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AF447 final crew conversation - Thread No. 1

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AF447 final crew conversation - Thread No. 1

Old 15th Oct 2011, 05:10
  #61 (permalink)  
 
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I think that software developer in post 50 not only brings us back to a major causal factor, but also explains it in a perfectly understandable way that for me makes it potentially the most important factor in the accident.

The stall warner was "inverted" or you could say reversed. Surely having a reversed/inverted stall warning in a night stall situation with unreliable indications will generate the same potentialy fatal conclusion as discovering (or in fact not discovering) that you have reversed aeliron controls as you correct a roll tendency at 200ft on departure ??
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Old 15th Oct 2011, 07:44
  #62 (permalink)  
 
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How do Airbus crew train stall recovery?
Generally speaking.
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Old 15th Oct 2011, 07:54
  #63 (permalink)  
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Hi all
Had a conversation with an AI FE. He told me about a test flight last summer.
3 test pilots, an air asia 330 And a flight test program. Vmc day light over the Jay of Biscaye in a dedicated flight test area.
This guys reconfigured the lad in alternate 2, stable fl 350, zoomed to fl380, entered a Stall. It developed into a deep Stall. No information about ths position though.
Eventually, they recovered at ...6000ft... As the elevator authority was lost, deep Stall, they found themselves powerless using standard techniques to recover from it. A rudder input induced a spin which Led to a dive And our test pilots recovered This tricky Stall. These guys reported that they felt the end was near...
I hope the live feed he witnessed that day Will be Made available for all pilots to learn from guys who were prepared And trained for that event.
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Old 15th Oct 2011, 08:04
  #64 (permalink)  
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We are getting a bit confused here between 'full stall' and 'deep stall' I think, and in the case of 447 it was being held in a (amazingly stable) full stall (not a 'deep stall') by THS setting and elevator, although I don't think any research has been done (for obvious reasons) on the longitudinal stability of the 330 in those conditions and it may be that there is an unexpected aerodynamic strong nose-up moment (Edit: I have just seen Lyo's frightening post regarding loss of elevator function, so yes, it looks as if could be described as a 'deep stall'). Regarding min recovery height, it is simply enough to do the sums, and I chucked my hat in the ring way back to say that I thought 20k would be the last point for recovery without hitting the water. This simply based on a descent rate of 10k a minute (2 minutes to impact) and a required pitch change of something like 40-50 degrees nose down, taking a few seconds (which would drastically increase the 10k down) reducing the remaining time, and then add the altitude required to transition from that descent to level flight without pulling the wings off or entering a manoeuvre stall. All subjective, of course - I have no desire to check my estimate.

DC-ATE - are you saying you were in a 'deep stall' (whatever you think that is) with 10kfpm down at 10k in IMC? Sounds like some really smart flying there to achieve that. I think I would have taken control a little earlier and called for a psychologist to meet the a/c on arrival.
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Old 15th Oct 2011, 09:48
  #65 (permalink)  
 
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What a former Airbus test pilot had to say the other day...

I am not an Airbus pilot.

When I attended a seminar on the topic of loss of control incidents and accidents, which was held by EASA in Cologne last week, there was a lot of discussion about these issues and pilot training in general.

It has been agreed, that stall training has to be revised and that merely 'powering yourself out of it' isn't enough.

Modern simulators do not replicate all aspects of aircraft behaviour 100% realistically, but they are considered to be close enough to the 'real thing' and also: they are the best we have.

Pilots should receive more training doing hands-on flying at all altitudes and in all configurations of their aeroplane.

Mr. C. Lelaie, a former Airbus test pilot and a well known capacity in the community, told me that the A330 is entirely controllable at all flight levels and in all modes or laws the airplane has to offer.

I know it must sound easy to somehow with Mr. Lelaie's background, but point he (and others, representing Boeing, NASA, the FAA, simulator providers and so on) was trying to make: scenarios like these should be practiced during training from time to time...

