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AF447 wreckage found

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AF447 wreckage found

Old 4th Aug 2011, 12:33
  #2561 (permalink)  
 
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Originally Posted by RWA View Post
...both the Flight Directors kept cutting out at intervals, so very probably they didn't have working artificial horizons either for long periods.
The Flight Director is a digital overlay on the ADI - non-presence of FD does *not* indicate that the AH component is not working.


Indeed, late on, the Captain told the PF to use the ISIS, the standby instruments - that's clear proof, to my mind, that they literally couldn't see 'which way was up' (or, very sadly, which way was DOWN) from the normal displays.
He says "Horizon - Standby Horizon", which could just as easily indicate that the two are in agreement and he is drawing their attention to that fact.

I believe that the spring-loaded, 'no feedback' sidestick was originally introduced purely as a weight-saving measure.
Not at all.

Monitoring what the other guy is actually doing is no problem with the traditional yoke or 'stick between the knees.'
Knocking the A/P out by bumping and getting foreign objects jammed in the traditional yoke or "stick between the knees" have caused accidents in the past too - it's not all one-sided.

Very much hope that Airbus review their whole 'design philosophy' about sticks etc. (especially the 'feedback' issue) as a result of this accident (plus others, like the Perpignan one). Might be a good idea to reconsider that decision, even if it does mean a few extra pounds of weight?
Of course, why not just throw away years of development and just make planes the Boeing way to satisfy a minority of pilots who can't deal with having the training wheels off? Yeesh...

@GerardC - that's fine but it's only one pilot's opinion. There are a fair number on this very forum who don't see the lack of backdrive as a problem because they have other methods that compensate for it. Also, as I've said more times than I care to recall, the A320 flight deck and controls layout didn't stop Sully!

Last edited by DozyWannabe; 4th Aug 2011 at 12:48.
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Old 4th Aug 2011, 12:38
  #2562 (permalink)  
 
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Without wishing to sound facetious, couldn't the PNF have asked the PF what he was doing?

I would have thought it's his job to.

Not doing so certainly turned out to be more than his life was worth.
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Old 4th Aug 2011, 12:49
  #2563 (permalink)  
 
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Here is what an A330 captain said about the crash:

The key ingredient most everyone seems to be overlooking: The flight control laws of an Airbus. An Airbus has flight envelope protections that cannot be overridden by the pilot. This is almost always a good thing because the airplane won’t allow the pilot to overspeed, stall, overbank or overload the airplane. In the peculiar case of [Air France Flight] 447, the airspeed reading was inaccurate because the pitot tubes were blocked — a very rare occurrence in a jet — almost never happens.

But when it does happen, the airspeed then acts like an altimeter: When the airplane climbs, the indicated airspeed increases, and when the airplane descends, the indicated airspeed decreases. My best guess for AF447 is that the airplane was climbing, most likely due to turbulence; I believe they were in a thunderstorm. From a pilot’s perspective, this is a bad place to be. It’s rough and difficult to read instruments. Autopilot disengages due to turbulence or ice on the airframe or pitot tubes. The airplane is climbing, and the pilot is wondering what the **** is going on. Then, as the airplane climbs, with the false readings still indicating increased airspeed, at high altitude the margin between cruise airspeed and overspeed becomes very small, so the airplane overspeeds — or so it “thinks,” due to the false reading. And it’s at this point, provided all of this is what really happened, that they’re ******.


Think back to the Airbus flight envelope protections I mentioned, and the fact that the pilot can’t override them. The airplane computers “think” the aircraft is overspeeding and therefore continue to increase the airplane’s angle of attack. That only makes it climb steeper, thus perpetuating this cycle of increasing indicated airspeed and increasing angle of attack. This continues until the airplane is at a ridiculously high nose-up attitude and stalls, regardless of pilot inputs.

