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AF 447 Thread No. 7

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AF 447 Thread No. 7

Old 29th Mar 2012, 13:24
  #1061 (permalink)  
 
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PJ2's reference to IR3, (p72 - 76) made me read those pages again. I was puzzled by the following reference to the FPV, since the trace on page 107 shows that HDG-VS selected all the time (my bolding):
At around 2 h 11 min 42, the Captain came back into the cockpit, (...) Neither of the two copilots gave him a precise summary of the problems encountered nor of the actions undertaken, except that they had lost control of the airplane and that they had tried everything. In reaction, the Captain said several times “take that”, doubtless speaking of the FPV. (...)
There also seems to be a translation error further down on the same page, where "nose-up" should read "nose-down" (à piquer in the french original):
Several nose-up inputs caused a decrease in the pitch attitude and in the angle of attack whose values then became valid, so that a strong nose-down input led to the reactivation of the stall warning.
Plusieurs actions à piquer provoquent une diminution de l’assiette et de l’incidence ...
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Old 29th Mar 2012, 13:55
  #1062 (permalink)  
 
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Originally Posted by HazelNuts39 View Post
I was puzzled by the following reference to the FPV, since the trace on page 107 shows that HDG-VS selected all the time
On both sides?
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Old 29th Mar 2012, 14:19
  #1063 (permalink)  
 
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Cool

Hi,

Clandestino
Graphic presentation of AF447 DFDR readout is accurate, consistent and informative enough for anyone able to read it. Airline pilots of sub-average grade and above should be able to understand what is drawn. Of course, there are lot of PPRuNers who are either unable to understand BEA data or insist on misunderstanding it as graphs contravene their pet notion of Airbus being intrinsically evil. "Why" is good question.
Do you have the FDR listing for support the BEA graphics ?
The answer is NO
Information is not complete .....
FDR data are not "emotional" like CVR (with all the speculations about each words) ... that's just technical data .. factual information
Why release fragments of the CVR and some graphics but nothing about FDR listing ?
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Old 29th Mar 2012, 14:31
  #1064 (permalink)  
 
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Hi DozzyWannabe,
On both sides?
The crew didn't selected their FDs off - the bars simply parked out of view when the Airspeed was considered invalid. When the airspeed became valid again, the FDs would reappear.

I can't find the FCOM reference - but I think on reappearance they default to the aircraft's present HDG & VS until reprogrammed.
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Old 29th Mar 2012, 14:32
  #1065 (permalink)  
 
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Dozy, I can't speak for the 330, but the narrowbodies only have one button on the FCP for FD type. If you select FPV, it applies to both sides.

Other than that, I concur with, "Heavens to Betsy, is this still going on"
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Old 29th Mar 2012, 14:42
  #1066 (permalink)  
 
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There also seems to be a translation error further down on the same page, where "nose-up" should read "nose-down" (à piquer in the french original): Quote:
Several nose-up inputs caused a decrease in the pitch attitude and in the angle of attack whose values then became valid, so that a strong nose-down input led to the reactivation of the stall warning.
Maybe not. Too much AOA on a surface can have the opposite effect and it can "lose its grip" and allow the aircraft to develop a pitch rate in the opposite direction. Then as AOA decreases, it would normally regain its "grip" and start pitching the nose back up creating the nose up and down bobble, but if the crew then relaxed their back stick at the bottom of the maneuver, the nose might continue further down than its normal range and allow airspeed to become valid and reactivate stall warning.
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Old 29th Mar 2012, 14:56
  #1067 (permalink)  
 
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@TTex600:
Same on A330: Picture and description of FCU are on page 45 of IR#2.

@Machinbird:
Maybe so, but that doesn't make the English version a correct translation of the French original text.

Last edited by HazelNuts39; 29th Mar 2012 at 15:15.
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Old 29th Mar 2012, 15:53
  #1068 (permalink)  
 
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Machinbird:
Maybe so, but that doesn't make the English version a correct translation of the French original text.
Oops, so you were basing that on the French original.
Google translate was no help.
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Old 29th Mar 2012, 17:34
  #1069 (permalink)  
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RRR; (like the handle...)


"It is very unlikely that the aircraft will reach these attitudes, because fly-by-wire provides protection to ensure rapid reaction far in advance. This will minimize the effect and potential for such aerodynamic upsets.

