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AF447 wreckage found

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AF447 wreckage found

Old 24th Aug 2011, 17:11
  #3221 (permalink)  
 
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Originally Posted by BOAC View Post
... and as I said before, that both AB and AB pilots are having some serious thoughts about the way they present and operate the type.
Airbus* changed their tune nearly two decades ago, after they lost Nick Warner. Honest question, and I don't want you to think I'm getting at you - when was the last time you honestly heard an Airbus pilot or TRE say that it was impossible to stall the aircraft under any circumstances? If it was more recent than the mid-'90s I'd be inclined to suggest you report them to their chief pilot, because that's a dangerous misapprehension.


I suspect/hope this and the PGF crash have opened a few eyes. The parallel I draw is the driver I saw last winter here who, dazzled by the brilliance of the 'perfect' ABS in his car, was amazed when it let him slide into another car on sheet ice.
Then that's another fundamental misunderstanding of how the ABS system works - it does exactly what it says on the tin in that it will release the brake pads for a split-second if it detects the wheels locking up - in essence it's just automating what is known as "cadence braking" if you do it manually. It doesn't necessarily stop you in any shorter distance than regular brakes (in fact some of the earlier systems actually induced a *longer* stopping distance than with correctly-applied conventional brakes), but what it does do is give you more control over steering than you have with locked wheels. On ice, even with ABS working full-chat, your stopping distance will still be significantly greater and your ability to steer will still be severely compromised. Heaven knows I've read many road safety articles over the years warning drivers that ABS will not necessarily stop them in a shorter distance even under normal conditions, let alone on wet roads or ice, and it's astonishing how little this information is understood by drivers, though in my experience most driving instructors are aware of those limitations if you ask them.

You'd like to think that pilots, TREs especially, would have a more in-depth knowledge of the systems they are training people to use!

@RWA - From what I understand from talking to current and former line pilots, the FBW Airbus simulators do indeed simulate the behaviour under different laws. I think it was PJ2 on the Tech Log threads who mentioned that he took a sim check that simulated failure all the way down to Manual Reversion mode, where the only controls available are the pitch trim and rudder - he also mentioned that he successfully landed the simulator, but was thankful he wasn't faced with the challenge in real life.

No design is perfect, but on here opinion seems to be clearly divided as to whether the decision to go without tactile feedback was a major oversight. The opinion that it was seems to be largely held by people who've never flown the thing, and it seems that most that have don't regard it as a major loss. As a non-pilot I'm bound to watch what I say and hold a neutral position on the subject, but from what I understand about the design and training as a holistic entity I'm inclined to agree with the latter. I have yet to be presented with incontrovertible evidence that any FBW Airbus incident to date would have been avoided by having the sidesticks connected via backdrive.

Opinion seems to be split as to how the A330 handles under Alternate Law - so far we've had one pilot saying that they were surprised at the increase in response, and IIRC two saying that there wasn't that much difference and they adapted to it fairly quickly. The pilot in the former case seemed to believe that Airbus was directly involved in the de-skilling of pilots, a claim which again I've seen no evidence to support - so I'm less inclined to trust his opinion. At least one of the latter is well-respected on here as a no-nonsense senior pilot whose opinion I therefore trust implicitly.

[* - By which I mean the marketing department and executives - the engineering department had always been realistic about the aircraft's capabilities (good though they were)... ]

Last edited by DozyWannabe; 24th Aug 2011 at 19:41. Reason: "presented", not "prevented"... D'oh!
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Old 24th Aug 2011, 17:35
  #3222 (permalink)  
 
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human interface

Safety Concerns
Stick feedback, throttle feedback, AOA indicators, direct law, normal law have had no effect on accidents for forty years.
That is your assumption, i know lots of accidents where one or another part was contributing to the cause.

The weakest link has always been and will probably remain the human interface, the pilot.
I hope that last sentence is a misspelling.

The pilot is not the human interface, he is the user of it.
The human interface starts with all aircraft systems which output information to the pilot and ends with all aircraft systems, the pilot operates, and the most important part is feedback.

If you see the pilot as human interface, then i understand your communication problem with the pilot community.

Last edited by RetiredF4; 24th Aug 2011 at 18:53.
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Old 24th Aug 2011, 17:38
  #3223 (permalink)  
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Dozy;
it's astonishing how little this information is understood by drivers,
Yep. Nature trumps automation every time.