This is why we really need to wait for a full analysis, so that investigators can figure out what the pilot inputs were and whether or not they were consistent with what the flight control surfaces were doing. In other words, were the pilots ******* up the control deflections, or were the Airbus flight computers ******* up the control deflections? Because the airplane eventually stalled, I can only surmise that it was the computers ******* up, because when the computers do their jobs correctly, they increase angle of attack in this situation — again, regardless of pilot input.

So the airplane stalled. One plausible theory is what I just described. (There are other scenarios in which the flight control laws are degraded and the airplane can stall under certain circumstances, but that’s a whole other set of seriously complex stuff. Who knows though? Maybe that’s actually what happened.) Even if this guess doesn’t explain precisely what took place, it constitutes a design flaw in the Airbus that needs to be fixed in that the flight envelope protections need to be disabled if they’re receiving inaccurate information.

Source:An Airbus Captain s Take on the Air France Disaster
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Old 4th Aug 2011, 13:10
  #2564 (permalink)  
 
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Management of Risk

A bit late in the day but thought that I would make an observation!

Apparently neither pilot was trained in high altitude flight. If that was the case they would not have practiced stall recovery in that regime. Neither is is logical that when pilots spend 60+% of their flying in this environment such an omission is tolerated.

Safety in aviation is usually calculated reference to the risk ratio of 1 in 10 to the -6 or 10 to the -7 depending on the critical nature of the system under consideration. The reliability of the airspeed sensors would come into this consideration i.e. the likelihood of failure is extremely remote. This all changes when such an event occurs. This was apparently the case with the A300 where such previous failures had occurred and a "fix" was in the pipeline.

While it would not be reasonable to stop all operations while "the fix" was being manufactured and incorporated, it would be more than reasonable to join the dots and realise that the reduction in risk should be ameliorated. In this case by highlighting the situation to the crews and by providing additional training to recognise and deal with the problem itself and the possible outcomes. In my view this is not "the benefit of hindsight" it is what management of safety and risk is all about.
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Old 4th Aug 2011, 13:26
  #2565 (permalink)  
 
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@martinhauptman007 - Unfortunately the aircraft was neither in an autoflight regime, nor did it have active hard protections (due to Alternate 2 Law caused by the blocked pitot tubes). So that article is misinformed.
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Old 4th Aug 2011, 13:46
  #2566 (permalink)  
RWA
 
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Quoting Dozywannabe:-

"Of course, why not just throw away years of development and just make planes the Boeing way to satisfy a minority of pilots who can't deal with having the training wheels off? Yeesh..."

Fair enough in its way, Dozy, mate.

But looking at it another way, for a bit longer than aeroplanes have been around, bicycles have. It would be perfectly possible, with today's 'electronic aids,' to design a bicycle that didn't need handlebars; so that the rider could turn just by 'body lean,' with his/her hands in their pockets....

But no-one has yet designed a bicycle that works that way. I'd venture to say, because yer av'rage rider would get a bit confused......

So precisely WHY, in your opinion, did Airbus opt for 'no feel/no feedback' etc.? A revolutionary change, after the best part of a century of producing aeroplanes that all 'worked' the same way?

My own view is that it was a matter of 'less weight/lower cost.' I can't think of any other reason?

Maybe you can?

Last edited by RWA; 4th Aug 2011 at 14:02.
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Old 4th Aug 2011, 13:55
  #2567 (permalink)  
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xcitation. Way too early for this, I warn. In the desription of fox3banana I see a Pilot (if description is accurate), displaying some troubling issues.

First, there is a friction in the PF/PNF dynamic. PNF has taken role of leader.

Second, PF appears unwilling to admit mistake, and "insists" on taking control.

He appears to act without "executive function", internally.

Oppositional, lack of executive thinking, and poor impulse control.

This is admittedly unsupported, and I apologize for even bringing this to the front. However, the investigation might seem to be heading into a Human Factors/Dysfunction moment.