The effectiveness of fly-by-wire architecture, and the existence of control laws, eliminate the need for upset recovery maneuvers to be trained on protected Airbus aircraft."

I think the last paragraph may have to be changed.
After one's initial PPC on a new type, approach-to-stall training is not required by the CARS (Canadian Air Regs):

(e) Manoeuvres
(i) At least one steep turn in each direction with a bank angle of 45° and a change in heading of at least 180° but not more than 360°;
(ii) Approaches to stalls

For the purpose of this manoeuvre the required approach to a stall is reached when there is a perceptible buffet or other response to the initial stall entry.

The following approaches to the stall are required during initial and upgrade PPC's:
(A) one in the take-off configuration, except where a zero-flap take-off configuration is normally used in that model and type of aeroplane;
(B) one in a clean configuration; and
(C) one in a landing configuration.
One of the approaches to stall shall be performed while in a turn with a bank angle of between 15° and 30°.
(iii) Steep turns and approach to stalls are not required when the PPC is conducted using either a LOFT scenario, a scripted PPC or a fly-by wire aeroplane; and
(amended 2000/12/01; no previous version)
(A) for an initial PPC on aeroplane type, steep turns and approach to stalls have been satisfactorily demonstrated during initial training;
(B) for a semi-annual or an annual PPC:
(I) steep turns and approach to stalls that are required in the applicable annual training syllabus have been satisfactorily demonstrated during this training; or
(II) steep turns and approach to stalls are not required in the applicable annual training syllabus.

Last edited by PJ2; 29th Mar 2012 at 17:58.
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Old 29th Mar 2012, 21:23
  #1070 (permalink)  
 
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More hamstering!

Several nose-up inputs caused a decrease in the pitch attitude and in the angle of attack whose values then became valid, so that a strong nose-down input led to the reactivation of the stall warning.
Post #1690 in AF447 - Thread No.5.
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Old 29th Mar 2012, 21:53
  #1071 (permalink)  
 
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The hamster has also noted that a certain contributor is still swearing blind that the climb was uncommanded, despite all evidence to the contrary, and the hamster is heartily sick of it.
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Old 29th Mar 2012, 22:20
  #1072 (permalink)  
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thanks mm43. Takata's #1692 is also interesting in that it touches on the baro-inertial vertical speed parameter! HtB...wait!...there's more! ;-)

Dozy, gums, nice to see you back for a visit and contributions. I look in once in a while and this time decided to join in for a bit but need to return to standby mode.
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Old 29th Mar 2012, 22:59
  #1073 (permalink)  
 
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Snoop un sytème dynamique doit être observable et gouvernable

"Effective aircraft" does not mean that you have, from left to right, a box for "human", an other independant "man-machine interface" box, and a third independant box "machine/system".

The three are mixed inside the effective aircraft. It is the interest of this concept to say that. The study of instabilities as Aviation SAfety and Pilot Control (so early as 1997) shows how it is wrong to imagine the system is well or faulty and the man is faulty or well, and shows it is the best way to continue with oscillations and divergences, and to never improve.

As any dynamic system, the AF447 effective aircraft has mandatory two qualities :
1. it must be observable
2. it must be controllable

1. To be observable the matrix describing the effective aircraft must include all the men-parameters, and all the system-parameters, it is a very big matrix, much bigger than this one from an non fbw aircraft. The correspondant sensors have to be connected.

To be controllable, the determinant of this matrix is not allowed to be zero. Correspondant actuators must be connected.

The man-machine interface is not an isolated box, but concerns many functions of the big matrix who must not be faulty, and allows the effective aircraft to be always observable and controllable.

The human factor is very much more complicated that a short description of psychologically confused crew in one isolated box It has his place in any of these many functions of the effective aircraft matrix.

The designers of the aircraft have to analyse very closely if all these many functions do what is expected from them.

For instance, if it is only the system who "observes" the AoA ("incidence" in french) (AoA present in the traces) , but the pilot has to take decision, to control the aircraft, we doubt about his real ability to control the effective aircraft without these information, and we can guess something is wrong in this architecture. Then the pilot is no more able to achieve his pilot task.

It has also to be said that the law does the airline who sells the ticket, responsible, is it directly or through his agent failure.

