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AF 447 Thread No. 9

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AF 447 Thread No. 9

Old 17th Jul 2012, 09:28
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Originally Posted by rudderrudderrat
The controls would feel lighter than normal - just like roll in ALT LAW
Thereby making it easier for the pilot bent on pulling to overstress or stall the aeroplane? Isn't it unsafe design? Unlike airbus where you are presented with constant stick force?

Of course I'm indulging in mockery here; both constant force sidestick and syntethic feel yokes are well thought-out systems with good and bad sides. Pilots who use them must be well acquainted with their normal and abnormal behaviour. PPRuNers would do well to remember that "natural feeling" yokes are in reality dependent on whole lot of instrumentation and electronics to simulate DC-3 like feel in modern aeroplanes.

Originally Posted by Lyman
Buffet was not noted on CVR
Neither was any explicit comment on stall warning, however there was an inanimate object that provided some clue on CVR:

Originally Posted by BEA final report on AF447, English edition, page 93
This modification of the behaviour resulted in the appearance of a high frequency
component of an amplitude increasing to up to about 0.1 g peak-to-peak, and with
a signature that is very different from a turbulence signature of aerological origin.
Furthermore, there is a noise on track 1 of the CVR, at about 2 h 10 min 55, which may
be the impact of the microphone striking a panel, heard at a stable frequency.
Originally Posted by Lyman
Buffet was determined by analyzing accel.
Well, not just that. As pre-stall buffet is defined and measured at cockpit and IRS tend to be near C.G...

Originally Posted by BEA final report on AF447, English edition, page 93
Additional analyses were conducted with Airbus to determine if this phenomenon
could correspond to buffet. The identification of this phenomenon is complicated by
the fact that the concept of buffet is defined as accelerations at the level of the pilots’
seats and not at the centre of gravity.
..some test flights were flown:
Originally Posted by BEA final report on AF447, English edition, page 93
Airbus subsequently flew special flights to collect more accurate data at high angles
of attack and with an aircraft configuration close to that of the accident (mass, flight
level, Mach, etc.). These tests made it possible to refine the preliminary correlations
and to establish that the level of buffet was considered to be a deterrent by the test
pilots when the angle of attack was about 10°, corresponding to normal acceleration
amplitude of 1 g at the pilot’s seat. This angle of attack was reached at about 2 h 10
min 57 s during the accident flight
However, I believe 1g to be a typo in both French and English versions. 0.1 G is more likely and nevertheless represents very significant vibration. At 1G amplitude, aeroplane would be buckling like mad.

Originally Posted by Lyman
The aC did not pitch nose down at Stall.
Because CM2 got in his head that he has to keep the nose high, even if it meant setting TOGA and pulling all the way back. That's the only constant about his behaviour; he pulled when stall warning blared, he pulled when it did not. He pulled when F/Ds told him to pull, he pulled when they were knocked out.

He was quite successful in keeping the nose high, too.

Originally Posted by gums
pull and pull to the limits and run outta energy while transitting the stall protection limits, then get to new territory. pushing forward would have equally bad outcomes if the "overspeed" "protections" ( how I hate that term) are FUBAR due to invalid speed inputs to HAL.
We are getting somewhere. Insane pushing could eventually get as dangerous as insane pulling. So question is why push or pull at all? Many a crew has survived the UAS ordeal by making no reaction to turbulence induced, high Ma induced low threshold stall warning at all, just keeping the usual cruise attitude. They would if they have gone for memory items, too.

Originally Posted by gums
From the CVR fidelity ( could detect switch changes) and the comments by the troops, doesn't sound as if the AB330 has pronounced buffet in the stall regime.
I don't mind having shaker or blinking red STALL light installed on Airbi. I explained why it was not required to be installed. Also I believe it would not make a lot of difference in AF447: I'm not buying aural saturation theory. Seemingly CM2 disbelieved everything he has seen or heard and somehow got idea pulling will get him out of the situation. Too bad he didn't comment out loud what he believed was going on, like capt of Birgenair 301 that first told his crew to disregard the warnings only to break down a few minutes later and dismiss every speed information as false, when 2 out of 3 were correct.