Interesting point made by someone from Lufthansa CityLine: SIM time is precious. Why not practicing system malfunctions in simpler cockpit procedure trainers rather than expensive full-motion flight simulators, thus leaving more time for manual flying of the aircraft?
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Old 15th Oct 2011, 11:02
  #66 (permalink)  
 
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Originally Posted by DC-ATE View Post
recovery from a deep stall is possible [from 10000 feet above ground] in a 737-200. Been there, done that !! No problem.
Originally Posted by DC-ATE View Post
Well, we weren't trans-oceanic, but it was night, solid IMC.
What amazes me is that you appear to have still not figured out how incredibly poor airmanship you had on that night. In fact you talk like you think you are a good pilot. Try scary.
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Old 15th Oct 2011, 12:12
  #67 (permalink)  
 
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Originally Posted by rmac View Post
I think that software developer in post 50 not only brings us back to a major causal factor, but also explains it in a perfectly understandable way that for me makes it potentially the most important factor in the accident.

The stall warner was "inverted" or you could say reversed...
Only towards the end of the sequence. The Stall Warning was sounding perfectly correctly for nearly a minute, during which the PF was still hauling back on the stick.

The reason the SW stopped sounding was because EAS (I think) was below 60kts. Not many flights encounter that kind of speed in mid-air.
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Old 15th Oct 2011, 12:41
  #68 (permalink)  
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Punkalouver

I wouldn't be too quick to criticise 'DC-ATE'. I suspect if he'd been on 447, things might have turned out better.

It was basic flying skill (lack of) that did for AF447. Whatever people say about 'ye olde dinosaur' pilots, they do have certain advantages over the children of the magenta line.
 
Old 15th Oct 2011, 12:58
  #69 (permalink)  
 
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rmac agree that the stall warning 'inversion' that occurred in this accident was likely a significant contributor to the confusion on the flight deck in the later part of the descent.

My understanding is that although the aircraft remained stalled throughout its descent, the stall warning ceased because the forward airspeed was too low to allow valid AOA measurement. Is there a flaw in this logic? Surely an aircraft is always stalled if it is in the air and has a forward airspeed so low that AOA cannot be measured, whatever the AOA. Why would you program the stall warning to stop under these conditions?

Related to the absent stall warning and the confusion it may have created; to what extent does the group feel that, absent reliable airspeed indications, the crew assumed that with engines at full thrust throughout the descent and no stall warning, it was not possible to be or remain stalled?
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Old 15th Oct 2011, 13:24
  #70 (permalink)  
 
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BOAC-
DC-ATE - are you saying you were in a 'deep stall' (whatever you think that is) with 10kfpm down at 10k in IMC?
Hi, BOAC. I don't recall now [it was over 40 years ago !!] what the descent was, but it was nowhere near 10K FPM. Probably on the order of 1500 FPM. As to 'deep' or 'full' stall, I think it was deep. There was NO elevator control at all. I think it was because we had at least 4 inches of ice on the stab. That's how much was on the wing when we turned on the ice light and then the wing heat. [No tail heat on that bird, as I said earlier] Maybe ice was involved in AF447; that hasn't been mentioned. All I know is I managed to recover "my way" vs the "book" way. But, again, we digress.


punkalouver-
What amazes me is that you appear to have still not figured out how incredibly poor airmanship you had on that night. In fact you talk like you think you are a good pilot.
Not sure what you're getting at. This was a training flight and I was flying right seat at the time. It's the Instructor who showed "poor airmanship" as far as I'm concerned by being there in the first place and NOT knowing WHAT to do to recover.
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Old 15th Oct 2011, 13:46
  #71 (permalink)  
 
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I love all the stories we keep hearing of a 'deep' stall and the notion that AF447 was being held in the stall by the THS and elevators. People, get this out of your heads.

Please go look at report #3 and the traces. At about 2:11:45, N1 was greatly reduced and the nose fell through with the pitch angle falling from 15 degrees nose up to 10 degrees nose down in about 10 seconds. The THS was at max nose up and the PF had full back stick yet the nose still fell through. Also notice, the airspeeds became valid and the stall warning sounded. The aircraft gained sufficient speed and the PF inputs and THS raised the nose ten degrees to a pitch of 0. However, as speed fell off, the nose again fell to 10 degrees nose down. Recovery at this point was not only possible but easily accomplished IF the pilots had recognized the REAL problem.

If you doubt this, look later in the flight at 2:14:10 when N1 was again reduced with the THS in full nose up and BOTH pilots pulling back on the sidestick. Again, the nose fell through from almost 20 degrees up to 5 down. Granted, by this time recovery was not possible.