Last edited by roulishollandais; 31st Mar 2012 at 17:29. Reason: replaced wrong english world "fautive" to "faulty" : thanks ChrisN !
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Old 30th Mar 2012, 02:26
  #1074 (permalink)  
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roulishollandais;

Re, "As any dynamic system, the AF447 effective aircraft has mandatory two qualities :
"1. it must be observable
"2. it must be controlable"

Je'm'excuse - Please forgive me if I misunderstand, but it is already this way in transport aircraft.

I'm not sure what you mean by "effective aircraft", but having flown Douglas, Boeing, Lockheed from 1973 and now the Airbus aircraft since 1992 these aircraft (A320 series, A330/A340 series) are eminently, (éminemment), "observable and controllable". They do not present unusual difficulties which require greater skill or knowledge than other transport aircraft today.

Nor do the accident rates indicate a large difference between aircraft types.

However, no aircraft, no design I know of is controllable or observable when it is taken into a full stall.

AF447 was recoverable even after entry into the stall but it required that the stick be pushed fully forward and held there until the wing began flying again. That would take between 15,000 and 22,000ft (I've flown this in the sim many times). This is Machinbird's "unloading of the wing" to which he referred some pages back.

Any transport aircraft in which the controls were moved in a way so that the stall of the wing is maintained as they were in AF447 would remain stalled.

Said another way, a B777 pulled up in the same manner and handled the same way as this aircraft was would also crash.

Also, I do not buy the sidestick vs control column argument one bit. Any pilot watching the pitch attitudes seen here does not need sidestick or column position to tell him/her that something extremely serious is about to happen if control of the aircraft isn't taken over immediately and the nose lowered to normal cruise attitudes.

This is the part that is very definitely not complicated.



Quite frankly, when I started, I flew with WWII guys who, if that kind of flying was ever done with the airplane he might break your arm while taking control from you. These guys were not pleasant to fly with but they knew how to stay alive in marginal conditions and made sure everyone else learned, one way or another.

Thank goodness those days are gone (because they also did stuff that scared the living daylights out of me), but today we talk about "managing" an airplane through the FMGCs and Autopilot instead of flying it. I recall watching someone actually try programming the Stadium approach to 31 at LaGuardia because he was uncomfortable flying it and that was a long time ago now.

In the present system, 99.9% of flights work well with SOPs, CRM, appropriate use of automation (according to enlightened airline policies which permit hand-flying), but the loss of such skills is nevertheless no longer a blip but a trend.

Last edited by PJ2; 30th Mar 2012 at 03:53.
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Old 30th Mar 2012, 04:54
  #1075 (permalink)  
 
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Originally Posted by PJ2
Thank goodness those days are gone (because they also did stuff that scared the living daylights out of me), but today we talk about "managing" an airplane through the FMGCs and Autopilot instead of flying it. I recall watching someone actually try programming the Stadium approach to 31 at LaGuardia because he was uncomfortable flying it and that was a long time ago now.
Now it's the Expressway visual to 31. As in the Long Island Expressway. Sadly, many guys build a place/bearing/distance off of DIALS and link it to the course fix for 31. Cross DIALS at 180kts, gear down and flaps 2, dial in some vertical speed, drop the rest of the flaps, manage the speed and all you have left to do is click the AP off on final. The techno savvy FO's look at me like I'm a fossil when I click off everything at DIALS and just fly it by the seat of my trousers.
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Old 30th Mar 2012, 05:09
  #1076 (permalink)  
 
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Clandestino
If I can perhaps explain further the situation is a lot more complex than my sentence indicates at first glance. A significant factor in all this is that the training and cultural deficiency doesn't necessarily manifest itself in a series of similar or repeated incidents and also that most pilots will not be affected by it. I suspect that every airline has pilots who whilst not being inadequate are not up to the skill levels of their counterparts. Most airlines are adept at weeding these out or conducting training in such a way that those individuals never become a threat. However, occasionally it seems an airline develops a culture which neglects training and develops a casual culture allowing a threat to develop. Examples where this can be identified would be Pan Am, Korean Airlines and China Airlines.
The incidents that happen do not occur in the same area but rather manifest themselves as lapses of judgment which a well trained pilot would not make. An airline in this situation may well have many competent and professional pilots but a laissez faire attitude. One thinks here of Pan Am's flight attendants unofficial blacklist of captains to avoid. Air France seem to have fallen into this situation - the past years incidents suggest that training is deficient and that culture is also an issue. The Air France safety audit report makes disturbing reading and what I note is that the terminology used to refer to the culture is similar in nature to the other airlines. It may be that we can consider this crew exceptionally unable but the A380 incident for example shows a disregard for basic standards at Air France that suggests otherwise.
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Old 30th Mar 2012, 05:40
  #1077 (permalink)  
 
