AF 447 Thread No. 8

[john_tullamarine]

AF 447 Thread No. 8

Thread part -

(a) #1 starts here (http://www.pprune.org/tech-log/395105-af-447-search-resume.html#post5303737) and finishes here (http://www.pprune.org/tech-log/395105-af-447-search-resume-195.html#post6408432). Posts = 3890
(b) #2 starts here (http://www.pprune.org/tech-log/449639-af-447-search-resume-part2.html#post6408428) and finishes here (http://www.pprune.org/tech-log/449639-af-447-search-resume-part2-127.html#post6476460). Posts = 2537
(c) #3 starts here (http://www.pprune.org/tech-log/452836-af447-thread-no-3-a.html#post6476336) and finishes here (http://www.pprune.org/tech-log/452836-af447-thread-no-3-a-104.html#post6515428). Posts = 2071
(d) #4 starts here (http://www.pprune.org/tech-log/454653-af-447-thread-no-4-a.html#post6515515) and finishes here (http://www.pprune.org/6561320-post1061.html). Posts = 1061
(e) #5 starts here (http://www.pprune.org/tech-log/456874-af-447-thread-no-5-a.html#post6561270) and finishes here (http://www.pprune.org/tech-log/456874-af-447-thread-no-5-a-99.html#post6638007). Posts = 1978
(f) #6 starts here (http://www.pprune.org/tech-log/460625-af-447-thread-no-6-a.html) and finishes here (http://www.pprune.org/tech-log/460625-af-447-thread-no-6-a-85.html#post6793822). Posts = 1683
(g) #7 starts here (http://www.pprune.org/tech-log/468394-af-447-thread-no-7-a.html) and finishes here (http://www.pprune.org/tech-log/468394-af-447-thread-no-7-a-68.html). Posts = 1354


Links to the various BEA reports are given below. If I have missed any of the useful papers, please PM me with the URL and I can include it.

(a) BEA site - French (http://www.bea.aero/fr/index.php), English (http://www.bea.aero/en/index.php)
- Report link page - French (http://www.bea.aero/fr/enquetes/vol.af.447/vol.af.447.php), English (http://www.bea.aero/en/enquetes/flight.af.447/flight.af.447.php)

(b) Interim Report (No, 1) Jul 2, 2009 - English (http://www.bea.aero/docspa/2009/f-cp090601e1.en/pdf/f-cp090601e1.en.pdf)

(b) Interim Report No. 2 Dec 17, 2009 - English (http://www.bea.aero/docspa/2009/f-cp090601e2.en/pdf/f-cp090601e2.en.pdf)
- Update Dec 17, 2009 - French (http://www.bea.aero/fr/enquetes/vol.af.447/point.enquete.af447.17.12.2009.pdf), English (http://www.bea.aero/fr/enquetes/vol.af.447/update.on.the.investigation.af447.17.12.2009.en.pdf)

(c) Estimating the wreckage location Jun 30, 2010 (http://www.bea.aero/en/enquetes/flight.af.447/phase3.search.zone.determination.working.group.report.pdf)

(d) Wreckage search analysis Jan 20, 2011 (http://www.bea.aero/fr/enquetes/vol.af.447/metron.search.analysis.pdf)

(e) Briefing and associated update May 27, 2011
- Briefing (http://www.bea.aero/fr/enquetes/vol.af.447/info27mai2011.fr.php) - update French (http://www.bea.aero/fr/enquetes/vol.af.447/point.enquete.af447.27mai2011.fr.pdf)
- Briefing (http://www.bea.aero/fr/enquetes/vol.af.447/info27mai2011.en.php) - update English (http://www.bea.aero/fr/enquetes/vol.af.447/point.enquete.af447.27mai2011.en.pdf)
- Briefing (http://www.bea.aero/fr/enquetes/vol.af.447/info27mai2011.de.php) - update German (http://www.bea.aero/fr/enquetes/vol.af.447/point.enquete.af447.27mai2011.de.pdf)
- Briefing (http://www.bea.aero/fr/enquetes/vol.af.447/info27mai2011.br.php) - update Portugese (http://www.bea.aero/fr/enquetes/vol.af.447/point.enquete.af447.27mai2011.br.pdf)

(f) Interim Report No. 3 July 2011 - French (http://www.bea.aero/docspa/2009/f-cp090601e3/pdf/f-cp090601e3.pdf), English (http://www.bea.aero/docspa/2009/f-cp090601e3.en/pdf/f-cp090601e3.en.pdf)

Miscellaneous pertinent links -

(a) Airbus Operations Golden Rules (http://www.airbus.com/fileadmin/media_gallery/files/safety_library_items/AirbusSafetyLib_-FLT_OPS-SOP-SEQ03.pdf)
(b) ALPA FBW Primer (http://cf.alpa.org/internet/alp/2000/febfbw.htm)
(c) C* and Civil Transports - Cranfield (https://dspace.lib.cranfield.ac.uk/bitstream/1826/186/2/coareport9303.pdf)
(d) Longitudinal Flight Control Design - RAeS (http://www.raes.org.uk/pdfs/2989.pdf)
(e) Longitudinal Stability: Effect of High Altitude and CG - Boeing (http://boeing.com/commercial/aeromagazine/aero_02/textonly/fo01txt.html)
(f) pitot static system performance - USN (Pax River) FTM (http://www.aviation.org.uk/docs/flighttest.navair.navy.milunrestricted-FTM108/c2.pdf)
(g) The Problem of Automation: Inappropriate Feedback and Interaction, Not Over-Automation. Donald A. Norman UCSD (http://www.jnd.org/dn.mss/Norman-overautomation.pdf)
(h) Upset Recovery - 16MB zip file (http://www.mediafire.com/?jrkvp2ysl7aea25)
(i) Ironies of Automation. Lisanne Bainbridge UCL (http://www.bainbrdg.demon.co.uk/Papers/Ironies.html)
(j) Cognitive Capability of Humans. Christopher Wickens Uni Illinois (http://www.humanfactors.uiuc.edu/Reports&PapersPDFs/chapters/Wickens_Durso%20Aviation.PDF)
(k) Trust in Automation: Designing for Appropriate Reliance John D. Lee, Katrina A. See; Human Factors, Vol. 46, 2004 (http://www.questia.com/googleScholar.qst;jsessionid=LHmZGvvpc1T1RT2pThDgGpvfwpMvh6f TTBPVC4hD8Tpg8J4LdQZy!-290722064?docId=5008765429)
(l) Training for New Technology. John Bent - Cathay Neil Krey's CRM site (http://www.crm-devel.org/resources/paper/bent.htm)


Search hint: You can search PPRuNe threads with a filter in Google by using the following search string example -

ths af447 site:http://www.pprune.org/tech-log/ (http://www.pprune.org/tech-log/)

This will search for mentions of THS in the AF447 threads of tech log only.

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a) indenting the text block with a (one) Tab, *and*

b) emphasizing the fact that it is a search text block with some manner of . . .
<SearchText>, or
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[CONF iture]

"On n'a pas une bonne annonce ... de vitesse" cannot imply anything else than a display AFAIK. What do you have in mind, regarding an "announcement" ??


But it is not : "On n'a pas une bonne annonce ... de vitesse"
It is : "On n'a pas une bonne annonce ..." 4 seconds later "... de vitesse"

The BEA wants to link those two pieces of the CVR ... I don't think they go together.

What would make more sense is : "On n'a pas une bonne annonce ... (de decrochage)" just following l'annonce "STALL"

The OSV info told them to not pay too much attention to spurious or even continuous STALL WARNING.
The Air Caraibes memo (if they read it) said that the crew righly disregarded 2 inapropriate STALL WARNINGS.


Later on the ON/OFF status of that STALL WRN without any notable change in the aircraft state confirmed to the crew that something was definitely wrong with that warning.

[CONF iture]

Also, as it is a new thread, I don't want to lose what was part of the previous one (http://www.pprune.org/tech-log/468394-af-447-thread-no-7-a-67.html#post7125872).
Beside the sidestick there are other concerns as :

the THS
the STALL WRN
the WRG message
the zipper shape of the selected V/S trace BEFORE AP DISC
These subjects must be fully addressed before reducing the investigation to three unfit pilots ...

[HazelNuts39]

The BEA wants to link those two pieces of the CVR ... I don't think they go together.What is "... de vitesse" linked to?

I agree with your (1) and (2) on stall warning. RE: the Air Caraïbes memo - Airbus could have more strongly opposed the Captain's 'intime persuasion'. I.e. the warning was "appropriate", even if it did not require specific action in the circumstances.

[TTex600]

May I suggest introductions again?

I'll start. I'm a US FAA certified narrowbody Airbus Captain with experience (DC9, not AB) in functional check test flying.

[Organfreak]

Ttex600 wrote:
May I suggest introductions again?

I'll start. I'm a US FAA certified narrowbody Airbus Captain with experience (DC9, not AB) in functional check test flying.

Good idea!

And I am a nobody who knows nothing (except what I've learned in this fab forum) who also pushes almost as many buttons as you guys do when I play my Hammond B-3 organ. (Yes, we get flying sometimes.) When I get confused/lost/push the wrong switch, I live to tell the tale.

Always wanted to fly. Never could afford the lessons. Been following jet transport issues since the early 70s. I really appreciate being allowed to hang in here with you experts, and occasionally contribute all I can bring to the party: good common sense. :p

[chrisN]

British Gliding Association (BGA) safety committee member, some experience of gliding accident analysis, current glider pilot and lapsed PPL.

I cannot claim any knowledge of CAT flying, but I do know something about glider flying and gliding training, and also something about gliding accidents and what surviving pilots have said on occasion.

And the reason I followed this from the outset through all threads – when a stressed pilot forms the wrong conclusion, he/she tends to stay with it regardless of ineffective attempts to correct the wrong problem. I have seen this in my field (gliding safety and accident analysis) – only test pilots, or rare individuals, can keep a clear head and systematically fault find.

[RR_NDB]

when a stressed pilot forms the wrong conclusion, he/she tends to stay with it regardless of ineffective attempts to correct the wrong problem. I have seen this in my field (gliding safety and accident analysis) (http://www.pprune.org/tech-log/482356-af-447-thread-no-8-a.html#post7130020)


The "model we are assembling" since the crash matches to your comment.

:ok:

only test pilots, or rare individuals, can keep a clear head and systematically fault find.

I personally had few incidents where this was observed. I started the observations 50 years ago and with maturity, experience and training (to develop methods) the "clear head and systematically fault find" was possible. And worked (and works) very well. In different types of machines sometimes in extreme and dangerous situations. Problem is when "things happens fast" Your chances dim very fast if initial solutions not the best. Fortunately i always had chances. Invariably staying "ahead". Even "ahead" i faced a surprise testing a car 19 years ago. (At night, light rain, concerned with a family member disease and a subtle hidden fault in a tire, aggravated by a little error :E).

[Organfreak]

ChrisN:
...I do know something about glider flying and gliding training, and also something about gliding accidents and what surviving pilots have said on occasion.

Things like, "Blimey!" and "Holy S***!"?

:}

[mm43]

As I hinted at in a post near the end of the previous thread, I have put together a customized Google Search Engine (http://countjustonce.com/pprune/) that will find your Search Term in an individual PPRuNE AF447 Forum thread, or if selected, in a search of all of the threads.

The Google search engine returns pages containing variations on a search term, e.g. the term 'site' [without the quotes] will also give hits on 'position, location' etc.. While a term in quotes, "tcas ra occurred before" will return hits only for pages that contain that term exactly.

There are, or have been 13 substantive PPRuNe Forum threads covering the total AF447 event saga, and one small one I found started in the Jet Blast Forum when the initial Air France A330-200 Missing thread was going 'mad'. The above search engine covers those threads that have made their way eventually into the Tech Log, plus the original Air France A330-200 Missing thread which remained in the Rumours and News Forum and was closed.

[gums]

Joined the fray just after the crash. Just interested in any FBW plane that has a problem. Thot I could learn something and maybe pass on some lessons-learned from the genesis of FBW flight controls.

Flew 600 +/- hours in first operational FBW jet from 1979 to 1984. Was staff puke or would have flown a lot more. Total time 4,000 hours +/- in F-101B, F102A, A-37A/B, A-7D and F-16A/B. 600 combat hours with about 400 combat missions.

Systems engineer after retiring from USAF.

[CONF iture]

What is "... de vitesse" linked to?
Considering it is just after the PNF comment "On a perdu les vitesses" it could be seen as an ackowledgement for the unreliable airspeed status, but in first intention "On n'a pas une bonne annonce ..." was IMO specifically directed to the STALL warning, not the speed.

Where I do ask questions following the Air Caraibes memo is here :
In addition, Airbus engineers have understood all the difficulty encountered by the crew for a rapid and effective implementation of the UNRELIABLE SPEED INDICATION procedure.
They agreed to the admissibility of our remarks and reflect therefore on a modification for the checklists.
The memo is 6 months prior AF447 - As a Manufacturer Airbus has many ways to communicate directly with the crews all over the world to dispatch safety information but nothing was done for that matter.

To answer TTex600 suggestion :
Very much interested in accident reports, try to learn from other's mistakes before I do them.
Looking for the full story not only the convenient part.
Have no trust left in the BEA but everybody knew it.
Flying for close to 25 years, 12 on the 330, but flew Boeing too.

[Old Carthusian]

I would say that none of the issues identified by CONF iture are actually of major importance in the cause of the accident and some can be said to be irrelevant. The cause of the accident is unfortunately the flight crew who did not respond in an appropriate manner to the situation.
I also wonder about all this mistrust of BEA - surely this is misplaced especially as the courts are involved? Having read several BEA reports they have always struck me as models of professionalism

[RR_NDB]

May I suggest introductions again? (http://www.pprune.org/tech-log/482356-af-447-thread-no-8-a.html#post7129590)

Actively investing in 2 Projects working as manager and R&D engineer.

Started professional career in aviation in 1970 and since then addicted to the multidisciplinary characteristic of this industry.

Was introduced to the anatomy (and it's subsystems) of old birds when 17 years old. (Connies, B25, C47, C46, GA, etc.) in a A/C scrap shop.

EMI/EMC specialist and HF radio operator since 1972.

Main objective (agenda) here: Aviation Safety through Synergy with people.

Mac

Extra interest: Be (in a proactive app.) prepared to better understand "She". (A/C, machines in general and also women :8)

Why? Because it's safer. :} (The surprises could be better "managed") :)

[RR_NDB]

I would say that none of the issues identified by CONF iture are actually of major importance in the cause of the accident and some can be said to be irrelevant. (http://www.pprune.org/tech-log/482356-af-447-thread-no-8-a.html#post7130429)

When investigating EVERYTHING must be considered. The final report is to be released. So we can ssume the investigation didn't finish yet. CONF iture listed possible contributing factors that could together represent important elements to the result.

The cause of the accident is unfortunately the flight crew who did not respond in an appropriate manner to the situation.


It seems, but need more information to say this We just don't have all "inputs" they received. And we don't know everything the machine "presented" to them. (to the crew).

I also wonder about all this mistrust of BEA

Having read several BEA reports they have always struck me as models of professionalism


It seems to me BEA could do better (just before Paris air show).It seems difficult to have all steps done at this time. It seems they became vulnerable since then.

Let's wait (being prepared to) to see the Final report.

* As you know, an accident statistically has multiple factors involved. Frequently the trigger is not a crew error. And a prepared crew could in many cases, save the day. And the opposite is true: :sad:

[A33Zab]

the zipper shape of the selected V/S trace BEFORE AP DISC

IMO you can skip this concern from the list.

The 'zipper' means it is - not active - (AP was in ALT HLD mode not in V/S mode)
You can notice identical 'zippers' to est. slide slip trace - after law change - de estimated slide slip is not calculated in ALT LAW.

The selected MACH trace - Page 109/110 BEA IR#3 EN - shows the 'zipper' too.
This trace for whole flight @ page 110 shows dark area but actually these are 'zippers'.

Also 'zippers' on the other parameters related to AS when these were NCD.

Why - the not active state - is reflected as zipper I don't know, maybe due to a reset signal to distinct from a steady 0 value?

[Old Carthusian]

RR-NDB
It seems to me that a post in response to Lyman is relevant here. Sometimes it is necessary to look at things x1 not x10,000. This is the case here. Ruling out the options is a common process in an investigation. The issues here would revolve around certain individuals' wish states not an objective look at the actual circumstances and occurences of the accident. It is also possible to be too sceptical and too cynical - if it looks like a duck and quacks like a duck chances are it is a duck. There is no need to invent other reasons for what is an accident based on pilot reactions, lack of adherence to SOPs, poor to non-existant CRM, no designated chain of command, training issues and possible cultural issues within Air France.

[airtren]

"On n'a pas une bonne annonce ... de vitesse" cannot imply anything else than a display AFAIK. What do you have in mind, regarding an "announcement" ??



But it is not : "On n'a pas une bonne annonce ... de vitesse"
It is : "On n'a pas une bonne annonce ..." 4 seconds later "... de vitesse"

The BEA wants to link those two pieces of the CVR ... I don't think they go together.

Later on the ON/OFF status of that STALL WRN without any notable change in the aircraft state confirmed to the crew that something was definitely wrong with that warning.

CONFiture has a point, and it's a good catch!

I can think of several words to use to describe the "visual" display of speed in French, but none of them would be "annonce", as "annonce" implies "sound". Indeed, the association of "annonce" with "de vitesse" makes no sense, or a lot less sense, than the association with the "Stall Warning", as the speed was NOT communicated using "sound", while the "Stall Warning" was.

[Linktrained]

O C may have been fortunate in his selection of pilots. All appear never to have been wrong.
Admittedly prior to CRM, I must have flown with more than a hundred airline pilots, some of whom learned from their own and doubtless the mistakes of others - possibly even some of mine !
My first CFI was the Chief Test Pilot of a Midlands aircraft manufacturer who would not allow me to go solo until I could stall and spin - and to recover !

Later I was to fly with perhaps eight graduates of the Empire Test Pilots School who had decided to become long-haul charter pilots. Two of them thanked me for teaching them to be First Officers. (By implication this had not been in their syllabus.) Both were kind enough not to say that they had learned from my bad example. ( I had myself, learned from watching a few bad examples over the years, the York captain who swung off the runway onto boggy grass by harsh engine handling, or the Captain who applied brakes when only the nose-wheel had landed !)

A look at the report on F-WWKH show what CAN happen with a well qualified crew anticipating and by day.

[Lyman]

Perhaps he is saying...... "The airstream sounds wrong"

Not bad airspeed, but wrong "speed of air". The airstream sounds quiet, or too fast?


If so, the two separated phrases still belong together.

"...announce de Vitesse...". Is it his first declaration "crazy speed?"

[roulishollandais]

when a stressed pilot forms the wrong conclusion, he/she tends to stay with it regardless of ineffective attempts to correct the wrong problem. I have seen this in my field (gliding safety and accident analysis) – only test pilots, or rare individuals, can keep a clear head and systematically fault find.

The cause of the accident is unfortunately the flight crew who did not respond in an appropriate manner to the situation.
　

If the pilot corrects the wrong problem, or if response is not appropriate, it means that the effective aircraft is NOT OBSERVABLE to him : not enough or not the good sensors and data to analyse the situation, or wrong connection in HMI (human machine interface partS, first of all SOPs, CRM, training, selection, health, etc.).

I say it never enough : To work a dynamic system has FIRST to be observable and controllable. Stability, sensitivenes, robustess, optimisation, price, etc. come long after.

[roulishollandais]

I also wonder about all this mistrust of BEA - surely this is misplaced especially as the courts are involved? Having read several BEA reports they have always struck me as models of professionalism


We have to accept the difficulty of the BEA's work, living day and night with the crash.:}

At the trials, reference to the Annexe 13 and the good use of the recommandations has to be said by pilot's unions. It would be the best way to help the BEA to do the safety problems OPEN.

In the forum we don't do another trial, nor another BEA report : we are together to get better, communicating in a larger point of view that the BEA is allowed to do.

[Lyman]

@roulishollandais

I say it never enough : To work a dynamic system has FIRST to be observable and controllable. Stability, sensitivenes, robustess, optimisation, price, etc. come long after.

Observable and controllable. Yes, but respectfully, this is a bare minimum.

This is (must be) the state at DEGRADED. Whilst in cruise, the system, no, the interface, must be INTUITIVE, No? Unremarkable and fluid "get" without Stopping to think.

Thinking takes time, sometimes too much. Here is the fulcrum of the issue, as the system is challenged, reversion in mechanical and Human actions must be synonymous, and synchronized. No time for independent reversion, the machine into less control, whilst pilot reverts to "abstract". The partnership should not degrade whilst facing rarities, it must grow closer. Confidence and continuity come first, always. How Stone Age to stop the flow, retrieve a handbook, and start to study......

[airtren]

Perhaps he is saying...... "The airstream sounds wrong"

Not bad airspeed, but wrong "speed of air". The airstream sounds quiet, or too fast?


If so, the two separated phrases still belong together.

"...announce de Vitesse...". Is it his first declaration "crazy speed?"
No Lyman... that's twisting it to non-sense....

"annonce" is like in the typical "voice announcement" of a train arriving, or leaving a railroad station, or an airport terminal station..

[Lyman]

As a Frenchman, pilot of AB, how would you say: "Sounds Fast" ?? How could he be commenting on Sound, and speed, unless CONFiture is dead on?

IOW, how to say: Noise inconsistent with IAS?

[mm43]

@Lyman

I have the distinct feeling that everyone is trying to read too much into the 'reported transcript' of the CVR.

Why? Because even with the short phrases that are being debated, the intonation has been lost in the transcription, and the BEA had the advantage in hearing the intonation and being able to help by adding 'linkage words' that weren't necessarily there. Let's face it, the ambient cockpit sound in which the words were spoken will have impacted on how the transcript was presented in the French language.