Originally Posted by slats11
Why did the Captain not get a useful handover when he returned to the cockpit?
Because co-pilots' performance in the cockpit was not matched to circumstances and can be described as useless.
Originally Posted by slats11
Had things already degenerated that much.
In my book, 40° AoA in public transport category aeroplane is that much degeneration.

Originally Posted by Turbine D
Guess the TAM folks proved the Air France FCOM wrong?
Pardon my level2 English: I meant to say that usual Frankensteinan idea that aeroplane has suddenly turned into monster prepared to kill her masters at the slightest provocation, which surfaces almost every time someone is killed in aeroplane accident, has no merit. FCOM recommendation to manoeuvre with care absolutely doesn't imply that very gentle adjustments of the sidestick are required. While TAM crew went against the recommendation of care, their roller-coaster ride did prove you can get away with being severely ham-fisted in high-altitude manual flight, as long as amplitude and average of your shenanigans keep you inside the envelope.

In law degradation, or control problem or whatever, control displacement or force gets second seat to taking feedback from instruments! "Hoot" Gibson did not care a little bit that post-dive it took him almost full roll control and considerable force to keep the aeroplane level, he was just interested in keeping it level and applied as much deflection and force as needed to achieve that goal. As should any instrument rated pilot.

Originally Posted by Turbine D
I am sorry Sir, that I gave you credit for something that didn't deserve credit.
Apology accepted.

Originally Posted by rudderrudderrat
It's a clue that you've just entered a region of much warmer air suddenly.
No trace of it on FDR concurrent with the comments. Blockade of TAT probe did rise the apparent temperature 40 seconds after the comments were made.
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Old 17th Jul 2012, 09:59
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Quote:
Originally Posted by Lyman
The aC did not pitch nose down at Stall.
Clandestino
Because CM2 got in his head that he has to keep the nose high, even if it meant setting TOGA and pulling all the way back. That's the only constant about his behaviour; he pulled when stall warning blared, he pulled when it did not. He pulled when F/Ds told him to pull, he pulled when they were knocked out.
He was quite successful in keeping the nose high, too.
Just to make sure that it is now understood, that after the initial pull with too high pitch attitude "not pulling" anymore" would not have been the solution to get the nose down by itself. A nose down push is necessary to change the trajectory in ALt2.

See below. I know, that Oozlum bird again....


BEA final report 2.2.5 (my bolding)
However, positive longitudinal static stability on an aeroplane can be useful since it allows the pilot to have a sensory return (via the position of the stick) on the situation of his aeroplane in terms of speed in relation to its point of equilibrium (trim) at constant thrust. Specifically, the approach to stall on a classic aeroplane is always associated with a more or less pronounced nose-up input. This is not the case on the A330 in alternate law. The specific consequence is that in this control law the aeroplane, placed in a configuration where the thrust is not sufficient to maintain speed on the flight path, would end up by stalling without any inputs on the sidestick.

Last edited by RetiredF4; 17th Jul 2012 at 14:14.
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Old 17th Jul 2012, 11:03
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OK so no spike in TAT concurrent with increased cockpit temperature.

