Nonsense. What is the purpose of resurrecting a thread when all that is happening are people repeatedly repeating what has already been repeated repeatedly? Including a lot of nonsense.

Hazelnuts39, I had the same reaction as you. As I understand it, that response is to a stall warning (warning of impending stall) and the remedy implies that
1. you aren't yet stalled and
2. following that should get you out of trouble and keep you from stalling when all protections are in play.

When stalled reducing AoA is typically the correct response.

I predict that the "why is there no AoA indicator" hamsterwheel begins in 3, 2, 1 ... :E

In all fairness to Capn, the THS would have trimmed nose down if the PF would have commanded nose down with his stick forward for whatever time constant the computers use. I beg all the "new" folks I have seen this past week to go thru the thousand posts on the other thread.

The THS implementation was discussed at length, and several of us agreed that it did not help things if the pilot continued to hold aft stick. Otto tries to reduce your stick position to achieve one gee corrected for pitch attitude, even in some of the reversion modes. 'Direct law" is a different story, and the AF crew never got there.

I shall continue to argue that seeing or feeling the other guy's stick or column or whatever was not the primary contributing factor to the crash. Tried to explain this, but I guess some folks don't understand.

At FL350 and -40 °C the presence of significant quantities of supercooled liquid water is highly unlikely. Therefore the blockage of pitots in AF447 was almost certainly caused by ice particles.

Some examples are shown here. How does one test pitots to ensure they are able to deal with such variety? Is it really sufficient to quantify icing conditions in terms of IWC (ice water content) and mean particle size?

I wanted to post this a while back, but didn't have a chance to . . .
 

But as long as this thread is seeing activity again, there are two things I wanted suggest as things I see as factors in AF447 - and both of them are design related.

The first has been discussed many times (including just recently) before, and that is I think there needs to be some form of mechanical feedback between the control inputs (whether actual or simulated). People are inherently tactile beings and they very much - despite training to overcome it - depend on haptic feedback when the brain is processing higher level intellectual tasks. Look at touch keyboards, musicians, even surgeons using robotic instruments. While they can function without it, people work better with it.

The second may have been mentioned, but I might have missed it in the thousands of posts on this thread. And that is the way that the stall annunciator logic operates. It is pretty clear that the audible "stall, stall" means just that - you are stalling. But in the Airbus, the stall annunciation can be silenced by either recovering from the stall, or in the case of AF447, when the system loses key data inputs (the pitot tubes clogged), yet the system does indicate which.

While the actual cause for the silencing of the warning could have been deduced from various other indicators, in a rapidly changing and unusual system, I think it would be easy for the mind to get into the wrong feedback loop. Warning=on, I'm stalled. Warning=silent, I have recovered from stall. I think that is exactly what happened on AF447 (read the transcript of CVR).

If the system was designed something like, warning="stall", you have stalled; warning=silent, you have recovered and the system knows it because it is fully functional; warning="stall warning suppressed", you can no longer rely on the stall annuciator for the status of your aircraft, I think the outcome may have been different.

Just my thoughts.

UAS checklists on any airliner do not include pull full back. Depending on altitude and weight you select an attitude and power setting which is quite simple and is in your check list. All pilots should be able to do this easily.

bubbers, do you recall any evidence that the UAS (current in June of 2009) checklist was used by this crew?

You're misinterpreting the significance of stall warning. It's function is to alert the pilot that he is approaching stall. The warning is given sufficiently in advance of the stall to allow the pilot to avoid stalling by taking the appropriate stall avoidance actions, i.e. stop pulling, reduce pitch until stall warning stops..

No, but it should have been used and they didn't.

Thanks for that. Would be nice to have them the other (to me logical) way round, although I suppose I could turn my monitor upside down when looking at those parameters! :ok: :)

By rules .. the "Stall Warning" must activate near the point that the aircraft will stall .. and continue if the aircraft (for any reasons) go in the stall mode
The stall warning must continue .. until the aircraft is no more stalled or no more near of the stall mode
By Airbus design the AF447 stall warning stopped when the aircraft was in stall ..
BEA notice in conclusions that this is a contributing factor for the accident

Sorry, I should have been more accurate with my description. But I think the false feedback effect would be the same - hear warning, take some action, warning stops, conclusion = action successful. That conclusion would be false if the warning was suppressed for reasons other than the corrective action.

Please close this thread now
 

I think just about everything that can be known about this tragedy is known. Everything that can be said about it has been said.

It is an important incident in the history of commercial aviation and, of course it will never happen again. There is no point having any more circular discussions about pitots, or center column vs side stick, automation vs hand flying, or B vs A in the context of this incident.