If it was the THS and pilot inputs holding the nose up, please show me the proof. And all these stories of 'deep stall' and losing elevator authority etc... Please give me a link not just the story because looking at the AF447 traces, appears to me all you have to do to reduce pitch angle is reduce N1.

In addition, commercial aircraft must have positive longitudinal stability which means the nose is going to fall through no matter what the flight controls are trying to do at a certain speed/angle of attack as long as the center of gravity is within the prescribed limits. However, with the power of the engines today and being under-wing, with full N1, you can get a situation like we see in AF447.
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Old 15th Oct 2011, 13:58
  #72 (permalink)  
 
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With all the learned (and others) discuisions about stalls, deep or otherwise, the point has been missed that when the airspeed became unreliable, the PF seems to have started at once to hold the stick back.
Until the event started, everything was normal: the aircraft was in trim, straight and level, and all was calm. Perhaps too calm for a relatively inexperienced, but no doubt keen to prove himself, young man, who may even been in a slight doze - not an unusual thing to happen, as I well remember from experience (thank goodness for an alert navigator who was always pernickety about heading).
Where calm analysis was needed, the PF started to thrash the stick about ("stirring the mayonnaise"), having probably never heard the adage (or its French equivalent) "Don't just do something, sit there", not forgetting the rider "but not for too long". Precipate actions started the whole sorry chain of events going.
From experience again, it's very, very hard when friends and "mates" foul up, and on occasions I had to protest strongly when an Inquiry seemed to be about to jump to conclusions, because drawing the right conclusions is the only way for lessons to be learned.
That's why I trust the BEA and its thorough methodology to "get it right" and why I haven't posted on this thread before (and for the last time).
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Old 15th Oct 2011, 14:00
  #73 (permalink)  
 
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Originally Posted by PuraVidaTransport View Post
The THS was at max nose up and the PF had full back stick yet the nose still fell through.
And came straight back up again because of the inputs and THS angle. Reducing thrust would have helped, certainly - but positive action needed to be taken to effect a recovery by keeping the nose down.

I can't help but think this conversation is off topic (which is the book and accompanying Daily Heil article), and properly belongs in the Tech Log thread however.

@BarbiesBoyfriend - saying that poor airmanship on the part of the F/Os at the controls is all there is to it is a very narrow viewpoint. The net needs to be cast wider - firstly to take into account the poor CRM on the part of the Captain in failing to explicitly assign roles to the crew dring the relief phase and finally to take into account the industry-wide misuse of automation to cut back on manual handling training. A side issue relates to the methods relating to the pitot tube repair/replacement schedule and whether more could have been done on the part of the regulator and manufacturer there.
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Old 15th Oct 2011, 14:48
  #74 (permalink)  
 
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Originally Posted by The Shadow
You really cannot blame the crew.
They experienced (i.e. quietly slipped into) a pitch-up (and thrust-) induced, and very insidious, deep-stall entry at high altitude - a straight unapparent and unremarkable entry into a very high descent rate, featuring a quite misleading and almost normal pitch attitude.
That could be good analysis of some accident that has not much in common with AF447. Before we go on having a productive discussion, please clarify: are you writing about AF447 at all? If so, do you have more reliable sources than BEA preliminary reports, because most of what you have written flies in the face of the data released by BEA so far.

Originally Posted by bubbers44
I know they were new pilots but why couldn't they figure out what was happening to them? pulling back for 3 and a half minutes goes against all of our survival instincts.
Well, they were 58, 37 and 32. Not young. Not new. Not inexperienced. Pulling back goes against pilots' survival instinct but it doesn't go against the earthlings' survivor instinct when flying: ground is dangerous, I have to get away from it as quickly as possible. Most of people undergoing initial pilots' training have to be taught not to climb too steeply after takeoff.

Not understanding the relation between pitch control and stalling, consequently pulling no-matter-what, was identified as cause of stall related accidents by Wolfgang Langewiesche as early as 1944. There's old aeronautical cliche: to go up, pull the stick back. To go down, pull stick back further. Still applicable.

Originally Posted by Burnswannabe
even given erroneous readouts, the pilots should have had enough overall awareness of there situation that a stall should have been self evident.
Correct.

Originally Posted by Burnswannabe
the current fear that manual flying skills will atrophy as systems take more of a role appears to be valid.
Company and pilot dependent. When I was on bus, I was allowed to take out all the automatics and fly even without the FPV (birdie) in CAT1 and above weather, provided my capt was comfortable with that. They always were.