Understand that the situation is incredibly challenging. I have experienced panic while flying in wind shear, and it took all the energy I had to properly focus. These guys had one hurdle after the next, and many all at once. Each person can revert to less than effective performance when in this sort of challenge. That is why the sterile cockpit, Alcohol rules, and distractions are taken so seriously.

Astronauts (Used to) undergo extreme Physchological evaluation; some of the testing was barbaric.

No authority can loosen these rules for those entrusted to transport People by Air. We cannot let a loosening of flight chsallenges to degrade stress/performance requirements.

No criticism intended, and it may be only that this Pilot did not bring his "A" game to this flight. That is as far (and as lenient) as the situation can allow, for the sake of safety.


RWA Have you ridden a SEGWAY scooter? Two wheels, the handlebars are to support only your arms, and it turns by the cg change of your body.

It's been around for many years.

Also. FBW. It is early, but the HUMAN BRAIN has been shown to change tune a radio by wirelessly comanding the change by "thinking". I kid you not. "Mind command" is not far off. With the fine tuning of the kit now working, it is conceivable a pilot may fly without touching anything! It also warns to be very very cautious of distraction?

AIRBUS. RWA, don't leave out another motive for a "change" in flight controls. Complexity for the sake of marketing. NEW!! DIFFERENT!! CHEAPER!! and did we say NEW!!
 
Old 4th Aug 2011, 14:32
  #2568 (permalink)  
 
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Thanks again for posting the graphs.

If one plugs in the Stick and Thrust graphs as well, one will see that on the Pitch graph the Pitch Nose Down, and Stall Warning OFF/ON/OFF corresponds to either Thrust action - reduce Thurst - or Stick action ND, or both. Thrust and Stick variations after the A/THR disconnect are both PF/NPF actions.



This brings Pilot action (thrust and stick) into correlation with all 10 OFF/ON/OFF Stall Warnings that occurred bellow FL350.

Regarding the interpretation of "coincidence" rather "consequence", it may be suffice to wonder if it really makes a difference, as the result was the same, one way or another: an addition to the other factor(s) of confusion.

While the reasons of the limitations are understood, with a systems engineering hat on, a behavior similar to the Stall Warning, would be ennoying if one had it on his car, or computer, or TV, or some other appliance, etc.... and would want it fixed. And sadly, one certainly would not want to have a chance to have it at all, in a "Hospital Surgery Room" or an airplane cockpit, in a critical life or death situation. (sad)





Originally Posted by DozyWannabe View Post
I'm trying to say that the stall warnings do not coincide with inputs, but with the attitude of the aircraft (which did not always correspond with inputs due to it's stalled state).

Really? To me it looks like (after the stall) the Stall Warning comes on as the nose begins to pitch back up, then switches off as the pitch-up causes the aircraft to assume an extreme AoA and slow down again. Then the nose comes down again, a little speed is picked up and the stall warning comes back on as the nose starts to come up.
....
Either way the path was not always under the control of the pilots, so my view is that while the stall warning logic is unsatisfactory in this extreme circumstance, I believe that if the stall warning did contradict or reinforce pilot behaviour, it was a coincidence rather than a consequence (note the nose going down several times while the PF's SS is back at the stops)

Last edited by airtren; 5th Aug 2011 at 16:03.
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Old 4th Aug 2011, 14:38
  #2569 (permalink)  
 
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Originally Posted by DozyWannabe
But there are thousands of Airbus FBW pilots around the word that do not consider it a problem - this is not about *my* opinion, this is about *theirs*.

... surely you must therefore consider that the theory which supports your personal preference may not necessarily be the solution in all cases?
Let them have their own voice then ... In this AF447 time, not too many Ziegler on the board I must say.
Never seen it as THE solution - Just a waste of a very valuable source of information.

Also, as I've said more times than I care to recall, the A320 flight deck and controls layout didn't stop Sully!
What's your point here ?
Don't mix everything.