But there will be new incidents like this (hopefully without loss of life) involving the whole system of pilots, CRM, automation and basic equipment faults. There are lessons for everyone. It was especially shocking for me reading the final report on AF447 to see that apart from the pitots, nothing actually failed on the aircraft, until everything did. A simple LOC grew out of all proportions into a major disaster. It happened in a manner that is a foretaste (a bitter one) of the kind of challenges that aviation is going to face. Every extra subsystem adds complexity. Failures, when they occur will be increasingly complex and ever harder to anticipate.

I think future discussions wrt AF447 should focus on this in general, not on the specifics of what happened to the pitots or what was in PF minds during the incident. Let them rest in peace.

It will do just that, except when the pilot ignores the stall warning and continues to pull until the AoA exceeds 40 degrees.
It doesn't.

glenbrook
I enjoyed your summary and your points, but let's not forget the trigger event: something did in fact fail (or become impaired): the pitot system. As noted numerous times in this four year long discussion, Air France had changed to the Goodrich pitot tubes on some of their fleet, but that particular hull had not yet gotten the change. Granted, a system malfunction need not become an emergency (nor an upset) as previously noted hundreds of times. That seems to be a key point of great interest to the flying public, to professional pilots, to regulating authorities, and hopefully the management of airline companies.

The pilots failed to maintain control with a simple pitot tube problem. They had a procedure to maintain attitude and power but they didn't use it. They chose to pull full back on the side stick against all procedures. They killed hundreds of people for no reason because they did everything wrong.

What's it say?

The objective of the SNPL is, and always has been, to support their members and to demonstrate that they were not at fault.

It has the merit of being clear.
.

@desiter And they had a plane that had little control feedback, basic instruments in the zone of view, and a system of Hal 9000 computers that for some reason they were told would protect them or they were made to believe that would allow them to act in a fashion such as pulling the stick back as necessary and that the ship was unstall-able.

Titanic 2.0 sans the Leo and Kate.

Hal 9000 vs Basic Flight Dynamics/Physics - the latter won.

jcjeant: is there a link to an English rendition of that declaration?

It's about the EASA director who would not answer questions of the judge (in charge of the AF447 case) .. citing the (his) European immunity
He finally answered after insistence of the judge
In his testimony we learn that the EASA considered only the information provided by the manufacturers without check or question
Thus incidents implicants pitot tube have been underestimated by the manufacturer
They were ignored and that at no time without the agency deems appropriate to investigate further then that is his mission
The Union notes that the testimony of the director of EASA confirms the doubts and suspicions which had already accumulated on the agency
This situation is very worrying for the institutional management of aviation safety in Europe

OCR and Google Translate
 

SNPL Roissy, May 15, 2013
France ALPA
Press release
Survey AF447: the European Agency
seriously defective air safety
The testimony of the Director of EASA shows the total absence
independence of the regulatory agency vis-à-vis manufacturers.
The SNPL France ALPA questioned since the beginning of the judicial inquiry into the role played by the European Aviation Safety Agency (EASA) in this painful case. During many months of August 2010 to April 2013, the Executive Director of the agency clung to its European immunity to avoid testifying. At the request of its board of directors and by the obstinacy of the instruction judge Zimmermann, he finally explained to justice. The SNPL France ALPA civil party had access to the evidence.
We discover that EASA has seriously failed in its duty of continuing airworthiness of aircraft considering only the information provided by the manufacturers, but never verify or challenge.
It is in this way that the incidents prior to the crash of the AF447 and precursors thereof, caused by icing of pitot probes, were underestimated by the manufacturer. They have been ignored, but that at no time the Agency considers it appropriate to investigate further, as this is where the heart of its mission.
This seems incomprehensible inversion prerogatives reduce EASA a simple transmission belt very bad quality.
The SNPL France ALPA said that in addition to finding a damning report of the Court of Auditors of the European Union in late 2012 involving the deplorable management of conflicts of interest within the EASA.
It is clear that the testimony of the director of EASA reinforces the doubts and suspicions which had already accumulated on the European Agency.
Put into perspective with the development of new FTL, in which the upper hand of airlines is well established, this situation is very worrying about the institutional management of aviation safety in Europe.
The Executive Office of SNPL France ALPA
For 1: SUV enformations. you izomys
Yves DESHAYES, President of ALPA SNPL France: 06 31 06 06 98
Carole Arnaud-BATTANDIER, Media Relations Manager SNPL France ALPA: 0686 709 702
NATIONAL UNION OF DRIVERS LINE FRANCE ALPA
AFFILIATE ACE IFALPA - SFtET N 785 743 246 0003 1 COOE APE 4420Z
Roissypéle The Dome - 5 denies the Hague-BP 19955-95733 Roissy CDG CEDEX
Tel (33) 01 49 89 24 00 - Fax (33) 01 49 89 24 10 - e-mail @ SNPL SNPL oom

What the SNPL doesn't say (important in my opinion) ..
 

If they had followed Air France procedures they wouldn't have crashed.

