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Old 28th Sep 2016, 14:20   #1121 (permalink)
 
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Very enlightening to someone not on the 'Bus. I have a much better understanding of what might have happened that night now and you have removed my prejudices of the plane and crew.
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Old 28th Sep 2016, 15:50   #1122 (permalink)
 
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TNX, Link.

I, too, can cut some slack WRT the crew, and seems I gave them a just a tad back when we were in the height of our analysis here and found out about all the aural warnings.

I will still support my belief that a HUD would have helped as much as AoA indication. Most have some type of aircraft reference line symbol and the difference between it and the flight path marker is your "overall" AoA, right? So AF447 crew would have seen the FPM caged at the bottom of the HUD, indicating an extrmely high AoA plus the precipitous descent even with the nose pointing above the horizon.

All this available WITHOUT air data!!! All inertial. And seems like many HUD scales have an instantaneous vertical velocity option in addition to the baro VV.

All that being said, some training is required to fully exploit the display(s), though I transitioned in a minute or so when first checking out in the A-7D with the Marconi HUD.

Finally, I wholeheartedly agree with "link" about tactile feedback. In the fighter community there can be a lotta audio from systems and other pilots/control agencies. And we fly looking outside a lot more than the commercial folks. I flew two jets with pitch "limiters" - neither vibrated or anything. At max AoA the flight control system just kept you from pulling more, and the Viper stick moved too little to tell max input and was a force input, not angle/position-related. The A-7D had no limiter, but the rudder pedal(s) vibrated enuf to warn you of impending loss of control.

And good to see so many familiar folks - what a wealth of experience and knowledge here.
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Old 28th Sep 2016, 16:47   #1123 (permalink)
 
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@uplinker

Very interesting expierience, thank you for sharing it!

And fully agree, reading of FCOM does not make a pilot, and reading up on emergency procedures does not prevent from acting differently in real live.
Fly safe.
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Old 28th Sep 2016, 17:56   #1124 (permalink)
 
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Quote:
reading of FCOM does not make a pilot, and reading up on emergency procedures does not prevent from acting differently in real live
Sure! That is why you need to do something more. But I also definitely know ignorance of FCOM did not help pilots of EK521 either, the recent Dubai 3rd August. One needs what they call KSA. Knowledge, Skill, Attitude.
Quote:
I was starting to think about unreliable speed when the over-speed warning went off.
If so then why on earth
Quote:
I deployed the speed brakes to no avail. I then pulled the thrust levers to idle.
After 17634 posts and in excess of 2.7 million views on AF447 what happened to pitch and thrust? Everyone feels sorry for loss of lives and anyone can make a mistake but the way you expressed your contrition it seemed to suggest that occurrence of UAR is a death warrant. Is it?
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Old 28th Sep 2016, 18:15   #1125 (permalink)
 
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CONF iture
I just posted airbus views about AOA. Not necessarily mine.
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Old 29th Sep 2016, 03:00   #1126 (permalink)
 
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Quote:
Originally Posted by vilas
But I also definitely know ignorance of FCOM did not help pilots of EK521 either, the recent Dubai 3rd August.
How can you definitely know something that has not even been mentioned yet ... ?

Quote:
Originally Posted by OG
(3) abiding by the vane manufacturer's DDP which gave the limits on output validity for the vanes?
According to A33Zab the vane in question has a limit close to 90 deg on the positive side, a A330 falling flat like a rock, so I think there was still some margin before invalidating the output.

Quote:
Originally Posted by vilas
I just posted airbus views about AOA. Not necessarily mine.
Not mine at all - I think their justifications are poor.
Like are their justifications for not thinking about linked sidesticks ...
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Old 29th Sep 2016, 04:02   #1127 (permalink)
 
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Quote:
Quote:
I was starting to think about unreliable speed when the over-speed warning went off.
If so then why on earth
Quote:
I deployed the speed brakes to no avail. I then pulled the thrust levers to idle.
After 17634 posts and in excess of 2.7 million views on AF447 what happened to pitch and thrust? Everyone feels sorry for loss of lives and anyone can make a mistake but the way you expressed your contrition it seemed to suggest that occurrence of UAR is a death warrant. Is it?
Vilas, I am just about to go flying so don't have time for a detailed answer, but please read my post again.