One can only but hope that the translation from French into English was peer reviewed using the same background knowledge - but probably not; and the reason for this debate.

[Turbine D]

mm43,

I have the distinct feeling that everyone is trying to read too much into the 'reported transcript' of the CVR.

Why? Because even with the short phrases that are being debated, the intonation has been lost in the transcription, and the BEA had the advantage in hearing the intonation and being able to help by adding 'linkage words' that weren't necessarily there

I agree with you. When the adrenaline is flowing big time as it must have been in this event in these moments, words may not flow smoothly as one is multi-tasking at the time.

In the AA DC-10 event in Chicago, there was one word on the CVR, Damn! That was it. Wonder how that translates into French...

[Lyman]

:ok:mm43 TurbineD

Fellas. I know you both too well to think your comments are intentionally patronizing. I know what I sound like, and readily concede I am looking under every stone. As my flight instructor said (ref: checklists), "leave no turd unstoned".

Four seconds after STALLWARN, and PNF "What's that?" PF says, "We have a bad announcement..." That means sound, and that also means STALLWARN, given the indexed chronology supplied by BEA. So a bad announcement may mean "Decrochage Faux...." Maybe not. By now, the adrenaline is still in the coolie hats atop their respective kidneys, they are cool.... I will keep that bit of information aside, but will not reject it. Notwithstanding the apologetic tone of you two guys, trying your best to put a happy face on......what?

:D

two much.....

[mm43]

Lyman,

Your version of "leaving no stone unturned" is commendable, and I'm not in the business of being patronizing.

However, this debate around what was said and what was seen by the pilots, is the very reason that the BEA wants mandatory recording of RHS parameters along with a "look" at what these guys should have been seeing. No doubt the BEA are confused by the actions taken and the words spoken when the recorded FDR LHS data shows something else.

Trying to recreate what was actually on the RHS PFD is fraught with danger.


It can be assumed the same was available on the LHS PFD, but
Was the PNF on the same page?
Neither of the pilots referred to any discrepancies between PFDs, and
The PNF was aware (at times) of what the PF was doing and commented when required.

Should data have subsequently been recovered from the QAR, I believe we would have heard through some 'leaky pipe' by now.

I am also unable to understand why the PF was able to look at an overly blue PFD and not accept that he was in fact "attempting a climb to the stars".

So, there you are. Was the RHS PFD overly blue??

[Lyman]

@mm43

"So, there you are. Was the RHS PFD overly blue??"

I have to say no, and guess that it showed some horizon, and a nose between 3 and 9 degrees UP. They were satisfied, reasonably, with the sitch til Stall. No screaming, no yelling, no snatching the SS. "We have the engines... So...".

What neither of them saw, anywhere, was AoA. Up to and through the actual STALL, there was no mention of doom. "Let's hope we're climbing, we are at four thousand."

Hyperfocused on loss of altitude, they had not noticed the Stall, would you? Nor had they any reason to mention anything, evidently. I frankly do not believe the data, as released, can lead to rational conviction of PE. Failing the release of all data, and I am a hard sell, to be sure, I think "Cause unknown" is as good as any. We don't know why, only what, and that is insufficient. Absence of evidence is not evidence of absence of care, or competence, it just is not.

My pea brain says even though they had nose up, and knew it, they could not get to "Stall..." only to: "push the Nose DOWN? Are you nuts? Look at the VSI!"

Ciao :ok:

[HazelNuts39]

How much blue? At 02:10:18 when the PF says "On a pas une bonne annonce de ... vitesse" (how many seconds to pronounce that sentence?) the Pitch Attitude is 11 degrees NU. The PFD then looks like this:
http://i.imgur.com/nB2BR.jpg?1

From the video posted here (http://www.pprune.org/tech-log/468394-af-447-thread-no-7-a-44.html#post7086679).

[Old Carthusian]

My point is this though - we can trust the information released by BEA and that their investigation will be fair and correct. I also understand the call for more transparency but they do have more important things to consider than keeping people informed about every little phase of the investigation. All that will happen is that the organisation will be delayed by queries and nonsensical comments from outsiders. Given the amount of comment that has already gone on on this topic without any conclusion one way or the other is it surprising that BEA are taking a long time. There is a lot to consider in this accident even if the basic causes are already known.
roulisholandais
I like the point about not observable but this is just one possible aspect of the problem which may in fact not be significant. It may be that the pilot himself is making the aircraft not observable and the available evidence actually points to this being the case. Given how many A330s, 320s, 340s are flying around without similar problems one has to think that indeed the flight crew were the main issue not the machine. I would expect many more accidents if the machine was a problem.

[mm43]

HazelNuts39,How much blue?Exactly! At FL370+ why?

We will never know.:sad:

[Lyman]

mm43

The altitude was barely above select cruise, @ 35.3k. @ 2:10:18. So my question might be: only 35,300? Why is this a/c climbing so sluggish? I don't dispute the Pitch picture, but it didn't match with Alt, necessarily, after ten seconds of climbing. The video catch does not represent the dynamic nature of the trends?

HazelNuts39

It was ".....annonce..................." " ........de vitesse......." Not ".....annonce de................". "...........vitesse....". Four seconds between annonce and de. Annonce and de are separated, not together.

PF was inputting ND three times at 2:10:18, and airspeed shows 70 knots, and we don't know if the displays were consonant with DFDR. A/S is duff, else he Stalls here...... He is comfortable with this Pitch, yes? What does that say? If it is what he sees, after all.....


I will ask my French expert re: " annonce". Besides, STALLWARN is a result of speed plus AoA, could he not mean "Stall 'vitesse' ? Not a reference to AirSpeed, but a ref to StallSpeed. Did he have the StallWarn bug present on his tape? Why is speed tape missing from video snatch? I believe his comment refers to a bogus StallWarn.

Your comments are most appreciated, it is quiet on my "side". :ok:

[CONF iture]

The 'zipper' means it is - not active - (AP was in ALT HLD mode not in V/S mode)
As you mention, the selected MACH trace shows also a similar 'zipper'.
But my question has been here all along :
WHERE is the AP/FD vertical engagement mode trace ???
That trace would tell if the 'zipper' is irrelevant.
In the meantime that trace is central to figure what were commanding the FDs when displayed.

Why such trace is missing ?

[CONF iture]

The PNF was aware (at times) of what the PF was doing and commented when required.
It is inexact to state so ... The 3 pilots were reading attitudes, vertical speeds, altitudes ... but at no time did we hear - PULL - PUSH - DONT PULL - STOP PULLING - YOU PULL TOO MUCH ...

Only in final despair, under GPWS warning, came up a - TIRE TIRE TIRE -

Sidesticks at their best ...

[Mr Optimistic]

I thought thought the zipper was doing nothing more than a resolution issue with the data ie the lsb switching on and off and nothing 'real'.

[Organfreak]

I really hate to say something so personal in public, but it needs to be said:

OC's posts all seem to be written entirely from the point-of-view of Airbus. No room for any possible factors other than pilot error. Seems preposterous to me that anyone would insist that it was just that simple. Unless I learn otherwise, I'm assuming that these posts are generated by someone at AB. (OC's profile is entirely empty. Who was that masked man?)

If I'm wrong, I am sure I'll burn in hell.

[HazelNuts39]

Organfreak;

Does it matter? I'd welcome Airbus participation in the discussion on this thread.

[KBPsen]

Better to remain silent and be thought a...

[Lyman]

Everyone must be heard. There can be no exclusions. Oddly enough, in the long term, the investigation profits from the lack of a frame, at this level. In confrontation can be progress. I for one am grateful to be heard at all, though it may not seem so, I am.

To the group, salut.

[Organfreak]

HazelNuts39 said:
Organfreak;
Does it matter? I'd welcome Airbus participation in the discussion on this thread.

Good point-- me too, as long as they weren't hiding behind a mask.

KSPsen added:

Better to remain silent and be thought a...

....ignoramus?

Ouch, touché! But me? Remain silent? What a concept! :)

[Lyman]

KBPsen, eh? Organfreak, some respect, start with spelling.

carry on

[Organfreak]

Lyman:
KBPsen, eh? Organfreak, some respect, start with spelling.

Sorry, just human error. I respect most everybody here, but in this case, this person has sent me creepy PMs in the past. :ooh:

[KBPsen]

But me? Remain silent? One can but hope. Someone mentioned that there had been some 25,000 posts on AF447. I would think some 22,000 of those is nothing but noise drowning the relevant.

There is little need for more noise or paranoia, again.

P.S. Feel free to post anything I have sent you. Fact is so much better than fiction.

[Lyman]

All my stupid questions never would have been asked, had BEA been even marginally more forthcoming. To that extent, the noise results from "natural cause". Paranoia? Hmmm......I see no evidence of that.

[Organfreak]

KBPsen done wrote:There is little need for more noise or paranoia, again.

P.S. Feel free to post anything I have sent you. Fact is so much better than fiction.

This is silly. I wouldn't post any private message, no matter how severely provoked. But, since it's out here now, I would remind you that you accused me of pretending to be somebody else, without saying who, in impolite terms, twice. It was offensive to me, since I am so utterly transparent about myself. Paranoid? Hardly. I'm a facts guy.

Incidentally, I realize that much of my posting could be considered 'noise' by unfriendly readers, however, my inbox is full of kind praise from more than a few pros on this forum, otherwise I would have left long ago.

OK, who did you "think" I was? And who are you?

[DozyWannabe]

... but at no time did we hear - PULL - PUSH - DONT PULL - STOP PULLING - YOU PULL TOO MUCH ...
...
Sidesticks at their best ...

Which unfortunately ignores the fact that at least two other airliners (a 727 and 757), both of which had linked control columns, also stalled out and crashed in exactly the same way following a UAS incident.

[A33Zab]

WHERE is the AP/FD vertical engagement mode trace ???
That trace would tell if the 'zipper' is irrelevant.
In the meantime that trace is central to figure what were commanding the FDs when displayed.

Why such trace is missing ?

Isn't the difference between V/S and V/S selected equal to the FD order?
They are both in the same trace.

V/S mode is active from 02:10:26 and on.
FD bars displayed when FG considers 2 or more speeds valid and consistent.
The first 10 sec. after FD comes available the bars are flashing dim/bright.

Max. limit is at 6000ft/min and actual limit is set by Vsw/Vmo when available. (meaning FD bars will not direct one into Vsw/Vmo)

Don't know the exact resolution as displayed on PFD and Vsw/Vmo were available at the moment FD bars were in view.
---

The PNF saw as much blue as PF, BEA and ACARS don't report any CHK ATT message/flag displayed, so FWC considered both attitude signals in agreement.

[Lyman]

@ Lyman: The altitude was barely above select cruise, @ 35.3k. @ 2:10:18. So my question might be: only 35,300? Why is this a/c climbing so sluggish? I don't dispute the Pitch picture, but it didn't match with Alt, necessarily, after ten seconds of climbing. The video catch does not represent the dynamic nature of the trends?

If we are 'speaking' may I ask what may be a clumsy question? The Nose was rising at a/p loss, and the PF input NU directly. Yet the a/c has only climbed 400 feet in approx. ten seconds. I've thought about this for some time. See pp 29 BEA#3. Is there any chance, given the FD were left on, that V/S got away from PF, and he was in the weeds, so to speak, re: PITCH and response, V/S?

I mentioned it long ago, something as: "Additive" input.

By the time (2:10:22) A/LAW is annunciated, the a/c is beginning a remarkable climb, can this have anything whatever to do with V/S and V/S select as the summed command, and the climb getting "Away" from the crew?

Thank you for your patience, here.

[glad rag]

Well "Bear" still hard at it eh?

[Mr Optimistic]

OC is on the money.

[Lyman]

OC is not wrong. Neither is he "on the money".

Hi glad rag. Target rich environment, via BEA default.

[Old Carthusian]

Hi Organfreak

I have no link to Airbus at all and never have had. I just acknowledge the unfortunate truth. If you do want to look at other airlines with similar issues to Air France then try Pan Am late 60's early 70's, Air China 1990's or Korean Airlines, pretty much from 1980s to date. There may well be a pattern here.

[Organfreak]

OC, thanks for your gracious reply. I take you at your word. Still, I think my question reflects the feeling that some of us have, that blaming this purely on the pilots is an over-simplification. Reasonable people may disagree, or so I've heard.

I'm familiar with the China and Korean stuff, but would you be kind enough to point me towards some of those old Pan Am flight numbers?

:8

[TTex600]

As a long time observer/participant in internet pilot forums, let me say this: unless you meet the guy in ground school, you NEVER know who you are talking to so you read the postings and make your assessments accordingly. If OC looks like an AB guy, it's because he posts things that appear to be slanted in AB's direction. No crime in that.

Don't judge me by my profession of being a line pilot, judge me by the content of my postings. I do the same and I don't have to bother my little brain wondering who works for who.:)

[PJ2]

Organfreak;

Dig the Hammond!

Re, "Still, I think my question reflects the feeling that some of us have, that blaming this purely on the pilots is an over-simplification."

Those who do this work and those who do flight safety work, investigative work, engineering work as well as human factors experts who write books on this and who may fly these aircraft or may not, know that this is not "just the pilots", and they know that there is no rational opportunity for a legitimate over-simplification of this accident. Most here who have engaged this dialogue already know this or have learned through careful and thoughtful readings of others' contributions. I believe that this is at least one thing which we can take from these eight or nine long threads.

All other crews encountering the variations of this abnormal survived. What is the difference that made a difference?

Their responses require as close an examination as possible so that a fine (as in fine-grained) appreciation of the context of crew-and-machine can begin to be seen which then becomes one context or template from which this accident may be examined and useful conclusions drawn regarding change. This means that airplane systems, procedures, as well as standards/training/checking regimes are all interwined in "the story" of this accident.

The notions of "blame" and "accountability" are legal and corporate terms which have nothing to do with safety processes and "finding out"; - they are not flight safety terms.

The notion of "responsibility" is quasi-investigative because it usefully enframes ways to ask questions, recognizing and beginning with the fact that there were the three crew members on board involved in the accident and that the aircraft was serviceable/flyable just prior to the event, (meaning, there was no catastrophic structural failure and the aircraft was controllable and was taken into and not brought out of a stall) and going from there regarding the trace of factors which may be counted as contributing to final outcomes.

This is a very long way from a view which indicts the PF/PM/Captain.

[Organfreak]

PJ2;

:D:

Oh, and,

:ok:

[CONF iture]

Isn't the difference between V/S and V/S selected equal to the FD order?
They are both in the same trace.
Open doors there were for ALT CRZ* around 35000ft on the way up and down as well ...
Also did they keep 35000ft in the FCU ALT window all the way ... ?
Was it selected at any time OPEN CLB ... ?

WHERE is the AP/FD vertical engagement mode trace ???


Early on every Airbus pilot is teached : I HAVE RADIO ECAM ACTION
No such basic wording for AF447 ... Do we think the ECAM control panel was completely forgotten as well during 4 minutes ?
There must be a trace somewhere to tell about the ECAM selections ...

Did they get to the RISK OF UNDUE STALL WARNING STATUS MSG following the little publicized AoA data differencies ?

[CONF iture]

Which unfortunately ignores the fact that at least two other airliners (a 727 and 757), both of which had linked control columns, also stalled out and crashed in exactly the same way following a UAS incident.
At least the information was readily available for the PNF to grab : Tremendous advantage !

[Old Carthusian]

Organfreak

The significant Pan Am flight numbers were PA217 (1968), PA816 (1971), PA806 (1974), PA812 (1974). A series of reports was produced by Pan Am and the FAA detailing the major problems with the airline but these were kept confidential. I would hesitate to use the word blame though. As PJ2 points out blame is a legal concept and a bit out of place. Of course like everyone I have been guilty of using value loaded terms like this because it is often easier to write. It is not a matter of blame as such but an inability to cope with the situation in hand. I detail what I think was missing but I do not believe that the aircraft was a factor in this. One can argue that if things have been different in design or warning features then the accident would haven't have happened. Unfortunately this is what I would characterise as a wish state. Other accidents have demonstrated that where these features were present they didn't necessarily prevent an accident. The question why comes down to the people flying the aircraft and their background. To try and evade that and attribute the accident to a machine fault is to my mind dangerous as it assumes that we can further design the pilot out of the loop.

[Machinbird]

OC
One can argue that if things have been different in design or warning features then the accident would haven't have happened. Unfortunately this is what I would characterise as a wish state. Nothing wrong with a "wish list" to prevent the next accident. You just might get the wished for item in time to save your posterior.

Other accidents have demonstrated that where these features were present they didn't necessarily prevent an accident.I'm not sure this is valid. What about the accidents that were prevented because of "these features"? Did anyone keep a record? Sort of like saying the new stop light didn't prevent having another accident at the intersection. Perhaps the circumstances are different.?

The question why comes down to the people flying the aircraft and their background. To try and evade that and attribute the accident to a machine fault is to my mind dangerous as it assumes that we can further design the pilot out of the loop. When all else fails, it is the people flying whose job it is to prevent accidents. Sometimes they fail too.

Have you ever been taken in by a con man? This happens through mis-direction. You are looking for a problem in one direction, and it sneaks in through the opposite direction. Not very different from aviation actually.:hmm:

[Old Carthusian]

A wish state not a wish list - the terms differ in their meaning and useage.

Some are advocating that the side stick was a factor in the accident because it was unobservable for example. But there are examples of where an accident has happened despite the yoke position being visible. We have to be careful in advocating a solution as a pancea to an issue.

'When all else fails, it is the people flying whose job it is to prevent accidents. Sometimes they fail too.'

Exactly this is what I have been saying all along.

[PJ2]

CONF iture;

re, "There must be a trace somewhere to tell about the ECAM selections ...", (Post #59 (http://www.pprune.org/tech-log/482356-af-447-thread-no-8-a-3.html#post7135517))

No, there almost certainly isn't.

As is frustratingly known, many parameters are simply not recorded, the Right-side PFD/ND displays being the most memorable losses.

It is my experience that ECAM actual text displays (what the crew sees/reads) are almost never recorded. This is because such detailed information is not mandated.

The actual legal requirements for what is mandated to be recorded are tiny in comparison with what is actually available on the SSFDR.

As I have offered a number of times now, the QAR, tradtionally employed for FOQA/FDM/FDA Programs records far more parameters and at higher sample rates. All it takes is money, first to pay for the design, create, execute the logical frame layout for the QAR and the aircraft installation and second to pay for the STCs/certification information either from the manufacturer of the specific dataframe layout in the installed DFDAUs or for a generic one which may be type-specific but not airline specific and so may not record some parameters which have different frame layout structures.

There is no legal guidance as to what must be recorded by QARs.

A data frame resembles an Excel spreadsheet. The frame layout is designed to expect very specific information from a specific source in a very specific format in exactly one row of cells, normally 4 columns wide and 256 or 512 rows long. If it doesn't get the specific "words", (usually 12-bit words), garbage results. There are many, many frame layouts even for one type of aircraft. They are tailored to each airline's specifications and aircraft configurations.

Frame layouts are explained in a number of places. I've quoted CAP731 (http://www.caa.co.uk/application.aspx?catid=33&pagetype=65&appid=11&mode=detail&id=1311) many times. CAP 739 (https://www.google.ca/#hl=en&sclient=psy-ab&q=cap739&oq=cap739&aq=f&aqi=g-s1&aql=&gs_l=serp.3..0i10.7736l8222l1l8486l2l2l0l0l0l0l202l321l0j1j1 l2l0.frgbld.&pbx=1&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&fp=e7236bc9180d9239&biw=2701&bih=1482)on FDM Programs is also helpful.

Your arguments regarding the unavailability of data, and the unavailability of data for parties outside the "official process" may not be with the manufacturer, who is not precisely responsible for the structure of the actual data frame layout on the SSDFR beyond what is mandated by the JARS/FARS/CARS etc, nor would it necessarily be with the BEA (or the TSB or the NTSB etc).

Your argument, one which I would support, is, I believe, for vastly enhanced recording capability as well as open sharing of such data, (which is doubtful for a number of reasons which need not detain us here). The first point requires an (optimistic!) freeing up of the frustrating proprietary nature of such data frames so that others who do not have rich data frame layouts may take advantage of designs that are more sophisticated, (meaning, they provide more data from a larger number of systems).

Data frame layouts are software designs and as such are almost always proprietary and for QARs, require an STC.

The time-consuming appropriation of such logical data frame layouts by others for general use can cost hundreds of thousands of dollars and still be quite incomplete due to the vastly different airline configurations of even one type. As described, these are tailored documents and software.

Specifically, it is not possible to obtain from the manufacturer of a DFDAU a specific data frame for your type of aircraft without paying significant licence fees and STCs for such installations. The appearance of a "reluctance to share" is not always a reluctance to share. The unavailability of data which all of a sudden is deemed important but once was not, is nothing more than someone's decision to not spend the money to record everything possible.

In fact, some airlines just choose a "sampling" of their fleet for FDA Programs, believing that statistics from a few types or a few airplanes may be reasonably extrapolated to the larger fleet population. A reasonable notion from a bean-counter's perspective but when a serious event occurs on one airplane that doesn't have an FDA QAR on it, the airline has blinded itself and the statistical model falls over. Again, another question entirely.

[RR_NDB]

To try and evade that and attribute the accident to a machine fault is to my mind dangerous as it assumes that we can further design the pilot out of the loop. (http://www.pprune.org/tech-log/482356-af-447-thread-no-8-a-4.html#post7135582)

You may have crew error(s) and a design related (the interface between the crew PF+PM) issue that contributed given the circumstances (rare).

I don't remember any post that put the A/C (or it's interface) as the only or even major cause of the accident.

I myself raised the importance of a good interface specially when dealing with unpredictable issues.

And in A330 at that time, obsolete sensors failing simultaneously in a "non redundant design" was a PREDICTABLE issue.

Despite being predictable nor the System nor the crew were able to promote the survivability. And the "effective aircraft" felt in "near terminal speed" very near the LKP (surprising everybody).

