Go Back  PPRuNe Forums > Flight Deck Forums > Tech Log
Reload this Page >

AF 447 Thread No. 12

Tech Log The very best in practical technical discussion on the web

AF 447 Thread No. 12

Old 19th Feb 2017, 16:53
  #1321 (permalink)  
 
Join Date: Nov 2016
Location: Lakeside
Posts: 534
Received 0 Likes on 0 Posts
"I went home that night and put away the better part of a bottle of Scotch . I honestly don't know how my friends who do crash investigations for a living do it..."

You're very gracious to respond. The final straw for me in the business was a homicide. Clearly and demonstrably perpetrated by a police officer, in uniform, the web of complicated conspiracy necessary to exonerate, and not even charge the suspect angers me to this day.

So, the suppression of evidence gets my blood to boil.

If I were given the job of writing a synopsis of 447 and the Report by BEA, I would likely have to experience the same sort of frustration....

In this accident, the technical, the scientific evidence has great representation. There were three (at least) eye witnesses of the entire four minutes; their voice record is not available.

In a capital case in this country, to withhold material evidence from the Court at trial is a felony, and would likely be charged and pursued. Keep in mind that those who retain it in this accident and prevent its propagation, are not even the "Police".

This is not complicated, and for those in the business who see it happening, well, I would hope they are as upset as I am.

My hope is that at trial, sanity prevails. A Subpoena by the Judge, and it's done. The recording is released, and since it bears so heavily on the Public interest, it likely would be made available to all.

If the evidence has been "lost", "modified", or destroyed, well, let's hope it remains available.

As a professional in the business, are you concerned about the doubt of the accuracy of the Report? It taints all the work done on the Report by everybody, it casts doubt on all...

Thanks also to IcePack....
Concours77 is offline  
Old 19th Feb 2017, 23:10
  #1322 (permalink)  
 
Join Date: Jul 2009
Location: Not far from a big Lake
Age: 81
Posts: 1,461
Likes: 0
Received 0 Likes on 0 Posts
Concours77, I am glad that we have your motivation and background out in the open. In a PM earlier I noted that I perceived that you were attempting to steer the narrative of the accident. The problem with that tactic is that you obviously did not have sufficient aviation background to do that successfully.

I have investigated aircraft accidents, witnessed aircraft accidents, and read thousands of accident and incident reports over the years and one thing I have learned is that there are extremely few new ways to have an accident. The addition of technology between the pilot and the aircraft opens up new possibilities for misunderstanding what is happening, but aerodynamics is till at work in the background to make things fly.

When you take an aircraft through the maneuvers depicted on the AF447 DFDR readout, it is obvious what put the aircraft in the water so the question I have, is what factors were influencing the crew to allow them to grossly mis-understand what their aircraft was doing. I would like to have a discussion what influence fear may have played in this accident. I am not considering the typical movie depiction of fear, but rather the built in physiological response to fear that any pilot worth his salt has experienced and overcome in training and operations. In my experience, professionals will typically attempt to keep solving problems right up until the end. The problems occur when the physiological response to fear/stress interferes with perception and with orderly thinking.
Machinbird is offline  
Old 20th Feb 2017, 01:48
  #1323 (permalink)  
 
Join Date: Nov 2016
Location: Lakeside
Posts: 534
Received 0 Likes on 0 Posts
Machinbird

I appreciate your level of experience. I would be interested still in your opinion regarding the Roll Direct issue at 02:10:05. Still PIO?

Stick and Rudder is what killed them, no doubt, but my interest is in their eye witness commentary on the way down.

Why do you make no complaint about the "CVRFile" being kept in the dark? You want progress in interface? You think Fear would be an interesting data set?

What do you expect to learn without the most valuable evidence available? I think you're on to something; do you not think the eyewitness record is or should be public domain?

What the hoarders of the record owe the public is clearly apparent. That they continue to block access is criminal, IMO.
Concours77 is offline  
Old 20th Feb 2017, 05:15
  #1324 (permalink)  
 
Join Date: Jul 2009
Location: Not far from a big Lake
Age: 81
Posts: 1,461
Likes: 0
Received 0 Likes on 0 Posts
do you not think the eyewitness record is or should be public domain?