Originally Posted by Burnswannabe
there is now doubt that increased automation has improved safety but the major accidents I can think of recently, in the western world, have been in spite of automation or directly/indirectly caused by it.
That's quite selective view, helped by noticing something is wrong only when number of dead westerners in an aeroplane crash goes above the detection threshold. We never had less killed passengers per RPK than nowadays. If you'd like to propose different criteria of measuring safety, be my guest.

Originally Posted by Burnswannabe
Perhaps we need, as an industry and as a fraternity, to invest more in operator input at the design stage.
Perhaps we do, perhaps we don't. Some things could be improved, but overall methinks designers are paying attention to pilots input. All the ergonomic problems I've came across while flying were results of grandfathers' rights - it was cheaper to do the things way they were done 40 years ago than to invest in redesign.

Originally Posted by Burnswannabe
It is oh so easy to sit in the sim expecting trouble but it is rare in life to find ourselves outside of the norms
Not true. Just take a look at the Aviation Herald and that's just a part of it. Troubles happen everyday but they're dealt with as expected. Someone with just a passing interest in aviation will notice them only when they lead either to spectacular incident or accident.

Originally Posted by Burnswannabe
I am certainly not suggesting we go back to fully manual control systems
It would make no difference whether you suggested it or not. We still carry them as backup and are supposed to know how to use it to extract us out of any corner autos have driven us into.

Originally Posted by Burnswannabe
I suggest that we all need to spend more time in the sim being surprised as opposed to just knocking out the stats, even if this means more expense.
Totally agree.


Originally Posted by Intruder
What would have happened if the pilots just took their hands off the stick altogether.
Probably not much. Some altitude excursion, some roll, unlikely to be as severe as were the one commanded.

Originally Posted by Intruder
What would the computer have done?
Nothing. It usually does nothing. In AF447 case as it was confused by disagreeing airspeed, it wouldn't even intervene as the aeroplane was approaching the edge of the envelope or attitude limits active in normal law.

Originally Posted by Croqueteer
With a traditional column if it is back past a certain point the wing is stalled, and it is pretty obvious that the a/c is being held in a stall, ie the stick position gives a idea of attitude.
This is so wrong that is bound to be quite lethal if one is to try it in real world, especially in THS equipped aeroplane where column drives elevators only.

Originally Posted by 4468
He doesn't even know it's possible to stall an A320 in normal law.
It would be beneficial for our discussion if you would be so kind to explain in exactly which way can be any FBW Airbus stalled in normal law. Your words or copy-paste. Please.

Originally Posted by in my last airline
The way forward is for an externally delivered LPC (regulator) every 3 yrs covering all the normal items plus any number of potential items. Let's get back to 'hard, firm and fair' training and checking.
You're onto something but I'd rather see the G-man on OPC and a bit more frequent than three years.

Originally Posted by wet vee two
How often have you all practiced unusual attitude/unreliable airspeed scenarios?
UA every 2 sims, unreliable airspeed every 4 sims. Bound to get more often. Last one was total static blockade at crusing level. Brought it down in one piece, didn't even overspeed gear or flaps, which is average performance expected of pilots in my gang.

Originally Posted by wet vee two
The size of a modern flight deck, the eyes have a long distance to travel across all instruments
Well, then the Airbus flightdeck is positively postmodern with its smallish, yet big enough PFD.

Originally Posted by DiamondBob
What did the other crews do when their pitots were blocked? Supposedly this occurred 32 times on A330s and A340s before AF 447, but I've never seen any accounts as to how this was handled in those situations.
Kept on flying. Some were so unmoved by the experience they even did not report it and it was only through thorough analysis of QAR data that some occurrences were discovered. Interim 2, pages 50-53 refer.

Originally Posted by Ashling
The crew failed to recover the aircraft because they failed to diagnose why they were out of control. They died not knowing what had gone wrong. To me its surreal that they could not recognise the stall
...so far so correct, but...
Originally Posted by Ashling
but it would seem that the situation was beyond their training, experience and competence. How could they be allowed to be in command of a commercial jet in that environment when they didn't possess the skills required to cope when it all went wrong?
... you have moved a bit offtrack here. That they didn't posses the skills to cope with the situation just when they needed to have them is quite certain. However, we'll need thorough HF analysis to see whether their ineptitude in handling the incident and turning it into an accident was deeply rooted or it was just fatal momentary lapse of airmanship, brought on by fatigue or whatever else. You might be right, Ashling, but currently only by pure chance. We still don't have enough data to make correct conclusion.