The rare circumstances led to the end in just 4 minutes just by PF (+PM) error?

An analysis normally is not "sharply digital", Yes or No. Normally there are "gradients" to be considered. Real world is not digital. It's a little bit :) more complex.

And is in interest of pilots to improve the interface. Or this is absolutely not necessary?

Improvements on the interface, not necessarily put the pilots further out the loop.

The idea is the opposite: To allow pilots to act easily and safer when (for any reason) they are required to enter the the loop.

And a good i(intuitive) interface even SIMPLIFIES training and allows a better (closer) interaction with her (A/C) :) .

[Machinbird]

A wish state not a wish list - the terms differ in their meaning and useage. OC, please expand. A state would imply a temporary or ephemeral condition, whereas a list would imply more permanence.

Some are advocating that the side stick was a factor in the accident because it was unobservable for example. But there are examples of where an accident has happened despite the yoke position being visible. We have to be careful in advocating a solution as a pancea to an issue. "Panacea" is a value judgement by you. Let me restate my point.

You have no evidence that having linked controls does not improve safety in dual piloted aircraft.. No one has recorded the accidents prevented by using linked controls, therefore there is no data. All you are stating is that accidents have happened in both non-linked side stick and linked control system aircraft. All we have are statistics showing that both linked and non linked control systems have a very good safety record.

Linking controls gives one the opportunity to monitor control inputs by tactile means, and if necessary, to assist or out vote the other guy. How is this additional capability a disadvantage?

[RR_NDB]

Pan Am flight numbers were PA217 (1968), PA816 (1971), PA806 (1974), PA812 (1974) (http://www.pprune.org/tech-log/482356-af-447-thread-no-8-a-4.html#post7135582)

May we think PAA was not able to adapt to the new environment from the old culture?

The carrier adaptability (not re engineering fast enough) to a different environment was a factor? The confidential report had some leaks indicating the probable reasons of the issue you pointed?

[RR_NDB]

Hi,

Which are the most important characteristics of the resources crew have "to fly" the A/C:

1) Deliver "inputs" to the machine (Yoke, SS, pedals, etc.)

2) Receive "outputs" from the machine (through System)

3) Receive any other inputs (visual, aural, sensations, etc.)

4) Deal with unpredicted situations (of any reason)

In complex machines we may say this is the resource called "man machine interface". (http://www.pprune.org/tech-log/481350-man-machine-interface-anomalies.html)

In the above thread we are starting to discuss some issues on this fundamental resource.

I suspect many incidents and accidents could be avoided with a better interface not necessarily more complex. Just better. Simple, highly sophisticated in the sense Leonardo da Vinci put: Simplicity is the ultimate sophistication.

Is this possible in advanced FBW planes? I think so. Current Interfaces are sophisticated enough to be simple, reliable and carefully designed to the safest operation of the advanced FBW planes?

The characteristics i consider important i listed in this post on "Basic requirements of the Interface" (http://www.pprune.org/tech-log/481350-man-machine-interface-anomalies-2.html#post7136740)

[jcjeant]

To read .. interesting ....
http://www.aaib.gov.uk/cms_resources.cfm?file=/Airbus%20A319-131%20G-EUPO%2004-12.pdf

[RetiredF4]

There are some interace features in modern FBW aircraft still like in the ages before.

- the gearhandle is formed like a little wheel, to put the gear down you have to put that little wheel in the down position

-the flaphandle, formed like a little flap

- the speed brakes formed like a little handbrake lever

- the throttles, formed like little engines

- the trim wheel, formed like in former times when you turned mechanical cables and pulleys with this wheel

Those switches (they are nothing else in these days) are neither cheap (a pushbutton or toggle switch would be cheaper) nor ergonomic (They use a lot of space), but they tell you something when you grab them: You got the right one mate!




OC
Some are advocating that the side stick was a factor in the accident because it was unobservable for example. But there are examples of where an accident has happened despite the yoke position being visible. We have to be careful in advocating a solution as a pancea to an issue.

@ OC: Despite this fact, gear, flaps, speedbrakes and trim has been mishandeled by young and old, expierienced and less expierienced pilots. Would that fact prove, that this feedback is not necessary and we should change to simple and cheaper pushbuttons or into a command line in some display?

'When all else fails, it is the people flying whose job it is to prevent accidents. Sometimes they fail too.'

Exactly this is what I have been saying all along.

I would like to rephrase a bit:

The industry (manufacturer, operator, crew) has to plan, design and train for situations, when all else failses, that the people flying are most probably able to prevent accidents. That needs an interface and training not only optimized for costs and normal operations, but also for the worst case of the life.

I therefore follow this discussion (and take part a bit) about possible factors influencing the outcome of this tragic accident with great interest, not to blame the aircraft or to absolve the crew, but in the hope, that the industry will learn its lesson in order to minimize future events with similar causes.

With the attitude "the machine behaved like it was designed......." we can shorten any accident investigation big time. In the end its always the pilot.

[Old Carthusian]

RR NDB
With Pan Am the issue was pilots lacking certain piloting skills continuing to fly. The culture of the airline allowed for these individuals to be passed by their check captains who either ignored the signs or were ignored. Pan Am also had a casual attitude to training and some information was outdated. This is a very brief summary but it was a cultural issue.
Air France may have also developed a similar lack of attention - the recent series of incidents does point that way and the Safety Audit also highlights issues in this direction. If this is so it would be unlikely that an interface change will have the effect you desire (and there is no indication that the current A330 interface is necessarily deficient). That is not to argue that things cannot be improved - far from it but it is important to locate the reason for the accident accurately and given the information we have we do not need to move beyond the crew in this case.
Machinbird
A wish state is a situation that you want to be a certain way. A wish list is a series of items you want to have. The latter is often achievable but the former is not. The term wish state indicates a desire that reality were not the way it is. I hope this helps. We all wish the flight crew of AF447 had been able to handle the situation they found themselves in adequately but they were not. Where the evidence points is that this was due to the flight crew and not the machine. Those suggesting that the machine was to some extent the cause of the situation are in a wish state. A panacea has to be understood in the context of a universal solution - as you note that does not exist. The side stick works - some pilots don't like it, some do. Some prefer the yoke but remember the yoke will not necessarily guarantee safety. Given that this is the case then one cannot criticize the side stick on the grounds it is less safe. One can say I prefer the yoke because it has this factor which is important for me but that is all. The important point here, I feel, is this - it frequently comes down to the flight crew and how they are trained. Well trained and aware flight crew following procedures should be able to deal with almost any situation they could encounter. This is what seems to have been lacking in this situation.

[Diversification]

Hi all!

After following this discussion for some years, I am still wondering about some things.
Why has BEA not released the current software versions used on the computers, e.g. ADIRU:s, Prim:s and Sec:s? These data may perhaps be more important than e.g. engine numbers.

Let me cite the following from ao2008070-final.pdf, §3.5.3 Software versions:
"The ADIRU software was changed from time to time as updates and improvements were incorporated. At the time of manufacture, units 4167 and 4122 had software version -0312 installed. Updated versions were usually promulgated as optional service bulletins140, and operators could decide whether the advantages of installing an updated version of the software were sufficient to justify the logistics of upgrading each aircraft (three ADIRUs per aircraft). The operator of QPA elected not to load software versions -0313 and -0314 in any of their ADIRUs. Software version -0315 was loaded on unit 4167 on 20 July 2005 and was the version installed at the time of the 12 September 2006 occurrence. Software version -0316 was released in August 2008; it was the version installed on unit 4167 at the time of the 7 October 2008 occurrence and it was also installed on unit 4122 at the time of the 27 December 2008 occurrence. As far as could be determined, most of the LTN-101 ADIRUs had software versions -0315 and/or -0316 installed."

Thus apparently at least one case is known where an update in the software apparently de-masked a hidden old software bug in an ADIRU unit.

Some food for thoughts: We are faced with a small number of UAS cases which may have increased in frequency with time. That could perhaps point not only to increasing icing but also to new software revisions making the UAS events more probable. Secondly the difference in probe type behavior might also be connected to ADIRU software and its sensitivity to e.g. noise and flutter on the signal from the probes - not necessarily only to sensitivity of probes to icing conditions.

A final remark is about redundancy and diversification. Redundancy is normally a repetition using the same equipment and systems which seldom helps to avoid problems which are due to a common cause. Diversification means that different methods and equipment are used as parts in several separate and parallel channels of a system. This reduces the risk of common mode failures.

I am not a pilot and these comments are only a few thoughts from one who has spent a long life writing real-time software and also directing/overseeing national research on nuclear power safety,

Best regards to all. Keep this interesting thread going!

[RR_NDB]

Why has BEA not released the current software versions used on the computers, e.g. ADIRU:s, Prim:s and Sec:s? These data may perhaps be more important than e.g. engine numbers. (http://www.pprune.org/tech-log/482356-af-447-thread-no-8-a-4.html#post7137766)

:ok:

We expect (hope) all relevant data to be published. So far the most important information is: The plane was OK. Published in a timing incompatible with a deep analysis of the issue. (before Paris Air show).

The 25,000+ posts here in PPRuNe indicates this accident is unique with respect to public interest.

Thus apparently at least one case is known where an update in the software apparently de-masked a hidden old software bug in an ADIRU unit.


:ok:

A final remark is about redundancy and diversification. Redundancy is normally a repetition using the same equipment and systems which seldom helps to avoid problems which are due to a common cause.


There is no Redundancy currently in the ENTIRE FLEET of A/C with respect to Air Speed meaurements. I consider this an ABSURD!

The current Pitot's are just OBSOLETE. Airbus SAS filed a patent on Laser based AS measurements.

Redundancy works when the diversified elements don't fail simultaneously.

In F-GZCP they (same type no longer being used) "failed" near simultaneously.

In editing later this post i could provide (mine) earlier posts dealing with the RIDICULOUS design, as i unfortunately had to classify it.(WRT to AS) :{

There is a trend (solid one due important reasons) for this crash to be remembered as "pilot error".

As engineer with a family closely connected to aviation (father, sun, cousins, etc.) i am keeping ON the suspicion on several facts that may indicate important "accident contributions."

We are starting to address anomalies (your post fits in a possible type) in thread:


Man-machine interface and anomalies (http://www.pprune.org/tech-log/481350-man-machine-interface-anomalies.html)

[Linktrained]

O. C.
I believe that PanAm latterly used Flight Engineers on most of their aircraft, relieving their pilots of some of their responsibilities, although the Captain remained ultimately responsible. On three of the four types of four-engined aircraft that I flew, it was usual for the F/E to handle the power settings, other than when it was necessary for a pilot to cut the power for an aborted T/O, prior to V1. ( I do not know what PanAm did.)

A Check Captain might well have flown as First Officer with this same Captain, years ago. ( As a 400 hour Pilot I has to "sign out" my then Chief Pilot, who was also my employer, on a type of aircraft which I had on my Commercial Pilots' Licence and he lacked on his ALTP - and he actually owned the aircraft... Could I have failed him ? He PASSED ! ( Even by my standards !) He usually flew the DC3, one with a Starboard passenger door, not many on the Register.)

[roulishollandais]

After following this discussion for some years, I am still wondering about some things.
Why has BEA not released the current software versions used on the computers, e.g. ADIRU:s, Prim:s and Sec:s? These data may perhaps be more important than e.g. engine numbers.

Let me cite the following from ao2008070-final.pdf, §3.5.3 Software versions:
"The ADIRU software was changed from time to time as updates and improvements were incorporated. At the time of manufacture, units 4167 and 4122 had software version -0312 installed. Updated versions were usually promulgated as optional service bulletins140, and operators could decide whether the advantages of installing an updated version of the software were sufficient to justify the logistics of upgrading each aircraft (three ADIRUs per aircraft). The operator of QPA elected not to load software versions -0313 and -0314 in any of their ADIRUs. Software version -0315 was loaded on unit 4167 on 20 July 2005 and was the version installed at the time of the 12 September 2006 occurrence. Software version -0316 was released in August 2008; it was the version installed on unit 4167 at the time of the 7 October 2008 occurrence and it was also installed on unit 4122 at the time of the 27 December 2008 occurrence. As far as could be determined, most of the LTN-101 ADIRUs had software versions -0315 and/or -0316 installed."

Thus apparently at least one case is known where an update in the software apparently de-masked a hidden old software bug in an ADIRU unit.
Since the HABSHEIM flare in the forest (AF, 1988) Nobody (BEA, Lawyers, Judges, Experts, Pilots, aso) understood nor wanted to understand how much these points are important, how real-time flying softwares work very different of traditional systems. Only one BIT 0/1 is generally false and the whole system fails... Nice exemple the ARIANE V (V501 Jun 4. 1996) where the false carry costed 8 billion FF. :mad:


We are faced with a small number of UAS cases which may have increased in frequency with time. That could perhaps point not only to increasing icing but also to new software revisions making the UAS events more probable. Secondly the difference in probe type behavior might also be connected to ADIRU software and its sensitivity to e.g. noise and flutter on the signal from the probes - not necessarily only to sensitivity of probes to icing conditions
Flutter ?
:eek:
A final remark is about redundancy and diversification. Redundancy is normally a repetition using the same equipment and systems which seldom helps to avoid problems which are due to a common cause. Diversification means that different methods and equipment are used as parts in several separate and parallel channels of a system. This reduces the risk of common mode failures
We will do ! Thank you. Vocabulary is important.:ok:

I am not a pilot and these comments are only a few thoughts from one who has spent a long life writing real-time software and also directing/overseeing national research on nuclear power safety,

Best regards to all. Keep this interesting thread going
Thank you for your science pages crosscheck ! This thread is interesting due to the many differences of all of us.:D

[Linktrained]

" The Log" of Apr/May 2012 has some stuff about AoA and High Mach Numbers on pages24 and 25. Some of this may be new to people... Talking about Pitch Limit Indicators...
Whilst they specify Brand "B", surely they are all aircraft flying through similar aerodynamic laws... I think.
( I was a Mach .5 man, some 40 odd years ago.... A bit out of touch.)

[fantom]

With the attitude "the machine behaved like it was designed......." we can shorten any accident investigation big time. In the end its always the pilot.

I am not the only one here with many years 320/330.

Let's go back to the start.

Given those pitot probes in that part of a Cb (perhaps) in that part of the world I really doubt I could have done any better.

Cut the clever stuff and agree: s**t happens.

Best regards to RetiredF4.

[Lyman]

@fantom

Cut the clever stuff and agree: s**t happens.

It is always true, but not always accurate. To the extent man designs, builds, and uses wonderful things, the shrug comes only after all bridges are crossed. I know that's what you meant.

cheers Captain

[jcjeant]

Cut the clever stuff and agree: s**t happens.Rummaging in my old books on the Titanic and after everything I've read and heard about AF447 ... I can not help but that this is a similitude on certain aspects .. from the urban legend (unsinkable) "a concierge can fly it" .. "he can't stall" .. to the bottom of the sea ...
Lesson not yet learned ?

[PJ2]

Feynman (http://en.wikiquote.org/wiki/Richard_Feynman) has been quoted on this human characteristic (hubris and arrogance in the face of summarily-dismissed non-equivocating odds), numerous times here and elsewhere:


"For a successful technology, reality must take precedence over public relations, for nature cannot be fooled.

Rogers' Commission Report into the Challenger Crash (http://en.wikipedia.org/wiki/Space_Shuttle_Challenger) Appendix F - Personal Observations on Reliability of Shuttle (http://history.nasa.gov/rogersrep/v2appf.htm) (June 1986) Full Report (http://history.nasa.gov/rogersrep/genindex.htm)"

Off the top of my head, I wonder if there is a strong relationship between "it can't sink" and "it can't stall"?

I wonder, because the certain and specific knowledge exists in which there are distinct and standard, trained circumstances where the airplane will stall and so all Airbus crews should be aware of this. However, metallurgical knowledge could not conclude at the time that the cold Atlantic would make those particular rivets brittle.

I think there is a vast hubris behind the first statement because technological "miracles" and an entire supporting social belief system were the order of the day, but just plain ignorance is behind the second.

[Lyman]

Hi PJ2

The TITANIC was unsinkable, but for an un-designed for event (clogged Pitots?), the way she struck the iceberg.

She was built of a horizontally stacking series of watertight compartments. But she struck the berg tangentially, a glancing blow. So she acquired a long gash in her hull, the first seven compartments communicating with the sea. A head on would have smushed her to three/four compartments back, and she would have remained on the surface.

Tragically, she should have been steered into the iceberg, not away. She sank to the bottom of the Atlantic, 12,500 feet down. At 2am, her Captain was called back to the bridge, (familiar?). He was too late, and could not have helped.

Hubris, Sir, indeed. Boasting at Nature's door, not advised, eh?

Take care,

[DozyWannabe]

Oh dear.

I think it's time to officially add Dozy's addendum to Godwin's Law here, namely:

"As a PPRuNe discussion involving Airbus continues, the probability of someone bringing up Habsheim and concierges approaches 1."

This may sound a little presumptuous of me, but I think I can get away with saying that Habsheim is not relevant to this incident or this discussion. Feel free to PM me if you want to know why. Regarding Ziegler and his oft-quoted "concierge" remark, he didn't say anything about his concierge being able to fly it in a degraded control mode or damaged state, so can we please leave that tangent there?

As it happens I'd be willing to go to the mat and bore for England on the subject of Titanic as well, but again it really isn't relevant to the case we're discussing.

It's pretty clear to me that until new information is released, this subject has been discussed to a standstill.

[Lyman]

Tex Johnson actually rolled one, and managed not to put it into the trees.

Chutzpah, claiming an addendum to one's own petard. :ok:

[DozyWannabe]

I don't follow.

Johnson planned and executed an unauthorised addition to a flightplan he otherwise stuck to like glue, but nevertheless had planned that addition in secret and went in knowing exactly what he was doing. Asseline got lost (not his fault) missed his TOD waypoint, tried to fudge his descent profile to catch up and ended up in the trees. Equally importantly, Johnson was not carrying passengers.

Quite what this has to do with AF447 is beyond me.

[Lyman]

Airbus, Flight Plan, Boeing, Display flight.

Wheat/Chaff

I think both were demo flights, wait, I know they were. Airbus needs to stop promoting to chief pilot or even F/O, those who lose the plot, in cahoots with the platform/Format. Funny how many nincompoops get into the front dere, yes?

Are you trying to tell me Airbus doesn't have a glossy release prepped at a moment's notice to exonerate the a/c for any foul/up? In at least one case, the manufacturer applied pressure to have the investigative body carry their d'Eau, No? Pre Paris Air Show? Fetes d'avions? Nothing wrong here, nope.

If Airbus wasn't addicted to excuse making, they might release all the data they own? IOW, the whole deal, they got off BEA? By that I mean, if they are innocent, what is behind the white knuckles holding on to 447's data?

Goes to motive, and intent.

Everything Airbus has done since 1988 pertains to 447. Didn't auto/recover from CFIT result from Asseline's folly? Not all bad, then? Weren't they attempting to get their arms around "Unreliable Speeds" when the 330 went down? At some point, it might be nice to admit a problem, take a breath, (PARK THEM), and not fly until the problem can be sussed and mitigated?

Mon Dieu! Je ne sais pas! Moment, s'il vous plait.

[DozyWannabe]

[Quoting in full in case the original post "disappears"... Apologies.]

Airbus, Flight Plan, Boeing, Display flight.
Wheat/Chaff
I think both were demo flights, wait, I know they were. Airbus needs to stop promoting to chief pilot or even F/O, those who lose the plot, in cahoots with the platform/Format. Funny how many nincompoops get into the front dere, yes?

Are you trying to tell me Airbus doesn't have a glossy release prepped at a moment's notice to exonerate the a/c for any foul/up? In at least one case, the manufacturer applied pressure to have the investigative body carry their d'Eau, No? Pre Paris Air Show? Fetes d'avions? Nothing wrong here, nope.

If Airbus wasn't addicted to excuse making, they might release all the data they own? IOW, the whole deal, they got off BEA? By that I mean, if they are innocent, what is behind the white knuckles holding on to 447's data?

Goes to motive, and intent.

Everything Airbus has done since 1988 pertains to 447. Didn't auto/recover from CFIT result from Asseline's folly? Not all bad, then? Weren't they attempting to get their arms around "Unreliable Speeds" when the 330 went down? At some point, it might be nice to admit a problem, take a breath, (PARK THEM), and not fly until the problem can be sussed and mitigated?

Mon Dieu! Je ne sais pas! Moment, s'il vous plait.

Forgive me if I'm appearing dense here, but it appears to me that despite the fact that you're using mostly English words, and your sentence structure is largely OK, I can discern no coherent meaning from that post at all.

If I sort of squint and angle my head slightly, however, it would appear that you've just tried to imply a conspiracy between Airbus and French authorities to absolve Airbus of any problems with their products and to blame pilots when things do go wrong - a conspiracy that is ongoing and goes back to 1988.

If that is indeed what you're saying, then you've basically confirmed what I've suspected for about a year now - that your continued posting of ever more bizarre theories, alternating with assurances of good intent, were nothing more than a smokescreen - behind which lurked merely another person who bashes Airbus because they never got over Habsheim.

To which all I can say is : Even Captain Asseline is over *$!?%&g Habsheim by now!

