AF 447 Thread no. 4
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ACARS message "NAV ADR DISAGREE"
That message, time stamped 2:12, was received at 2:12:51. At that point in time the airplane was already in a full stall, with all airspeeds probably misreading due to pressure errors at the pitots and at the static sources due to the high AoA. I wonder if that could tell us anything about the speed displayed on PFD2 prior to stall, but can't figure it out. Anyone?
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Originally Posted by HN39
based on the entirely arbitrary assumption that the pilots observed the departure in pitch, v/s and altitude and discussed it
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Was the PNF possibly too busy/engrossed/distracted with pages of ECAM warnings and alerts to notice what the plane was doing?
GB
GB
Not noticing is something humans are very good at, unlike computers
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Hi,
Indeed you right.
BEA reacted strongly for support the Airbus claim
Indeed for "le citoyen" lambda people the note of the BEA (and emphasized in newspapers) the pilot error is what made fall the plane.
Even the minister Mariani confirmed this after the BEA release.
The seed is planted
The context of this note should be taken into account: the BEA was under pressure to anticipate their analysis of the newly recovered DFR/CVR, some results were leaked and Airbus was already claiming that the analysis of the recorded data had shown that the plane was not the problem. The BEA reacted strongly to this claim, making clear it is the only authorized entity to establish new facts about the AF 447 accident, that those leaked/unauthorized informations were not helping the families who had lost a relative, that it will soon release a first set of new facts derived from the recorders and an interim report by the end of july. A bone to gnaw, waiting for the main course.
BEA reacted strongly for support the Airbus claim
Indeed for "le citoyen" lambda people the note of the BEA (and emphasized in newspapers) the pilot error is what made fall the plane.
Even the minister Mariani confirmed this after the BEA release.
The seed is planted
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This whole "pilot error" discussion puts me in mind of the deceptive term "pilot induced oscillation" which is actually an airframe problem. PIO is often known as Pilot in the Loop Oscillation or also Aircraft Pilot Coupling, but the key point is that it is more an aircraft design problem-not so much a pilot technique issue.
I can already see that the AF447 cockpit was not well designed for pilot situational awareness in the type of flight conditions encountered by the AF447 crew: No direct AOA indications, no old fashioned steam gage altimeter unwinding, no bell or clacker on the trim wheel to draw attention to its motion, too many competing alarm sounds in the cockpit.
Then there are training issues surfacing and also fundamental how do you fly the 'Bus issues that are surfacing.
We are left with three core issues relating to piloting and aircraft systems.
I can already see that the AF447 cockpit was not well designed for pilot situational awareness in the type of flight conditions encountered by the AF447 crew: No direct AOA indications, no old fashioned steam gage altimeter unwinding, no bell or clacker on the trim wheel to draw attention to its motion, too many competing alarm sounds in the cockpit.
Then there are training issues surfacing and also fundamental how do you fly the 'Bus issues that are surfacing.
We are left with three core issues relating to piloting and aircraft systems.
- What did they see on their radar and how did they interpret it?
- Why did they allow the aircraft to climb from Fl 350 to 380?
- Why did they not succeed in recognizing/recovering from the stall?
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Dozy, the Lufthansa preceding, and the Iberia and Air France following, on the same airway as AF447 that night 'saw' the Cbs and deviated, AF459 rather dramatically with its zig-zagging total of about 100 NM to the left and right of the track. Dispatch had sent AF447 a message regarding satellite observation of Cbs vicinity of ORARO and TASIL well before AF447 reached ORARO.
Until the full CVR is released, we won't know what the crew of AF447 saw (or failed to see) on their radar after ORARO.
Until the full CVR is released, we won't know what the crew of AF447 saw (or failed to see) on their radar after ORARO.
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SaturnV (liking the handle!):
Absolutely - I wasn't trying to imply one way or the other - I was just expressing the opinion that the investigation should be thorough.
jcjeant:
The way I read it the BEA were actually a bit annoyed at Airbus for jumping the gun, so they released the "note" to calm the press, which naturally went into something of a feeding frenzy as soon as the recorders made it back to Paris. You *could* read it as the BEA supporting Airbus's statement, but alternatively it could simply mean that while Airbus jumped the gun, their information was solid.
Absolutely - I wasn't trying to imply one way or the other - I was just expressing the opinion that the investigation should be thorough.
jcjeant:
BEA reacted strongly for support the Airbus claim
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One thing that has puzzled me, in the interaction between the two copilots. If the Junior one was flying and the senior one thought he was screwing up in a big way, I can see an advisory call of the problem followed by "I have the aircraft" if the senior guy still was not happy with the other man's performance. (And proper CRM says the reverse can happen too). But this apparently did not happen. Was the senior copilot not concerned with the junior one's performance? Or was he too busy with other things?