What the hoarders of the record owe the public is clearly apparent. That they continue to block access is criminal, IMO.
Concours77, there exists an uneasy relationship between pilots and things that record what they do and say in the cockpit.
In order to have CVRs in the cockpit, the authorities have had to agree that pilots last words will not be made public in raw form, otherwise pilots have means of defeating such recording devices in order to maintain their privacy. In unusual circumstances, raw recordings have been made available to the public, but I for one am willing to forego someones final expressions of dismay in order to have access to the bulk of what was said in written form. I know other clues to look for to draw the bigger picture.

I would be interested still in your opinion regarding the Roll Direct issue at 02:10:05. Still PIO?
I have had extensive discussions with Owain Glyndwr who possess much more detailed aerodynamic knowledge than I will ever hope to have. He has mathematically demonstrated that it was not a classic PIO, however I have enough physics to know that any system with feedback and too much gain will go unstable. A pilot is a variable gain feedback device and a highly excited pilot is very likely to increase the rapidity and level of his feedback if he perceives the aircraft is not doing what he mentally expects it to. Add interesting effects such as time dilation to the pilot's time perception and who knows what the result can be. These effects are extremely difficult to generate for scientific study. I do know that two Airbus aircraft have been lost after the PF inexplicably pulled back on the stick and pretty much held it there after experiencing roll instability at the transition to Roll Direct in alternate law. (AF447 & QZ8501)
Machinbird is offline  
Old 20th Feb 2017, 14:42
  #1325 (permalink)  
 
Join Date: Nov 2016
Location: Lakeside
Posts: 534
Received 0 Likes on 0 Posts
Machinbird

Hello.

"Concours77, there exists an uneasy relationship between pilots and things that record what they do and say in the cockpit."

Colgan gave us the first officers final scream. Some doomed pilots have uttered infantile and guttural sounds. So let's be honest. An "uneasy relationship" is a political expression of an adversarial discussion....

At some point, one needs to judge whether public safety is more important than politics....I believe it is. Your position seems that it is "negotiable".

Post 447, the pilot group at Air France threatened a strike unless the Thales pitots were changed out on a more urgent basis....remember? That is "public safety" as an expression of a professional group with an informed and common position....

So we appear to disagree, fundamentally....

I do not suggest that the record be exposed on some ridiculous reality show, but shared respectfully with unbiased and neutral professionals.

I find it interesting that virtually all of the "transcribed" CVR releases conform with what amounts to a consensus informed with data that is not complete.

Without any bias whatever, an investigator could (would)? challenge the secret CVR as suggestive of fraud; something that would certainly be added to the other data as a matter of obvious duty?

Either the Report is true to its mission of public safety, or it is not.....Censorship is not only inappropriate, it should be an embarrassment to the mission....
Concours77 is offline  
Old 20th Feb 2017, 14:46
  #1326 (permalink)  
 
Join Date: Nov 2016
Location: Lakeside
Posts: 534
Received 0 Likes on 0 Posts
Also, re PIO

Did you miss the Captain's command to PF much later in the chronology?

"....Watch your Lateral!!...."

What do you make of that?

"I do know that two Airbus aircraft have been lost after the PF inexplicably pulled back on the stick and pretty much held it there after experiencing roll instability at the transition to Roll Direct in alternate law. (AF447 & QZ8501)"

"Inexplicably"? My first assumption would be that pulling back stick kept the aircraft "controllable".

That remains my working theory with AF447.....and,

, however I have enough physics to know that any system with feedback and too much gain will go unstable. A pilot is a variable gain feedback device and a highly excited pilot is very likely to increase the rapidity and level of his feedback

Do you include the aircraft in this supposition? Or, just the pilot?

Last edited by Concours77; 20th Feb 2017 at 15:05.
Concours77 is offline  
Old 20th Feb 2017, 16:33
  #1327 (permalink)  
 
Join Date: Jul 2009
Location: Not far from a big Lake
Age: 81
Posts: 1,461
Likes: 0
Received 0 Likes on 0 Posts
Do you include the aircraft in this supposition? Or, just the pilot?
In this case of AF447, just the pilot as in gross over-control.

Did you miss the Captain's command to PF much later in the chronology?

