tight. However, it does show that these individuals and many, many more don't have the appropriate training or experience to overcome that primal instinct. I think removing spinning and aeros (or at least reducing the amount done) and reducing the stalling exercise amount in licence training (at all levels from PPL to ATPL) is a big mistake. I can't help feel that a large amount of training at the edge of the flight enveloppe would sharpen trainee's handling and hone the correct reflexes.

Tdracer - I understand what you're saying about the aural stall warning in 'busses, and agree. Unfortunately, its not possible to fit stick shakers in those crappy little side sticks. I like the idea of a side stick, but I'm horrified that they have no feedback of any sort from the autpilot or other stick. That is a lethal design flaw. I will always be convinced that it is a principal factor in both the relevant accidents and will kill more people yet because the pilot who understands what is happening to the aircraft doesn't realise what the other pilot is doing to the controls, assuming basic competence of not holding an ac in the stall.
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