The sim experience (fully manual flight on THS and differential engine thrust) was done during the initial course on the A340 and it worked sufficiently to get onto the runway. The A320 was much easier to control under the same circumstances, primarily due to mass and the need to anticipate much earlier for the A340 and would be a huge challenge but doable.

Tactile feedback simply wasn't an issue for most. While there are always counterexamples, no pilots I discussed Airbus issues with commented that moving thrust levers, sidestick positions, artificial pressure during out-of-trim conditions etc were fundamental to flying the aircraft. The key discussion point for us was always the airline's restriction on hand-flying and the absence of such practise in the simulator. The manual was written in such a way as to permit/encourage hand-flying and there was also an "appropriate-level-of-automation" list which provided good guidance for the engagement of automation, (fully automatic, to fully manual), but the trouble was, because no one was practised at it, they lost the touch and the confidence to disengage everything and that is a self-fulfilling series of actions. The policies were good and permitted the decision to disengage, but were not actively encouraged, the reason given being "fuel consumption". But automation is a god-send at the end of a long-haul flight and is an enormous enhancement to flight safety - it just has to be understood, and trained/checked well.

At least one exercise should be included in any practise session (not on the ride), and that is climbing and descending S-turns with changes in speed - fully manual flight including manual thrust levers, and no flight directors. It is a worthwhile exercise which takes about 20 minutes of sim time for both pilots and is a lot of fun (and is very revealing!)

A no-FD hand-flown ILS approach to CATI limits is already in the script and so are steep turns, but the above exercise is a good coordination, instrument-scan one...it should be done in Alternate then Direct Law, but one thing at a time.
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Old 24th Aug 2011, 19:34
  #3224 (permalink)  
 
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human factors

Some pieces out of the final report from Gulf Air manamana 2000
final report

The accident itself has nothing in common with AF447, but it highlight the human factor somewhat closer. That might help the discussion in understanding the difference between blame and detailed accident investigation.


2.3 Analytical Methodology
A review of the factual information indicates that this accident was primarily
attributable to human factors, there being no technical deficiencies found with the aircraft and its systems. Consequently, the following analysis focuses on these human factors issues, both at the personal and the systemic levels. The analysis adopts the philosophy of Annex 13, which is well articulated by Dan Maurino, Coordinator of the Flight Safety and Human Factors Study Programme, ICAO. ‘To achieve progress in air safety investigation, every accident and incident, no matter how minor, must be considered as a failure of the system and not simply as the failure of a person, or people’.
The term ‘human factors’ refers to the study of humans as components of
complex systems made up of people and technology. These are often called ‘sociotechnical’ systems. The study of human factors is concerned with understanding the performance capabilities and limitations of the individual human operator, as well as the collective role of all the people in the system, which contribute to its output. There are two primary dimensions of human factors, these being the individual and the system.

In this context the following analysis addresses the human factors issues: at
the individual level, and at the systemic organisational and management level.
2.3.1 Individual Human Factors
In considering the role and performance of individuals it must be recognised
that people are not autonomous, they are components of a system. Therefore
human performance, including human errors and violations, must be onsidered in the context of the total system of which the person is a part. There is a need to investigate whether such errors or violations were totally or partially the products of systemic factors. Some examples are: training deficiencies, inadequate procedures, faulty documentation, lack of currency, poor equipment design, poor supervision, a company’s failure to take action on previous violations, commercial pressures to take short cuts, and so on.
2.3.3 The Reason Model of Safety Systems
At the 1992 ICAO AIG meeting it was recommended that the Reason Model
should be used as a guide to the investigation of organisational and management factors.

The Reason Model is described in the ICAO Human Factors Training
Manual (1998, Chapter 2). The model and its application is described in more detail in the book Managing the Risks of the Organisational Accident (Reason, 1997).

Operational experience, research and accident investigation have shown that
human error is inevitable. Error is a normal characteristic of human performance and while error can be reduced through measures such as intensive training, it can never be completely eliminated. Consequently, systems must be designed to manage human error. What follows is an integrated systemic analysis based on information drawn from all the specialist groups involved in the investigation. It is conceptually based on the Reason Model of safety systems.