To answer your "points" (after which if you want to talk about this it does not belong in the AF447 thread) :


Both were demonstration flights, but AF296 was carrying passengers because it was due to continue from Habsheim to a sightseeing flight over Mont Blanc. The Dash-8 barrel roll would never have been considered under those circumstances. The decision for the former lay with AF ops, not Airbus - the latter lay with the test pilot alone (AF447 : No relevance)
Capt. Asseline was an AF training captain, *not* an Airbus employee (AF447 : No relevance)
*Every* airframe manufacturer will, in the absence of an obvious design problem, try to prove their product is not at fault - think Boeing and the 737 rudder PCU issue (AF447 : No relevance)
The decisions as to how much data is to be released, when, and to whom are based on relevance and made by the investigating authority, not the manufacturer. No investigation bureau in the world has ever released full, unexpurgated FDR traces, and yet you conclude that because the BEA is doing the same, they or Airbus must be hiding something. Paranoid much?
The pitot tube replacement work was scheduled at the airlines' discretion, not Airbus's. In the meantime Airbus met due diligence criteria and published a procedure to be followed in case of UAS, which was not followed by this crew
An AD grounding the fleet would have been overkill in this instance, because procedures were established to deal with the problem without incurring additional risk - just like the increased approach speed numbers to counteract the 737 rudder hard-over fault in the late '90s


I dread to think how many hours I've spent patiently explaining documented facts that refute the claims of skulduggery between the BEA and Airbus either then or now, so I'm not going to repeat myself further.

I'm glad you've finally revealed your true colours Lyman. I'd like to say it's a weight off my mind, but frankly I've barely given this any thought of late - and will not be doing so until more information is forthcoming.

[Owain Glyndwr]

I'm sympathetic to Dozy's pov that missing new data the subject has been done to death, but we need not expect to see any new factual data ex BEA since their "cartoons" already give much more information than is customary in accident reporting. The data has, after all, been enough to keep these threads going for a year or so!

OTOH, with HN39's help (but any errors are mine!) I have been able to construct a means of calculating performance at and beyond the stall, and this in turn allows a systematic study of recovery possibilities - something that AFAIK has not been presented here before, so perhaps it qualifies as "new data"?

On the diagram, the yellow line is the actual AF447 flight path derived from BEA traces of inertial ground speed and barometric altitude, corrected for wind effects wherever possible.

The purple line is a theoretical calculation of that flight path using the developed method with actual flight pitch and power (N1) as input data. Given the fact that the aircraft was gyrating with six degrees of freedom and the model is restricted to three, I think it a reasonable match which gives some credence to any recovery calculations. Others may differ.

http://i1267.photobucket.com/albums/jj541/owainglyndwr2/Flightpaths1804am.jpg

Wherever you see a red line the stall warning was, or would be, operative.
The blue bits on the recovery trajectories are the final pull ups.
All recoveries assume 104% N1 throughout.

The interesting finding for me was that it is not necessary to go to extreme nose down attitudes to recover - in fact it may even be counterproductive, since although you arrive at a good 'flying' speed at a higher altitude, you have further to go in pitch and if you do that at a moderate rate the extra time uses up all the benefit. Countering that by a more aggressive pitch up rate looks as if it may get you into secondary stall territory.

The other point is that the actual rate of pitch down at entry into the recovery is not all that important either. If you are going to be in a 10 deg ND dive for 60 seconds it really makes little difference if it takes you a few seconds more or less to get there.

[CONF iture]

No, there almost certainly isn't.
And you are most certainly correct, not in the FDR, in the QAR most probably but the chance we are informed some data were retrieved from the QAR would be that those data can further advance the main idea behind that last piece of mind formatting :

AF 447 - Pieces a conviction - MAR 2012 - FR3

Still, the AP/FD vertical engagement mode trace must be one from the FDR. I am concerned we have not seen it yet, like I was concerned we have never seen the vertical acceleration trace for Perpignan ...

Some prefer the yoke but remember the yoke will not necessarily guarantee safety. Given that this is the case then one cannot criticize the side stick on the grounds it is less safe. One can say I prefer the yoke because it has this factor which is important for me but that is all.
Sidesticks suppress information of GREAT value for a PNF – Did it play a role for AF447 ? – I think it did.

The interesting finding for me was that it is not necessary to go to extreme nose down attitudes to recover
It depends at which AoA the recovery process is engaged. At 40 degrees of AoA anything short of 30 degrees of negative pitch is useless. Airline pilots are not trained to command such negative pitch especially at a time when minimum altitude loss was the most important credo.
In the meantime I must admit your graph is a bit complex for me.

[Lyman]

ACARS: Excellent system. It worked, brilliantly.

Two way Comms: FAIL

UAS drill: FAIL

RADAR sytem: FAULT

Engines: Excellent

INTERFACE FAIL

PITOT PROBES: FAIL

Coincidence? A a=system designed solely to make money, to minimize gear down time, and streamline operational reliability, performs flawlessly. Had they arrived, the work would have begun at chocks in.

Is this a commentary on priorities? Yes.

UAS drill? Any pilot who cannot keep current with instant P/Power values, and be ready with gentle and decisive handling, needs to be back at ops, in the sim. Even DOZY can get a sim ride, AF is too cheap to add a drill of 7 minutes to the syllabus?

If it continues, perhaps we should address an upgrade to the way we fish parts and bodies out the SEA........

I have one word for the designers: PROACTIVE

[Machinbird]

Very interesting graph Owain Glyndwr. It appears that at lower altitudes, the nose down control is much more effective and thus the pitch down to flying AOA occurs much more quickly.

What assumptions are made in this graph regarding nose down trim performance by the flight control system? What assumptions are made with regard to AOA management by the crew since the flight control system does not manage AOA in Alt law.

They could have still recovered down to ~5000 feet if all went perfectly? What a tragedy.:(

[DozyWannabe]

Dozy got a sim ride through an act of incredible kindness on the part of three people he will always be eternally grateful to (one in particular).

Dozy managed to perform a manual takeoff first time, followed the FD around, recovered the aircraft from the AF447 scenario *twice* and managed a successful FD-led landing on the second attempt (having fumbled the throttle/stick co-ordination on the first). Dozy did all that in around an hour and a half. Dozy hadn't been anywhere near the controls of an aircraft since he last got out of an AEF Chippie in 1993.

How you can say there's anything wrong with an interface that allows a clumsy doofus like Dozy to manage that I cannot fathom.

[Lyman]

Doze. If you expect to be taken seriously, you will have to be serious. It is outrageous that you should compare your jaunt with a certificated long haul ATPL.

OWAIN. The graph is beautiful, but I too am having some difficulties. Could you take us through some of the data? For instance you have a G demarcation that looks luscious, but can you give some direction as to how it may have felt, indexed with a/s, and ROD?

many thanks.

DOZY: "Followed the FD around...." There's a ripe apple, can you elaborate?
Is that something an ATPL in 447 land might do?

[Owain Glyndwr]

Machinbird

What assumptions are made in this graph regarding nose down trim performance by the flight control system? What assumptions are made with regard to AOA management by the crew since the flight control system does not manage AOA in Alt law.None - it is just a performance calculation in which the crew is assumed to apply pitch at a given rate until the desired steady ND value is achieved, and then to fly constant pitch attitude until about 250 kts EAS at which point it is assumed that pitch is reversed at the same rate as going in, unless the S/W boundary is exceeded in which case the pitch rate was backed off to keep inside the limit (this only applied in the 3 deg/sec FL350 case). There is an implicit assumption that since the crew did not have AoA information they couldn't fly to manage it, but they could fly pitch.

Don't look for too much detail in this picture - it isn't there.

They could have still recovered down to ~5000 feet if all went perfectly? What a tragedyYes, but can you see anyone passing through FL60 at 10,000 fpm applying 10 deg ND pitch and holding it? This line unfortunately is very theoretical.

Lyman

For instance you have a G demarcation that looks luscious, but can you give some direction as to how it may have felt, indexed with a/s, and ROD?

Since there is no G on the graph I am at a loss how to reply, but the pull-up 'g's were in the range 1.4~1.7

[DozyWannabe]

I'm not comparing anything, I know full well that controlling the aircraft is merely the base level of what you can achieve. An ATPL would have to do a lot more. However, "following the FD" is *exactly* what the AF447 pilots had been trained to expect to do 99% of the time.

The reason I was able to recover (aside from the complex psychology behind me knowing I was in a sim and them knowing they weren't and that their lives were on the line) was the fact that I knew what was coming and how to recover, whereas it would appear that they did not. I had about 5-10 minutes following the FD on a departure orbit to get a feel for the thing before the scenario was loaded and I got dropped in the doo-doo.

That wasn't me blowing my trumpet by the way, that was me saying that the Airbus cockpit ergonomics are in fact very good. So good that even I could acquit myself with minimal egg on my face.

There was no radar "fault" either - the radar's exactly the same as in any other airliner of that vintage.

[infrequentflyer789]

How you can say there's anything wrong with an interface that allows a clumsy doofus like Dozy to manage that I cannot fathom.

Your day job wouldn't be concierge by any chance... ? :E

[jcjeant]

Hi,

Owain Glyndwr
The data has, after all, been enough to keep these threads going for a year or so!Can be also ...
The lack of data has, after all, been enough to keep these threads going for a year or so!

[OK465]

O.G.:

I'm curious about your Mach lines vs CAS vs altitude.

For example, your chart shows Mach 0.8 at 30,000 is 288 CAS.

I get 304 CAS for Mach 0.8 at 30,000.

In addition, I show A330 Va reaches about 315 KCAS at 27,000 where it intersects the Mach 0.78 Va limit for the aircraft.

You have 0.78 Mach intersecting Va at about 290 KCAS.

:)

(Is it an ISA + x thing?)

[CONF iture]

Yes, but can you see anyone passing through FL60 at 10,000 fpm applying 10 deg ND pitch and holding it?
No way 10 degrees ND was enough to go anywhere, be it at 5000, 20000, or 35000 feet on the way down when the AoA was already above 30 degrees.

[Owain Glyndwr]

OK465

I'm curious about your Mach lines vs CAS vs altitude.

......
(Is it an ISA + x thing?) No, it's a senior moment. I picked up the wrong values from the spreadsheet. The Mach lines shown are EAS not CAS. doesn't change the other numbers though which are all CAS - these Mach lines were just for background info. Thanks for the correction.

[DozyWannabe]

Your day job wouldn't be concierge by any chance... ? :E

No mate, way above my pay grade. ;)

[CONF iture]

No, there almost certainly isn't.
After revisiting Habsheim, I'll have to contradict you here.
On page 48 of the Habsheim report, the page selection for the ECAM lower display or SD was already available :

http://i45.servimg.com/u/f45/11/75/17/84/af447_31.png (http://www.servimg.com/image_preview.php?i=145&u=11751784)


If I was one of those 3 pilots, I would make sure, where ever I am ... to provide ALL the data to my family and friends, before I let them kill me a second time.

[Lyman]

@CONFiture

If I was one of those 3 pilots, I would make sure, where ever I am ... to provide ALL the data to my family and friends, before I let them kill me a second time.

The inference is clear, and your standing is one of integrity and passion. Can you elaborate? I for one believe the power of silence and secrecy must stop. It can stop with this tragic loss.

What are the data going to say to us? (Possibly). It is quite clear, and do not believe those who say: "It is traditional to keep data witheld". That is true, but does not suggest why, only that it is 'traditional'.

No human being or group has the right to keep secret material that is relevant and has bearing on Public Safety. Secrecy is toxic to Safety, and the right of all people to decide their own agreements and plans in public carriage, finance, and destiny. Enough of this.

with respect

[CONF iture]

Thanks for your support Lyman.

Following any accident, serious incident, or incident that requires data extraction, AS SOON AS the data are extracted, a FULL copy should go to :

the investigation body
the manufacturer
the airline
the pilots, or their pre-designated representatives
Add anyone you like to that list … but #4 is ineradicable.

[Lyman]

Thank you. I find it reprehensible that those here who would defend the secrecy clamor for us all to assume that the displays were available and accurate for the crew, when they need a leap of faith, yet the actuals re: ECAM, clearly extracted, get no such clamor. What is the fear? Alice would be pleased at the hypocrisy.

Two then, for the heirs to be informed.

[bubbers44]

So you think the FDR readouts were different than the flight instruments the pilots saw? Just asking??? Both sides of the cockpit attitude indicators failed so the PF pulled up into a stall? The senior FO not flying let him do it?

[jcjeant]

So you think the FDR readouts were different than the flight instruments the pilots saw? Just asking??? Both sides of the cockpit attitude indicators failed so the PF pulled up into a stall? The senior FO not flying let him do it? Anybody can think anything .. as anybody (public) haven't seen so far the AF447 FDR listings
If the FDR is published .. methink many speculations (anyone) will be shut down
When we say a small child can not open the cabinet because it contains a secret .. his imagination will invent many things
Only when he opens it he will know the truth and imagined jams and sweets can maybe be no there as expected :)

[Lyman]

Bubbers, jcjeant

I would ask that you read BEA IR #3 pp. 79 to wit:

"4.3 Recommendations relating to Flight Recorders
Analysis of the FDR parameters and audition of the CVR provide information that is essential to an understanding of the event. However, it is difficult to reconstruct the indications that were available to the crew on their instrument panel, especially the instructions given by the Flight Director crossbars when they reappear. It is also impossible to see whether there have been any attempts to re-engage the autopilot. A view of the instrument panel would complete the information provided by the FDR and the CVR and would make it possible to confirm the indications that were available to the crew and the actions that they made. Numerous recommendations have already been made on this subject over the past ten years without any real progress having been made.4.3 Recommendations relating to Flight Recorders
Analysis of the FDR parameters and audition of the CVR provide information that is essential to an understanding of the event. However, it is difficult to reconstruct the indications that were available to the crew on their instrument panel, especially the instructions given by the Flight Director crossbars when they reappear. It is also impossible to see whether there have been any attempts to re-engage the autopilot. A view of the instrument panel would complete the information provided by the FDR and the CVR and would make it possible to confirm the indications that were available to the crew and the actions that they made. Numerous recommendations have already been made on this subject over the past ten years without any real progress having been made."

It is BEA who suggest there are serious problems with the indications available the pilots, as to reconstruction, availability.

Specifically, autopilot commands, attitudes and speeds. OH, and FLIGHT DIRECTOR CROSSBARS


Thought you might be interested.

respect

[Old Carthusian]

Habsheim - interesting accident. A pilot performs unauthorised manoeuvres and then blames his machine. The luddites immediately rush to support him. Fast forward to now certain individuals are trying to link this to AF447. This isn't a quest for the truth this is a quest to prove outlandish theories. Let us lay out the reality of AF447 - the pitots iced up causing UAS. That is all. There is literally no evidence that any of the other instruments went Lady Gaga. The flight crew didn't respond to the incident in an appropriate manner putting the aircraft into a stall. That is all. No smoking gun, no conspiracy, no manipulative manufacturer. Just mundane errors - a whimper not a bang.

[Linktrained]

One commendable early notification was along the lines:
" We do not know yet what has happened to AF447 but it may be connected to Pitots and / airspeed..."
(Was this from AF, AB or BEA ? It doesn't matter.)
This would give any pilot a chance to reread the UAS Drill for his aircraft. Do people still do " Touch Drills " ( Touch - but don't move anything...) ?

[Lyman]

OC The attempted linkage of Habsheim/447 is in your mind. If you had taken the time to read for comprehension, the nexus was only that ECAM artifacts are available via DFDR post accident/incident. There are similarities whenever complex machinery of any kind meets its destruction. Wiser people than us seek out these commonalities, and forge us new processes.

Linktrained. I for one get immense pleasure and some comfort when you share your history here. Everything has a beginning; we stand on the shoulders of our forebears, and ridicule them at great risk to our safety, if not our conceit.

[bubbers44]

It is possible the PNF was getting out the UAS checklist while the PF was pulling up because of fear of being too fast if the overspeed was going off. Every jet I flew had an UAS checklist to fly with inop airspeed indicators. It seems he would have monitored what the PF was doing while he was getting it though. Just read an article in a pro pilot magazine about knowing how to fly with no operable air speed indicators. Seems like some of the corporate pilots have a higher understanding than airline pilots how to deal with their planes when they develop a problem. The last jets I flew with AOA indicators were corporate aircraft decades ago.

[Machinbird]

Let us lay out the reality of AF447 - the pitots iced up causing UAS. That is all. There is literally no evidence that any of the other instruments went Lady Gaga. The flight crew didn't respond to the incident in an appropriate manner putting the aircraft into a stall. That is all. No smoking gun, no conspiracy, no manipulative manufacturer. Just mundane errors - a whimper not a bang.
Well, the stall warning system did not behave as most of us would have expected it to, but other than that, I agree.

Now if you were in BEA's position, what kind of recommendations would you be developing to prevent the next accident?

[bubbers44]

The stall warning should not operate before takeoff speeds are achieved so why should they not be silenced if they go to those low speeds. They are normal for in flight conditions.

[Machinbird]

The stall warning should not operate before takeoff speeds are achieved so why should they not be silenced if they go to those low speeds. They are normal for in flight conditions. One good reason would be that there was no weight on the wheels, i.e. they were airborne where such things matter greatly.

[jcjeant]

Anybody of you the experts can tell me other type of aircrafts (excepted Airbus) that the stall alarm stops when the aircraft is still in full stall state ?

[Lyman]

jcjeant

Howdy there. AF447 died of a frequently terminal (fatal) condition called STALL. She did not crash due to STALL WARNING.

On an a/c that shuns manual control and seat of the pants flying, there is no ALERT/STALL. ONLY a WARNING. It is clear the crew rejected STALL, (both its warning, and its physical eveidence) at least to me. Therefore, they are left with textbook aero behaviour of the STALL condition to diagnose it: Nose Drop and BUFFET, to get that the airframe is STALLED. The NOSE did not drop, at least characteristically, in fact, the PF may have lifted the NOSE each time he started to recover! Leaving the Mush state, and transiting through the beginning of LIFT, the Nose would have dropped, and the STALL WARN activated, at least once.

The "Buffet" that is touted by BEA as "possible", to me seems questionable, and anyway, it did not serve to alert the crew sufficiently to STALL.

So here. The evidence strongly points to crew ignorance of the STALL condition, and the physical clews were missing also. Without some emphatic a/c warning of ACTUAL STALL, the outcome is assured, as we see. There is no recovery from STALL, absent strict and prescribed maneuvers, as discussed here at length. Without a starting point (diagnosos of STALL), the crew will drop into the sea, again, as we see they did.

It is not a fault of the aircraft sufficient to even raise one's eyebrows. (IMHO).

The problem is straightforward. The Autopilot will not operate without Airspeed reporting that meets its criteria. The crew will not be able to fly without accurate a/s either, failing certain requirements that were obviously missing. At the very least, the Pilot Flying did not immediately acclimate to manual control, and never did understand his instruments, (assuming they were working, and accurate).

The a/c crashed due to the events we see reported by BEA, the picture is clear.
Unprepared, in turbulent air, and without accurate airspeeds, the plot was lost from the git by PF, and the PNF either did not understand either, or lacked the training to seize immediate control, instead (we assume) calling for the Captain, to help. What exactly caused the chain to fracture so quickly and terminally is open to discussion. By the time the a/c departed aero flight, there was no chance to recover, given the conditions to hand.

For me, the table appeared to be set for disaster directly by the lack of response in changing out defective (in theory) probes, and indirectly due lack of even a basic recognition of the dangers in flying an aircraft with such rapid changes occurring in a very narrow window of parameters. I do not understand how some here (with a straight face) are so dismissive of the piloting, and so reassured by the a/c. The a/c was no more in a state of readiness than the people. IMHO.

bon nuit

BTW, what happened to that leak re: Captain's initial reaction upon re-entering the cockpit? He is upposed to have said, "What are you doing? That is a STALL, Go with the nose down!!? " The quote in the report is "Er...what are you doing?"

Any question, regardless of content missing, means he knows something is wrong. On page 31 BEA IR #3, the last thing reported from CVR is "Er...what are you doing...." The conversation is then shut down, no more CVR, indexed with the plane's attitude. Why not? Those three pages, if continued further in sequence would tell us the rest of the story.

[Old Carthusian]

Lyman
Of course there is an attempt to link Habersheim with AF447 otherwise why mention it?

Machinbird
A very interesting question - will a UAS warning system actually be practical or developable? If so will it actually be feasible in service? We know that pitot tubes are being changed to the more reliable Goodrich models. However, it is probably time to replace the pitot tube with something new though what that could be is beyond me. I would recommend considerably more training and hands on experience for pilots and a thorough reorganisation of Air France's flight operations (which might even be underway as we speak) as I do believe that there is an airline specific cultural issue here.

[Mr Optimistic]

'The stall warning should not operate before takeoff speeds are achieved so why should they not be silenced if they go to those low speeds.'I was under the impression that aircraft systems have some idea of altitude. Seems reasonable to enable the stall warning as appropriate when at 35000 ft irrespective of any other logic.

[jcjeant]

Hi,

Old Carthusian
I do believe that there is an airline specific cultural issue here. If you challenge the culture of the company .. you must also include the various unions of Air France pilots
They are to represent the pilots .. but not only
They are guard dogs and should intervene when things do not unfold as planned by the rules
More .. there are also official control agencies who must play a role
If Air France has reached the point of having a bad culture .. one can not discount some others players
The Helios accident report:
Latent causes
1. The Operator’s deficiencies in organization, quality management and safety culture, documented diachronically as findings in numerous audits.
2. The Regulatory Authority’s diachronic inadequate execution of its oversight responsibilities to ensure the safety of operations of the airlines under its supervision and its inadequate responses to findings of deficiencies documented in numerous audits.
Contributing Factors to the Accident
3. Ineffectiveness of international aviation authorities to enforce implementation of corrective action plans after relevant audits.

Airline execs convicted over 2005 Greece crash | Athens News (http://www.athensnews.gr/portal/9/55115)

[A33Zab]

All Thales probes have been replaced per AD.

Besides the probe replacement program, several hardware and software changes have been introduced, IMO they are optional and not mandated.

- BUSS (SW always available) - already available before AF447!
- FMGEC: AP/FD not available after UAS condition. (Last MOD)
- FCPC: F/CTL ALT LAW (PROT LOST) ECAM MSG accompanied with reason. (Last MOD)
- FCDC: More rigid USE MAN PITCH TRIM PFD message when autotrim not available. (Last MOD)
- FWC: **NAV IAS DISCREPANCY MSG When 2/more IAS are detected to be different.
Added AoA data filtering to improve SW detection in turbulent conditions.