No the situation is not a death warrant. I was trying to explain that the situation is very subtle - it initially looked like an autothrust fault - and the overspeed warning is so loud and distracting that I did the wrong thing in the SIM - I tried to stop the noise by slowing the aircraft out of overspeed (compounded by my thinking it was a V aplha prot problem). I have admitted that I made this mistake in the SIM and shared it here, so I do not expect criticism thanks. 'Why on earth' you say, and I totally agree - I can't believe I did it myself, and my reason for posting was to give some insight into perhaps why the AF447 pilots got confused and did what they did.

I think it was an extremely valuable exercise the TRE and Captain gave me, - very subtle unreliable speed at max altitude - and I think we should all experience it WITHOUT prior knowledge of what is going to happen.
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Old 29th Sep 2016, 06:34   #1128 (permalink)
 
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Uplinker
Quote:
I was trying to explain that the situation is very subtle
. Sure it is. Read my post
Quote:
UAR is very serious situation to identify and correct and in my opinion something that was not going to happen by accident.
As you found it. It only means proper training which the 447 crew didn't have. And in absence of that I had said
Quote:
When looking for possible improvements of the equipment we should look to future and not bring in AF447 because how an insufficiently trained crew would have used that enhancement is impossible to guess.
But I definitely have problem with
Quote:
reading of FCOM does not make a pilot, and reading up on emergency procedures does not prevent from acting differently in real live.
Fly safe.
To fly safe without knowledge needs lots of luck which the unfortunate crew of 447 and EK521 didn't have. If the pitots had not frozen that fateful night or had the crew of 521 not decided to GA after touch down they may have retired peacefully after 20 years without knowing what they would have done on those occasions. But lesser mortals need to survive through knowledge which may keep them alive through the experience should it happen.
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Old 29th Sep 2016, 14:39   #1129 (permalink)
 
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Uplinker


“I AM A HISTORY MAJOR. I BELIEVE THAT THE PAST IS PROLOGUE. BUT MOST AIRCRAFT ACCIDENTS ARE NOT ACTS OF GOD. WE TAKE WHAT WE LEARNT SO IT DOESN’T HAPPEN AGAIN. BUT THAT AIN’T GONNA HAPPEN IF NOBODY SAYS ANYTHING.THAT’S THE DARN TRUTH.” JAMES HALL, NTSB
How true!
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Old 29th Sep 2016, 15:54   #1130 (permalink)
 
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@Confiture

If you read Chris Scotts posting 1107 you will see that the discussion related to the 60kt validity limit not the maximum angle the vane could read so your remarks aren't really relevant to Chris's point.
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Old 29th Sep 2016, 16:24   #1131 (permalink)
 
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@Uplinker: thank you for sharing your experience. That sim you were on was a training event, and I tip my cap to the Captain and TRE who provided you with a training opportunity.


In one of the early threads I asked "what did they see?" meaning the two in the two seats of AF 447. You have given me an idea of what they saw, but more importantly, what they heard and what they didn't hear. I think your sim experience on a surprise UAS confirms a suspicion a lot of people had (in the early discussions) that in the back of PF's mind was the idea to not overspeed the aircraft.
But that may have been somewhere more than the back of his mind: if the aural warning just would not stop, what he heard, and what he didn't hear, might be just as critical to understanding how that event played out as it did. (Points made above about audio channel saturation will not be repeated.)