Originally Posted by HPSOV L
They were an average crew on an average day. Maybe even above "average" when you consider their experience and the fact that they continued to try to understand the problem and regain control all the way down.
They tried and failed. Their methods were found to be wanting. Whether they were average, or even above-average crew, we'll need deeper HF analysis to tell us.

Originally Posted by HPSOV L
Statistically then it is likely that most of the posters on this forum, thrown into the exact same circumstances, would also end up in the ocean. And I include myself in that, hand flying skills and all..
You are right, as most of the posters on this forum are not A330 rated and quite a lot have zero hours TT therefore your claim is not particularly relevant in discussion about AF447. Interim2 is pretty clear on how other crews resolved similar situations. It's 37:1.

Originally Posted by ManAdaSystem
How do Airbus crew train stall recovery?
Currently, line pilots don't. Subject to change soon. That large majority of PPRuNers have no ability to tell stall from stall warning and consequently "stall recovery" from "approach to stall recovery" has lead to quite large waste of bandwidth and I don't expect it to change.


Originally Posted by lyo
Had a conversation with an AI FE. He told me about a test flight last summer.
Wow. I mean: wow! Such a spectacular flight and no one heard about it before you decided to share it with us. Either Toulouse is more secretive than Kelly Johnson's Skunkworks or someone let his imagination run wild.

References, please! Even if you have to shoot me after you tell me.

Originally Posted by BOAC
We are getting a bit confused here between 'full stall' and 'deep stall' I think, and in the case of 447 it was being held in a (amazingly stable) full stall (not a 'deep stall') by THS setting and elevator
Don't forget the engines. Low q, high trust.

Originally Posted by BOAC
I have just seen Lyo's frightening post regarding loss of elevator function, so yes, it looks as if could be described as a 'deep stall'
I've seen many posts like it and stopped considering them frightening, As long as we don't see some solid confirmation of it, I'll classify it as "sad".

Originally Posted by BarbiesBoyfriend
Whatever people say about 'ye olde dinosaur' pilots, they do have certain advantages over the children of the magenta line.
Have a look what Aviation Safety Network to see what real 'Ye olde dinosaur' pilots did. Not everything was related to not having autos or nav and safety equipment we enjoy today. Like hitting the ground below airport elevation.
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Old 15th Oct 2011, 14:50
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I usually just read these threads and remain silent because "it's better to keep your mouth shut and be thought stupid, than open your mouth and remove all doubt", but I keep reading something that must be addressed.

Stall recovery vs. "approach to stall" recovery. Actual pilots can now skip to the last paragraph.

To those of you not studied in stall training above the private/commercial level, we DON'T train nor practice "stalls" at the ATP (US) level. We train for "approach to stall". Pilots of my generation fully understand that you must reduce the angle of attack - lower the nose - to unstall the wing. We also know that the ATP (an instrument rating) requires that we recover from an approach to stall with minimum altitude loss. In an approach to stall, the wing never stops producing lift. When the system senses the onset of a stall, it provides warning; warning that if followed will result in preventing the stall and avoiding altitude loss. This is simply due to the type of aircraft we fly in the air transport business (those being transport category birds that are certified to give proper stall warning), and to the rules which apply to those aircraft and their airline operation.
Airline pilots fly transport category certified aircraft and train to instrument procedure standards, a situation that demands that approaches to stalls are dealt with by increasing power ( to recover from the low speed condition) and maintaining altitude (to prevent hitting the ground if the approach to stall happened near the ground - as in an instrument approach).

Those of you who continue to stress your disbelief that the pilots didn't dump the nose need to recognize that the pilots were not trained to do so. They were trained to follow their instruments and use a specific procedure to deal with the situation. The AF447 pilots were faced with instruments that couldn't be trusted and a situation for which they had never trained.