So what else can suddenly lead to increased cockpit temp? I mean both guys commented on an abrupt and significant increase in temp. That's odd surely. So what are the possible explanations for this? (other than increased TAT overwhelming climate control which the evidence does not support as the explanation)
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Old 17th Jul 2012, 11:13
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Originally Posted by Clandestino
However, I believe 1g to be a typo in both French and English versions.
BEA#3 page 17:
Note 1: The appearance of buffet (buffet onset) is defined by an oscillatory vertical acceleration whose amplitude reaches 0.2 g from peak to peak at the pilot’s seat. The notion of deterrent buffet is subjective.
BEA#3 page 44:
Note: Examination of flight test data revealed, based on the frequency and amplitude, that this signature could in fact be that of buffeting. By drawing analogies with the flight tests, the amplitude of 0.1 g at the centre of gravity suggests that the amplitude of the buffeting at the pilot seat is high (approximately 0.6 g peak to peak).
I don't think it is a typo. Buffet onset is defined as 0.2 g and is considered the lowest level of perceptible buffet. The buffet onset boundary is scheduled in the FCOM and QRH. In the conditions of AF447 it occurred at M=0.64 and AoA=7.7 degrees. The 'deterrent' buffet described on page 93 of the Final Report is so severe that it is considered an effective deterrent to further speed reduction, so that in certification stall tests the airplane would be considered 'stalled' and recovery would be initiated as soon as that condition is reached.

P.S. Sequence of AF447 events:
02:10:51 AoA=6 deg, stall warning triggered
02:10:53 AoA=7.5 deg, buffet onset
02:10:57 AoA=10 deg, deterrent level of buffet reached

Last edited by HazelNuts39; 17th Jul 2012 at 12:16. Reason: P.S.
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Old 17th Jul 2012, 12:09
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Hi slats11,
OK so no spike in TAT concurrent with increased cockpit temperature.
There are very few TAT recordings reported.
However, please see the report published in July11, page 86.
Time 0hr.09min FL. 34.992 Static temperature (°C) -43.5
Time 2hr.10 FL 35.044 SAT -38.8

From the CVR report:
02.06.54 the crew say "Minus forty-two we won’t use the anti ice that’s a plus."
02.08.41 "What's that smell" .. It's Ozone...You can feel already that it's a lot hotter...It's amazing how hot it is all of a sudden.."
02.09.40 Change in background noise (from impact ice crystals)
02.10.03 Engine anti ice is turned on (in response to TAT being warmer than -40)

The TAT has warmed from -42°C to -38.8°C over a very short time.
They must have just entered the warm rising air of a CB.

The Turbine Bypass Valves in the Air Conditioning Packs move slowly, the SAT rise was felt by the air conditioning temperature rise.

Last edited by rudderrudderrat; 17th Jul 2012 at 12:11.
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Old 17th Jul 2012, 13:41
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The TAT has warmed from -42°C to -38.8°C over a very short time. They must have just entered the warm rising air of a CB.
OK. But this is at odds with Cllandestino

Originally Posted by rudderrudderrat It's a clue that you've just entered a region of much warmer air suddenly.
No trace of it on FDR concurrent with the comments. Blockade of TAT probe did rise the apparent temperature 40 seconds after the comments were made
So did the outside temp really increase as the crew believed (and turned on anti-ice)? Or was this increase due to a blocked TAT probe?

OK. Assuming they are talking about increasing cockpit temp rather than outside, I guess the possibilities include:
1. Increased heat production within cockpit. Unlikely.
2. Increased transfer of heat into cockpit. Increased outside temp and lag in climate control adjusting for this would be one cause, but there are others..
3. Decreased transfer of heat out of cockpit.
4. Loss of (or decreased ) air flow around the pilots leading to decreased evaporative cooling. This would only cause an perception of increased temperature rather than a true increase in temperature.

Many of these explanations involve altered internal air flow. So what exactly is the "change in background noise" noted twice at 02.08.17 and 02:09:40. During this 83 second period, the PF questioned whether the PNF had adjusted the A/C, both pilots noted a smell of ozone, and both pilots noted increased cockpit temp.

I can accept increased TAT due to rising air from Cb, and this explains the ozone. However Clandestino states TAT did not rise during this period, and further that the FDR did not record a change in vertical acceleration.