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Selected Items, Part 25—airworthiness standards: Transport category airplanes

Granted the A330 was not certified initially under US guidelines, but I thought it interesting to see how well it met US standards. As the title says, this is selected information by me.
§ 25.181 Dynamic stability.
(a) Any short period oscillation, not including combined lateral-directional oscillations, occurring between 1.13 VSRand maximum allowable speed appropriate to the configuration of the airplane must be heavily damped with the primary controls—
(1) Free; and
(2) In a fixed position.
It would seem that the A330 meets this standard very well...............until it gets into Alt2 Law. Then in is not heavily damped in roll.
§ 25.201 Stall demonstration has some interesting specifications:
(3) As soon as the airplane is stalled, recover by normal recovery techniques.
(d) The airplane is considered stalled when the behavior of the airplane gives the pilot a clear and distinctive indication of an acceptable nature that the airplane is stalled. Acceptable indications of a stall, occurring either individually or in combination, are
(1) A nose-down pitch that cannot be readily arrested;
(2) Buffeting, of a magnitude and severity that is a strong and effective deterrent to further speed reduction; or
(3) The pitch control reaches the aft stop and no further increase in pitch attitude occurs when the control is held full aft for a short time before recovery is initiated.
AF447 seems to have demonstrated #1 and #3 a number of times during the prolonged stall.
#2 Buffeting apparently was not a strong and effective deterrent to the crew of AF447 and the Captain back in the cabin apparently did not recognize it either.

Is this knowledge well known among crews in general? Shouldn't it be? Suppose your stall warning system fails?
§ 25.207 Stall warning.

(b) The warning must be furnished either through the inherent aerodynamic qualities of the airplane or by a device that will give clearly distinguishable indications under expected conditions of flight. However, a visual stall warning device that requires the attention of the crew within the cockpit is not acceptable by itself. If a warning device is used, it must provide a warning in each of the airplane configurations prescribed in paragraph (a) of this section at the speed prescribed in paragraphs (c) and (d) of this section.
It has been discussed a number of times in the AF447 threads, but the amazingly minimal response of the crew to the audible stall warning indicates to me that the concept of stall warning needs better human interface engineering in general.

For example, Colgan overrode his stick pusher! Maybe what is needed is not more force, but something that is harder to ignore. I really liked my pedal shaker in the Phantom, but the stick shaker is more applicable to the airline environment. Has anyone seen a better warning system? We do not seem to have quite the correct solution yet.
Here is your link to the reference: Electronic Code of Federal Regulations:

Last edited by Machinbird; 30th Mar 2012 at 05:44. Reason: Add reference
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Old 30th Mar 2012, 07:27
  #1078 (permalink)  
 
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Unloading the wing

Hi,

PJ2,


unloading the wing is used to prevent entering a stall, even when the aircraft is well below its normal level flight stall speed.


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Old 30th Mar 2012, 07:31
  #1079 (permalink)  
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TTex600;

Yes, Expressway 31, thank you. We used the FDM program to monitor these approaches (de-identified) and then picked a gold standard, hand-flown approach, turned it into an animation and showed the troups, the idea being "the window". The numbers were as you say.

It's not a matter of being a whiz with the automation - that's easy stuff. It's a matter of thinking ahead two to six miles and keeping an eye on the guy you've been cleared the visual behind, at night, against NY city lights.

O.C., good thoughts - in my view you do capture some of the factors which I think are at the heart of this accident. I also agree with you on the Op-Safety Review - despite the caution not to view the document as connected in any way to the accident, the document means something...not everything, but it is a reasonable part of the mix.
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Old 30th Mar 2012, 08:11
  #1080 (permalink)  
 
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Thanks, Old Carthusian, fully concur.

For example, Colgan overrode his stick pusher! Maybe what is needed is not more force, but something that is harder to ignore.
Seemingly the stall warnings in both Colgan and AF447 cases were not ignored but the reactions to them were terminally wrong. We are not necessarily looking at perception but rather cognition malfunction.

Is this knowledge well known among crews in general?
It is. trick is knowing it so well it could be remembered easily at 4 am.
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