- AoA: Conical shaped ground base to prevent water ingression. (Last MOD)

** Don't know if F-GZCP was equipped with this mod but the mod was available at that time. (BEA doesn't mention the presence of this message, suspect it was NOT available in F-GZCP)

The B787 is equipped with ADR voting logic, details are not known by me, but the fault isolation logic determines which ADR supplies PFD.
Above that there seems to be a synthetic AS available when the voted fails

http://i474.photobucket.com/albums/rr101/Zab999/Vsyn.jpg

[Machinbird]

Lyman
Still pushing an agenda I see. Practicing the lawyer's art are you? :rolleyes:

At least your factual arguments are getting more factual. It is just your IMHOs that we have to be careful of. It is not a fault of the aircraft sufficient to even raise one's eyebrows. (IMHO).What effect do you suppose the extinguishing of the stall warning had on the captain when he re-entered the flight deck? In his shoes, wouldn't you normally think that the guys in the seats had reduced AOA? That affected his mental starting point, and the bunnies in the seats then didn't help with their minimal brief.

[Organfreak]

Machinbird, agreed. While we have every right to expect fully-trained personel on deck, this airplane needs much more work on idiot-proofing. :eek:

[TTex600]

Now if you were in BEA's position, what kind of recommendations would you be developing to prevent the next accident?

At the very least, I would change the UAS drill to require cross cockpit crew communication.

Either pilot should be allowed/required to challenge air speed reliability and there should be a SOP in the manual for exact phraseology to be used in such an event. The challenge should be required and the response exact. i.e., "UAS suspected, Left side indicates xxx. What is your airspeed?" followed by "Right side indicates xxx, Stdby indicates xxx" . Or something to that effect.

We take our time dealing with engine failures at V1, why not take our time dealing with UAS?

As written, the UAS procedure is "immediate action" and it appears that the rote response to immediate action could have been incorrect in this AF447 case. (at the very least ;)

[OK465]

...what kind of recommendations would you be developing to prevent the next accident?

Be willing to pay more for a ticket (or e-ticket as the case may be).

[Machinbird]

Either pilot should be allowed/required to challenge air speed reliability and there should be a SOP in the manual for exact phraseology to be used in such an event. The challenge should be required and the response exact. i.e., "UAS suspected, Left side indicates xxx. What is your airspeed?" followed by "Right side indicates xxx, Stdby indicates xxx" . Or something to that effect.

We take our time dealing with engine failures at V1, why not take our time dealing with UAS?
This particular recommendation would have had a positive influence on the outcomes of at least 3 accidents that I can immediately think of. Is there any down side to this type procedure? Are there any limitations on when to apply it?

[mm43]

787 Synthetic Airspeed

Calculated from angle of attack and inertial data
- AOA - voted dual sensors plus inertial data
- Accurate Coefficient of Lift (CL)
- Airplane Mass from FMC - Validated after Takeoff

Algorithm developed for enhanced stall protection

Avoid displaying data known to be bad
- Loss of valid voted VCAS = Display synthetic airspeed VSYN
- Loss of valid voted PSTATIC = Display GPS altitudeThanks for posting the B787 method of using "synthetic" airspeed and GPS altitude when discrepancies with the Pitot/Baro system are detected. I've placed the details of the image you posted (http://www.pprune.org/tech-log/482356-af-447-thread-no-8-a-6.html#post7149737) in quotes above, mainly so that it will be found when searching the thread.

So my answer to Machinbird's challenge is for Airbus to implement a similar system as described above and alluded to by me as early as July 2009 in post #3999 (http://www.pprune.org/tech-log/376433-af447-200.html#post5094004) in the AF447 Thread and recently in post #616 (http://www.pprune.org/tech-log/454653-af-447-thread-no-4-a-31.html#post6547413) in AF447 No.4 Thread.

Now I haven't heard of any B787 pilots objecting to not having to deal with UAS - has anyone else??

[Machinbird]

So my answer to Machinbird's challenge is for Airbus to implement a similar system as described above and alluded to by me as early as July 2009 in post #3999 (http://www.pprune.org/tech-log/376433-af447-200.html#post5094004) in the AF447 Thread and recently in post #616 (http://www.pprune.org/tech-log/454653-af-447-thread-no-4-a-31.html#post6547413) in AF447 No.4 Thread. and as suggested by Machinbird in July 2009 in the same thread http://www.pprune.org/5093224-post3981.html:) and probably by a number of others as well.

Boeing is one upping Airbus in the technical wars of how to design a better airliner. Now we can have competitive pressures to add to pressures from regulators to improve the existing Airbus design.:ok:

[infrequentflyer789]

and as suggested by Machinbird in July 2009 in the same thread http://www.pprune.org/5093224-post3981.html:) and probably by a number of others as well.

Boeing is one upping Airbus in the technical wars of how to design a better airliner. Now we can have competitive pressures to add to pressures from regulators to improve the existing Airbus design.:ok:

Airbus already has backup speed scale - BUSS - which is effectively a synthetic airspeed from same source parameters as the Boeing one.

How many types is Boeing implementing this on ? I think BUSS is available on everything later than 320, and mandatory on 380 onwards ?

[Machinbird]

BUSS is really an AOA indicator gussied up to look like the PFD airspeed indication as best they could. Very different principle compared to Boeing's synthetic airspeed (from what we can learn from A33Zab's post).

[Organfreak]

...And as long as BUSS is optional there are thousands more lives it can't save.

[bubbers44]

A competent pilot would not pull up into a stall ignoring his altitude and pitching far above any attitude that would provide any hope of recovery. These new guys needed the captain to help them because they were lost as far as flying properly and not prepared to fly the plane properly. Copilots should be able to handle these situations if properly experienced. These two were not obviously. I just wonder if they have improved the FO standards since this happened. Most US FO's have over 10.000 hrs before they fly the long hauls over the Atlantic. Much more before they can be a captain. We can do it so why can't they?

[CONF iture]

- BUSS (SW always available) - already available before AF447!
- FMGEC: AP/FD not available after UAS condition. (Last MOD)
- FCPC: F/CTL ALT LAW (PROT LOST) ECAM MSG accompanied with reason. (Last MOD)
- FCDC: More rigid USE MAN PITCH TRIM PFD message when autotrim not available. (Last MOD)
- FWC: **NAV IAS DISCREPANCY MSG When 2/more IAS are detected to be different.
- Added AoA data filtering to improve SW detection in turbulent conditions.
- AoA: Conical shaped ground base to prevent water ingression. (Last MOD)

Interesting, you are pretty well informed here.
I note the one on the non availability of the FD … part of the reason I am very much interested in the AP/FD vertical mode trace.
Some seem to be a consequence from Perpignan, some others maybe already from AF447 …

NAV IAS DISCREPANCY ECAM MSG became standard on our fleet sometimes between 2008 – 2009 but I could not tell precisely which month. I would have thought AF447 was equipped, but I’ve been wrong on the electrical rudder already so …

[CONF iture]

Habsheim - interesting accident. A pilot performs unauthorised manoeuvres and then blames his machine. The luddites immediately rush to support him. Fast forward to now certain individuals are trying to link this to AF447. This isn't a quest for the truth this is a quest to prove outlandish theories.
...
Of course there is an attempt to link Habersheim with AF447 otherwise why mention it?
If I sort of squint and angle my head slightly, however, it would appear that you've just tried to imply a conspiracy between Airbus and French authorities to absolve Airbus of any problems with their products and to blame pilots when things do go wrong - a conspiracy that is ongoing and goes back to 1988.
The real link between Habsheim and AF447 is that the BEA is investigating an Airbus accident.

Habsheim – 2 pilots decided to present the brand new 320 at very low speed very low altitude with minimum preparation. To perform such maneuver with just the front crew onboard would have been questionable already, but to perform it with a pax loaded cabin was a total lack of judgment. Obviously the crew decision is the reason for the crash and must be remembered as such.

But did it absolve the BEA to tell the all story ?
Is it the BEA mission to cover up the truth ?

The truth had to be told – The crew would not have been considered less responsible.


When the pilot applied the thrust, one engine stalled, and the other one responded much slowly than expected. As the captain had that very bad idea to fly below the trees line ... happened what happened.
When the pilot applied full back stick, the airplane refused to deliver alpha max. That characteristic will be documented 20 years later by the NTSB following the Hudson ditching. Maybe at the end that would not have done any difference, but it was the role of the BEA to detail that flight control behavior below 50 feet.
It is not called a conspiracy Dozy, it is called damage control.

[DozyWannabe]

Funny - I've seen the footage lord alone knows how many times and not once did I hear anything indicating a compressor stall. The engines were *spooled down*, because that's what had been ordered to try and fudge the rushed approach.

The aircraft *did* gave him alpha max, but alpha max was *limited* by the airspeed. To have increased the AoA much further would have induced a stall and probably would have killed most of the people on board.

Now - AF447 please.

[Lyman]

"Funny - I've seen the footage lord alone knows how many times and not once did I hear anything indicating a compressor stall."

Funny, instead of listening, LOOK, it is VISIBLE........

Could the crew have survived if they had lit the APU? (447, Doze. Oh for some alpha prot above the Atlantic....).

[rudderrudderrat]

Hi CONF iture

The only similarity between the accident reports for Habsheim http://www.bea.aero/docspa/1988/f-kc880626/pdf/f-kc880626.pdf and AF744 is that both have the CVR transcript & Flight Data.

Page 35.
The aircraft is at 30 radio,
At 12:46:34 the CVR picks up the sound of the TLs going through 3 clicks to TOGA.
At 12:46:37 the Co-pilot reads the FMA "TOGA SRS"
At 12:46:39 the sound of impact with the trees.
At 12:46:39 the Captain says "M....!" (code for merde?)
At 12:46:41 Fin.

I believe the agreed display was a fly past at a height of 500 ft.
At 30 ft radio, with thrust at flight idle, speed back to Alpha Protect and below, don't you think the application of power just 5 seconds before impact with the trees is leaving it just a tad too late?

[DozyWannabe]

Funny, instead of listening, LOOK, it is VISIBLE........

No it isn't.

[Turbine D]

Hi CONF iture,
Relative to Habsheim:

I don't believe there was a compressor stall in one engine at all. indeed the engines did not spool up in 1 or 2 seconds. This comes from the a pilot error of setting the engines at minimum flight idle. In this case, engines may take 5 seconds to increase from complete idle to good power (80% of continuous max). The lack of power was made worse with the slowing down and the extremely low speed in such a way that the tail was lower than the undercarriage. It can be pointed out that those conditions never happen during a normal landing, that is why pilots have been baffled with the airplane's poor reactions. Air France had been informed by CFMI of the 5 second delay in spool up from minimum flight idle, but the word was never passed to the Habsheim crew before the flight. Subsequently the delay in spool up was fixed by CFMI, probably by changes made to the engine control electronic management system.

[DozyWannabe]

Air France had been informed by CFMI of the 5 second delay in spool up from minimum flight idle, but the word was never passed to the Habsheim crew before the flight.

I'm not so sure. The much-referenced delay in spooling up (and the reference to earlier problems in the A320 testing regimen) referred to slow spool up at medium to cruise altitude, and thus a completely different area of the flight envelope compared to the position of the Habsheim jet.

The consensus as I understand it was that allowing high-bypass jet engines of any type and on any airliner to spool down at any point of the approach was a big no-no, and pilots of the calibre and experience of those in command on the day should have been well aware of that fact.

[Lyman]

:mad:#2, about 200 meters short of the trees, keep looking. And he did not say 'compressor'.

Now I had to go look. It is #1, looks more surgy than stally. sheesh.

Of all the posters, Turbine D is one I never even bother to check/question. His posts are impeccable. There was a bulletin (OEB) sent to Air France prior, and the Engines were modified as a result of Habsheims folly. So from Habsheim comes progress. Had Asseline been less stupid, would the initial crash/failedGA of a 320 loaded with pax been inevitable? Life is strange.

Dozy, CONFiture has a pov, one that involves BEA doing some questionable things re: reporting. I happen to agree with him. You have the advantage of being so sure of yourself, it is clear you buy their perfection. I am merely sceptical, and worship at no altars involving the technical work of mere humans.

I am agnostic.

[HazelNuts39]

The consensus as I understand it was that allowing high-bypass jet engines of any type and on any airliner to spool down at any point of the approach was a big no-no, and pilots of the calibre and experience of those in command on the day should have been well aware of that fact.Not just a consensus, but a feature of all jet engines, not just high-bypass engines. The very reason for having a flight idle higher than ground idle is the spool-up time. Since the adoption in 1958 of Special Civil Air Regulation Nr. SR-422A for Turbine-Powered Transport Category Airplanes of Current Design, the 'baulked' landing climb requirement must be met with:
All engines operating at the power and/or thrust which are available 8 seconds after initiation of movement of the power and/or thrust controls from the minimum flight idle to the takeoff position

[Turbine D]

Lyman,

#2, about 200 meters short of the trees, keep looking. And he did not say 'compressor'.

Now I had to go look. It is #1, looks more surgy than stally. sheesh.


The year was 1988. What you are "seeing" is neither a "stall" or a "surge". It is a result of a throttle burst from minimum idle to max thrust. In those days, when you did that, even on a test stand, you would see unburned fuel vapors out the tailpipe. It had to do with the state of design knowledge in those days regarding the combustor and fuel insertion into the combustor. With today's combustor sophistication and knowledge rarely would you see this.

Anyhow, both engines performed as advertised, with power application being just a little late.

Dozy,

I'm not so sure. The much-referenced delay in spooling up (and the reference to earlier problems in the A320 testing regimen) referred to slow spool up at medium to cruise altitude, and thus a completely different area of the flight envelope compared to the position of the Habsheim jet.

Without getting into a lot of detail, I am sure. It was a warning and reminder of the spool up time required on this engine from minimum flight idle to TOGA thrust, whether it takes place at 50 feet or 250 feet from the ground, much more critical than at or near cruise altitude.

[thermostat]

I believe that we all as pilots knew very well that jet engines took about 8 seconds to spool up. That was the case on the B727 when I flew them back in the 70's. I am quite sure it was a lack of knowledge and experience that caused that accident. The A320 was new and no one quite understood it's idiosyncrasies. When I started my training on the A320, I realized how complicated the technology was and understood then why they lost that first one at the show. Remember too that the A320 of today is very different to the one that crashed. Many mods over the years. I don't fault the pilots. The technology was new, difficult to understand and the training possibly inadequate. It's so easy to point fingers after the fact.

[thermostat]

First of all that :
(1) Pilots understand and respect high altitude flight into thunderstorms
(2) Radar must be properly setup at Top of Climb.
(3) Pilots understand "supercooled water" and how it behaves.
(4) Respect SOPs and apply them
(5) Better training on high altitude manual handling
(6) More use of GPS info. A separate GPS readout of speed (GS), altitude (true), and track, would have saved the day. I carried a handheld unit and it made me feel sooooo good. It was all I needed to land the thing if all was lost.

It's hard for me to accept the loss of a perfectly good airplane due to all of the above. Hope we all learn from it.

[DozyWannabe]

This statement:

CONFiture has a pov, one that involves BEA doing some questionable things re: reporting. I happen to agree with him.

and this one:

I am agnostic.

are logically incompatible with one another. Either you believe that the BEA are involved in an ongoing effort to shield Airbus from blame by fudging information or you don't. You cannot claim to be agnostic and hold the viewpoint in the first statement.

Don't you dare put words in my mouth - I "buy" nobody's "perfection". I just don't believe the BEA are any less independent than any other international accident investigation body you care to name.

@thermostat and Turbine D:

I'm happy to bow to those more knowledgeable, but I'm having a hard time reconciling the idea that the A320 had any specific "idiosyncrasies" regarding engine spool-up time that the crew would have been unaware of if the guidelines regarding spool-up time were known of in the B727 days.

The captain of AF296 was AF's second most experienced pilot on type - he was well aware that the aircraft would limit alpha-max if there was not sufficient airspeed to initiate a climb. I believe that he simply became so goal-focused on getting to 100ft at the runway threshold, that he didn't factor in the side-effect of expediting his descent (by throttling back to spool-down) to do so. "There but for the grace of God" is one thing, but to blame the aircraft for being inscrutable is a cop-out.

[Clandestino]

The real link between Habsheim and AF447 is that the BEA is investigating an Airbus accident.

Since appointment of BEA as investigating authority for both Habsheim (which definitively is not another name for "Paris" or "Le Bourget") and AF447 disasters is perfectly IAW Annex 13, it is either completely normal or we are all doomed because ICAO is part of conspiracy to cover-up the fatal design flaws of FBW Airbi.

:E

What recommendations ??If your desire is to increase informational value of the thread, read and understand reports before posting something brutally at odds with them, without source of reason why you disagree. If you are participating in discussion for entertainment purposes only, keep up the good work.

According to DFDR readout, no penetration of storm cell occurred. Discussed to death but the notion keeps re-spawning.

[jcjeant]

Hi,

Something certain about the crash at Habsheim :
Both flight recorders (CVR and DFDR) disappear the evening of the event, transported by air by the Director of the DGAC Daniel TENENBAUM without any judicial seal there is affixed by the Prosecutor of Mulhouse, Jean WOLF.
It is therefore by an illegal act that begins the investigation
I am not surprised, therefore, of the controversy that followed and which is still not closed for some
BTW ... there is good reason for all the publicity that was made during the sealing of the black boxes of AF447 .. it was even filmed and shown to public

[DozyWannabe]

It is therefore by an illegal act that begins the investigation

Or a mistake.

I am not surprised, therefore, of the controversy that followed and which is still not closed for some

A lot of that "controversy" was manufactured by a private Swiss investigator who was paid to come to the conclusions he came to.

The BEA were so horrified by the accusations levelled at them that they (and the local gendarmerie) wouldn't touch the recorders from the subsequent Air Inter crash until the NTSB team that they had brought over were able to confirm that no tampering with the CVR and DFDR had occurred. The NTSB team were genuinely worried that the data would be lost due to remaining in the burning wreckage for so long.

[jcjeant]

Or a mistake.Mistake or not .. it's illegal act .. turn it how you want !
What followed I don't bother anymore .. it's history ..

[DozyWannabe]

Maybe so, but the DGAC is *not* the BEA. What followed was an honest attempt on the BEA's part to prove to the doubters that whatever happened with the boxes from AF296 would not be repeated on their watch. The people who won't let the aftermath of AF296 go conveniently forget about those efforts, and do themselves no favours by doing so, because it doesn't suit their agenda.

[KBPsen]

it's illegal act Perhaps it was, but that was completely irrelevant to the investigation just as it is completely irrelevant to AF447.

Turn it how you want, it was said. Another oblique swipe at BEA seems to be the favoured direction

[Mr Optimistic]

And where exactly are we going now?

[Linktrained]

SAFETY FIRST issue 11 Jan 2011 page 8

Under STALL WARNING and STALL

A340-600 " performing a low altitude level flight deceleration at idle until SW is triggered and then push the THR levers to TOGA...

The thrust actually reaches TOGA (20 seconds later), the aircraft stalls ... "

Others may know whether this information is helpful - or relevant.

I had a new Captain nearly do this unintentionally with a very empty Britannia freighter, where the time would have been less but still seemed an age. It was night time... I learned from that example... I didn't copy !

[jcjeant]

BPBsen
Perhaps it was, but that was completely irrelevant to the investigation Sorry for return on this subject .. but if this is not revelant to an investigation .. why the boxes must be sealed ?
What is the exact purpose of affixing seals ?

[DozyWannabe]

And where exactly are we going now?

Round in the same old circles until new information comes out.

@jcj : The seal is for the judicial inquiry, not the accident investigation.

[jcjeant]

@jcj : The seal is for the judicial inquiry, not the accident investigation. Thank you .. so it's a very important matter of the judicial inquiry ( Pièces a conviction - exhibits ) like a gun discovered on a crime scene ...

[KBPsen]

And where exactly are we going now?It is the usual attempts by the usual suspects to cast doubt on BEA's credibility with the usual Have-you-stopped-beating-your-wife type of questions.

A form of early insurance in case the contents of the final report is not liked, I suppose. Or perhaps just a case of disliking anything French and having a dig any which way.

[jcjeant]

Hi,

Voss Says Pilots Must Back Up Automation
http://www.ainonline.com/aviation-news/ainsafety/2012-04-23/voss-says-pilots-must-back-automation

[thermostat]

Clandestino. Have you heard the saying "Doctors differ, patients die" ?
I watched an informative video in 4 parts with a pilot. 2 investigators (one English and one American) and an expert in weather matters. They showed a segment on supercooled water and how it reacted when disturbed. This video was extremely well done and all the ppruners should watch it. My experience in aviation spans 32 years, and I do my own thinking thank you. Common sense mixed with experience on different jets allows me to draw my own conclusions.
It's very clear to me (as I have posted many times before) why the accident happened.

[Turbine D]

thermostat,

They showed a segment on supercooled water and how it reacted when disturbed.

Do you really think they encountered supercooled water? Wouldn't ice crystals clogging the pitots be a more likely scenario? I think they finally saw what was ahead on the radar (somewhat late) and started to skirt around the worst of the CB. I am of the impression that CBs in the ITCZ are different than those over land in that the updrafts around the edges of the CBs are warmer (ocean warm water effect) and wouldn't produce supercooled water at the altitude they were cruising at. In fact, they couldn't climb because of the warmer temperature. Am I wrong here?

[Clandestino]

I watched an informative video in 4 parts with a pilot. Good for you. Since the topic we are discussing is AF447 accident and not some informative video, did you read BEA's third interim report? The one with DFDR and CVR readouts?
Common sense mixed with experience on different jets allows me to draw my own conclusions.
It's very clear to me (as I have posted many times before) why the accident happened. You are claiming that AF447 entered the storm cloud, which is at odds with Nz trace. Would you mind explaining the process that enabled you to heartily disagree with official interim report?