The bare minimum I would expect to read in the findings (and I'm not even talking about recommendations) :
  • The sidestick ergonomy as implemented by Airbus deprieved both PNF to actually realize what control inputs were applied by the PF.

But BEA is absolutely unable to formulate anything in that direction.
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Old 4th Aug 2011, 14:44
  #2570 (permalink)  
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Also for @martinhauptman007's 'Captain' - I see no evidence that the FDR thought there was an overspeed.
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Old 4th Aug 2011, 15:01
  #2571 (permalink)  
 
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I don't think that the airbus design philosophy of a sidestick without feedback has caused the accident. Also, how do you generate the feedback when the speed data is lost? You can synthetize something based on the AOA vane sensor, but the fact that there was icing in this case precisely meant that all data was suspect. IMHO generating a feedback based on faulty sensors is even worse than no feedback at all.

But that doesn't remove the fact that the stall alarm design is completely unnatural and misleading, which is a big design flaw.
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Old 4th Aug 2011, 15:40
  #2572 (permalink)  
 
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The KEY FACTOR

Considering :

2:11:37 : PNF takes controll after the PF having said 'I have lost the plane"

2:11:39 : PF re takes control from the PNF witout annoucement

2:11:42Captain enters

2:11:45 : End of CONTINUOUS stall

So the capt could believe the PF has save the plane but from 2:11:39 the PF is no longer a professional pilot.

In an army, had he survived, he proubably would have go to the martial court for insoumission.

Before 2:11:39, the PF was a bad pilot. From 2:11:39, he could well be judged as a criminal...

Last edited by JJFFC; 4th Aug 2011 at 16:06.
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Old 4th Aug 2011, 16:10
  #2573 (permalink)  
 
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@JJFFC

I understand your emotional response to this very tragic incident. However I think we all owe it to the pilots to give them the benefit of the doubt. They did behave professional considering their level of training, experience etc.
Remember PF was confronted with a situation that he was not trained for i.e. UAS at high altitude. Throw in IMC and ITCZ and you have a nightmare. Clearly there was some mitigating circumstances and we only have a subset of the data. To their credit at no point did the 3 pilots give up trying. They fought for control down to the last second. For that they should be commended and we owe them the same professionalism.
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Old 4th Aug 2011, 16:52
  #2574 (permalink)  
 
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PF was confronted with a situation that he was not trained for i.e. UAS at high altitude.
I think this is too charitable. The one thing that we know they knew is that they were descending very rapidly. Aerodynamically, there are two ways for this to be the case: (a) they were in a deep (and fast) head-first dive; or (b) they were in a full tail-first stall. [Note, I am excluding the situation of the plane being fully laid over on its side.] Is it possible that things were so upset in the cockpit that over the course of three minutes in this attitude they were unable to discern the 60+ degrees of pitch difference between (a) and (b) -- and to remain convinced that it could only be (a)? I guess "yes," because the computer game stall warning was "god," aerodynamics be damned.
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Old 4th Aug 2011, 16:54
  #2575 (permalink)  
 
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@Xcitation

I apologize for this emotional response and I wasn't in that plane.

My point is about the PF' action :

2:11:39 : PF re takes control from the PNF witout annoucement

This is not a mistake, a lack of training it is a fault regardless the point of view, the country, the period in the history.

From Julius Caesar it is a fault..
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Old 4th Aug 2011, 17:30
  #2576 (permalink)  
bearfoil
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SeenItAll

Don't forget the Lateral. Put together, it was a hell of a ride. Oh, and strictly speaking, it wasn't a "tail first STALL"?
 
Old 4th Aug 2011, 17:31
  #2577 (permalink)  
 
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Hi, I see it this way:

The aircraft type fly-by-ware, in the cockpit there should be 2 emergence switches placed in standby instruments area (horizon-indicator,speed indicator-altitude indicator, also their systems must be totally separate from the other system, also add and mounting 4 ° pitot tube and 4°static port)

In the unusual emergency phase of putting on 1 switch must be activated on the system of flight controls direct with protection dumping elevator and rudder, but at the same time it must overraide all computer law: the normal law, alternate law , direct law, etc..
On news airplanes fly-by-ware, in the unusual emergency, last action must be only the pilots and not the law of computer. The computers works very goodin normal operations, but they’re stupid when in terrible Cb.

