AF447 wreckage found
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jcjeant
No traces of gee? How is that possible? Is the report available through the FAA? I can't imagine not, the A320 is everywhere over here.
complexman
As to resin, 447 had few composites in structural places. If it actually did, please don't tell me. As one who has designed and built in composites for ~40 years, I am most apprehensive about two things. Elasticity, and Fire.
No traces of gee? How is that possible? Is the report available through the FAA? I can't imagine not, the A320 is everywhere over here.
complexman
As to resin, 447 had few composites in structural places. If it actually did, please don't tell me. As one who has designed and built in composites for ~40 years, I am most apprehensive about two things. Elasticity, and Fire.
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Airbus has the obsession to use composites in much of the tail in most of its models. Joining a metallic component with a composite one is like asking for trouble. Always. (e.g. see section 19 on the A380). But that is not what is worrying me - I am scared of the 787. Rumors indicate that it actually would be lighter had it been built of Al instead of composite. This is because composite have never been used on such scale before so large safety margins are used to absorb the uncertainty.
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NOD, stepwilk, aguadalte,
I was reacting to above statements
Yes, in a climb or descent pitch=speed, but then power becomes rate
But otherwise:
In a prop: pitch=speed, power=altitude
In a jet: pitch=altitude, power=speed
When you fly an ILS and you get a little high, you don't pull the power, you put your nose down.
What I am objecting to is GB's notion that the 2 mentioned accident are attributed to this pitch/power thing, and what I object most to is his "advice":
Now back to the AF447 and all this discussion about the stall recovery "procedure".
Stalls aren't trained anymore, they are such basic flying skills that the only time you do them is as mandatory items during type conversions,
but on every type conversion from the very beginning of my flying career they are (with the exception of the option of flapextension on some types) the same: lower your nose (on the horizon will do most of the time) and put on some power and you're out of it.
I can't believe that a pilot with the experience that equals the AF447 least experienced pilot consciously counteracts a stall with pitch-up command.
The big issue here is what the pilots felt and saw, and the BEA statements are a bit puzzling here.
I don't understand the sequence of AP and ATS dropping of before the airspeed indications became faulty. You only get alternate law after ADC's become unrelaible but the aircraft was already in alternate law before the speed dropped from 275kts to 60.
I don't understand the low speeds; I would expect speed increasing with altitude with blocked pitots.
I also don't understand the pilots perseverence in maintaining pitchup command; in his situation I could understand a temporary wrong input, but why so long?
Personaly I think the BEA has not given the full picture regarding actual flight laws; I am also afraid some unknown pitch protection feature played a role, pulling the nose up, while we are thinking it was the pilots doing...
Anyway the pilots were most likely overloaded, spatially disoriented and fooled by their indications, as we all would be.
I don't think an industry wide change of flying technique "Pitch equals speed", as GB suggests, would have saved the day here.
And as much as I like to be a "hands on" pilot, I think the prevention of this happening again will be a technical/engineering solution and not a piloting skill.
BTW, no, I am not a FS wannabe
Pitch controls airspeed.
Power controls altitude.
Power controls altitude.
Yes, in a climb or descent pitch=speed, but then power becomes rate
But otherwise:
In a prop: pitch=speed, power=altitude
In a jet: pitch=altitude, power=speed
When you fly an ILS and you get a little high, you don't pull the power, you put your nose down.
What I am objecting to is GB's notion that the 2 mentioned accident are attributed to this pitch/power thing, and what I object most to is his "advice":
Trying to control altitude with pitch is a loser, regardless.
Stalls aren't trained anymore, they are such basic flying skills that the only time you do them is as mandatory items during type conversions,
but on every type conversion from the very beginning of my flying career they are (with the exception of the option of flapextension on some types) the same: lower your nose (on the horizon will do most of the time) and put on some power and you're out of it.
I can't believe that a pilot with the experience that equals the AF447 least experienced pilot consciously counteracts a stall with pitch-up command.
The big issue here is what the pilots felt and saw, and the BEA statements are a bit puzzling here.
I don't understand the sequence of AP and ATS dropping of before the airspeed indications became faulty. You only get alternate law after ADC's become unrelaible but the aircraft was already in alternate law before the speed dropped from 275kts to 60.
I don't understand the low speeds; I would expect speed increasing with altitude with blocked pitots.
I also don't understand the pilots perseverence in maintaining pitchup command; in his situation I could understand a temporary wrong input, but why so long?
Personaly I think the BEA has not given the full picture regarding actual flight laws; I am also afraid some unknown pitch protection feature played a role, pulling the nose up, while we are thinking it was the pilots doing...
Anyway the pilots were most likely overloaded, spatially disoriented and fooled by their indications, as we all would be.