The ice crystals that are main suspect in the AF447 pitot blockage are found near active cells but not within them. Avoiding the radar returns won't keep you clear of the naughty ice.

[Organfreak]

Thermostat said:
I watched an informative video in 4 parts with a pilot. 2 investigators (one English and one American) and an expert in weather matters. They showed a segment on supercooled water and how it reacted when disturbed. This video was extremely well done and all the ppruners should watch it.

Indeed we should. So, will you share with us the name of this program? :)
It sounds like the NOVA special (PBS) that came out before Interim Report #3. (Or was it before #2?) Though highly speculative, I thought it was really well done, considering they didn't know what the hell they were talking about! :)
It didn't posit a horizontal splashdown, even. :rolleyes:

[mm43]

Here is a quote from a declassified U.S. Army Missile Command, Redstone Arsenal, AL, document by Dorathy Stewart dated 27 June 1990 and entitled -

"Occurrence and Detection of Supercooled Water in the Atmosphere" (http://www.dtic.mil/dtic/tr/fulltext/u2/a225715.pdf)

- with reference to - "Supercooled Water; Aircraft Icing; Clouds; Climatology".
The atmosphere typically contains particles which act as freezing nuclei between -15°C and -20°C. In one study (Jursa, 1985), 90 percent of clouds with supercooled water were warmer than -20°C. A few studies Indicate that water in the atmosphere may occasionally contain impurities which have the opposite effect and permit it to supercool well below -40°C. Seagraves (1981) reported supercooling to -46°C In the atmosphere,
and Curran and Wu (1982) found -47°C. Laboratory experiments by Hoffer (1961) demonstrated that droplets saturated with soluble salts commonly found in the atmosphere froze at much lower temperatures than the freezing point of pure water drops.and another;It must be reiterated that a low temperature does not guarantee the absence of supercooled drops. According to Sassen, Starr, and Uttal (1989), airframe icing at temperatures from -42°C to -51°C has been reported. Impurities in drops can permit excessive supercooling. It is also possible for icing to occur in updrafts of air with droplets which have not yet reached a temperature in equilibrium with the air temperature at the new level.The last sentence of each quote is important, as we are dealing with events that had their beginnings in relatively clean air above an expansive maritime environment.

So it would appear that the military had at their disposal some definitive data on this form of icing over 20 years ago.

[HazelNuts39]

As BEA puts it on page 30 of Interim Report No.1:
the presence of super cooled water at FL350 is not very probable and would necessarily have been limited to small quantities.IMHO the heating of the pitots is designed and has been demonstrated to function in any quantity of supercooled liquid water likely to be encountered. The icing detectors would have detected the presence of significant quantities of liquid water.

Clandestino,

For distribution of liquid water and ice particles in convective clouds, read IR#3 page 50.

[HazelNuts39]

No way 10 degrees ND was enough to go anywhere, be it at 5000, 20000, or 35000 feet on the way down when the AoA was already above 30 degrees. Well, I thought so too, but changed my mind after looking at Owain Glyndwr's data. With Owain's help I did a similar analysis and got similar results shown in the graphs below. The second graph shows how AoA slowly reduces until the airplane is unstalled.
http://i.imgur.com/1cftr.gif?1
http://i.imgur.com/Z2Saq.gif?1

[mm43]

Originally posted by HN39 ...
... the presence of super cooled water at FL350 is not very probable and would necessarily have been limited to small quantities.The BEA's comments are accepted as such, but at the time of making them they hadn't completely ruled out that possibility. I have pointed out that the known science doesn't rule it out either.

In respect of Owain Glyndwr's stall recovery scenario, your follow-up is appreciated. It follows what I had in mind when creating graphics showing the relationship of elevator and THS angles to the relative airflow - some time back. As the pitch is reduced, the applied thrust leads to increasing IAS which rapidly reduces the the AoA and the wing attains the lift to allow the recovery. At the time I had envisaged no more than 10° ND would be required to get the wing flying again, and that appears to have been borne out.

[RetiredF4]

Would somebody explain, on what facts the following happens in the first 12 seconds of the above graph:

Pitch is reduced from +15° to -10° = 25° change
FPA increases from -22 to -34 = 12° change
AOA decreases from +35 to +22 = 13° change

Speed in this timeframe is not specified, but is esentially important for generating lift. Drag in this AOA regime has an influence as well, where can it be found in the graph?

On what ground would the AOA change (13°) be grater than the FPA change (12°) by changing pitch (25°)?
Wasn´t the initial AOA according BEA higher than 40°?


Out of my own expierience with such a high initial AOA and such low speed the pitchdown initially increases the FPA by the same amount, the pitch is decreased,, giving only a minimal change in AOA and an increase in FPA and descent rate.

The expierience in the A330 sim from PJ2 and another Airbus pilot make me believe, that this magic graphs miss some vital points. Also all accepted procedures for combat jets as well as the new updated stall recovery procedures speak of the need to place the stick forward until the stall warning stops, which would not be the case until 45 seconds into the recovery like shown in the graphs.

[HazelNuts39]

RetiredF4,

To begin with your last point: If the nose-down pitch rate is maintained until the stall warning stops, that would occur at t=21 seconds and 27 degrees ND pitch. Level flight would be achieved at t=42.5 seconds, FL262, 324 kCAS. I suspect that Owain Glyndwr did not show that scenario in his graph because he found it difficult to imagine that an ATP would deliberately do that in an airliner.

Owain explained the 'Performance Model' in his post #87:
OTOH, with HN39's help (but any errors are mine!) I have been able to construct a means of calculating performance at and beyond the stall, and this in turn allows a systematic study of recovery possibilities - something that AFAIK has not been presented here before, so perhaps it qualifies as "new data"?

On the diagram, the yellow line is the actual AF447 flight path derived from BEA traces of inertial ground speed and barometric altitude, corrected for wind effects wherever possible.

The purple line is a theoretical calculation of that flight path using the developed method with actual flight pitch and power (N1) as input data. Given the fact that the aircraft was gyrating with six degrees of freedom and the model is restricted to three, I think it a reasonable match which gives some credence to any recovery calculations. Others may differ.The 'Performance Model' consists of lift, drag and thrust data as functions of relevant parameters, and the trajectory then follows from Flight Mechanics, i.e. Newton's laws. It is driven by the specified variation of pitch attitude versus time. As opinions differ regarding the the achievable rate of pitch change, Owain's graph shows trajectories for pitch rates of 1, 2 and 3 degrees/second. These rates bracket the values observed by PJ2 in the simulator, and the responses of the airplane to elevator movement observed in the DFDR traces of AF447.

"Wasn´t the initial AOA according BEA higher than 40°?" The recorded AoA at 02:11:45 was just about 40°. In my graph I chose to stay with the recorded pitch attitude and calculated flight path angle, which result in AoA=36° for symmetrical flight in still air. The difference between that value and BEA's is attributable to the bank angle of 30° existing at that moment.

[RetiredF4]

The 'Performance Model' consists of lift, drag and thrust data as functions of relevant parameters.....


and there are drag-data available for those flown AOA´s, despite the fact, that this area was neither tested nor evaluated?

[HazelNuts39]

RetiredF4;

The pre- and post-stall aero data have been obtained from analysis of the DFDR data. Within the normal flight envelope these match authentic Airbus data. Outside that envelope the verification consisted of running the model through the recorded time histories of pitch and N1, and comparing the resulting 'model' trajectory (the violet line in Owain's graph) to the actual DFDR trajectory (the yellow/red line).

[Machinbird]

Well, I thought so too, but changed my mind after looking at Owain Glyndwr's data. With Owain's help I did a similar analysis and got similar results shown in the graphs below. The second graph shows how AoA slowly reduces until the airplane is unstalled.I'm glad we are bringing up this subject again. Pointing the nose below the horizon adds effective thrust along the aircraft axis in the amount of sine(negative pitch angle) x weight of the aircraft. In effect you are powering out of the stall with sufficient power to let the aircraft accelerate despite the high induced drag.

This probably isn't the most efficient way to get an airliner out of a stall, but for one that does not have an AOA indicator, it has a lot to recommend it in that the likelihood of secondary stall is drastically reduced. You just have to get the nose low enough initially so that you can actually accelerate. Surprisingly, angles of as little as 10-15 degrees nose low seem to be sufficient for the A330 to accelerate, despite having a very high initial AOA.

In the military aircraft I've flown, we were always concerned with departures from controlled flight (spins), thus the importance of unloading the wing promptly before you began to generate unintended rates of yaw/roll.

With an aircraft that is (relatively) stable in the stall, you just have to avoid doing something stupid with the controls.

I hope someone (like NASA) does further study on this method of stall recovery.

[HazelNuts39]

OK465,
Sorry, I forgot to label the secondary axis. Yes, it is Nzw, the acceleration normal to the flight path in 'g'.

[OK465]

Thanks. (deleted the post with the question, thinking some more about it.)

Why doesn't Nzw go to 1 at zero FPA?

[roulishollandais]

Due to not enough test flights, knowledge of A330-200 limits and rate limitations of flight envelope is not sufficient.

Loss of speeds gets a critical situation to the aircraft's system design, reconing and protections. So the system reversed to Alternate 2B Law.

At this time we find a total lack for man-machine interface in terms of effective aircraft observability.

In that moment the restitution of human's classic hand and high altitude skills is not possible due to bad selected, bad teached, undertrained concierge-pilots. Don't forget their questions have been throwes off since 1/4 century by airlines, national and former european civil aviation autority.

That situation means that UAS is first an unsolved SYSTEM problem (despite inertial system exists on the aircraft which may not be clogged by ice ?) which will get a human UAS unsolvable problem,

Recording more and more parameters in the black boxes would be useless at preventing next SUCH accident.

Engineers and pilots have first to coordinate on the ground to elaborate transfer from process to SOPs.

We do not know the total conversation (due to BEA decision) and why1, why2, why3, why4, why5, and how the crew pulled to stall.

But, as they are not teached to, AF pilots could not invent "unloading the wing" technic, nor imagine computed but not displayed AoA, to replace the airframe shape in the airflow to recover.

1. None of the three simulations reported in the thread, and very well compilated by TurbineD, can get accreditation from test pilots, as simulators have not enough information. So no available SOPs can be written on these simulator experiences basis.

2. Owain G. takes only the half of the problem as stall is not a speed problem but an AoA problem :i.e. a free faller diving at 300 km/h falls without lift, only drag, but may deplace himself forwards with felt , strong lift, 40° pitch ND, falling 200 km/h changing only a little his arms positions and Cg position.

The deepstall is another case were you have speed and not enough lift.

3. On the other side, the "unloading the wing" technic, that Machinbird pulled like a magician from his large fight piloting science, is used in 0g certified Airbus flights to train astronauts. An that technic combined with official performance calculations reported by Hazelnuts39 show that THAT TECHNIC , and only that technic, could have been used with AoA and training, to overcome the stall with relieble new SOP.

In conclusion, developing these two points, further AF447 may be avoided. ;)

[Owain Glyndwr]

Would somebody explain, on what facts the following happens in the first 12 seconds of the above graph:

Pitch is reduced from +15° to -10° = 25° change
FPA increases from -22 to -34 = 12° change
AOA decreases from +35 to +22 = 13° change

Speed in this timeframe is not specified, but is esentially important for generating lift. Drag in this AOA regime has an influence as well, where can it be found in the graph?

On what ground would the AOA change (13°) be grater than the FPA change (12°) by changing pitch (25°)?
Wasn´t the initial AOA according BEA higher than 40°?


Out of my own expierience with such a high initial AOA and such low speed the pitchdown initially increases the FPA by the same amount, the pitch is decreased,, giving only a minimal change in AOA and an increase in FPA and descent rate.

The expierience in the A330 sim from PJ2 and another Airbus pilot make me believe, that this magic graphs miss some vital points. Also all accepted procedures for combat jets as well as the new updated stall recovery procedures speak of the need to place the stick forward until the stall warning stops, which would not be the case until 45 seconds into the recovery like shown in the graphs.Franzl,

Good questions that deserve a reasoned reply. Sorry to have got out of sequence, but domestic duties got in the way.

I assume we are not doubting that stuffing the nose down will eventually give increased EAS and reduced AoA, the debate being the mechanism by which one achieves that end state.

I rationalised it this way:

Suppose we start with pitch +15, Gamma -25, AoA +40 and instantaneously pitch down through 25 deg to -10. (this is a thought experiment so we can do that)

AoA remains at +40 for the moment as you suggest, but that means gamma goes to -50. EAS hasn't changed, neither have CL and Cd at constant AoA so drag and lift are unchanged. However we now have a large additional gravity component so the aircraft will accelerate in absolute terms, i.e.TAS will increase, again as suggested in a later post. But in addition the aircraft is now descending more rapidly into denser air so there is a double effect on EAS, and the thrust is also increasing due to altitude effects which also helps a bit although this is not anything like as important as the gravity effect since the maximum thrust one might get at say FL350 is only about 7%W whereas a 25 deg FPA shift is worth 42%W.

If EAS increases at constant AoA the aircraft will develop an upwards acceleration normal to the flight path and thence an upward velocity component which, with the increased airspeed will result in a reduction in FPA. You can see this in HN39's traces. [It will also of course experience an increase in drag which partially offsets the benefits, but I think this only partially offsets them]

A reduction in FPA, WITH PITCH HELD CONSTANT, will give a reduction in AoA.

Cd is very sensitive to AoA above the stall, so the drag reduces more than the effect of increased EAS and the whole response is "speed unstable" as it were, with an increasing acceleration and reduction in AoA as time goes on until the AoA is reduced to below S/W limits.

That is, I think, the basic recovery mechanism, but in the early seconds the exact response depends on a changing balance between the various effects, and these in turn depend on the exact time history of applied pitch, so it is really quite difficult to answer your questions about the first twelve seconds.

Drag (and lift) in this case were calculated by analysis of the traces extracted from the BEA cartoons, the only assumption needed being how thrust varies with altitude and RPM and there are well established scaling rules for that. The justification for staying with these values is that the actual trajectory can be calculated by inputting just pitch and power, the output being speed and altitude. Hence the purple line on my original graph.


I don't think there is any conflict with your point about holding forward stick until the S/W stops, the only qualification is that I assumed the pilot flew constant pitch.


I don't think PJ2 will be upset if I say that in my conversations with him he confirmed that on at least one occasion he executed a recovery from 30 deg AoA using 10 deg ND pitch - it took about 15000 ft.

[Lyman]

@Owain Glyndwr
"That is, I think, the basic recovery mechanism, but in the early seconds the exact response depends on a changing balance between the various effects, and these in turn depend on the exact time history of applied pitch, so it is really quite difficult to answer your questions about the first twelve seconds."

In the early seconds of each partial recovery, wasn't the crew presented with a "re-invigorated" STALLWARN?

Having sussed all the napkin calcs presented here, would the PF go immediately to ND? Or would he secure TOGA thrust, and "maintain altitude" with aft stick?

The DFDR tells us little of theoretical benefit to our crew from possibilities that were never entertained at any level of practicality.

Call me a wise ass, but I venture to say the crew was so absorbed in trying to "PREVENT" a STALL, that they spent no time trying to recover from one. Again, the focus is shifted from the problems that caused the crash to hypotheticals re: after the fact suppositions? IMHO.

[Owain Glyndwr]

In the early seconds of each partial recovery, wasn't the crew presented with a "re-invigorated" STALLWARN?

Having sussed all the napkin calcs presented here, would the PF go immediately to ND? Or would he secure TOGA thrust, and "maintain altitude" with aft stick?

The DFDR tells us little of theoretical benefit to our crew from possibilities that were never entertained at any level of practicality.

If you have read my previous posts you will be aware that I avoid any comment on what pilots might or might not have done - I leave that to more qualified observers.

The DFDR is not intended for the use you imply, but you cannot say that 10 deg ND is a theoretical possibility outside the levl of practicality since they actually went there just after 02:12:45

[Lyman]

With great respect I am saying that 10 degrees NOSEDOWN was not done for reasons discussed at length, specifically, a proposed fear of Overspeed, and the fact they didn't suss STALL.

I think you misunderstand my DFDR remarks.

At 2:12:45, at 10 degrees NOSE DOWN, were they there due command, or airframe trying on its own to recover from STALL?

[Owain Glyndwr]

IIRC, as looking at the traces will tell you, at 02:12:45 they were at 10 deg nose down with full up elevator and flight idle power. The aircraft, as I have said before, has no natural nosedown pitch at the stall. It responds to applied elevator and thrust. In this case it seems that reducing thrust to idle or thereabouts produced enough pitch to get to -10 deg.

[Lyman]

No natural tendency to lower its nose in Stall? Are you sure? I thought that was one of the cues for a Stall suss. Is there something I am missing re: CG?

[RetiredF4]

Thank you for your kind and detailed answer. I have nothing to add to the main part of your explanation, it is along my thinking.

That is, I think, the basic recovery mechanism, but in the early seconds the exact response depends on a changing balance between the various effects, and these in turn depend on the exact time history of applied pitch, so it is really quite difficult to answer your questions about the first twelve seconds.

Imho it is even more difficult, when we consider that the aircraft was not that stable at all. Well, it did not depart into some kind of spin, but looking at the traces we had rolling, banking and pitching movements of the aircraft, and those might have been present due to pilot action or despite pilot reaction on aircraft behaviour. Those aircraft movements and associated flight control deflections cause aditional drag and prolong any kind of recovery.

The assumption of instantaneous pitch down by 25° assumes, that enough authority is available even with thrust at TOGA, or when thrust would be in idle we would have to consider the later application of thrust, its effect on pitching moment and the spool up time, which again would influence the acceleration. We assume, a pilot in this situation can decrease the pitch in a most expedite way by 25° and maintain exactly -10° pitch over a time period of more then 30 seconds, while still stalled despite the fact, that his aircraft is in a degraded mode of operation (not to talk about the stress of the crew itself). Those 30 seconds with an unwinding altimeter would be like ages.

I don't think PJ2 will be upset if I say that in my conversations with him he confirmed that on at least one occasion he executed a recovery from 30 deg AoA using 10 deg ND pitch - it took about 15000 ft.

I buy that value, it is a fifty percent increase against the posted values in the graph. If we further consider, that the average descent rate at that time was around 15.000´/min (at 02:11:45 at 35372 feet, 22 seconds later at 02:12:07 at 29736 feet, and that those values where present without stuffing the nose down (which would increase initally the descentrate), we can assume an aditional altitude loss of at least 5.000 feet for time delays due to this unplanned stall situation any crew would be confronted with even after this discussion here.

In a practical sense we would end up somewhere between 20.000 and 10.000 feet when starting the recovery close to FL 350 and we might crash with the same procedure when stalling at FL 250.

My harsh assesment (no offence intended) would be, it might look good on a piece of paper in a warm office, but i doubt the practical use of it.

Reduce the AOA until stall warning stops, and the sooner it stops, the better it will be.

I´m not saying that those calculations are wrong in any way, but i dont think they will lead to a practical recovery technique.

[gums]

Glad to see we're back to recovery possibilities and maybe even probabilities.

Liked 'bird's and Retired's responses, a lot.

Unlike that little jet I flew long ago, the Airbus does not appear to have that "bucket" in the pitch moment characteristics. In other words, no "deep stall" and some semblance of pitch control by the humans besides those inputs otto is cranking in. Otherwise, why would the pilot even need to hold back stick? And it also appears that a few nose down( or even a few less nose up) inputs resulted in actual pitch changes, no?

The flaky AoA indications available and the system's disregard of AoA for a short time didn't help, but seems the speed indications came back fairly soon.

So I throw my hat in with 'bird and Retired and others postulating that a moderate nose down command and increase in thrust made recovery possible, and not requiring 20,000 friggin' feet. In other words, it was possible to fly out of the stall.

But ya gotta realize you are stalled! And seems some warnings were being blared on and off for the whole time. Apparently, the clue light never came on.

With the crappy AoA indications, all ya got is altitude and IAS/EAS/CAS ( pick one) to show you are making progress. No big deal, as once nose down 5 or even 10 degrees, the speed indications now available would show a slow but steady increase. And as O.G. points out, drag decreases immensely when lowering AoA from extreme values. I would imagine seeing a few knots increase every few seconds.

If I don't see some drastic changes in training and warnings to the crews about stalls and stall recoveries, I shall be greatly disappointed.

[HazelNuts39]

Why doesn't Nzw go to 1 at zero FPA?
(earlier reply withdrawn).

That was caused by an error in the mathematical model. Thanks for pointing out the error. The erroneous graphs have been replaced by corrected versions.

[Linktrained]

Would the performance graphs have looked different if they had been made following the suggestions in AB's" Safety First" -Page 10 issue Jan 2011 ?

These include :

"Autopilot and autothrottle...Off
Nose down pitch control...Apply until out of stall...
Nose down pitch trim...As needed ...( ...this will also address autopilot induced full back trim.)
Thrust.... As needed.....for engines installed below the wing applying maximum thrust can create a strong nose up pitching moment if the speed is low......
Speed Brake...Retract
Bank... Wings level Apply gentle action for recovery to avoid secondary stalls, then return to desired flight path."

The main differences appear to be Thrust and some contributors seem to think that 10 -15 degrees ND might be more appropriate or enough.

[Owain Glyndwr]

Lyman

No natural tendency to lower its nose in Stall? Are you sure? I thought that was one of the cues for a Stall suss. Is there something I am missing re: CG?
Yes, you are missing something. I gave a description of stall on modern airliners is Post #294 of Thread 5.
Franzl

Imho it is even more difficult, when we consider that the aircraft was not that stable at all. Well, it did not depart into some kind of spin, but looking at the traces we had rolling, banking and pitching movements of the aircraft, and those might have been present due to pilot action or despite pilot reaction on aircraft behaviour. Those aircraft movements and associated flight control deflections cause aditional drag and prolong any kind of recovery.