"....Watch your Lateral!!...."
No, didn't miss it. He is being thrown around in the cockpit as the aircraft experiences wing drop in the stall, a logical speculation as to the meaning of the comment.

"Inexplicably"? My first assumption would be that pulling back stick kept the aircraft "controllable"
Probably not too far from the truth. Once stalled, as the aircraft became slower, the wing drops likely became less violent. (speculation again.) However, initial pull up into the stall was due to a fear response (more speculation) caused by rapid oscillatory roll rates (AF447 & QZ8501)

Regarding CVR records,
I do not suggest that the record be exposed on some ridiculous reality show, but shared respectfully with unbiased and neutral professionals.
So how do you propose that can be done without losing control of the raw audio?

As an investigator in an accident (military), I have sometimes been asked to consider a particular viewpoint.. That is an undesirable position to be in when the person making the request also writes your personnel evaluation. The more independent parties to an investigation that there are, the better the likelihood that the truth will out.
Machinbird is offline  
Old 20th Feb 2017, 18:09
  #1328 (permalink)  
 
Join Date: Nov 2016
Location: Lakeside
Posts: 534
Received 0 Likes on 0 Posts
Machinbird

"Probably not too far from the truth. Once stalled, as the aircraft became slower, the wing drops likely became less violent. (speculation again.) However, initial pull up into the stall was due to a fear response (more speculation) caused by rapid oscillatory roll rates (AF447 & QZ8501)."

Let's start here,
I sense some common ground....

Do you know our Pierre Bonin? Of course not. From what I derive from Lo these many threads my conclusion is different than your supposition that the initial pull up was a response to fear. It is highly unlikely.

My suppose is his inputs were generated from anger...not fear. From Owain Glyndwr, we know his control inputs were immediate, and fear takes time to develop. Now it is possible that his fear had presented prior to manual control, but if so, I suggest his emotions were supportive of action, Not patience.

Patience is the cure for panic, as well as other unwanted emotion....if one is healthy, and understands his emotions, his patterns.

Fear is basic, the mother of all emotion, even Love. To reach the kind of fear you are suggesting takes input, observation. the lizard brain demands data, it cannot think on its own.

Would you consider broadening the discussion, without judgment? I do repeat however, the only real data that would be instructive is inside that sequestered chip.....?
Concours77 is offline  
Old 20th Feb 2017, 18:56
  #1329 (permalink)  
 
Join Date: Jul 2009
Location: Not far from a big Lake
Age: 81
Posts: 1,461
Likes: 0
Received 0 Likes on 0 Posts
and fear takes time to develop
Well, I think I will take issue with this statement. From practical experience, the acute attention physiological response (Fear response)takes about 1 heartbeat. You know when it hits you because your heart violently contracts (like it did the time another formation interleaved the formation I was in at 90 degrees to our heading).

Can you quote your source for this physiological observation of yours?
To reach the kind of fear you are suggesting takes input, observation. the lizard brain demands data, it cannot think on its own.
Machinbird is offline  
Old 20th Feb 2017, 21:33
  #1330 (permalink)  
 
Join Date: Nov 2016
Location: Lakeside
Posts: 534
Received 0 Likes on 0 Posts
Stimulus, Response. No Stimulus, no Response. That is the role time plays in the emotion called fear.

"(like it did the time another formation interleaved the formation I was in at 90 degrees to our heading)."

What caused Bonin's "Response"?

I have postulated that his initial Pitch up was a result of the aircraft's nose down attitude...why would that create (result from) fear? To me, it was the correct response. Similarly, as he struggled (and mastered) the Direct Roll, he likely noticed it came about in conjunction with his back stick? You admit the docility he may have experienced in Roll might be due to his conclusion that Pitch Up made the a/c more controllable?

Now. We know that the first time the crew demonstrated a knowledge of loss of speeds and the Law degrade was at 02:10:22. Seventeen seconds AFTER the DFDR posted the data.

It is not logical to assume that because we have the DFDR, and a timing of the changes, that the crew did also.

In fact, it is preposterous. Why? Because we have a pilot who is struggling, and convinced that Pitch Up is necessary to maintain controlled flight? Do we even know if he is aware that the aircraft is in Roll Direct? The evidence shows that he probably does NOT recognize Roll Direct, his first Roll input was made to correct for turbulence!! Why is he expected to be able to differentiate turbulence from Roll Direct?