If Clandestino is correct, there must be another explanation for the increased temperature. The changed background noise and the smell of ozone (or whatever) may be relevant to this explanation.
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Old 17th Jul 2012, 13:59
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Lyman,
Yes, my question was rhetorical. I fail to see what the temperature has to do with how the crew handled the last four minutes or so of "flight".
Slats wrote: The captain seemed very slow to act.
Slow to act? The captain did not act at all. He merely dispensed advice, some of it useful (use the rudder rather than the ailerons), some of it not (repeatedly urging that the wings be kept level), and at one point exclaimed despairingly "Damn, that's not possible!" (without specifying what wasn't possible).
I always thought the captain is the guy who's supposed to take over when things go pear-shaped.
Slats is also under the impression that the PNF had better situational awareness than the PF.
This is debatable. When the PNF formally took control from the PF, at 2:11:37.5, instead of pushing the sidestick forward, he held it hard left exactly as the PF had been doing. That's just one example of deficient SA. However, to his credit, the PNF did realize that they were not in an overspeed condition and told the PF smartly to stow the speed brakes that he was deploying at max thrust at FL297. Incidentally, this episode elicited no comment from the captain.
No, Lyman, you could not make this stuff up.
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Old 17th Jul 2012, 14:08
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Originally Posted by slats11
I can accept increased TAT due to rising air from Cb, and this explains the ozone. However Clandestino states TAT did not rise during this period, and further that the FDR did not record a change in vertical acceleration.
Blockage of TAT probes tend to occur suddenly, similar to pitots. In this case the TAT rose gradually between 2:09:52 and 2:10:04, while the airplane was entering a vertical gust that reached 22 kt at 2:10:03.5 - see figure 64 of the Final Report, the correct one, not the figure 64 erroneously included in the English version.
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Old 17th Jul 2012, 14:09
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Hi slats11,
OK. But this is at odds with Clandestino
It probably is - but I'm using BEA's reports as my reference, not something that Clandestino thinks.
So what exactly is the "change in background noise" noted twice at 02.08.17 and
02:09:40.
From the CVR report 2012, page 23:
"2 h 09 min 46. Background noise increases (typical noise of impact of ice crystals, identified by A330-340 pilots) "

However Clandestino states TAT did not rise during this period, and further that the FDR did not record a change in vertical acceleration.
The autopilot was engaged, flying ALT CRUISE. Why do you think there would be a change in vertical acceleration? The AP would simply reduce the pitch attitude slightly.
I posted the FDR TAT record in my previous, and the crew's observation of the TAT.

They are all classic symtoms of flying into CBs.

If Clandestino is correct, there must be another explanation for the increased temperature.
Excuse me if I don't hold my breath.

Last edited by rudderrudderrat; 17th Jul 2012 at 14:15.
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Old 17th Jul 2012, 14:41
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Blockage of TAT probes tend to occur suddenly, similar to pitots. In this case the TAT rose gradually between 2:09:52 and 2:10:04, while the airplane was entering a vertical gust that reached 22 kt at 2:10:03.5 - see figure 64 of the Final Report, the correct one, not the figure 64 erroneously included in the English version.
Fair enough. Thanks for clarifying. So then why did both pilots notice increased temp more than a minute before the TAT increased? If rising TAT led to increased cockpit temp, then the sensed TAT (measured externally) should rise before this warmer air led to increased cockpit temp.