Yeah I agree the lateral behaviour complicates matters. A lot of that motion might be the natural response of the airframe when taken to those levels of AoA, not helped by the fact that the wing mounted roll controls would have been virtually ineffective and that the fin/rudder effectiveness was also compromised by their high effective sweep at high AoA. Not sure about drag, although there was a lot of scatter in the results which could have been disguised roll/sideslip effects, but also there might have been induced AoA effects.

The assumption of instantaneous pitch down by 25° assumes, that enough authority is available even with thrust at TOGA, or when thrust would be in idle we would have to consider the later application of thrust, its effect on pitching moment and the spool up time, which again would influence the acceleration. We assume, a pilot in this situation can decrease the pitch in a most expedite way by 25° and maintain exactly -10° pitch over a time period of more then 30 seconds, while still stalled despite the fact, that his aircraft is in a degraded mode of operation (not to talk about the stress of the crew itself). Those 30 seconds with an unwinding altimeter would be like ages.
Hey, I wasn’t assuming the aircraft could be pitched down instantaneously! That was a gross simplification to get the explanation across more easily. Neither would I assume that a pilot would in practice be able to maintain an exact nose down pitch. The sums, such as they were, were intended to give some idea of what MIGHT have been possible if mental blocks hadn’t got in the way not as actual recoveries.
I buy that value, it is a fifty percent increase against the posted values in the graph. If we further consider, that the average descent rate at that time was around 15.000´/min (at 02:11:45 at 35372 feet, 22 seconds later at 02:12:07 at 29736 feet, and that those values where present without stuffing the nose down (which would increase initally the descentrate), we can assume an aditional altitude loss of at least 5.000 feet for time delays due to this unplanned stall situation any crew would be confronted with even after this discussion here.


The starting conditions included the rate of descent, so that bit shouldn’t apply. My typical calculation for recovery from FL350 took about 12000 ft, and I was fairly happy to say that looked reasonable against 15000 ft especially when one considers that the simulator modelling was probably even less representative than mine.
Let me put it clearly – my sums are intended to illustrate the sort of recovery that MIGHT have been possible. I am only too aware of their shortcomings. But even so I think they are a good indication that, as Gums says, the aircraft could have been flown out of it – if only!

My harsh assesment (no offence intended) would be, it might look good on a piece of paper in a warm office, but i doubt the practical use of it.


Well I leave that to others more skilled than I in practical piloting.

Reduce the AOA until stall warning stops, and the sooner it stops, the better it will be.:ok:

[DozyWannabe]

If the A330-200 is balanced similarly to the A320, the nose will pitch down upon stall as long as the CoG is not set too far aft (it was well within the limit as I recall). In the A320 sim I had to work quite hard on the sidestick to keep the nose at 15 degrees up both on approach to and during the stall.

Lyman, if they were trying to avoid stalling, they were going about it in a very unusual manner - in fact they were doing precisely the opposite of what they should have been doing. Coupled with the "crazy speed" remarks, I think the PF, at least, was fighting a non-existent overspeed.

[bubbers44]

"Well I leave that to others more skilled than I in practical piloting.

Reduce the AOA until stall warning stops, and the sooner it stops, the better it will be."

They decided to hold the side stick full back for some reason and continued to do so with impact with the Atlantic Ocean. Several minutes was not enough time for them to figure it out. Too bad the passengers didn't understand who would be commanding their aircraft that day. How can you justify that lack of skill?

[Organfreak]

Dozy sayeth:
If the A330-200 is balanced similarly to the A320, the nose will pitch down upon stall as long as the CoG is not set too far aft...

Well, whyinheck would they be similar? Two entirely different airframes, aren't they?

[DozyWannabe]

Well, whyinheck would they be similar? Two entirely different airframes, aren't they?

Designed to respond in as similar a manner as possible though. Remember type conversion between the two is supposed to be largely a matter of learning new numbers (and the odd difference in systems behaviour).

I'd have tested in an A330 sim, but there wasn't one available.

Also worth bearing in mind that according to the DFDR traces, the nose did come down below the horizon several times during the stall, even with the THS at 13 degrees nose up. None of the nose-down inputs were enough or held long enough to have commanded the pitch-down achieved, so I think it's reasonable to assume that the A330 is fairly benign in terms of stall characteristics.

[Lyman]

Dozy. Yes, she wanted to fly, and without lift and tail to keep her flying, she will fall, nose first, of course. Agreed. So it becomes ever more important to suss the "place" of the crew. HF.

[OK465]

The starting conditions included the rate of descent, so that bit shouldn’t apply. My typical calculation for recovery from FL350 took about 12000 ft, and I was fairly happy to say that looked reasonable against 15000 ft especially when one considers that the simulator modelling was probably even less representative than mine.

(Bold is mine)

That is certainly an intriguing statement. :)

[DozyWannabe]

Well, the sim I was in certainly got the gist of it, even if the numbers might not have been that exact. Specifically the loss of effective aileron control once established in the stall, necessitating use of rudder (albeit *very* gingerly) to level the wings. We know that the crew didn't try using rudder until very late in the sequence, and that some very aggressive aileron roll inputs were made, which might have mad a bad situation worse.

We all know that when that far outside of the flight envelope, the data is based on extrapolation from the numbers gleaned in flight testing rather than real numbers - but that doesn't mean the sim cannot be a useful learning tool.

I don't doubt that the PF and the rest of the crew were doing everything they could think of to rescue the situation - the question is why did their training not encompass the *correct* things to do?

[Lyman]

Dozy.
Their training no doubt did include recovery from STALL, if not the 330, other airworthy examples that would translate to 330. The training that lacked was high altitude manual handling, and a complete understanding of the UAS. The rough handling can be laid at the PF, but the lack of a proper syllabus to include a fully understood UAS was not given, if even available. I think with gentle handling the rest may not have happened. There is a very suspicious lack of training re: STALL recognition, but as said, it shouldn't have STALLED.

No?

[Clandestino]

Clandestino,

For distribution of liquid water and ice particles in convective clouds, read IR#3 page 50. Very good, and I am not saying it ironically, I really think it's good we are starting to discuss reports and not media hype.

So let's take this line of discussion a bit forward; page 50 of interim 3 deals with general distribution of water and ice particles in convective cloud, as introduction to principles of operation of Wx radar.

Interestingly, BEA findings on the conditions that were most likely encountered by AF447 crew is also on page 50 but of interim 2.

The crews reported not observing any significant radar echoes on the
chosen flight path(8) but to have identified active zones nearby or lower,
which is also noted in a study by Météo France on these events undertaken
at the request of the BEA;

(8)Some crews had deviated from the planned flight path for meteorological reasons before the events occurred.

I don't doubt that the PF and the rest of the crew were doing everything they could think of to rescue the situation - the question is why did their training not encompass the *correct* things to do? The crux of the matter is not "doing" but rather "recognizing" the correct thing to do. I have not an ounce of doubt that the crew believed they were doing their best to save themselves up to the very end. That their perception of the situation had 180° phase shift relative to reality is tragic and it must not be simply written off as "pilot error". To paraphrase sir Winston Churchill: "The cost of solving the AF447 mystery must be reckoned in neither money nor manpower."

[DozyWannabe]

That their perception of the situation had 180° phase shift relative to reality is tragic and it must not be simply written off as "pilot error".

I don't think it is being (and I don't think you do either). The BEA's output thus far seems to be much more nuanced than that. Combine that with the sheer amount of time spent on this (by which I mean if it was considered a simple case of pilot error, the final report would have followed hot on the heels of interim #3), along with the collaboration between Airbus and Boeing regarding UAS and stall procedures - and I think we're looking at a landmark report here, once it finally arrives.

[Owain Glyndwr]

Dozy

I had to work quite hard on the sidestick to keep the nose at 15 degrees up both on approach to and during the stall.There is a big difference between an uncontrollable nose down pitch when the aircraft stalls in the classic manner and the need to hold back stick in ever increasing amounts as AoA is increased.

The former is a sort of instability the latter a natural characteristic of a stable airplane. The A330 and A320 are alike in this respect and if you go back to that pseudo-pitching moment curve I posted many moons ago (and which mm43 referred to more recently) you will find a continuous relationship between elevator (sidestick) position and AoA.

[Owain Glyndwr]

bubbers44

How can you justify that lack of skill?

I'm not trying to - as I said I leave that to others who know more about it. Doesn't stop me having an opinion though!

[Owain Glyndwr]

OK465

That is certainly an intriguing statement. http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/smile.gifNot meant to imply anything more than that the simulator aerodynamic model would have been validated up to the stall but not beyond and that (for us) the simulator modelling beyond that is unknown so we cannot assess how realistic the response might be.
In that respect, and in that respect only, my simplified model might be equally representative to the simulator in that there was at least an attempt to use realistic post stall aerodynamics.

[Owain Glyndwr]

Dozy,

If he was fighting an overspeed, why would he select TOGA?

[jcjeant]

If he was fighting an overspeed, why would he select TOGA? Coupled with the "crazy speed" remarksHow speed ?
Aircraft operating in an environment has three dimensions
Vertical speed ?
Horizontal speed ?
Lateral speed ?
The combination of the three ?
I've said in other posts
The extracts of the BEA CVR show a dialogue crazy .. or as coming from people who are not in a same place
"You are going up
I'm going up?
I then descends"
And this continues throughout the recording
So when we study the CVR .. it does not really help understand what has happened ... instead it gets complicated

[HazelNuts39]

Since there seems to be consensus that the pitch-down should continue until the stall warning stops, here it is:

N.B. The pitch-up rate has been reduced to 1.5 deg/s to respect stall warning.

http://i.imgur.com/Jvchu.gif?1
http://i.imgur.com/Qfp1h.gif?1

[DozyWannabe]

If he was fighting an overspeed, why would he select TOGA?

The "crazy speed" comment comes well after selecting TOGA if I recall correctly. There seems to be a significant deterioration in joined-up thinking from the crew - and the PF in particular - after taking manual control.

This is why I am and always have been focused on where the training went wrong (and incidentally, why I get very antsy when others claim I'm arguing for a conclusion that begins and ends with pilot error). The consensus seems to be that the correct course of action would have been to cover the controls, but not actually do anything with them (or indeed leave them alone completely) until the aircraft's response to the conditions had been monitored for at least half a minute. It's all very well saying that from the comfort of our keyboards, but on a psychological level it's another thing entirely to have an aircraft suffer a failure in marginal conditions and retain the willpower to not intervene - especially for less-experienced flight crew.

Holding back and seeing how the aircraft copes is a universal thing, by which I mean it's true regardless of whether one is flying a FBW jet with bells and whistles, or something more traditional - because in both cases the aircraft has been trimmed to remain more-or-less stable. The exception to this rule is of course when a flight surface problem has occurred - but such events are rare enough to be a fair way down the mental list of potential failures.

[rudderrudderrat]

Hi DozyWannabe,

From Page 88.
"The A/P2 disconnects. The roll angle changes from 0 to 8.4° in 2 seconds whereas the sidestick is at neutral. The pitch attitude is 0°."

I'm sure they would have loved to have waited 30 secs before touching the controls, but with that roll rate, they could have been beyond 30 degs bank within 7 secs. Most pilots would do something before it went beyond 20 degs.

[DozyWannabe]

Hi rudderrudderrat :),

This is why I said "cover the controls". The aircraft was in moderate turbulence, enough to give it a nasty bump, but probably not enough to turn it over. My suspicion is that the bump that hit at roughly the same time as A/P disconnect is the cause of that roll. It's a nasty rate, for sure - but if you're in turbulence, it's rare for it it last long enough to turn it over, or even much past 10-15 degrees of bank.

Now here's where I need your input. Airliners are designed to be stable. In layman's terms they "want" to fly straight and level. In roll direct, I suspect that 8.4 degree bank angle would remain when exiting the turbulent air pocket - am I right in thinking that unless something has happened to the flight surfaces that angle will hold until corrected?

In any case, the deviation from straight-and-level on exiting the bump was a moderate roll with a minor nose-down pitch component. Of course the roll will need decisive correction - but I think (and please correct me if I'm wrong) that "decisive" can still be smooth and gentle in execution. The pitch component was barely half a point nose-down and should have corrected itself via trim.

The question is why the sudden aggressive pitch-up command when it wasn't necessary?

[ In case it wasn't clear, 30 seconds was a theoretical average - of course that'll be different depending on the circumstances, but I think most agree that the sidestick commands were well in excess of what was required, and to me hint at the classic signs of a startle response. ]

[Lyman]

It was not .5 degree ND. More like 3.5. You assume too much re: bank. The pilot's reactions were necessary. BEA, in #3: "The Pitch reached 10 degrees NU and the a/c began to climb." Have you reviewed how long it took to get to 10 degrees NU? Without horizon, a ten degree input (from outset) is only six degrees NU from cruise.

Whatever the lay analysis; here, at a/p loss, was the beginning of upset, can we agree? In that beginning, a change in LAW and PILOT both became too much to smooth over. I venture that upset began whilst a/p was still latched, for the attitude in PITCH and ROLL needed correction, having begun in auto.

What began as respect for the conditions at hand for 447 has morphed into a mere and casual dismissal of the challenge. c'est la vie..... If only to read a respectful approach to the pilots, I long for the final report.

[gums]

Looked up the "laws" and reversion sequence again, and seems the system continues to use "normal gee" as the pitch command, and roll rate, but not roll angle "protection". That right?

So why have to hold back stick? Further, the 'bus has a pitch attitude correction for the Nz the plane tries to maintain with stick neutral. Otherwise, at just a few hundredths of a gee less than 1 gee the thing would continue to go nose up in order to maintain 1 gee. We saw this in our little jet once pitch was above 10 or so degrees, and it was quite noticeable above 30 deg of pitch. What, 0.87 gee for constant pitch angle?

I understand some folks pointing out a rapid roll change just after UAS could be disturbing, but seems about right for a bit of turbulence.

I can also understand a very slight nose up command if worried about overspeed, but only for a few seconds and then back to whatever pitch was before the UAS.

The CVR comment about crazy speed might be explained, as vertical velocity was extreme but indicated speed was what, 107 or 135 knots? So PF wondering about why such a slow speed if descending so fast. Maybe started to question the altitude readings, too, for first 30 or 40 seconds.

As another contributor has opined, this will be a "landmark" report and I think the recommendations as well.

[rudderrudderrat]

Hi DozyWannabe & salute Gums,

On page 112 Lateral parameters, Estimated side slip shows a distinct asymmetry after the AP disengaged. If I'm reading the trace correctly, it shows a Left Hand side slip DA. Since it was in ALT LAW, the the pilot will have to constantly apply aileron in one particular direction (LH in this case), until the side slip was trimmed to neutral.

I don't think the roll was turbulence induced because the effect lasted too long and would be random L/R. I think the aircraft was out of lateral trim (due some fuel imbalance, or asymmetric thrust, or rudder trim applied by the AP just before disconnect.)

All Boeing pilots are familiar with this problem, because we frequently re-trimmed the rudder during the cruise to keep the ailerons neutral. I've never had to do this on the Airbus, because the AP does it automatically for me.

If the FOs had never flown a Boeing, they would possibly not know about the requirement to re-trim the rudder to facilitate manual flying in ALT Law.

[DozyWannabe]

Lyman, I'm referring to the position on the artificial horizon from 0, not the cruise pitch angle. We've gone through this a dozen times or more, but the autopilot did not induce the climb. There was a nose-up trend before the PF took manual control, but it was gradual, minimal and entirely consistent either with the autopilot regaining cruise pitch, or the aircraft attempting to regain cruise pitch via the trim setting.

The abnormal pitch angles that followed were entirely a result of manual sidestick inputs made by the PF.

Gums, our Francophone colleagues have asserted that "crazy" in this sense refers to high speed, not low speed. The PF talks about a sense or feeling of "crazy speed", and he does not refer to the instruments.

Rudderrudderrat - interesting. However I think turbulence had to have been involved even if the rudder trim was slightly off, because there was a pitch component to it. I know that yaw inputs tend to bring the nose down, but not 3.5 degrees off where it was supposed to be, surely? The estimated side slip trace looks to be in excess of what could be expected if the rudder was out of trim in calm air, no?

[roulishollandais]

In other words, no "deep stall"
nor a free-faller ! Kiss
But ya gotta realize you are stalled!
The CVR comment about crazy speed might be explained, as vertical velocity was extreme but indicated speed was what, 107 or 135 knots? So PF wondering about why such a slow speed if descending so fast. Maybe started to question the altitude readings, too, for first 30 or 40 seconds.

At 02:11:50 Vz=15000 Ft/mn = 148 KTS ; CAS=50 KTS

conclusion is easy :
SPEED VECTOR INTENSITY = (148² + 50²)^.5 = 156 KTS ;)

HOW MUCH IS THE STALL SPEED ?!?!

STALL is a problem of AoA, and never a problem of SPEED !

Giraud did fly to speed near of zero in the airflow without to stall...:ok:

Sorry ! That is "unloading the wing", balistic flight, that all combat pilots know. :rolleyes:

[rudderrudderrat]

Hi DozyWannabe,

On reflection, I think the side slip trace has some error - I can't see why it would peak at -10 so regularly. So ignoring that:

If you look at Aileron Displacement, before AP disconnect the pattern is symmetrical and seems to include all 4 ailerons.

After AP disconnect, the trace only shows the inner ailerons were active. The deflections show far more LH Inner Aileron around> -10 ( = Left inner UP). It indicates that the aircraft had a continuous desire to roll right, counteracted by a more frequent roll Left command.

The tendency to roll could have been solved with rudder trim.

[gums]

Thank you Roul and Rat.

I was not looking carefully at the yaw trace on the recorder.

@ Roul

The technique of "unloading" is maybe foreign to many of the "heavy" pilots. No problem. And my reading of the existing procedures of many airline jets at the time emphasized minimum loss of altitude. Funny, but if you get those wings producing lift quickly, you'll lose less altitude. Worry about the gee limits later when recovering from the lower pitch attitude.

That being said, pilots must realize that you are either approaching a stall or actually in one. Looks to this old dinosaur that the 'bus has excellent yaw stability ( or great dampers) and decent roll characteristics even when the wing is completely stalled. So it comes down to the continued nose up command on AF447. Didn't see drastic roll angles or yaw excursions on the traces. You can pull all you want, but all you'll get is the gee commanded position of the elevators and the THS following to help trim.

What's funny to me was that the primitive FBW system I flew actually moved the stabilizers for nose down when we got to our AoA limit, regardless of our gee command. Gee, imagine using AoA sensors regardless of CAS once weight-on-wheels flipped once airborne.

@Doze

Maybe the overspeed control was what the dude was thinking due to the unusual noise from a fully stalled wing. Dunno.

[DozyWannabe]

@rudderrudderrat

Looking at it again, you're right - the estimated sideslip trace shows evidence of partial data recovery, which is not in itself surprising.

The aileron traces are as you say - but prior to autopilot disconnection they are spiky, indicating regular correction. There's no consistency until after autopilot disconnect, when aileron input, which is manual, trends to the left. This does not necessarily prove a right roll condition, however it does show that the PF *believed* he was correcting a tendency to roll right. But because there is no point at which manual input is not being made post-disconnect, it is impossible to say whether that tendency was consistent, or whether it was transitory.

I'm going to need some input from the better-versed here. I know that upon autopilot disconnect, pitch trim remains in auto in Alternate Law. I know that rudder function reverts to a hard-limited yaw-damper mode in Alternate Law. What I need to know is what happens with rudder trim upon autopilot disconnect in Alternate Law - does it hold the last setting prior to disconnect, or does it return to neutral?

[rudderrudderrat]

Hi DozyWannabe,
...what happens with rudder trim upon autopilot disconnect in Alternate Law - does it hold the last setting prior to disconnect, or does it return to neutral?
It holds the last setting.

[DozyWannabe]

OK - next question. Is that behaviour covered in type conversion training? Is there a "CHECK RUDDER TRIM" in the autopilot disconnect procedure?

NB. While this is an interesting line of inquiry, it doesn't explain the magnitude of the roll inputs made by the PF to my mind, or their apparent aggressive reversals. The mantra for manual control on the FBW Airbus is more-or-less "observe and correct and observe and correct". The DFDR traces show a lot of attempted correction, but no significant period of observation.

[Machinbird]

Dozy, just personal opinion, but she must have been out of trim in yaw.

It kept wanting to turn right and did a 270 turn to the right in increments on its way down. A swept wing bird at high AOA is very sensitive to rudder input. Very insensitive or even contrary to aileron input.

Why out of trim in yaw? Probably a rigging issue. How often does someone actually check this on a flight-probably never, or almost never.

[DozyWannabe]

@Machinbird - If you substitute "must" with "may", I'd be happier about getting on board (if only to not rule anything out). If the rudder was out of trim, then you'd see consistent corrections in the traces prior to A/P disconnect - there aren't any as far as I can see.

The consistency, magnitude and frequency of manual inputs post-disconnect occlude any reasonable conclusion as to what the aircraft would have done if left to it's own devices. If the PF was correcting a constant roll to the right, why the sudden reversals of bank input to the sidestick? Surely a gradual and consistent left bank input would have been enough prior to stall - after which, as you say, ailerons become ineffective.

[Machinbird]

If the rudder was out of trim, then you'd see consistent corrections in the traces prior to A/P disconnect - there aren't any as far as I can see. If the yaw damper function requires an airspeed input to properly set the gain, it may have ceased functioning. This would likely put the BYDU on the line (but I think I remember information that the BYDU was not activated). In any case, the yaw damping function is not identical between Normal law and Alternate law (Yaw Alt). I know that we have discussed this a number of times in some detail, but I no longer remember the details. Getting forgetful in my old age I guess.:O:}


If the PF was correcting a constant roll to the right, why the sudden reversals of bank input to the sidestick? Surely a gradual and consistent left bank input would have been enough prior to stall - after which, as you say, ailerons become ineffective. Dozy, remember the roll PIO theory? If he had come in gently on the controls, we probably would not be reading about this accident. Instead (probably through inexperience in this flight regime) he came in with ~ 2/3 of full left roll displacement and it took over half a minute before he got the wings settled down. In the meantime, the pitch went to unsustainable levels.