Is there something exclusively in the interaction between copilots that would act to inhibit this type of takeover of control. Perhaps Captains orders who was to fly a segment?
Is there something exclusively in the interaction between copilots that would act to inhibit this type of takeover of control. Perhaps Captains orders who was to fly a segment?
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Originally Posted by Graybeard
Was the PNF possibly too busy/engrossed/distracted with pages of ECAM warnings and alerts to notice what the plane was doing?
Originally Posted by BEA
From 2 h 10 min 05, the autopilot then auto-thrust disengaged and the PF said "I have the controls". The airplane began to roll to the right and the PF made a left nose-up input. The stall warning sounded twice in a row.
Originally Posted by BEA
At 2 h 10 min 16 The airplane’s pitch attitude increased progressively beyond 10 degrees and the plane started to climb. The PF made nose-down control inputs and alternately left and right roll inputs. The vertical speed, which had reached 7,000 ft/min, dropped to 700 ft/min and the roll varied between 12 degrees right and 10 degrees left. The speed displayed on the left side increased sharply to 215 kt (Mach 0.68). The airplane was then at an altitude of about 37,500 ft and the recorded angle of attack was around 4 degrees
Originally Posted by BEA
At 2 h 10 min 51 , the stall warning was triggered again.
Originally Posted by BEA
At around 2 h 11 min 40 ... During the following seconds,
all of the recorded speeds became invalid and the stall warning stopped.
all of the recorded speeds became invalid and the stall warning stopped.
Originally Posted by BEA
...The altitude was then about 35,000 ft, the angle of attack exceeded 40 degrees and the vertical speed was about -10,000 ft/min. The airplane’s pitch attitude did not exceed 15 degrees and the engines’ N1’s were close to 100%. The airplane was subject to roll oscillations that sometimes reached 40 degrees. The PF made an input on the sidestick to the left and nose-up stops, which lasted about 30 seconds.
The plane turned the stall warning OFF when it had no good reason to do so. So what's this nonsense BEA has been spouting that the plane is not at fault? The plane has a critical design flaw in its software that conditions pilots to do the wrong thing even when they know better.
In the past four days worth of posts on catch-up reading I've seen nothing to change my view in this regard.
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HN-39
At this point, without clear cut evidence on the accelerometers of a monster updraft, I don't think so. (But it was night IFR conditions)
Those that wish to add a large turbulence/updraft element to this loss of control seem to be putting unnecesary sauce on the stew. Occam's Razor applies.
There appears to be sufficient explanation in the pitch angle achieved to account for the climb to FL380.
Apart from the ice particles that blocked the pitots, do you think that the weather played an important role in this accident?
Those that wish to add a large turbulence/updraft element to this loss of control seem to be putting unnecesary sauce on the stew. Occam's Razor applies.
There appears to be sufficient explanation in the pitch angle achieved to account for the climb to FL380.
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JD-EE:
You're not taking the training around loss of air data into account. One of the things quickly learned from the pitot/static failure accidents in the 1990s was that aural warnings generated were confusing, thus the correct thing to do is to disregard them and fly pitch-and-power until the speed readings become valid again. This is not something peculiar to the A330, it is common to all advanced jetliners.
If the pilot were simply reacting to those warnings, when he had visual cues in the form of the ADI in front of him and the power settings - neither of which requires air data to function, and are therefore likely to be correct - telling him that he was too nose-high for the power he had selected at that altitude, then he was either not adequately trained for this scenario, or so thrown by the sudden onset of the situation that the training went out the window.
You're not taking the training around loss of air data into account. One of the things quickly learned from the pitot/static failure accidents in the 1990s was that aural warnings generated were confusing, thus the correct thing to do is to disregard them and fly pitch-and-power until the speed readings become valid again. This is not something peculiar to the A330, it is common to all advanced jetliners.
If the pilot were simply reacting to those warnings, when he had visual cues in the form of the ADI in front of him and the power settings - neither of which requires air data to function, and are therefore likely to be correct - telling him that he was too nose-high for the power he had selected at that altitude, then he was either not adequately trained for this scenario, or so thrown by the sudden onset of the situation that the training went out the window.
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Originally Posted by machinbird
If the Junior one was flying and the senior one thought he was screwing up in a big way, I can see an advisory call of the problem followed by "I have the aircraft" if the senior guy still was not happy with the other man's performance. (And proper CRM says the reverse can happen too). But this apparently did not happen. Was the senior copilot not concerned with the junior one's performance? Or was he too busy with other things?
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The pilot made a nose down input.
Last edited by HazelNuts39; 19th Jun 2011 at 17:10.