2.4.6 Information Overload
The circumstances in the cockpit, and the behaviour of the captain, indicated
that at this time (1929:41) the captain was probably experiencing information
overload. While there are a number of theories of human information processing, one characteristic that they all share is the concept of some form of overall central limitation on the rate at which humans can process information. This may take the form of a ‘bottleneck’, a pool of limited attentional resources, or an ‘executive controller’, supervising and co-ordinating multiple information processing resources.
However, while the underlying more esoteric theoretical issues continue to be investigated, the research carried out over the last 50 years or so, combined with actual operational experience has provided a practical first order working model of the fundamental capabilities and limitations of human information processing. This model is applicable to ‘real world’ situations, such as the analysis of human performance in complex socio-technical systems, accident investigation and training.

Some key aspects of the model are briefly described as follows:

At the conscious level, the human brain functions as if it were a single channel information processor of limited capacity. Under conditions of information overload, responses fall into one or more of the following categories:

Omission - ignore some signals or responsibilities.
Error - process information incorrectly.
Queuing - delay responses during peak loads; catch up during lulls.
Filtering - systematic omission of certain categories of information according to some priority scheme. This can lead to the focussing, or ‘channelling’ of conscious attention on one element of a task, or situation, to the exclusion of all others.
Regression - reversion to a previously over-learned response pattern.
Approximation - make a less precise response.
Escape - give up, make no response.

High levels of stress and anxiety can increase these effects. The situation had progressively deteriorated from the time of high speed initial approach, and the subsequent actions not achieving the desired results. It is also probable that the captain’s level of stress and anxiety had progressively increased as the initial approach, and then the orbit, did not go as he had intended.
As said before, there are no similarities between the accidents, this post only should point to the fact, that pilots are no supermans and that human errors are also mostly systemic errors.

Last edited by Jetdriver; 25th Aug 2011 at 05:28.
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Old 24th Aug 2011, 19:54
  #3225 (permalink)  
 
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Cool

Hi,

Maybe not to you, since they don't match your conspiracy theories.
I doubt you've ever been part of a real accident investigation.
I suppose you will tell the same to the judges (and lawyers) in the court of justice to refute the findings or even possibly say that there are no courts to judge the case since the justices have never participated in an investigation of aviation accidents.
Do you think your arguments will be reviewed and considered ?
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Old 24th Aug 2011, 19:55
  #3226 (permalink)  
 
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no retired F4 I just lost it with those tunnel visioned pilots determined to run down a perfectly good and very safe but not perfect technology at any cost.

My point is this isn't about A V B, this is about moving forward with design improving its user friendliness and ability to produce the necessary feedback in a manner which ensures maximum transfer of info without overloading.

I cannot and will not accept the constant uneducated, ill informed, negative comments about one manufacturer's approach based upon emotion and not fact.

There is no way to communicate that message politely because one is dealing with ignorance.
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Old 24th Aug 2011, 20:23
  #3227 (permalink)  
 
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@jcjeant - As I said to Bearfoil/Lyman on the Tech Log threads, be very careful when tangling with ChristiaanJ - on the off-chance you're unaware, the man was a senior engineer on Concorde during development and service and - to coin a phrase - he's likely forgotten more about aircraft design in terms of aerodynamics and the human/machine interface than you or I could ever hope to know, and just from reading his public posts I've learned an absolute shedload.

Apropos of nothing, here's a brief blogpost on the man responsible more than anyone else for the A320's (and by extension her descendants) handling characteristics:

Gordon Corps (1929-1992)

Sentences that should be paid particular attention to include (emphasis mine):

In 1964, after his RAF service he joined the Air Registration Board. He became chief test pilot to the Civil Aviation Authority in 1981 on the retirement of Dave Davies.
(Yes - *that* Dave (D.P.) Davies, the one who wrote what many still consider the Bible of heavy jet handling characteristics nearly 40 years after it's last edition. Prior to that, Captain Corps was effectively Davies' SIC)

He joined Airbus Industrie in Toulouse in 1982 as an engineering test pilot. In the intervening 10 years, he had been involved in flight-testing the Airbus A310, A300-600 and A320 airliner family, with special responsibility for flying qualities.
I hope this helps to lay to rest any remaining belief that the A320 series was designed without the input of pilots, and indeed was designed with the input of at least one of the most skilled and safety-conscious pilots who ever lived.

It was Captain Corps who devised the previously-mentioned simulator test that proved to at least one sceptical pilot that the A320's systems, including bank and pitch limitations, were more than capable of permitting emergency escape maneouvres with a better success rate than conventional control designs.

Captain Corps sadly died of altitude sickness in 1992 when investigating a fatal accident on Talkuassir mountain, which, though tragic, demonstrated his commitment to safety in the air above all else (and frankly what our cousins in the US would call "brass balls") - how many 62-year-old men can you think of who would risk a treacherous journey to the Himalayas just to be the point man for an accident investigation?

From a personal perspective, another tragic consequence of his death, which I've mentioned before, is that the contributions of Captain Bernard Ziegler (who was first and foremost a sales evangelist) to the history of the Airbus FBW project, of which there were many that were controversial, are common knowledge among the piloting community - but the contributions of Captain Corps (who was a technical and engineering pilot with hours logged in more types than many can name off the top of their head, and an acute knowledge of the good and bad points of *all* of them) are nowhere near as well-known. Part of me wonders whether if he had lived long enough to complete his retirement, he'd have written a book which would have picked up where Davies left off, and left no doubt in the minds of the pilots and engineers who read it, that the design considerations of the A320 series were thoroughly thought through and had to get through the approval of this formidable aviator before they would pass muster.

Last edited by DozyWannabe; 24th Aug 2011 at 22:11.
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Old 24th Aug 2011, 20:30
  #3228 (permalink)  
 
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Safety Concerns
Stick feedback, throttle feedback, AOA indicators, direct law, normal law have had no effect on accidents for forty years.
I doubt you can support that statement, given how contributory factors add up in aircraft mishaps of any brand, not to mention the variety of change, modification, and adjustment the industry has made in forty years.

But let's try another view on this: is half a truth a whole lie? If it is, then you could be accused of lying (or simply being wrong) even if there is something in your statement close to the truth.

You can make a case that any single one of the above were not the sole cause of a mishap over the past 40 years, and my guess is that you'd be able to support it.

Since we may never get good granularity on the recent crash (early morning) in Libya, thanks to that bit of Arab Spring, whatever factors contributed to that remain lost to the industry at large.

(Here's hoping I am wrong about that).
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Old 24th Aug 2011, 20:42
  #3229 (permalink)  
 
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Dozy, FWIW ... from an older thread ... PPRuNerNorman Stanley Fletcher
The Airbus has to be considered as a box of tools - there is a tool for just about every occasion in the locker. The problem for many Airbus pilots is that they only use a few of those tools nearly all the time. Such skills as manual flying are often neglected. My personal philosophy is that at least once a week or so, I switch the autopilot, autothrust and flight directors off and do a raw data approach to minimums. It is hard work as raw data instrument flying is a perishable skill which significantly decays through lack of use. If you are not careful you end up losing key abilities that you had in your early years. To be a good Airbus pilot undoubtedly requires a solid grasp of the numerous flight guidance modes, but it also requires the ability to switch the whole lot off should the need arise. I personally encourage low-houred Airbus pilots who have become familiar with the Airbus over say the last year to stretch themselves and periodically switch off the automatics - weather and ATC environment permitting.

This is not just an Airbus problem but a problem related to all new aircraft types (B777, B787, A380 etc, etc). Increasingly we as pilots are becoming systems managers - and it is absolutely vital we have a full grasp of those systems.

Nonetheless, it is also imperative the basic handling skill are not allowed to erode. All the 'stick and rudder' men may despise the realities of modern aviation - they alas need to embrace the new skill set required of them. Equally a whole generation of Airbus pilots need to ensure their systems management capabilities, good as they may be, are not maintained at the expense of basic flying skills.
When there is a corporate disincentive to hand flying, and even punishment, Norman's appeal may become increasingly difficult for anyone to hear, particularly those who are not pilots, who need to hear it loudest.
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Old 24th Aug 2011, 20:49
  #3230 (permalink)  
 
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Safety Concern
I cannot and will not accept the constant uneducated, ill informed, negative comments about one manufacturer's approach based upon emotion and not fact.
It always takes two for a disagreement. The fire keeps burning by the aditional coals those two groups are shoveling in. It´s like feeding trolls, wherby i´m not saying that those posters are trolls, but there are parallels.

Honestly i´m tired with this A v. B talk (and i think others too) and it is hindering reasonable discussions. I think you have higher qualities and can contribute more for future safety when letting A v. B. and stone age v. future at rest. If it gets that bad at you that you mix up the pilot (a human being) with the human interface (technical system asociated with the necessary training), then it is time to disregard those posts.

No harm intended.
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Old 24th Aug 2011, 21:05
  #3231 (permalink)  
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Franzl;

Jim Reason's Swiss Cheese model, extremely useful, has provided a good insight into human factors but is being challenged in the way any theory is challenged - through increased research and new knowledge, some of it made possible by a powerful computing capability which did not exist at the time the model was introduced.

Alongside (and not in place of!), Reason's notions are those of some superbly-insightful writers such as Sidney Dekker, John Stoop, Charles Perrow, Nancy Leveson, certainly PBL (Why-Because Analysis), who has contributed here in the past and others who are taking "systems theoretical" approaches (to describe it broadly...they may disagree!). Each are worth the trouble in looking up and reading, just as Reason is, for an understanding of this approach. Such an approach is (again!), entirely blame-free; - rather, it attempts to find things out.

Let us examine two notions. This isn't unique and is said in my own words. Others will have expressed these notions differently.

One way to think of an accident is a series of elements or things, which then interact (or don't interact). The focus is upon "things" as (philosophically) solid items with a fixed nature, which then interact with other "things" with their fixed natures which are then portrayed as "causes", which have "outcomes". It is perhaps a mirror of the way the western world approaches most things...in a Cartesian manner, or a mental model that looks at the world as "mechanically linked" in terms of cause and effect, (note the singular form of these words!).

Because human factors deals naturally with the way humans see their world, another way to examine an accident sequence (and view the world!), is in terms of relationships...that which occurs "in-between" things. It no longer sees "things-in-isolation" but instead sees primarily relationships...what goes on in-between things and how relationships change those things. So, an organizational system, which can be printed out as the usual "org-chart" isn't a "thing", it is a living organism which materially affects the behaviour of people within such a system. Therefore, the notions of "cause" and "effect" are significantly changed. So much so, that analyzing a series of events from a "Cartesian" view, (as one might do a physics experiment), cannot work and a better model is needed. Charles Perrow first broached this notion in 1984 in a ground-breaking book entitled, "Normal Accidents". Perrow is emminently worth reading and listening to.

Diane Vaughan (sociologist), wrote about the Challenger accident in a way that analyzes the organizational structure of NASA - the relationships between engineers and managers - there was very little analysis of "things" in Vaughan's work.

Many of us here understand this stuff intuitively but many others do not, and are perhaps a bit stuck in a Cartesian world view in which the notions of local cause/effect = blame are legitimately/automatically attached to any understanding of what happened in the accident and why. Concepts like blame and accountability are legal terms and the legal discourse is quite different than the discourse of the safety process, which is being discussed by Safety Concerns.

This applies to AF447 in ways that have already been very well described and written about here by those who know this aspect of flight safety work. The importance of the sociologists' work in this cannot be over-emphasized, but nor can the engineers' work be set aside. The two need to work closely and this is where the field is tending - a systems theoretical approach.

In the July - September 2011 issue of ISASI Forum has an excellent article on this approach - it is the paper presented by Sidney Dekker and John Stoop at the 2010 ISASI conference entitled, "Limitations of 'Swiss Cheese' Models and the Need for a Systems Approach". I tried the link to that issue of the magazine and it doesn't work yet, but it does work for the entire Seminar Proceedings Vol 14, and you can find their presentation there.

I believe we will learn far more about AF447 using this approach and indeed this has already been put into practise in many of the posts here, but there is always more learning! The benefit of such robust process is it provides a solid basis upon which pet theories and recurring themes may be judged in terms of relevance and consistency as well as their contributory value towards understanding, and where indicated, safely set aside.
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Old 24th Aug 2011, 21:19
  #3232 (permalink)  
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Originally Posted by Dozy
Then that's another fundamental misunderstanding of how the ABS system works
- actually THAT is a fundamental mis-understanding of my post. Try substituting the players in 447 into the story. The parallel? The 'surprised' human factor (or 'interface' as some see it. Gulp) - how can aviation safety progress with that frame of mind?

New sheets, nurse! When is the next BEA report if there is to be one?
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Old 24th Aug 2011, 21:25
  #3233 (permalink)  
 
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PJ2

Thank you very much for sharing,
i will have weeks to read and study!
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Old 24th Aug 2011, 21:44
  #3234 (permalink)  
 
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BOAC

Final report publication is planned by BEA in first half of 2012.

So, we've got many more months to quarrel on A vs B, pilots vs engineers, conspiracy theorists vs rational guys, blame vs safety...
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Old 24th Aug 2011, 21:55
  #3235 (permalink)  
 
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@LW_50 (and again, you make me break my personal limits on daily post count - curse you! )

I followed that thread closely at the time, and in essence I agree whole-heartedly with what NSF said, with the proviso that I would have included the A300, A310, MD-11, B747-400, B757 and B767 (and to some extent, the B737 Classic and NG) in that list. Something that has rarely been clearly delineated is the distinction between FBW technology (which applies to the aircraft he lists, along with Concorde, albeit using analogue technology in that case), and FMS technology (which applies to that list as well as any Western airliner that came off the drawing board post-1972). My contention is that the former does not necessarily impact negatively on currency in hand-flying expertise, while the argument that dependence on the latter makes it possible to do do definitely has merit.

If you look at how some people respond to my posts, as opposed to what I've actually been saying, you would think that I must be some kind of blinkered supporter of automation ueber alles, which I categorically am not - and have gone out of my way to make that clear several times. While I agree with some of what people like SC and JD-EE say in terms of the reality of the systems (and respect their expertise), I do not share their confidence in the ability of these systems to operate successfully and safely without the need for human intervention, particularly when the situation begins to degrade from normal to FUBAR.

So all I can do is reiterate the gist of some of my most recent posts - you have two clear cases of recent accidents where a lack of proper training and a lack of understanding as to just how important it is that pilots be fit for duty have clearly contributed significantly. You've got Airbus (of all manufacturers!) expressing concern that manual handling skills have been allowed to deteriorate and that action must be taken to resolve this. There will probably not be another opportunity to take the fight to airline management across the industry for a very long time, so please understand that I am four-square behind any effort on the part of pilot unions and associations to do so. I get weary of all the old Airbus canards being brought up over this accident because it is a distraction from the real problem - a new breed of airline management and executives that don't know anything about the sharp end of the industry that they are supposed to be managing, nor do they understand why the cost-cutting measures that they were taught and are routinely applied in other industries are simply inappropriate for airline operation.

@BOAC - I was referring to the misunderstanding on the part of the driver who expected ABS to save his bodywork and spare his blushes - clearly he believed that ABS was a "magic" braking system that would contravene the laws of physics and make everything alright. Right now, we don't know why the AF447 crew (and the PF in particular) did what they did, whether it was overconfidence in the system through lack of understanding and/or training, whether it was a sustained panic reaction which would have led to the same result in any other airliner, or whether it was a simple case of pulling back on the stick while attempting roll corrections without realising it - to name but three possibilities. It is likely that we will never be 100% sure, so we must work with the information that we do have.

Last edited by DozyWannabe; 24th Aug 2011 at 23:46. Reason: Clarifumucation...
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Old 24th Aug 2011, 22:04
  #3236 (permalink)  
 
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PJ2,
Thanks for the link.
Too late in the evening to read it fully now and make full sense of it.... it's on the to-do list for tomorrow.
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Old 24th Aug 2011, 22:36
  #3237 (permalink)  
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I don't blame AB for the lack of piloting skill which 447s' crew exhibited.

It could have easily happened in another type.

The fault was the pilots', plain and simple. They let the a/c get away from them while effectively flying 'partial panel'.

If they had been better trained, or even spent more hours actually flying (by hand) their aircraft then this accident could easily have been avoided.

Probably ( although the wx may have been a factor) all they had to do was leave things as they were and hang on until their airspeed problem went away- as it was bound to.

Straight and level was beyond them. So used were they to the automatics that the concept of actually flying the aircraft was too much.

Autos- and the way they degrade those hard earned flying skills- are the new killer.
 