[Linktrained]

Since Giraud has been mentioned:
Something perhaps similar to Giraud's Mont Blanc technique, was taught and used at the French National Gliding Centre at Montaigne Noire, close to Revel, some miles to the east of Toulouse in 1950. This involved landing to the south, up a steep slope and with a tail wind. One aimed to stop near the top so that a short winch launch could be used so a further flight could be made, after turning the glider round and into the wind. Most flights were done taking off and landing along the ridge, to east or west.

[mm43]

@ Machinbird, DozyWannabe;

This Rudder / Yaw Damper problem has been raised in the past. I have been looking carefully at the DFDR traces post stall and find that the heading is changing at a fairly constant rate (clockwise) when the SS is held over to the left for a reasonable period of time. This lead me to looking at the Inner Aileron traces, and I believe that the RH Inner Aileron when down was effectively creating drag, whereas the LH Inner Aileron when up was in the wake vortex and ineffectual. This drag on the right was causing yaw, and the the Rudder/Yaw Damper didn't exactly help, though in the same vein, the Rudder Trim was offset 0.4 degrees to the left which may have helped create the right wing down bias.

[gums]

Well, MM43, how about "adverse yaw"? Could have been a player.

When Doze tried the sim he used rudder to correct roll, not aileron. Using aileron at extreme AoA will definitely cause the nose to move the opposite way you are used to at low AoA. Retired will tell you that in the Phantom, guys would lock the stick between their legs and use rudder for roll when at high AoA. The A-7 was not as bad, but we used the same technique.

Of course, using rudder trim could have helped, if not cured, the constant turn we see in the traces.

Let's face it. The crew was not prepared to fly the beast outside the envelope they were trained to do. Maybe a cosmic test pilot would have seem what was happening and done real fine, but the crew was not trained for that, nor probably had no experience in high performance jets that routinely flew at the limits or even exceeded them. So I'll cut them a small amount of slack in that regard.

[Clandestino]

Gentlemen, you are discussing the dynamics of aeroplane falling with low speed and extreme, never-before-achieved AoA for the type, using assumptions valid for normal, unstalled, flight. Your theories might be correct... by pure chance.

The crew was not prepared to fly the beast outside the envelope they were trained to doWhy should they be prepared to fly the beast outside the envelope? Key issue is how the aeroplane got out of the envelope in the first place.

Maybe a cosmic test pilot would have seem what was happening and done real fineMaybe there are not test pilots but rather ordinary line jocks out there who would keep on flying reasonable pitch+power when faced with unreliable airspeed. Does anyone know any other case of loss of all IAS on A330?

The consistency, magnitude and frequency of manual inputs post-disconnect occlude any reasonable conclusion as to what the aircraft would have done if left to it's own devices. Yup. If only we had some other case of A330 losing all airspeeds for comparison. If only...

[mm43]

As Gums has implied, the Vertical Stabilizer coupled with the Rudder is the only airfoil capable of behaving with any degree of reliability at such an extreme AoA when dropping like a stone with limited IAS.

So when outside the known envelope, some g-estimates are inevitable, and further study of the DFDR gives evidence that some of the roll component is being driven by the Yaw Damper, i.e. the YD is leading the roll by between 1 and 2 seconds.

Clandestino;

Yes, your post is noted, and the input of those with experience in military types may actually be of value in understanding the aerodynamics:eek: experienced by this unlucky A330. http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/wink2.gif

[HazelNuts39]

My suspicion is that the bump that hit at roughly the same time as A/P disconnect is the cause of that roll.
I don't think the roll was turbulence induced because the effect lasted too long and would be random L/R.
Turbulence is not always random and perhaps its effects should not be dismissed so easily. The 'bump' around 02:10 lasted about 10 seconds, as shown below.

P.S. The derivation of the formula for vertical gust velocity can be read here (https://docs.google.com/open?id=0B0CqniOzW0rjRTctcVUxU3Z2Mzg) .

http://i.imgur.com/zQ21c.gif?1

[philip2412]

i`m no pilot,nor an engineer or pc expert.and english is no my native language as you will easy notice.
and excuse if i am too much OT.
there is sometong i`ve been wondering about from the first time i have read the cvr as everybody has done it a few times:

PNF: you`re going up !

PF: i`m going up ?

how comes that he did not expect the a/c to go up when pulling the stick backwards ?
better said,what was he intending when pulling back
he seemed surprised and not expecting to go up

answers ?

P.s. my only "experience" is, i`ve read about all NSTB and britisch acc.inv.reports from 1950 -2011

[jcjeant]

Hi,

how comes that he did not expect the a/c to go up when pulling the stick backwards ?
There are several similar dialogues ... here is another just little time before the end CVR
2 h 14 min 05 4,024 The pitch attitude is 14°.

Captain :Watch out you’re
pitching up there

PF: I’m pitching up?

PNF: Well we need to we are
at four thousand feet As I already pointed out several times .. these are very strange dialogues
And they only add lanes and deadlocks in the maze leading to the discovery of what happened to those pilots that night

[DozyWannabe]

Yup. If only we had some other case of A330 losing all airspeeds for comparison. If only...

I was referring to the theory being put forward by Machinbird that this *particular* A330 was poorly-rigged. I don't see it myself, but on the other hand, don't want to appear dismissive of possibilities just because I don't happen to agree with them**.

[** - Unless they're *really* stupid and/or offensive... :E ]

[gums]

Thanks for nice words, mm43.

and the input of those with experience in military types may actually be of value in understanding the aerodynamics experienced by this unlucky A330.

Only reason I joined the discussion was my interest in any FBW system that had a crash or unusual flight condition.

Once the wreckage layout became available, my first impression was a fairly level impact at relatively slow speed. The Viper deep stall came instantly to mind. But I soon found out that the 'bus did not have the area of negative pitch moment coefficient that we had. Back to what happened. I then figured that the jet was very stable in yaw and roll at extreme AoA. So why hold the sucker there? Why not either let go or push forward a bit and see what happens? Never happened.

My point is that we folks here ( 'bird, Smilin', Retired and I) have seen the phenomena and are here to talk about it. And to contribute to an understanding of how many swept-wing jets behave at "abnormal" AoA, and some possible recovery techniques. Our second input has to do with recognition of the jet's actual flight condition.

The AF447 crew did not recognize their condition. Period. Whether they figured the system would prevent a stall or provide warnings (which it seemed to do), was prolly due to their training and experience at "normal" flight conditions.

I certainly do not advocate the same training that we had in our actual jet, but seems the carriers could get the crews up in a trainer such as NASA used for the Shuttle and let them see what it feels like ( jump on that comment Doze and Cland and...), and then what to do.

respectfully submitted

[roulishollandais]

@linktrained

Vous êtes un connaisseur !

Giraud did not officialy nor not officially teached low-g flying. But among his many many glaciers and mountain pilot-pupils, some copied his complex way of doing, without really understand wath he was doing. I only discovered that in 1999, and discussed with him about that : He looked around him if nobody could listen what he was saying, and told me about 3th "regime"...

Great great ART of Monsieur GIRAUD !:D:D:D

[DozyWannabe]

...but seems the carriers could get the crews up in a trainer such as NASA used for the Shuttle and let them see what it feels like ( jump on that comment Doze and Cland and...)

Jump on it? In an ideal world I'd be 100% behind it!

I think more realistically (on cost grounds), putting line crew back in a Cessna to revise the basics immediately after hiring, and thence one every couple of years would be a good start. The bean counters would probably have an aneurysm going even that far, and some experienced pilots may even balk at the idea, finding it demeaning.

However - the status quo at the moment is that even fresh recruits may not have actually practiced recovery from a real stall since they got their PPL - which can be months or years before they're put into the right-hand seat of an airliner, and then training becomes all about mastering the systems of these wonderfully complicated beasts (I'm not just talking about Airbus FBW types here), and practicing rote drills using those systems to avoid trouble.

This is fine to some extent, because there's no doubt that automation and modern systems have by and large improved safety. What bothers me is that because basic flying skills are rarely revised once an ATPL is granted, the piloting "instinct" seems to suffer. In the case of AF447, at no point did the crew do the basic calculation:

UAS + Nose up + unwinding altimeter + poor roll response = STALL

I would hope that most pilots with an understanding of the principles of flight should be able to perform that calculation, but the truth is that these skills need to be exercised fairly regularly to stay current in the ol' grey matter - and the longer you do a job without needing that information the more likely the knowledge will disappear further into the recesses of long-term memory if not forgotten altogether.

Take my job as a software engineer - we have these wonderful tools and languages these days that abstract away all the nitty-gritty of understanding how these machines work underneath, and except for very specialised parts of the industry, the basics of understanding low-level code and the principles of a von Neumann machine are never used, because all the business is interested in is the speed of delivery and quality of the final product. The tools turn out final code that's *almost* as good as properly hand-optimised assembler, and because machines are so fast these days "almost as good" is usually more than enough. But on the rare occasion that it isn't, you can find yourself galloping up Diarrhoea Drive without a saddle as you try to remember all that stuff about memory pointers and opcode cycles. This has only happened to me once, but from then on once or twice a year I fire up a C64 or Amiga emulator and make myself do some rudimentary assembler just so it's relatively fresh in my head - and the first time I did I was genuinely aghast at how much I'd forgotten.

All this, and at no time was I in danger of injuring anything more than my pride. Airline pilots are risking considerably more than that, even if it's unlikely they'll draw the short straw.

[HazelNuts39]

The CVR comment about crazy speed might be explained, as vertical velocity was extreme but indicated speed was what, 107 or 135 knots? When the PF made that remark his PFD was on ADR3 and had no airspeed display. Shortly after that the angle of attack 2 was temporarily valid at 41°, and the stall warning was triggered. That means that ADR2 speed was temporarily greater than 60 kts. His PFD on ADR3 indicated temporarily also above 60 kts. The actual speed was then about 140 kts CAS.

[Owain Glyndwr]

http://i1081.photobucket.com/albums/j351/OwainGlyndwr/NASAupsetresults.jpg

MM43,

Sorry, I have to disagree with you on fin and rudder remaining effective at high AoA. In fact the increased sweep coming from the geometric sweep plus the AoA means that the fin and rudder lift curve slopes fall sharply as AoA get large - see Fig9 on the figure. OK, this is obviously a Boeing design, but fifty plus years in aerodynamics tells me that the A330 isn't going to be a mile different. So although the yaw damper was working the rudder pretty hard, I doubt it was really driving anything since at 40 deg AoA it was down to about 1/3 power.

In addition, when a swept wing aircraft gets to that sort of AoA the lateral behaviour changes from a classic dutch roll to something more like a simple roll oscillation. This isn't sudden, and (of course:D) the A330 at 30~40 deg AoA lies in the transition zone. But a feature of this change is that the relative phasing of yaw rate and roll rate alters, so it is impossible to say that the yaw damper is driving roll - it is more likely to be lagging it considerably.

Clandestino;

You are right to express caution on using classical unstalled equations to explain AF447 behaviour when stalled, but there are other theories that may throw some light on it - but treat with care! - and they will only give an indication of what might be happening.

Amongst other things there is a little matter of asymmetric shedding of vortices off the forward fuselage at high AoA (see picture), and this can be time variant, so it is a brave man who says he can explain what is happening (or one with a lot more data and computing power than I possess)

[DozyWannabe]

Sorry, I have to disagree with you on fin and rudder remaining effective at high AoA.

I think what mm43 was saying was that rudder is *more* effective than aileron in the stall regime, which is undoubtedly true. Obviously at extreme AoA this effectiveness will decrease - possibly rapidly.

That graphic you've posted (thanks by the way - very illuminating) shows that rudder effectiveness on that design approaches 0 at around 60deg AoA. AF447 maxed out in the 40s. Fig. 9 suggests that rudder remains significantly effective at that point.

[Linktrained]

Roulishollandais #228

Hi,

Thank you for your praise - I wish that it was deserved. At Montaigne Noire this technique was taught and practiced without MY understanding, I think - but that was 62 years ago. I was to make my longest duration flight without FOUR engines whilst there. (I had seen the eight engined 100 Passenger "Trans Atlantic" Bristol Brabazon at Farnborough in 1949. Things have changed !)

[bubbers44]

Hopefully no pilot will get into a situation like this again. Losing airspeed at FL350 should not put you into a 14 degree nose up attitude because the overspeed was sounding putting you into a full fatal stall. All airliners have UAS charts to set power and attitude to deal with that. I am sure AF did too. I am sure they do now.

[bubbers44]

To clarify, no airliner at FL350 can go over 2 degrees nose up at cruise power without stalling. What they did was way out of the envelope. We need to hire pilots that can fly and not just button pushers that can't handle a simple autopilot disconnect.

[gums]

@Bubbers

C'mon, two friggin' degrees nose up or you fall outta the sky? BEAM ME UP!

A nice, slow pull without violating the control law AoA limits or gee limits can be done, then a gentle nose down should not be a big deal. The situation you describe reminds me of a U-2.

If the 'bus or any other airliner design requires that much attention and skill, then we're outta luck as SLF.

Sorry to be harsh, but I think the 'bus design and other jets have a lot more tolerance in attitude and such.

[bubbers44]

Not 2 degrees but 14 degrees nose up at FL350 doesn't work at FL 350. Anything much over 2 degrees will catch up with you rapidly and put you in a stall at that altitude. These two managed to do it in less than a minute with their maneuver. I think they really screwed up. Competent pilots don't do that.

[mm43]

Originally posted by Owain Glyndwr ...
So although the yaw damper was working the rudder pretty hard, I doubt it was really driving anything since at 40 deg AoA it was down to about 1/3 power.Thanks for the graphics (think HN39 posted a link to them some time back) and your explanation.

Not being an aerodynamics expert by any stretch of the imagination, I had concluded that the lateral/transverse stability of the aircraft at such a high AoA and low IAS was balanced on a knife edge, and even with the reduced efficiency of the rudder it would still be possible to induce a roll moment. You doubt that that was the case, but as I stated in my earlier post, the DFDR data is pointing toward it doing just that.

To emphasize what I am getting at, I have blown up part of the Roll trace and and superimposed the Rudder trace on top of it. In addition, an expanded (replotted) 30 second section is shown where (if the traces have been synchronized by the BEA) the rudder is constantly leading the roll and not the other way.
http://oi47.tinypic.com/2wncs20.jpg
I'm still puzzling over the constant yaw to the right and its cause. Were the ailerons responsible, asymmetric drag, or a side-slip component? Though the more I look at it, I have come to realize that the PF had one hell of a fight on his hands just keeping the wings level, though through mostly of his own doing.

[Owain Glyndwr]

http://i1081.photobucket.com/albums/j351/OwainGlyndwr/Pinskeronlaterals.jpg

Dozy
I think what mm43 was saying was that rudder is *more* effective than aileron in the stall regime, which is undoubtedly true. Obviously at extreme AoA this effectiveness will decrease - possibly rapidly.

Since the aileron effectiveness is just about zero in fully stalled conditions this has got to be true.;)
But I didn't mean to say that the rudder was completely useless, just that it was operating at about 30% effectiveness relative to normal conditions.
Incidentally, I forgot to mention that the effectiveness is further reduced by the fin being swept by the low energy wing wake at some AoAs

MM43
Not being an aerodynamics expert by any stretch of the imagination, I had concluded that the lateral/transverse stability of the aircraft at such a high AoA and low IAS was balanced on a knife edge, and even with the reduced efficiency of the rudder it would still be possible to induce a roll moment. You doubt that that was the case, but as I stated in my earlier post, the DFDR data is pointing toward it doing just that.

To emphasize what I am getting at, I have blown up part of the Roll trace and and superimposed the Rudder trace on top of it. In addition, an expanded (replotted) 30 second section is shown where (if the traces have been synchronized by the BEA) the rudder is constantly leading the roll and not the other way.

Yes, I see where you are coming from and understand how you might have come to that conclusion; but I am coming, quite literally, from the opposite angle.:)

When you put an aircraft up at those sort of AoAs funny things start to happen to the lateral behaviour, of which perhaps the most important is that you develop a direct kinematic interchange between roll and sideslip - bottom left in the graphic. When this really gets going the dutch roll disappears and is replaced by an oscillation which depends on roll-sideslip-rolling moment due to sideslip- roll - sideslip. This oscillation really doesn't involve any significant yaw motion. The top right picture in the graphic is the nearest I can find to an A330 situation - the relevant CL would be in the range 1.2~1.4.

I don't think that AF447 got fully into this state, but if you look closely at the estimated sideslip trace then when it is not saturated the peaks in sideslip coincide timewise with the peaks in bank angle, so there is an element of this phenomenon present I think.

Again, if you look at the rudder traces you see that in the timeframe you cite there was no rudder pedal movement worth a damn and that all the rudder movement was commanded by the yaw damper. Philosophically, the yaw damper is a follower and shouldn't be driving the motion unless the system designers really fouled up and produced an unstable system (which they did not).

More practically, the yaw damper is just what it is called - it applies rudder proportional to rate of yaw, so in this case if you are thinking about the relationship between rudder angle and bank angle you really need to consider the relationship between bank and rate of yaw.

In a conventional dutch roll the rate of roll lags the rate of yaw by about 160deg, so that bank angle will lag rate of yaw (or yaw damper input) by 250 deg. When you get into the roll oscillation mode this may increase a little.

I don't want to sound dogmatic about this because we really don't know where the A330 might sit in the spectrum of possibilities, but it seems to me that the observed relationship between rudder angle and roll could be a big lag rather than a small lead (which would anyway imply some sort of system malfunction).

So in the time interval you quote I see an aircraft with saturated, but ineffective, roll control operating without any effective pilot contributions so that the response is something like the 'natural' one, which in this case is a very lightly damped oscillation more or less confined to roll/sideslip variations. Experience with other aircraft suggests that although the roll oscillation is lightly damped, it won't go unstable.

So far as the drift to the right is concerned I share your puzzlement. It looks like some sort of out of trim coupled with slightly negative spiral stability and if you digitise the estimated sideslip trace ignoring the obvious saturation errors you see an intriguing drift from zero to about -1 deg (left slip) over about 3 minutes. At the same time the rudder trim trace shows a constant 0.5 deg right turn deflection which is at least consistent.

So it is possible that there was a standing out of trim which was being held by the A/P, but whether the numbers stack up I just wouldn't know.

[HazelNuts39]

AF447 maxed out in the 40s.It didn't. It went to 60 - 70 but became NCD above 40.

[HazelNuts39]

I was wondering whether (similar to wind speed and direction) the 'estimated sideslip' is a function of indicated airspeed and hence erroneous if airspeed is erroneous (AoA>25°). Does anybody know how it is calculated?

[A33Zab]

For the guys with the graphs:

The estimated sideslip (elaborated in FCPC) is NOT used in ALT2(& DIRECT) and replaced by Ny rear accelerometer.

The FCPCs are located below cockpitfloor and the Ny rear accelerometer in the tail compartment.

@HN39:

Don't know the equation but it is Ny acceleration corrected by Rudder deflection and roll and yaw rate. (Inertial data)

Seems to be ADR DATA is supplied also:

http://i474.photobucket.com/albums/rr101/Zab999/Est_Sideslip.jpg

[mm43]

@ Dozy, Owain Glyndwr, A33Zab;

Thanks for all your inputs, but as the sun is on the backside of the planet in this part of the world, I'll have a closer a look at all your contributions in my morning.

[Gegenbeispiel]

The Daily Telegraph claims to have a leaked draft of AF447 (central Atlantic, all lost) final acc. reprt. Doesn't look too credible/accurate to me. Comments?

Air France Flight 447: 'Damn it, we're going to crash - Telegraph (http://www.telegraph.co.uk/technology/9231855/Air-France-Flight-447-Damn-it-were-going-to-crash.html)

[RetiredF4]

There is not one thing new, which would lead to the conclusion, that it originates on the future final report.

[hetfield]

There is not one thing new, which would lead to the conclusion, that it originates on the future final report.

Indeed, but for the public it's a not so bad summary.

[wozzo]

The Daily Telegraph claims to have a leaked draft of AF447 (central Atlantic, all lost) final acc. reprt. Doesn't look too credible/accurate to me. Comments?
Maybe they changed the story, but I couldn't find any claim that they actually have a copy of the report (or its draft). Only wording like "All the indications are that the final crash report will confirm ...", which implies the opposite.

[LiveryMan]

The telegraph throws in it's tuppence:

Air France Flight 447: 'Damn it, we&rsquo;re going to crash&rsquo; - Telegraph (http://www.telegraph.co.uk/technology/9231855/Air-France-Flight-447-Damn-it-were-going-to-crash.html)

[EMIT]

Yes GUMS,

Performance of big jets is appalling, compared to fighters.
At optimum flight level, at cruise speed, pitch will be around 2 1/2 degrees nose up. For a climb to the next level, once you have burned off enough fuel so that optimum level will have increased by 2.000 ft, you increase thrust (wow, an extra sneeze is all you get) and you "pull up the nose" by about one degree. Of course you will not stall immediately if you pull up steeper, but you will not maintain speed if you do.
If you want to speed up at cruise level, well you will accelerate with about 1 knot per 10 seconds - a long way removed from the 1 second per 10 knots of our previous life!
The margin between high speed red line and low speed red line is not nearly as small as on the U-2, but thrust margin is not big; when you reach cruise level, 1.000 to 1.500 ft/min is all the climb capability that's left.

In the handling of the situation by the pilots of AF447, the biggest communication error, in my opinion, is the talking about "climbing" and "descending" instead of "pitch, check pitch attitude, set pitch 0 degrees".

[up_down_n_out]

DT masters of drivel & badly informed speculation as usual. :ok: