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AF 447 Thread No. 6

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Old 31st Aug 2011, 10:37
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Originally Posted by xcitation
PF/PNF did fly pitch and power but it was for the low altitude UAS as they had practiced in the sim, Rio departure, 3 months prior to the incident. The key difference being the high 15 deg pitch at low altitude UAS compared with 5 deg pitch high altitude (now revised 2.5 degree). No high altitude UAS was trained for in the sim. Therefore it would appear they both applied the nearest training they had in the abscence of specific training.
I disagree, here.
Had they followed the same drill as in their sim check (Rio depature) they would have :
- indeed seeked for 15° pitch attitude
- but also set TOGA at the same time.

TOGA was selected around 02:10:50, i.e. 40" after the NU first input, and at a time where the PF was lowering the nose, and just after the stall warning begun.
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Old 31st Aug 2011, 10:44
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VSI

HazelNuts39
Quote:
Originally Posted by RetiredF4
What are the limits, within those the VSI needle displays vertical speed?
Maybe this picture from a sim gives a rough idea?
Thank you, that´s what i´m looking for.

If i read it correct, it shows a descent rate of 1.800 fpm (number 18 besides the needle)

Would it look the same and would there be the number 100 for a 10.000 fpm descent rate?
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Old 31st Aug 2011, 10:55
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Originally Posted by Retired F4
What are the limits, within those the VSI needle displays vertical speed?
And what is the picture, when vertical speed is greater then the display available?
VSI needle is green and it beautifully simulates looking at the needle hinged to the right of the scale and being looked at through narrow slit - it appears to thicken with deflection from zero. Scale limits are 6000 fpm up and down, when they are exceeded needle is stuck at maximum deflection but it turns yellow as the digital readout adjacent to it. I don't recall any limitation to digital VSI value.

It's possible, though I can't say how probable it is, that VSIs blanked out sometimes during the descent. Someone with engineering expertize of A330 ADIRS and displays would be better suited to answer that than me.

Originally Posted by CONF iture
Let me see, if rudder control is electrical does it mean it can be mechanically-controlled too … ?
Rudder actuators are mechanically connected to pedals via mech mixer. Yaw damping, turn coordination, trimming and travel limit are achieved electrically. THS actuator is mechanically linked to trimwheels. FCOM chapter 1.27.10 and 1.27.30, part that describes mechanical backup refer.
Originally Posted by CONF iture
'Arrogant' takes double 'R' I think but I’m not sure about 'Pretentious' is it double 'T' ?
I couldn't have put it better myself, sir.

Originally Posted by xcitation
PF/PNF did fly pitch and power but it was for the low altitude UAS as they had practiced in the sim, Rio departure, 3 months prior to the incident.
Seemingly they forgot everything they ever learnt about high altitude aerodynamics and performance. Actually, they needed not to know anything about it, it would be enough just to follow the procedure in order to survive. If your notion is proved to be true (which I mildly doubt) crew applied part of UAS drill that was not to be used above acceleration altitude (most of the time 1500 ft above runway) at FL330. I say it was incap.

Originally Posted by Machinbird
Ian W knows of what he speaks.
I prefer to have the opinion that he does not. It is much more comforting to think his biased views stem from the ignorance of the matters aeronautical, rather than from agenda. Basically he claims that the cognitive overload of AF447 crew makes the whole Airbus man/machine interface wrong and disregards tens of thousands normal flights made by FBW Airbi crews every day. He disregards 32 UAS that ended as very minor incidents. Applying such a hasty generalization is something that we have used to expect of politicians every day, yet it doesn't make it a lesser logical fallacy.

Originally Posted by Machinbird
Any of you who think you can always multitask in a highly demanding environment have forgotten your early days of instrument training where it was easily possible to break down your scan
Multitasking, whether it involves human or electronic brain, is not about doing many things at once. It is about properly managing cognitive/computational resources in sequential manner. Of course I can do just one thing at the time but in proper instrument scan, that one thing can be done a couple of times a second.

Pilots who don't show improvement of their instrument skills during their initial training to the point where they meet minimum applicable standards, don't get IR and are therefore unable to fly airliners. In a perfect world, anyway. Curves of pilot skill required vs pilot skill available are as important to flying as power required vs available. When skill required exceeds available, trouble is guaranteed.

Originally Posted by Ian W
Books will be written about this incident
To borrow the phrase from Peter Garrison: most of them will be written by the folks with "movie rights" stenciled on their glasses.
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Old 31st Aug 2011, 11:38
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JD-EE
There is no evidence that data presented to the pilots was inadequate and even if it was this is another training issue. There are procedures for dealing with loss of information which should be followed. It is not a problem with the aircraft or its displays.

I am interested in the idea that humans can only handle one cognative input at a time. Under certain circumstances this is true but only during times of stress. Outside such situations the human brain can handle several. The point of proper training, CRM and well defined procedures is that they put the pilot into a situation where the cognative input is controlled and directed towards solving the situation. All of these factors give the pilot the ability to overcome the narrowing of inputs and continue to function normally. Iain W's reference to Wickens MRT Model though could be thought of as misleading - it is a much more complex theory than the element presented and in fact as Wickens talks about people having problems when handling more than one task which requires the use of the SAME resource. This is slightly different to a statement that we are able to handle only one cognitive input at a time. Visual perception and auditory perception would in fact constitute two different resources. Thus conducting a proper instrument scan and hearing the stall warning would not be mutually exclusive. I do not feel that this can be an adequate explanation for the accident and in fact would even go as far as to doubt it especially as Wickens also notes that as workload increases performance can also increase.
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Old 31st Aug 2011, 12:52
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Dear Ian W!

I take your comment as one of the most significant in the af 447 case and on this forum. This what it all boils down to, a human error with huge consequences. Lost in 90 seconds. What really scares me is how close you are to catastrophe as a defenseless passenger when those ones who are paid for, respected, carefully selected and appointed to deal with just this type of situations, are so near their limits of capacity. Bear in mind also those "Close call", similar cases referred to earlier.
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Old 31st Aug 2011, 13:18
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human cognitive limitations

Hi Clandestino,

You will have had cognitive overload on many occasions - but probably have not realised it. Have you never missed an RT call?

These pilots are suffering from cognitive overload - and all they are doing is flying an approach:

Those who don't appreciate that it is a human limitation should not be in aviation.
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Old 31st Aug 2011, 13:32
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Originally Posted by RetiredF4
If i read it correct, it shows a descent rate of 1.800 fpm (number 18 besides the needle)
Yes.
From the FCOM:
The displayed vertical speed information is normally based on both inertial and barometric data. If inertial data is not available, it is automatically replaced by barometric information. In this case, the window around the numerical value becomes amber.
No mention of what is to be displayed when the barometric value is unavailable in the FCOM. I thought BEA wrote something about that in one of its interim reports, but cannot find it at the moment.

Originally Posted by RetiredF4
Would it look the same and would there be the number 100 for a 10.000 fpm descent rate?
Look the same : almost.
As V/S is > 6000 ft/min (climb or descent):
- the needle would turn amber
- the needle would stay at the end of the scale
As V/S is > 6000 ft/min (climb or descent):
- the analog display would turn amber, too
- no mention (FCOM) of a change of value/scale with this display for 10K ft/min, so I assume it would read 100.
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Old 31st Aug 2011, 13:42
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Cool

Hi,

Hi Clandestino,

You will have had cognitive overload on many occasions - but probably have not realised it. Have you never missed an RT call?

These pilots are suffering from cognitive overload - and all they are doing is flying an approach:
Same .. but with a tragic end at take off (at 6min10)
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Old 31st Aug 2011, 14:18
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WRZ

Seems to be a fascinating movie. Thanks for the link jcjeant.
I haven't read the report, so I don't know, but it looks that the crew decided to voluntary ignore the warning, or link that warning to something else they could deal with without rejecting ?
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Old 31st Aug 2011, 14:28
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Captain Clandestino

Originally Posted by Clandestino
Rudder actuators are mechanically connected to pedals via mech mixer. Yaw damping, turn coordination, trimming and travel limit are achieved electrically. THS actuator is mechanically linked to trimwheels. FCOM chapter 1.27.10 and 1.27.30, part that describes mechanical backup refer.
As I told Dozy, SmartCockpit is not necessarily updated. I have well tried to put doubt in your mind … but what could we teach to a guy with the head of your size after all.



Now, give a call to Airbus, they might reinstall a mechanic link on the rudder, just for you. Who knows ?

I make fun of you, Captain, but by reading your replies to others ... you fully deserve it. Reserve, modesty, humility … can be part of the picture too you know ?
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Old 31st Aug 2011, 15:12
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Clandestino:
More correct version would be: pilots must be able to manually fly the aeroplane out of any situation automatics put it into.
Cannot agree more. If one could get that written into an FAA training standard, and into design standards, and I believe three generations of airline pilots will thank you profusely.
It would be interesting to hear what this might do to training costs ... and thus ticket costs. Ya get what ya pay for, eh?
Ian W knows of what he speaks.
I agree in general, in terms of task load and cognitive channels.