At this point, my working hypothesis would be "Split Mode, Roll Direct, disguised as turbulence". Throw in a surmised solution of Nose Up controls flight path, and for seventeen seconds, he has done the wrong things; we know it, he couldn't have?
Concours77 is offline  
Old 21st Feb 2017, 05:09
  #1331 (permalink)  
 
Join Date: Jul 2009
Location: Not far from a big Lake
Age: 81
Posts: 1,461
Likes: 0
Received 0 Likes on 0 Posts
Concours77
Stimulus, Response. No Stimulus, no Response. That is the role time plays in the emotion called fear.
I'm not sure if we are on the same page, Concours. Do you now agree that an extreme fear response can occur virtually instantly or do you hold a viewpoint that it takes a significant amount of time to develop? From my own experiences, it can hit you like a hammer blow.

I am pleased to see that you are attempting to look at the AF447 event from the the "inside" view rather than as a judgemental external viewer. I think we will be able to do some thought experiments to validate/invalidate your concept.

From my personal experience again, any time an aircraft does not appear to be following your control inputs for reasons that you do not understand or cannot control, it will immediately trigger a strong physiological fear response in the pilot flying.. By fear response, I am referring to the typical fight or flight reactions.

I would like others who have also encountered this situation to either confirm or refute this observation so as to confirm if it is inherent to general pilot behavior. I would not expect every pilot to necessarily have had such experiences, however.
Machinbird is offline  
Old 21st Feb 2017, 05:43
  #1332 (permalink)  
 
Join Date: Apr 2012
Location: Europe
Posts: 29
Likes: 0
Received 0 Likes on 0 Posts
AF 447 similarities

I must say after watching the air crash investigation episode of Air Asia A320 over Java sea, the similarities were striking. Yet the French BEA investigator or the episode failed to mention 447 by a word. As if Airbus is covering up known weaknesses with stall at high altitude. Any other with thoughts around this?
Life on top is offline  
Old 21st Feb 2017, 14:45
  #1333 (permalink)  
 
Join Date: Nov 2016
Location: Lakeside
Posts: 534
Received 0 Likes on 0 Posts
Machinbird

"From my personal experience again, any time an aircraft does not appear to be following your control inputs for reasons that you do not understand or cannot control, it will immediately trigger a strong physiological fear response in the pilot flying.. By fear response, I am referring to the typical fight or flight reactions."

Biochemistry describes these responses accurately. Can we agree that the kind of fear we are discussing wants an observed (experienced) stimulus?

If so, then I propose one that might fit your parameters. At loss of autopilot, the a/c was reporting a deviation in altitude of (-) 400 feet. It also, via FD, showed a roll to starboard.

The pilot, probably in concert with ".....I have the controls....", made inputs to climb, and roll left. The aircraft did not immediately respond in Pitch (BEA). In fact, the record shows it took eleven seconds for "....the aircraft began to climb..."

Does that qualify as a stimulus sufficient to gain the pilot's concern?

Life on Top

Don't forget the Captain's exit from his seat to disable the ELAC? There is record on the ACARS of 447 of what looks like an attempt to gain Direct Law by disconnecting "....Prim/Sec......" Also 447's "uncommanded roll", "unresponsive controls" and "Stall,Stall" as the autopilot quit? "Buffet"?
Concours77 is offline  
Old 21st Feb 2017, 15:07
  #1334 (permalink)  
 
Join Date: Oct 2011
Location: invalid value
Posts: 39
Likes: 0
Received 0 Likes on 0 Posts
Concours77, isn't this the 5th or 6th username you have used to engage in a circular, obtuse and amphibolous style of debate on this subject?
Hamburt Spinkleman is offline  
Old 21st Feb 2017, 20:46
  #1335 (permalink)  
Thread Starter
 
Join Date: Oct 2013
Location: Wengen
Age: 53
Posts: 380
Likes: 0
Received 0 Likes on 0 Posts
Concours77:
1) No ELAC on A330
2) Dubois was always standing
Winnerhofer is offline  
Old 21st Feb 2017, 21:07
  #1336 (permalink)  
 
Join Date: Dec 2015
Location: France
Posts: 507
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by Life on top
I must say after watching the air crash investigation episode of Air Asia A320 over Java sea, the similarities were striking. Yet the French BEA investigator or the episode failed to mention 447 by a word. As if Airbus is covering up known weaknesses with stall at high altitude. Any other with thoughts around this?
It is not the fault of Airbus if an airplane stalls when pulled up at a high altitude !!
On the contrary, Airbus does everything in its power to help airplanes keep their normal flight laws and associated protections.