Through incompetence they flew a plane into a stall then into the Atlantic.
.

Thank you, jc, and thank you Mac. :ok:

Thank you, one and all!

Also....A-HA!

@toffeez:
Yes indeed, but the training was clearly deficient.

Is that an "Airbus" design or an "Industry" design, i.e. same situation or comparable airliners (Boeings, Bombardier, Embraer...) ?
This is, I think, a question that was never answered.

As Mac the Knife's translation shows, it says that EASA failed in its duty of assessing airworthiness of aircraft under its juridiction.
Sadly, it remind me of the FAA and the 787 certification (batteries...)
Could agencies do their job? They seems to have neither the competences nor the will (or power, budget...) to do so. Meanwhile, the aircraft become more complex...
Systemic issue?

AZR:
 

It is a ADIRU issue, no airliner is supposed to be capable of flying! at 60 kt or less.
ADIRU ARINC Air data output is set to AoA NCD(No Computed Data) to the subsystems (e.g. FWC) at 60 kt or less and air speed output NCD below 30 kt or less.

IIRC Boeing T7 ADIRU sets NCD <30Kt and SAARU <50 kt-

"Airbus" design offered several options like analog AoA indicators and/or BUSS (AoA output thru IR part of ADIRU i.s.o. Air Data part).

It is up to the operator(pilots?) to select such an option or not!

Link to AF BUSS

Absolutely correct. The rest of the :mad: on this thread is simply a distraction from the core issue.

They had a problem. They didn't follow the QRH. They killed their passengers and themselves....

Perhaps a little emotive or tactless to word that last sentence so, for they were not willful acts of negligence.

would ' which incompetence was the root cause of this horrific disaster' be an improvement?

With respect to you and your many followers here:

QRHs were around about 1969-72 for me (Hunter then F4). Airbus aircraft are a lot more sophisticated and, as you are doubtless aware, are not used these days.

Am I the first to admit I would have been severely challenged and, probably, overcome by the situation?

Mind you, I have only twenty years Airbus and extensive examiner experience.

What, in your opinion, is the core issue?

BEA - Final Report
So the BEA did get it wrong??

The lesson I take home from all this is that very complex systems generate very complex and confusing failure modes that software engineers and designers cannot possibly discover.

This means that:

1. Automation must never be totally trusted.

2. It must be possible for the crew to revert to basic mechanical instruments and hand fly the aircraft from first principles.

3. Modifications and upgrades are going to become a nightmare for Airbus because it is impossible to completely understand if new failure modes have been created.

I make exception for the basic fly by wire automatics, but nothing else, and if you are going to use side sticks they had better have a mechanical connection so it is patently obvious to blind freddy what control inputs are being applied.

I expect more of these type of accidents.

but simply following your points 1 and 2 could prevent a lot more happening.

or stop calling them pilots - Digital Device Programmed Anomaly Corrective Operatives - seems more appropriate these days. Pilots fly aeroplanes.

I recall a cartoon in Punch, after the first, much publicised, auto-land event, drawn by a very well known Punch cartoonist - so well known that I've forgotten his name ! - it showed a uniformed pilot in a glass cage at the back of the flight deck, with a hammer hanging on the front bearing the notice " In Case of Emergency Break the Glass "

'course - the decision than would be when to break the glass - or call the Captain back from the bunk ?

Thanks A33Zab :)

OK, and does that NCD prevent the stall warning to work, as in the A33x?

NB : This post is intended as summary only - as PJ2 says, the arguments were exhaustively played out over 11 threads in Tech Log.

@Sunfish - This was not a complex or unforeseen failure mode. Unreliable Airspeed Indication causes a drop to Alternate Law, which has no hard protections. This was well-understood by all the engineers, and if it was not communicated to line pilots, it should have been. We know Airbus sent out a bulletin describing a workaround procedure while the problematic pitot tubes were being replaced. How well this was disseminated by airlines amongst their crews is less certain, but we do know that over 30 UAS incidents occurred before AF447, and all of them were successfully resolved by their crews.

@AZR - I don't know for certain, but an educated guess says that NCD on a T7 will cause stall warning to cut out, because with no valid data, the stall warning subsystem has nothing to work with.

For Gods sake what harm could be done by linking the sidesticks so they move together?

Anyone?

@AtomKraft - see the Tech Log threads. There are several pros and cons that go both ways regarding connected versus unconnected primary flight controls.

I have read all these AF447 threads. I can only recall one airline pilot who was opposed to connected side sticks. A few thought it would make no difference to the outcome. The vast magority thought connected side sticks would have contributed to a better outcome.

This is just another generalised summary. I dont wish to infame another polarised debate.

@Cool Guys - I think you'll find that the "pro-connection" folks were the same people posting repeatedly. Additionally, I don't think it's a case of pro vs. anti - it's just that objectively there's no evidence that one is superior to the other.