Old 24th Aug 2011, 23:48
  #3238 (permalink)  
 
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Originally Posted by BarbiesBoyfriend View Post
Autos- and the way they degrade those hard earned flying skills- are the new killer.
Make that "misuse of/overreliance on" autos and you've got my unequivocal support. The autos themselves care not how they are used.

@exeng (below) - Actually, I seem to recall reading on the EgyptAir 990 accident that if the yokes on the 767 are pulled and pushed opposite each other that the design caused one elevator to deflect up and the other to deflect down (which I think was later changed). Ultimately the Airbus FBW design depends on co-ordinated flight deck roles to a greater degree, but I don't think it's demonstrably less safe. One can argue that if the PNF had the courage of his convictions he should have held down the priority button and stated "I have control" in no uncertain terms, which would be a variation on the procedure practiced in Airbus training, which makes the reasonable assumption that the pilot relieved of control should relinquish their sidestick. The overriding impression I get from the AF447 interim reports is that the lack of clearly-delineated flight deck roles, for which the ultimate responsibility lies with the Captain, led to confusion as to which F/O should be doing what and may have contributed to the PNF's uncertainty as to whether he had the right to relieve the PF of control.

Last edited by DozyWannabe; 25th Aug 2011 at 00:19.
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Old 25th Aug 2011, 00:06
  #3239 (permalink)  
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I agree with Barbies

An awful situation to find oneself in, but nevertheless basic attitude + power should have seen them through the airspeed issue.

The stall warning should have alerted the PF to the situation. Even in low level stall training ( I understand the PF had this) then a reduction in pitch should have been almost automatic I would have thought.

Where I have sympathy for the Pilots is in the extreme angles of attack following the stall when the stall warning disappears - and yet when nose down inputs are made the stall warning re-appears. I know others have made the point but I felt it worth re-stating.

The pitch angles on the ADI are abnormal for the stage of flight (i.e. cruise + stall) but not abnormal for take-off and initial climb. 'So what' some may say - but the PF may have thought that such a pitch angle was not so out of the ordinary. (importance of training aginn)

Interesting to note that the PNF took control quite late in the proceedings (probably too late to effect a recovery) and I believe he made a nose down input. I also understand that the PF almost immediately took control agian (or overode the NPF's input) with a nose up input.

Whilst I don't want to start an A/B versus Boeing scrap again I feel that the sidestick logic is flawed in this respect amongst others. On a Boeing it obvious which way the elevator is moving (and in some cases therefore the THS) and on the A/B it is not obvious. I've flown both by the way (including the 320 and the 777 but not the A330).

Both types of aircraft are well designed - some have advantages or deficiencies when compared against each other.

The clue is in training - and what we have in this terrible accident is a crew that has been poorly prepared for the situation they find themselves in. Complex aircraft need rigorous training - but the airlines won't pay for it - and A/B don't recommend it's necessity.

I hope that some changes in attitude from the various CAA's will follow the final report - I won't hold my breath.
exeng is offline  
Old 25th Aug 2011, 00:19
  #3240 (permalink)  
 
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Procedure that required setting 5°/CLB by heart was in force at the time of the accident. Page 59 of interim 3 report in English refers.

I see there's fear that it's unsafe and leads to zoom climbs ending in stalls.

It is not and it does not.

You will climb out of cruise condition but if your significant cockpit other fumbles with QRH for a half an hour, you will simply and gently level off at altitude where power required meets power available at 5° AoA. There's no aeroplane that can not sustain 5° AoA below Macrit, from Sopwith Camel, to Belanca Airbus, to CitationJet, to B747, to whatever and with thrust to weight ratios and of modern passenger jets, you will be far fom Macrit at 5° AoA. Do you understand that, for all practical purposes*, your AoA is difference between pitch and flightpath and in level flight AoA=pitch?

Does anyone have anything to add to this except his feelings and suspicions? Like arguments?

Granted, there's no need to go climbing but procedure is not about maintaining altitude. Speedwise, it gives you safe pitch and power for any weight, until actual settings are taken from the table. 5/CLB is just temporary measure and IMHO can be skipped if one knows his cruise power settings and attitudes for different weights by heart or if he was in stable cruise condition and just maintains last pitch and power. However, this would be overriding the prescribed emergency procedure and one must be better sure he knows what he is exactly doing.


*disregarding wing incidence and vertical air currents
Clandestino is offline  

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