"2 h 09 min 46. Background noise increases (typical noise of impact of ice crystals, identified by A330-340 pilots) "
Sure, the report explains this instance of increased background noise as being due to ice crystals. It makes no interpretation of the two previous references to change in background noise at 2.08.17 and again at 2.09.40. The CVR transcript merely states "change in background noise". These comments are earlier, on page 22.
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Old 17th Jul 2012, 15:16
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Y'all have been having some fun since I last visited.
Clandestino
gums
Good grief, Doze, how ya gonna get an overspeed warning if the air data system is FUBAR?
Good grief, Gums, where would the energy for overspeed come if you are at practical ceiling and pulling up like mad?
clandestino
gums
So maybe the junior crewmember up front was more worried about overspeed than stall or something else.
Maybe, but if he was, he was dead wrong and consequently just dead.
I'd rather be in a bar with you two, talking this over, a few pints included. T'would be goodness.
clandestino
AP was off and by the time descent started it was blocked off by ADR rejection due too to low forward airspeed. Capt was unable to grasp the situation so he thought it would be good idea to press the non-function AP button, without explaining it, either for the benefit of co-pilots or CVR.
Your analysis, not necessarily a fact. But I'll bet with your read on that one, if we have to go to Vegas on that.
gums
I read the CVR again, and the experienced pilot is telling the other guy to stop climbing and to be "gentle". After a minute of fruitless talk, he calls for the aircraft commander. All the while the stall warning doofer is going off.
This is CRM training module X: What does it take for the copilot to say "I have the controls," take the controls, and make the right thing happen? Over to the cockpit gradient sub discussion we go ...
Rockhound
Why was there not a proper handover to the captain when he returned to the cockpit?
slats:
Why did the Captain not get a useful handover when he returned to the cockpit? Had things already degenerated that much. He got garbled bits if information plus lots of warnings and alarms plus a feeling that things were not right ( abnormal pitch attitude). It would have been perplexing to understand what had gone wrong in the brief interval since he had left the cockpit.
The PF was task saturated. As I analyze the event, PNF had at least partially bailed out (mentally) when he called for adult supervision. (Aircraft Commander). The clue to this for me was the "where is he" and frequent call up.
That aside, the time and environment for "briefing" is when you are in control of the situation. The two up front were, from the evidence, NOT in control of the situation, but were playing catch up.
slats:
It would have been perplexing to understand what had gone wrong in the brief interval since he had left the cockpit.
Yep. Fatally perplexing.
Although we don't have the audio, it is likely that PF and PNF were somewhat agitated (or more) when the Captain returned. Lack of clear handover. And then confusion, lack of assertiveness, and likely increased agitation.
That's how I'd bet it in Vegas.
mm43
Nothing coherent (crew wise) happened in that cockpit from the A/P disconnect through to the end. It would seem that the BEA's Human Resources Group were not able to format a reasonable explanation for this behaviour either.
They were left guessing, but one wonder just what the "command climate" is at AF, and in AF cockpits. (Air France, not Air Force, about whom I have other doubts. )
Clandestino:
Because CM2 got in his head that he has to keep the nose high, even if it meant setting TOGA and pulling all the way back. That's the only constant about his behaviour; he pulled when stall warning blared, he pulled when it did not. He pulled when F/Ds told him to pull, he pulled when they were knocked out.
He was quite successful in keeping the nose high, too.
Seemingly CM2 disbelieved everything he has seen or heard and somehow got idea pulling will get him out of the situation.
Training issue, and possibly an Airbus and Air France Indoctrination Issue. Education and training go hand in hand with indoctrination.

HN39 in re buffet: thanks, well explained!

The TAT has warmed from -42°C to -38.8°C over a very short time.
They must have just entered the warm rising air of a CB.
I almost hear Linda Ronstadt singing "Heat Wave" in the background.
Rockhound
No, Lyman, you could not make this stuff up.
Well said. Truth is once again stranger than fiction.
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Old 17th Jul 2012, 15:27
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maybe i can get some support from hf experts, because it`s quite difficult to explain with my bad command of english.
there`s something missing from the BEA report,which in my mind is one important cause for the crash.
the command structure in the cp when the cp left.Bonin was the assigned pilot flying although he was younger and had less hours on type.
Maybe there was one though on his mind,that when the cp returns,he didn`t expect that he,Bonin , had given up command.that maybe the reason for taking back command from dubois .And dubois thougth the same: the cp does not expect me having taken command when he comes back.
that could be the reason for such bad crm.
I´m sure had command been given to dubois by the cp that he would have taken command immediatley from Bonin because he had a right guess.
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Old 17th Jul 2012, 15:42
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relaxed static stability

Thanks for finding that pearl about the static stability, Retired. Thank you, thank you.