Thank you, again, for sharing your training experiences.
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Old 29th Sep 2016, 16:42   #1132 (permalink)
 
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that in the back of PF's mind was the idea to not overspeed the aircraft.
But that may have been somewhere more than the back of his mind: if the aural warning just would not stop, what he heard, and what he didn't hear, might be just as critical to understanding how that event played out as it did.


A pilot uses more than one sense. Under stress it is usually the sound (ears) that gets filtered out first and sight takes over. Sight can then become very tunnelled and all other things are shut out. PM is shouting at you WTF; then they are trying to give guidance about how to escape the problem: all to no avail as you do not hear them. Neither do you see all the other information that is screaming (visually) at you. You are focused on the PFD because that is what you have always done.
Time to pause and realise that the senses do not combine into common sense. Something must be wrong; it does not compute. High attitude at FL370 means an impossible over speed. The warning must be false. So what is correct? Difficult at 3000', but 37,000. That's a lot of time.
There was a B727 (Air Peru I think) that had a faulty static line at medium level. (not the B757 with blanked static ports during takeoff). The guys pushed & pulled believing the altimeter and ASI; but of course they were acting in the opposite sense. I'm not sure power/attitude entered the analysis. They were in an idle descent I think.
At soem point there needs to be a pause, back to basics, and then an analysis with all senses to discover what you can trust. In AF it's curious that the sound over-rode the visual.
I've seen RTO's in the sim, with the crew calling Mayday to ATC with the fire bell still ringing.

There were many human factors at play, plus training factors.

Last edited by RAT 5; 30th Sep 2016 at 07:16.
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Old 30th Sep 2016, 00:11   #1133 (permalink)
 
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Quote:
Originally Posted by OG
If you read Chris Scotts posting 1107 you will see that the discussion related to the 60kt validity limit not the maximum angle the vane could read so your remarks aren't really relevant to Chris's point.
And I question that 60kt validity limit.
Why CAS measurements should invalidate AoA values and shut down the stall warning ?
That aircraft was in an airflow of 100kt, ample airflow for the AoA probes to positively confirm the stall.
Just when the captain enters the flight deck, the stall warning quits. For him if stall there was, it is not anymore. His mental perception of the situation is send on erroneous tracks.
As Uplinker mentioned in his experiment, when you start thinking in one direction, it is hard to turn back.
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Old 30th Sep 2016, 07:00   #1134 (permalink)
 
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Uplinker
Quote:
VIRTUALLY ALL AVIATION ACCIDENTS ARE CAUSED BECAUSE SOMEONE DOES TOO MUCH TOO SOON, FOLLOWED VERY QUICKLY BY TOO LITTLE TOO LATE. Steve Wilson, NTSB 1996
This can happen with any abnormality and unless it is recognised you will only insulate yourself against UAR. Airbus climbing to REC MAX over speed is the last thing likely to happen. Unable to cancel over speed warning, application of speed brake in climb, not noticing increase in VLS and thrust lever to idle, stall and application of Abnormal Valphaprot was it or abnormal Vls to a stalled aircraft, didn't hear stall warning which goes on and on with a priority over other warnings and at the end of it you suggested radical changes to aircraft systems such as over speed warning, stall warnings with hepatic feed back, changes to Pitot static concept of speed measurement, you forgot to ask for AOA gauge may be you are not sure you would have noticed it anyway. On top of everything you said you were going on a flight I thought a vacation to an exotic south Pacific island was a better option. All that happened was due to a wrong diagnosis, no corroboration due to fixation, confirmation bias only looking for evidence to confirm the faulty decision and rapid application of inappropriate corrective actions. all forms of UAR are already explained at length, stall warning already has priority over others.
Cheers and happy flying.

Last edited by vilas; 30th Sep 2016 at 07:32.
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Old 30th Sep 2016, 08:39   #1135 (permalink)
 
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I agree with you that the airspeed was well above 60 kts and that the AOA signals were in reality valid. My point is that if the vane manufacturers had declared their equipment to be reliable only above 60 kts then AI had no choice but to use that value in their logic.