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jcjeant:
The way I read it the BEA were actually a bit annoyed at Airbus for jumping the gun, so they released the "note" to calm the press, which naturally went into something of a feeding frenzy as soon as the recorders made it back to Paris. You *could* read it as the BEA supporting Airbus's statement, but alternatively it could simply mean that while Airbus jumped the gun, their information was solid.
The way I read it the BEA were actually a bit annoyed at Airbus for jumping the gun, so they released the "note" to calm the press, which naturally went into something of a feeding frenzy as soon as the recorders made it back to Paris. You *could* read it as the BEA supporting Airbus's statement, but alternatively it could simply mean that while Airbus jumped the gun, their information was solid.
All I have / recall is Airbus release (I believe approved by BEA) that no action was required for 330 operators yet - on the basis of analysis of the data at that point. That got turned by the media into "plane not at fault", along with other leaks leading to headlines like "no pilot in the cockpit" and other idiocy. BEA release was to stamp on the media leak/bulls**t fest - which it laregly did.
AFAICS neither Airbus or BEA can possibly come out and say the plane wasn't at fault - because the pitots (brand / model) were (and still are) held to be at fault.
Airbus might not have built the pitots, but they approved them for the a/c (and maybe because they are French...), so they are on the hook. The fact that they advised AF to replace them 2yrs before the crash, and AF blocked it, may get Airbus back off the hook (certainly doesn't make AF look good) but the plane is clearly still part of the cause. And that is before we even get into any possible human factors issues in the control system design, warnings systems, THS etc.
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That nose-down command between 2:10:16 and 2:10:50 reduced the vertical speed from 7000 fpm to 700 fpm and AoA to (less than - in my simulation) 4 degrees (reducing v/s implies less than 1g, hence reduced AoA) - no stall warning at that point. Then a nose-up command must have followed calling for about 1,1 g and an AoA that exceeded the stall warning threshold, and ultimately the stall AoA. The 1,1 g increased the vertical speed from 700 fpm (to about 2500 fpm in my simulation). Look at BEA's "3D view" for the partial level-off followed by a steepened final climb just before the apogee. The airplane stalled before the apogee.
By now the PF was "conditioned". He was rewarded for NU and punished for ND.
The frigging plane turned the stall warning OFF when it had no good reason to do so. So what's this nonsense BEA has been spouting that the plane is not at fault? The plane has a critical design flaw in its software that conditions pilots to do the wrong thing even when they know better.
The frigging plane turned the stall warning OFF when it had no good reason to do so. So what's this nonsense BEA has been spouting that the plane is not at fault? The plane has a critical design flaw in its software that conditions pilots to do the wrong thing even when they know better.
UAS is known to be a situation where alarms, alerts and warnings can be misleading - training dictates fly pitch and power until speed indications recover. Which in flight, unless I'm seriously off-target, they have proven to always do (excepting situations were pitots have been blocked due to human error or bees - never did like bees).
I'm sure that the BEA and Airbus will be looking at the stall warning behavior very closely, but let's not loose sight of a couple of key issues that are VERY UNLIKELY to be the aircraft's fault:
1) Flying THROUGH the CB area was the initiating and fundamental cause. All other flights on the same airway track deviated. Had they done the same we would not be here.
2) The reaction to the stall warning was NOT the initiating problem. The problem was how they arrived at the stall condition in the first place, i.e. pitch and power at the loss of airspeed indication would not lead to this.
Therefore I would suggest that the real work needs to be focused on why they elected to NOT deviate. Everything else falls out in turn.
I think it fair to say that 99.9% of pilots would claim to have NEVER flown through a CB - because it is known to be a very, very bad thing to try. There are a few stories around from those few that made that mistake and sadly the majority end badly.
The fact that the pitots iced in this situation was a prior issue, one that Airbus had already issued a warning, that for whatever reason AF was slow to action. Whether the appropriate regulatory authorities should set in when there is a potential safety of flight concern, is another topic worth discussion.
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Southern Airways Flight 242 - Wikipedia, the free encyclopedia
" Before the battle of Verdun, our activity was disturbed by frequent thunder-storms.
Nothing is more disagreeable for flying men than to have to fly through a thunderstorm. During the Battle at Somme, a whole English Flying Squadron was forced down behind our lines and became our prisoners of war, because they had all been surprised by a thunderstorm.
I had never yet made an attempt to get through thunder clouds, however I could not suppress my desire ' to make the experiment.'
During one whole day, thunder was in the air. But in order to look after various things, I had flown over to the nearby fortress of Metz.
I had an adventure during my return.
After visiting the aerodrome of Metz, I had intended to return to my own base, when an approaching thunderstorm became noticeable. As it approached from the north, its vertical clouds looked like a gigantic . . pitch-black wall.
Old, experienced pilots, there, urged me not to fly. However, I had promised to return to my base. I should have considered myself a coward if I had failed to come back because of a silly thunderstorm.
Therefore, I meant to try.