For those that have not flown a FBW system that has "limits" or "protections" embedded in the flight control laws, you are only commanding control surface deflections when rotating on the the runway to get airborne. So if the system is using gee as the primary "command" or even "limit", then the elevators could be moving all on their own despite your stick inputs to achieve that gee. This is a player when at a steep climb unless the system compensates for the pitch attitude ( as the 'bus does in Normal law). The system will move the elevators and THS to achieve 1 gee, but you really should be commanded less than 1 gee. For example, at 30 deg of pitch we should be holding 0.87 gee to maintain a 30 deg pitch while climbing ( honest, the VooDoo required that until about 25K when in an afterburner climb). If you command 1 gee, then you continue to increase pitch attitude.

And now, Airbus shows us that the jet DOES HAVE a point on the pitch coefficient curve that is "neutral". It's why I jumped in here initially to show that the Viper has such a point and we didn't find it until well into the program. But the combination of relaxed static stability and the control laws ( gee command and AoA function) allowed us to get to a deep stall and stay there with hands off the stick. We got there by doing exactly what AF447 did - climb at a sufficient angle and power setting to run outta energy/aerodynamic effectiveness of the elevator before the system could get the nose down. I posited this scenario the instant I saw the graphic of the wreckage. Looked like a classic deeply stalled jet pancaking into the water at a high, very high AoA.

The BEA comment about positive static stability and stall entry was a good one. Before FBW, it worked. You had to work hard/pull hard to get to the stall. Let go and most planes would pitch nose down to achieve the trimmed AoA. But the FBW systems will allow you to get to the stall if the laws are heavily biased for gee command, and do not blend in AoA, pitch rates and so on.

The second "aha" for me was the buffet values were established. Certainly high enough for most pilots to realize that something was wrong, as in an approach to a stall. Before this, I felt that the jet was so smooth that a stall entry buffet was too low to provide a tactile warning. Personally, a buffet of 0.1 gee Nz seems adequate to provide a warning without any fancy chimes/clangs/etc. And a buffet much higher than that once in the stall should have been a very big indication of what the jet was doing.

The good news is that we can train to handle the situation, even prevent the situation.

I would also like to see Airbus use the AoA in conjunction with the gee command to keep the jet from trying for gee "uber alles". This is in alternate laws, as the thing seems to do this in Normal.

The air temp and ozone stuff seems irrelevant other than distracting the crew. And an apology to OKie. I wanted to fly the F-4 when it first came out, and even a C-130 if I couldn't make the cut for fighters. Nevertheless, I never wanted the degree of responsibility required to get a few hundred folks to their vacation venue, so took a pass on an airline job once outta the fighter community. If I screwed up, then it was my skinny butt and not a slew of others. Just my personal philosophy, and no offense to all here that have accepted the responsibility and have survived along with their passengers.
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Old 17th Jul 2012, 16:27
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Captain's late return

02:10:51 AoA=6 deg, stall warning triggered
02:10:53 AoA=7.5 deg, buffet onset
02:10:57 AoA=10 deg, deterrent level of buffet reached
With severe buffet at 02:10:57, the Captain would have felt it too. He must also have noticed an unusual, continued climb >1/2 min before that.

So why didn't he return to the flight deck earlier than 2:11:40, and should he even need a briefing from PNF to connect those dots?
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Old 17th Jul 2012, 16:43
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BWV 988
With severe buffet at 02:10:57, the Captain would have felt it too..........
I think that´s not a too difficult question to do some guessing answer.
While expieriencing buffet while flying through bad weather seems a normal and often expierienced event, buffet due to approaching stall sure was the first time in their life in an aircraft.

And even in the simulator AFAIK stall approaches are not trained with nose high attitudes but beginning from decelerating in straight and level flight.

The mindset of the complete crew was not orientated to a loss of control situation in the classical sense, meaning stall, but in the sense that the aircraft does not react like expected. "What´s happening? We dont know......"

BWV 988
He must also have noticed an unusual, continued climb >1/2 min before that.
In a full motion simulator we can feel climbs and descents, acceleration and deceleration along the longitudonal axis by just tilting the box. So pilots are not used to base their judgement on the bio vestibular system when lying in the crew bunk or being on the way to the cockpit.