I learned well how any crew can be eventually task saturated. It was done to me, and by me, in some of the more rigorous sim training events we used to do in my squadron, a lifetime ago ... some of the best training I got.

Any of you who think you can always multitask in a highly demanding environment have forgotten your early days of instrument training where it was easily possible to break down your scan.
Yep.
There is no pilot alive who's scan cannot be broken by the right circumstances. It is how you recover from this mess that separates the men from the boys.
Yep
The term scan as I am using it refers to the multi-sensory process of acquiring information regarding your flight from all sources. It is very close in meaning to situational awareness.
Machinbird, I respectfully submit that scan (instrument / vfr / combined) is a subset of situational awareness. It is a critical part of what informs your situational awareness, but not all of it.
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Old 31st Aug 2011, 15:23
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@CONF iture:

A330 has 2 versions of the ruddercontrol system.

1/ original system with mech cable loop (like F-GZCP) is called - mechanical rudder - altough the cable loop is a backup system.

3/ the enhanced version without mech cable loop is called - electrical rudder - the backup is here electrical by means of the BCM (Backup Control Module).

Last edited by A33Zab; 31st Aug 2011 at 15:42.
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Old 31st Aug 2011, 18:51
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Originally Posted by rudderrrudderrat
You will have had cognitive overload on many occasions - but probably have not realised it. Have you never missed an RT call?
I certainly did, but as a firm believer that aeroplane flies thanks to principles discovered by Bernoulli and not Marconi, I have never dropped the aeroplane to fly the mike.

Originally Posted by rudderrudderrat
Those who don't appreciate that it is a human limitation should not be in aviation.
And what bearing on AF447 does it have? That it was inevitable? That we have to change instruments to fight it? That the 32 crews that didn't put themselves into stall when faced with UAS were just lucky? Of course anyone can be overloaded but simple loss of IAS resulting in cognitive overload (provided it's proven) is not something anyone reasonably informed of airline flying would be expecting to see. Besides, if cognitive overload resulted in stupor, aeroplane would probably fly itself to the other side of the ice clouds and chances are everything would be just fine afterwards.

Originally Posted by CONF iture
As I told Dozy, SmartCockpit is not necessarily updated. I have well tried to put doubt in your mind … but what could we teach to a guy with the head of your size after all.

Now, give a call to Airbus, they might reinstall a mechanic link on the rudder, just for you. Who knows ?

I make fun of you, Captain, but by reading your replies to others ... you fully deserve it. Reserve, modesty, humility … can be part of the picture too you know ?
Originally Posted by A33zab
1/ original system with mech cable loop (like F-GZCP) is called - mechanical rudder - altough the cable loop is a backup system.
Thank you very much, gentlemen, for kindly answering my question whether Airbus has recently modified the A330 rudder. So it did, but seemingly not before F-GZCP left the Toulouse on her maiden flight. Seemingly we can not blame whatever happened to AF447 on alleged idiosyncrasies of the new electric rudder after all.

CONF iture, reservedly, modestly, and humbly claiming that e.g. Habsheim crash was caused by software protecting the aeroplane was never my cup of tea. I prefer to have my opinions as closely aligned to facts as it is possible and am not particularly caring about sugarcoating. I accept that many time I will be wrong but I also expect that I will be corrected by someone more knowledgeable than me. Way the corrections are delivered is of no particular interest to me. FWIW, I have no problem with them being extremely derisive, as long as I get facts straight. I have always preferred substance to style.

Originally Posted by ventus45
Perhaps a better way to put it would be:
"An aircraft that can not be demonstrated to be average line pilot worthy, shall not be certified as airworthy".
That's one of the main points of airworthiness certificate since the first one was issued.
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Old 31st Aug 2011, 19:21
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Previous 32 UAS events

Originally Posted by Clandestino
That the 32 crews that didn't put themselves into stall when faced with UAS were just lucky?
Basically, yes.

Those previous 32 UAS events (which you've mentioned a few times now, in an apparent attempt to show that AF447 was the exception), were not all identical in their effects, and many of those crews also made various mistakes in handling them (some of which were the same as AF447 e.g. not treating it as a UAS event in the first place!). Look at BEA Interim Report 2, page 51 onwards (English version of the PDF) for the evidence.
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Old 31st Aug 2011, 19:26
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Originally posted by HazelNuts39 ...