>And I question that 60kt validity limit.

Only the vane manufacturers could tell you why 60 kts real airspeed was the limit.

>Why CAS measurements should invalidate AoA values and shut down the stall warning ?

Because nobody is going to certify a system that continues to work normally even though it knows (or is being told) that its input data is wrong - in old computer terms garbage in, garbage out. The fact that there is a cross linking between the CAS/EAS relationship and very high AOAs complicates matters

That being said, there is a simple change in the logic which would eliminate the problem - the stall warning, having been activated by a valid AOA signal should remain latched until is receives a valid signal that AOA has reduced to below the stall trigger value
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Old 30th Sep 2016, 08:50   #1136 (permalink)
 
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I echo Lonewolf and I did thank my SIM TRE and Captain that day. The scenario was the Captain's idea - he is a TRE as well. I am not the only line pilot to have become trapped by this - he said that everyone he has done this to in the SIM have reacted in the same way I did, (apart from the V alpha prot OEB).

I am a normal line pilot with experience of basic turboprops as well as basic jets and of course Airbus. My reaction to this scenario in the SIM was terrible and I am of course very embarrassed, but I had not actually seen this demonstrated, and the lead-up to the event is very subtle. I posted my SIM experience so that other normal line pilots like myself could be made aware of how subtle this can be - I don't think there is enough training in this area.

Vilas you seem to suggest that I SHOULD have heard the "stall stall", but the point I am making is that I am telling you that I didn't, and those poor sods on AF447 obviously didn't either. You might think it is impossible not to hear the spoken warning, but my brain blocked it out, that's what I am telling you. You also suggest I should have a vacation and your implication is a vacation from flying - well that is charming, but no thanks.

I did not have to tell everybody how I up - I could have kept quiet, but I thought it was more important to post my experience for the greater good.

As I said: if ever the speed tapes are doing something that seems even slightly unusual, no matter how slowly or gently they move or how much they might agree with each other : follow the unreliable speed drill. Both tapes may well appear to be perfectly normal and both may seem to indicate the same speed and speed changes.

Be aware that the overspeed alarm may well sound and remember it can be cancelled by using the emergency cancel button; something I temporarily forgot.

Last edited by Uplinker; 30th Sep 2016 at 09:02.
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Old 30th Sep 2016, 10:36   #1137 (permalink)
 
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Uplinker,

As some others have already said, your experience has given much food for thought, and FWIW I raise my hat to you for bravely sharing it with us.

Good flying!
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Old 30th Sep 2016, 11:34   #1138 (permalink)
 
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Uplinker, thank you for sharing your experiences.
The greatest experiences are those which are learnt, better still when shared, and of even greater value when heeded by others.
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Old 30th Sep 2016, 14:01   #1139 (permalink)
 
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Quote:
Originally Posted by OG
That being said, there is a simple change in the logic which would eliminate the problem - the stall warning, having been activated by a valid AOA signal should remain latched until is receives a valid signal that AOA has reduced to below the stall trigger value
But isn't it already exactly what the official documentation pretends to be doing :
When the threshold is reached, a permanent aural alert (“STALL, STALL” synthetic voice then cricket) is triggered until a correct angle-of-attack is recovered.

How 60kt can be a limit for the stall warning when officially unreliable speeds do not affect that stall warning ???
Unreliable speeds can be anything, from high numbers to zero.
Rely on the stall warning that could be triggered in alternate or direct law. It is not affected by unreliable speeds, because it is based on angle of attack.

I do question the Airbus documentation ...
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Old 30th Sep 2016, 15:11   #1140 (permalink)
 
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The bold wording describes how the system operates when supplied with valid aoa data.- as I am sure you understand very well. A stall warning system that uses aoa as a primary input cannot function if deprived of that data, which is also something I think you understand.
But we are going over old ground and I see little point in repetition
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