Same flying technique as AF447 but in normal law would have resulted in a perfectly normal flight !
KayPam is offline  
Old 21st Feb 2017, 21:09
  #1337 (permalink)  
 
Join Date: Nov 2016
Location: Lakeside
Posts: 534
Received 0 Likes on 0 Posts
Winnerhofer
My reference was to Air Indonesia A320, and not DuBois.

Hamburt Spinkleman
No.
Concours77 is offline  
Old 22nd Feb 2017, 03:17
  #1338 (permalink)  
 
Join Date: Jul 2009
Location: Not far from a big Lake
Age: 81
Posts: 1,461
Likes: 0
Received 0 Likes on 0 Posts
Concours77, we know you are a lawyer (with light aircraft experience) trying to make sense of the AF447 accident. Others are also interested in the accident and what can be taken away and used. Many are not primary English speakers. You would do everyone a favor if you would try to suppress the lawyer lingo and use simple sentence structure. Also, this is not an adversarial proceeding where you must hide your hand and then spring it on the other side at the most opportune time. Just relax and lets see what we can figure out about this accident.
Machinbird is offline  
Old 22nd Feb 2017, 04:09
  #1339 (permalink)  
 
Join Date: Jan 2015
Location: Near St Lawrence River
Age: 53
Posts: 198
Likes: 0
Received 0 Likes on 0 Posts
On the contrary, Airbus does everything in its power to help airplanes keep their normal flight laws and associated protections.
There was "alternate 2B law", the roll is direct but pitch is still a g load factor law or "normal'' but no stall protection.
After autopilot disconnect, the aircraft banked to the right and lost in altitude. Then possible Bonin grabbed the sidestick instinctively from a reclined seating position. The "normal" flying technique (mayonnaise stirring) put him quickly into PIO with large lateral inputs and an average(30%) nose up. It took about 10 seconds to stabilize laterally, but meanwhile the aircraft changed flight path from horizontal to climb. During next 30 seconds, before stall warning blared into cockpit, the pitch input averaged around neutral = "0" change in flight path (climbing). Now, here is the catch -> Low Energy Awareness: "Past experience on airplanes fitted with a flight-control system providing neutral longitudinal stability shows insufficient feedback cues to the pilot of excursion below normal operational speeds. The maximum-angle-of-attack protection system limits the airplane angle of attack and prevents stall during normal operating speeds, but this system is not sufficient to prevent stall at low-speed excursions below normal operational speeds. Until intervention, the pilot has no stability cues because the aircraft remains trimmed"
_Phoenix is offline  
Old 22nd Feb 2017, 05:42
  #1340 (permalink)  
 
Join Date: Jul 2009
Location: Not far from a big Lake
Age: 81
Posts: 1,461
Likes: 0
Received 0 Likes on 0 Posts
Hand flying strategies

Concours77, you may not have realized how different hand flying in the mach number range at altitude is from your experience in hand flying light aircraft at lower altitudes.

The very high true airspeed causes the aircraft to generate significant rates of climb/descent with extremely small pitch changes. During normal level flight cruise, typical pitch inputs would be on the order of 1/2 degree, with 1 1/2 degree pitch change being a large correction. To do this requires a high level of concentration on the attitude indicator.

At the same time, the high true airspeed reduces the aircraft's turn rate significantly and thus requires less scanning effort on the aircraft heading since that changes slowly. The piloting strategy is then to keep the wings dead level which will stabilize the heading and concentrate on the pitch indication almost exclusively. The ratio of pitch scanning versus heading scanning is probably in excess of 85-15 whereas down low, it is probably more like 50-50.
Machinbird is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.