In the Airbus I fly, the only concrete information I can see from my seat is the horizon in front of the windscreens. EVERYTHING else is computer/electronically generated. Please remember that when you question the actions of three pilots who were faced with: dark skies, thunderstorms, unreliable instruments, turbulence, no visible external cues, myriad ongoing nuisance warnings, .............. This was NOT an accident caused by a single factor!(IMHO) The final finding will likely indict everything from aircraft systems and philosophy to government oversight to airline training philosophy. In the mean time, let's not waste the opportunity to change things for the better by taking the easy way out and blaming the dead guys.
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Old 15th Oct 2011, 15:16
  #76 (permalink)  
 
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The only addition to the STALL discussion is that these guys were NOT treated to the standard airframe cues of STALL. Did they hear the actual STALL WARN? Did they feel vibration, loss of noise of airstream, etc?

Later, out of energy and PITCHED up, there was no NOSE drop, and prior, there had been no BUFFET, a clue to imminent loss of lift.

What were the feel cues? What about this STALL entry was so unlike what might have reasonably been expected in Vanilla Stall? Further, what about this entry hypnotized all three into functionally eliminating STALL from the list of possible failures?

It is not complicated. Yet it continues to be passionately discussed. In the Flight environment of the instant, one only has instruments with which to troubleshoot. Before making judgments, it would be best to more fully understand the instruments, and those that failed.

And try not to be seduced into a post mortem of the part of the flight that is selling newspapers, and is virtually bankrupt of lessons, and ultimate justice.
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Old 15th Oct 2011, 15:20
  #77 (permalink)  
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Originally Posted by DW
I can't help but think this conversation is off topic (which is the book and accompanying Daily Heil article), and properly belongs in the Tech Log thread however.
- good call, Sir.
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Old 15th Oct 2011, 15:25
  #78 (permalink)  
 
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Hi all
Had a conversation with an AI FE. He told me about a test flight last summer.
3 test pilots, an air asia 330 And a flight test program. Vmc day light over the Jay of Biscaye in a dedicated flight test area.
This guys reconfigured the lad in alternate 2, stable fl 350, zoomed to fl380, entered a Stall. It developed into a deep Stall. No information about ths position though.
Eventually, they recovered at ...6000ft... As the elevator authority was lost, deep Stall, they found themselves powerless using standard techniques to recover from it. A rudder input induced a spin which Led to a dive And our test pilots recovered This tricky Stall. These guys reported that they felt the end was near...
I hope the live feed he witnessed that day Will be Made available for all pilots to learn from guys who were prepared And trained for that event.
I have serious doubts about the validity of this report and suggest that it should be discarded or confirmed before using up more bandwidth discussion in yet another AF447 thread
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Old 15th Oct 2011, 15:31
  #79 (permalink)  
 
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@TTex600

For what it's worth, I'm not a pilot and am well aware of the difference between approach-to-stall procedure and stall procedure. I'm also aware that the ATP training only deals with the former. However I'm pretty sure that stall training itself should be part of the pilot's toolkit before getting anywhere near a jet - i.e. at the PPL level.

It looks like airline training was relying on that being somewhere in the background (at the 'riding-a-bike' level) and focusing on the approach-to-stall procedure to the exclusion of stall recovery, and I think all people are suggesting is that in future this might not be such a good idea.

Finally, the only instruments that were "untrustworthy" were the ASIs, and any gizmos that relied on them. Crucially, they had a working altimeter, working ADIs and working engine instrumentation - which was more than enough to stabilise the aircraft using pitch and power *if you know how to do it*. Transducers have been used in aircraft instrumentation since the 1970's and are no less reliable than their mechanical forebears.

Again, I think this discussion is better suited to the Tech Log thread.
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Old 15th Oct 2011, 16:36
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Agree with DozyWannabe,

Most displays would show the correct indication IF actually only the ASIs were affected. May I add, and raise a question at the same time (maybe already noted somewhere before), what about the VSI readings in front of each pilot? According the A320 manuals (my current aircraft), it is given by both the static ports AND the IRUs, I would imagine the A330 to be wired with the same logic, so even in case of FULL loss or ADR DATA or ADR voted out by the system, the VSI should (was?) still be showing from the IRUs inputs.

Despite the apparent confusion, night IMC, probable turbulence at some point, the VSI would have been a good confirmation that the aircraft was going downhill?

Of course this is just one aspect and does not pretend to invalidate any findings, I am just curious I have not seen it here.

Flex
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