When pitch is established (lets sáy 10°) and the aircraft is decelerating, the body would feel a descending sensation even if still climbing.


BWV 988
So why didn't he return to the flight deck earlier than 2:11:40, and should he even need a briefing from PNF to connect those dots?
Answer see above.

Last edited by RetiredF4; 17th Jul 2012 at 17:08.
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Old 17th Jul 2012, 19:01
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Philip,
I think you have confused the cast of characters. The captain's name was DuBois, the left-seat copilot was Robert and the right-seat copilot was Bonin.
When the captain left the flight deck to take his rest, Robert had just returned from his rest. The captain did not unambiguously assign crew responsibilities in his absence. For example, although Robert occupied the LHS, the captain did not explicitly designate him PIC.
What do you mean by "cp"?
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Old 17th Jul 2012, 19:08
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@slats11.....

"OK. Assuming they are talking about increasing cockpit temp rather than outside, I guess the possibilities include:
1. Increased heat production within cockpit. Unlikely.
2. Increased transfer of heat into cockpit. Increased outside temp and lag in climate control adjusting for this would be one cause, but there are others..
3. Decreased transfer of heat out of cockpit.
4. Loss of (or decreased ) air flow around the pilots leading to decreased evaporative cooling. This would only cause an perception of increased temperature rather than a true increase in temperature."


Could I add...

5. Loss of dedicated cooling to the avionics.

A lot of stacks of heat producing equipment. If I was a smartie, I might exhaust the heated cooling air from the avionics bay into the cockpit environment?

Might that explain the smell?

Might be easy to check, it could be entirely off base... If a fan motor went tu, could it produce the noise referenced by BEA as "increased cockpit noise" (unidentified)?

BWV988

02:10:51 AoA=6 deg, stall warning triggered
02:10:53 AoA=7.5 deg, buffet onset
02:10:57 AoA=10 deg, deterrent level of buffet reached
With severe buffet at 02:10:57, the Captain would have felt it too. He must also have noticed an unusual, continued climb >1/2 min before that.

So why didn't he return to the flight deck earlier than 2:11:40, and should he even need a briefing from PNF to connect those dots?


Long ago, I reminded myself that a return up the aisle to his (Captain Dubois) office would be seriously "uphill"... Quite a climb actually...About four times as steep as he may have "expected". He walked into three seconds of STALL WARN, so combined with the uphill climb and the chirp of STALL: "hey knucklehead, get the nose down, you looking for a swim?"

At this point, and due to Autotrim, if he continued to use Approach to Stall recovery method, he would merely "relax" back pressure, not actively lower the nose, and the THS would prevent the nose from dropping, further confusing the frustrated recovery... If there was one.

Last edited by Lyman; 17th Jul 2012 at 19:27.
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Old 17th Jul 2012, 19:12
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As a non-aviator I was interested in the many posts referring to Buffet. So I did a little research on my own with the hope of understanding this phenomena. I think I have a basic idea of what Buffet is. (Both over speed and under.)

So, the question I pose is this: could both the PF and PNF, distracted as they were by so many issues going on at the time, have thought that buffet was, instead, a result of turbulence? (The same turbulence which PF was obviously so focused on prior to AP disconnect.)
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Old 17th Jul 2012, 19:22
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rg, that's an interesting question. I surmise from three years of discussion on this topic that few to no A330 pilots have been in a training flight that included actual stall buffet. As I understand the training rig, pre stall conditions are responded to with a series of actions to prevent getting into a stall. (There is considerable merit in "an ounce of prevention being worth about 230 tons of cure" as shown by this case. )

Note: If I am wrong about this training regimen, I ask the A330 pilots and trainers to correct my surmise. Being wrong is one way to learn something.
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Old 17th Jul 2012, 19:23
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Hey rg... Any question will get you several answers here. Here's mine.

Of course the Buffet was charged off to turb, else they would have mentioned it.

Slag on, mc duff.
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