Alpha Max for M=0.65, the Mach number at 02:10:56, is 7.6 degrees.
Thanks for the reply and the attached s/s graphic. Will have a good look at it shortly.
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Old 31st Aug 2011, 19:45
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Perhaps a better way to put it would be:

"An aircraft that can not be demonstrated to be average line pilot worthy, shall not be certified as airworthy".
Ventus, since most of the people who fly the 330 seem to like flying it, and seem to manage flying it, odds are that in this case, it meets that standard.
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Old 31st Aug 2011, 20:18
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Originally Posted by Clandestino
That the 32 crews that didn't put themselves into stall when faced with UAS were just lucky?

Originally Posted by Diagnostic
Basically, yes.

Those previous 32 UAS events (which you've mentioned a few times now, in an apparent attempt to show that AF447 was the exception), were not all identical in their effects, and many of those crews also made various mistakes in handling them (some of which were the same as AF447 e.g. not treating it as a UAS event in the first place!). Look at BEA Interim Report 2, page 51 onwards (English version of the PDF) for the evidence.
Of course they aren't all the same, but one can't help noting a few similarities between the 13 incidences they examined more closely: IMC, cruise level, slight to strong turbulence, a/p disconnect, alternate law (in 12 cases). Sounds quite familiar so far...

"The variations in altitude stayed within a range of more or less one thousand
feet. Five cases of a voluntary descent were observed, of which one was of
3,500 feet. These descents followed a stall warning;"


That indeed makes AF447 sort of an exception, having quite involuntarily descended 48000 ft from FL350.
Whatever the other crews did - they didn't point the nose into orbit and kept it there for minutes a couple of seconds after they had to start flying their plane themselves. Please tell me that isn't considered a matter of luck these days?
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Old 31st Aug 2011, 20:38
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Originally Posted by Zorin_75
Whatever the other crews did - they didn't point the nose into orbit a couple of seconds and kept it there for minutes after they had to start flying their plane themselves.
Agreed, of course

The point I was trying to make, is that to lump the other 32 UAS together as some kind of non-events, and not the near disasaters which some could have been due to poor / incorrect handling in some cases (e.g. re-engaging A/P immediately after the disconnection, not recognising that it was a UAS at all etc.) is ignoring that some of them could have turned out differently IMHO.

As I agreed above, other crews didn't make the same major mistake as AF447 which you mention, but potentially disasterous mistakes in handling some other UAS events were made, as described in the report. That none of those resulted in crashes does have an element of luck IMHO (swiss cheese model).

Or to put it another way - I doubt that the AF447 crew were the only crew at that time, with the same lack of training/practice in handling/recognising UAS and hand-flying at cruise altitudes. If one of the other crews mentioned in the report, who didn't handle their one of the 32 other UAS well, had been in the AF447 situation at that height, time of day, flight deck situation (2 x F/O) etc. etc., would they have done better? I wouldn't bet on it. That's all I'm saying.
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Old 31st Aug 2011, 23:11
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If one of the other crews mentioned in the report, who didn't handle their one of the 32 other UAS well, had been in the AF447 situation at that height, time of day, flight deck situation (2 x F/O) etc. etc., would they have done better? I wouldn't bet on it. That's all I'm saying.
I, perhaps naively, somehow hope that pilots being competent to fly a plane are still the norm rather than the exception, but maybe you're right and the odds are decreasing. If so, we can only hope that AF447 will be a wakeup call, the price was high enough.
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Old 31st Aug 2011, 23:41
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Originally Posted by Zorin_75
We can only hope that AF447 will be a wakeup call
Agreed completely.

From what I read on here, training (which is where I see one of the main deficiencies in the set of "holes" leading to the tragedy) has already been improved. If the A/P can disengage at FL350 and dump the plane into the hands of the flight crew, in Alt2 law, in some turbulance, at 2am, then they had better be trained and allowed to practice to cope with that event. It may not be a common event (and that may have driven budget decisions about training), but the criticality of hand-flying at that altitude (as explained by the ATPL pilots here) makes me think that the AF447 crew were put into a situation they were ill-prepared for. Of course there were other factors too.

I also think that luck (that word again!) played a part with AF447, in the sense of bad luck, with the timing of the Captain's departure to go on his break. If only that had been delayed by a few mins, he would have been on the flight deck when the problems started, and so the less experienced F/O wouldn't have been PF. Also the Captain would have been "caught-up" with events because he would have been there as the situation developed, so he wouldn't have been left with that "information void" which he had upon re-entering the flight deck that night etc. etc.

Anyway, just to summarise, I only posted earlier as the comparison seemed to be being made of: 32 other crews performance with UAS = good; AF447 crew performance with UAS = bad. IMHO, as explained in that 2nd Interim Report, the comparison is not so clear-cut.
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