I'm Sorry, I Not well writing English language.

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Old 4th Aug 2011, 17:54
  #2578 (permalink)  
 
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Originally Posted by SeenItAll
I think this is too charitable. The one thing that we know they knew is that they were descending very rapidly. Aerodynamically, there are two ways for this to be the case: (a) they were in a deep (and fast) head-first dive; or (b) they were in a full tail-first stall. [Note, I am excluding the situation of the plane being fully laid over on its side.] Is it possible that things were so upset in the cockpit that over the course of three minutes in this attitude they were unable to discern the 60+ degrees of pitch difference between (a) and (b) -- and to remain convinced that it could only be (a)? I guess "yes," because the computer game stall warning was "god," aerodynamics be damned.
Except we do not have all the facts, nor lives on the line. How do you eliminate any margin of doubt and come to blame pilots. Even if they would have correctly identified a stall how would they recover. It is not a fighter, it was a fully loaded transport a/c. I read somewhere that they had 40 secs to correctly identify stall and begin recovery. Even then recovery could fail. Not a big time window given the confusing circumstances. 80% piltots have opposite/wrong reflex to stall warning. He was young and inexperienced, perhaps he was not in your 20%. This was all dumped on him by a long list of errors (training, experience, CRM, ALT law, software design, pitot fail, policy, accountants, weather...). Yes he made the wrong call. IMHO the question should be why not who.
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Old 4th Aug 2011, 18:30
  #2579 (permalink)  
 
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About Reflexes

Unfortunately, when a pilot becames proficient in instrument flying and his reflexes on bringing back pitch and roll are sharp, then he goes to airline piloting. It is SOP to takeoff and in less than 5 minutes turn on the AP.

I wonder how many hands on (on type) flight time an experienced pilot (say, 5.000 hours) has.

I wonder if nowadays an airline pilot is able to hand fly his Airbus or Boeing from takeoff to FL 370 and hold it there for one hour smoothly, without sweating.

I can almost bet that this is prohibited by Ops Manual, or Regs.

All those sharp reflexes are long gone, and learn to hand fly smoothly only in an emergency, in only three minutes, how this is possible?

IMHO, in long duration flights, pilots should hand fly for at least one hour. And this would mean only 10% on the flight.

What is the percentage of hands on flying, nowadays, on a 10 hour flight?
One percent, maybe?

Many here will remember how difficult it was to believe the instruments on the beginning of IFR training, on real IMC conditions.

And, IMHO, the only way to stay proficient in IMC is flying with no AP. Flight SIM is kind'a OK, but how many SIM flight time an airline pilot gets in a month?

I think these pilots (AF 447) were good pilots, but they were victims of the system.
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Old 4th Aug 2011, 18:57
  #2580 (permalink)  
 
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For Bearfoil and Rob2:

I have studied in minute detail hundreds and hundreds of DFDR readouts/data in the study of events of various types where the F/O was PF. In many of them there were instances where it was obvious that the captain should have intervened earlier yet he did not. This where the command structure is self evident. Now we had the case where 2 F/Os were flying together. It is not surprising that there was indecision when it came to such a need for intervention. There is a very strong case for mandating that the senior (and one hopes more experienced and competent) always assumes the role of PF when the captain is absent from the flight deck. Thus this CRM issue is avoided.

As for manual flying, it is worth bearing in mind that when flying in RVSM airspace there is a requirement for the a/c to have a serviceable autopilot. Should the autopilot fail ATC must be informed and the a/c leave the designated air space. The inference is clear that manual flight is not permitted. We may not like it and the downside is obvious but we are where we are!
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