I was in the air when the rain began falling. I had to throw away my goggles, otherwise I should not have seen anything. The trouble was that I had to travel over the mountains of the Moselle, where the thunderstorm was now raging.
And as I rapidly approached the black cloud which reached down to the earth, I said to myself that probably I should be lucky to get through it.
As I flew at the lowest possible altitude, I was compelled absolutely to leap over
houses and trees with my machine.
Very soon . . I no longer knew where I was. The gale seized my machine as if it were a piece of paper and drove it along. My heart sank within me. I could not land among those hills.
I was compelled to go on.
I was surrounded by an inky blackness. Beneath me the trees bent down in the gale. Suddenly, I saw right in front of me a wooded hill. I could not avoid it. I was able to fly only in a straight line. My Albatross managed to avoid its trees. And now I had to quickly avoid every obstacle that I encountered.
My flight became a jumping competition.
Purely and simply. I had to jump over trees, villages, spires and steeples, for I had to keep within a few yards of the ground . . otherwise I should have seen nothing at all [ in the dark, obscuring rain and violence. ]
The lightning was playing around me. At that time I did not yet know that lightning cannot touch flying machines. I felt certain of my death for it seemed to me inevitable that the gale would throw me at any moment into a village or a forest. Had the motor stopped working I should have been done for.
Suddenly, I saw that on the horizon the darkness had become less thick. The thunderstorm had passed, over there. If I were able to get that far, I would be saved.
Concentrating all my energy, I steered towards the light. Suddenly I got out of the thundercloud. The rain was still falling in torrents, but still I felt . . saved.
In pouring rain, I landed at my aerodrome. Everyone had been waiting for me. Metz had reported my start and had told them that I had been swallowed up by a thunder cloud. Withstanding the dangers during my flight, I had experienced glorious moments . . and I now realize that it was all very beautiful. But I shall never again fly through a thunderstorm . .
. . unless the Fatherland should demand it. "
Source : Manfred von Richthofen's letters to his family
Nothing is more disagreeable for flying men than to have to fly through a thunderstorm. During the Battle at Somme, a whole English Flying Squadron was forced down behind our lines and became our prisoners of war, because they had all been surprised by a thunderstorm.
I had never yet made an attempt to get through thunder clouds, however I could not suppress my desire ' to make the experiment.'
During one whole day, thunder was in the air. But in order to look after various things, I had flown over to the nearby fortress of Metz.
I had an adventure during my return.
After visiting the aerodrome of Metz, I had intended to return to my own base, when an approaching thunderstorm became noticeable. As it approached from the north, its vertical clouds looked like a gigantic . . pitch-black wall.
Old, experienced pilots, there, urged me not to fly. However, I had promised to return to my base. I should have considered myself a coward if I had failed to come back because of a silly thunderstorm.
Therefore, I meant to try.
I was in the air when the rain began falling. I had to throw away my goggles, otherwise I should not have seen anything. The trouble was that I had to travel over the mountains of the Moselle, where the thunderstorm was now raging.
And as I rapidly approached the black cloud which reached down to the earth, I said to myself that probably I should be lucky to get through it.
As I flew at the lowest possible altitude, I was compelled absolutely to leap over
houses and trees with my machine.
Very soon . . I no longer knew where I was. The gale seized my machine as if it were a piece of paper and drove it along. My heart sank within me. I could not land among those hills.
I was compelled to go on.
I was surrounded by an inky blackness. Beneath me the trees bent down in the gale. Suddenly, I saw right in front of me a wooded hill. I could not avoid it. I was able to fly only in a straight line. My Albatross managed to avoid its trees. And now I had to quickly avoid every obstacle that I encountered.
My flight became a jumping competition.
Purely and simply. I had to jump over trees, villages, spires and steeples, for I had to keep within a few yards of the ground . . otherwise I should have seen nothing at all [ in the dark, obscuring rain and violence. ]
The lightning was playing around me. At that time I did not yet know that lightning cannot touch flying machines. I felt certain of my death for it seemed to me inevitable that the gale would throw me at any moment into a village or a forest. Had the motor stopped working I should have been done for.
Suddenly, I saw that on the horizon the darkness had become less thick. The thunderstorm had passed, over there. If I were able to get that far, I would be saved.
Concentrating all my energy, I steered towards the light. Suddenly I got out of the thundercloud. The rain was still falling in torrents, but still I felt . . saved.
In pouring rain, I landed at my aerodrome. Everyone had been waiting for me. Metz had reported my start and had told them that I had been swallowed up by a thunder cloud. Withstanding the dangers during my flight, I had experienced glorious moments . . and I now realize that it was all very beautiful. But I shall never again fly through a thunderstorm . .
. . unless the Fatherland should demand it. "
Source : Manfred von Richthofen's letters to his family