I don't think an industry wide change of flying technique "Pitch equals speed", as GB suggests, would have saved the day here.
And as much as I like to be a "hands on" pilot, I think the prevention of this happening again will be a technical/engineering solution and not a piloting skill.
BTW, no, I am not a FS wannabe
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golfyankeesierra
I more or less resent the ease with which pilots are doubted, and the fall back is "It did what it is programmed to do". Fine, perhaps because pilots can think and
innovate, there is some residual resentment that programming gets a look once in a while. For what it's worth, any discussion should have some (alot) of room to wander, we're stuck with fbw. Not that it is poor, it is fine, but it gets this knee jerk defense where professionals get the magnifying glass.
So be it. My baseline is that this crew were eminently qualified, and perhaps more so than the bus. If there is a fault, it may be (probably) that the orchestra hit some sour notes, whether flute or conductor, no matter. The deal is that not enough practice leads to "Prior Planning Prevents Piss Poor Performance". Will the Bus surprise? It is certain, for there is simply no way this crew flew to STALL without some mitigating events. I think this should continue, for it is only the pressure of the folks that will goad the sloth.
I more or less resent the ease with which pilots are doubted, and the fall back is "It did what it is programmed to do". Fine, perhaps because pilots can think and
innovate, there is some residual resentment that programming gets a look once in a while. For what it's worth, any discussion should have some (alot) of room to wander, we're stuck with fbw. Not that it is poor, it is fine, but it gets this knee jerk defense where professionals get the magnifying glass.
So be it. My baseline is that this crew were eminently qualified, and perhaps more so than the bus. If there is a fault, it may be (probably) that the orchestra hit some sour notes, whether flute or conductor, no matter. The deal is that not enough practice leads to "Prior Planning Prevents Piss Poor Performance". Will the Bus surprise? It is certain, for there is simply no way this crew flew to STALL without some mitigating events. I think this should continue, for it is only the pressure of the folks that will goad the sloth.
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Bear, not doubting the pilots, nor the plane.
I think the 'bus is as safe as any other plane, probably even more.
But I do think there will be some "discoveries" in the course of the investigations revealing a) new notions in passing through weather in that particular area of equatorial Atlantic, and b) new insights in the A330's FBW system.
BTW, remember the Lufthansa A320 tipstrike at Hamburg? In the course of that investigation it showed that most pilots were unware of a specific behavior in the roll-authority at touchdown:
BFU report page 62
I guess the AF447 final investigation report will spit out similar words..
I think the 'bus is as safe as any other plane, probably even more.
But I do think there will be some "discoveries" in the course of the investigations revealing a) new notions in passing through weather in that particular area of equatorial Atlantic, and b) new insights in the A330's FBW system.
BTW, remember the Lufthansa A320 tipstrike at Hamburg? In the course of that investigation it showed that most pilots were unware of a specific behavior in the roll-authority at touchdown:
The pilots could not have been aware of the specific flight system control response characteristics
during a landing with a gusty crosswind ...
during a landing with a gusty crosswind ...
I guess the AF447 final investigation report will spit out similar words..
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There is no enormous debate about the THS, it behaved correctly and if the correct actions had been taken I am sure the A/C would have been recoverable.
So you dont think autotrim will feature in the report then?You're quite confident that the automatic application of full ANU tim followed by auto-cutout is a good example of "fail-safe" design?And that the transition from auto to manual (when how why it occurs) is intuitively understood by the poor pilot?So why perpignan and now AF?or the tarom or taipei?
It behaved correctly?It behaved as designed.
You might think your oh-so-clever destruction of Gretchenfrage's points were on the nose but you forget one thing;those planes crashed and Im afraid the pilots didnt really know why they were crashing.THEY DIDNT UNDERSTAND WHAT THEY HAD/HADNT DONE.If a design is ambiguous,then it is deficient.
Do you have anything to say about the stall warning inhibit?Id love to hear your thoughts on this one.Over to you ace.
(read BEA note !)
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Hi,
A little of topic but an interesting table ....
By the ACARS ... the BEA ?? .. and many people of this forum had concluded that the plane was falling rapidly (a stall or spin condition)
So (I already commented) I still puzzled with the management of the researches by the BEA (almost two years spend in thin air ..)
A little of topic but an interesting table ....
By the ACARS ... the BEA ?? .. and many people of this forum had concluded that the plane was falling rapidly (a stall or spin condition)
So (I already commented) I still puzzled with the management of the researches by the BEA (almost two years spend in thin air ..)
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It used to be said that the only really silly question is the one you don't ask.
I'm wondering WHY the autotrim 'decided,' in both accidents, to go to 'THS full up' in the first place? And then STAY there, even though both pilots were in the end pushing the stick forward? Anyone know what the 'system logic' that could cause that reaction is?
The BEA gives us no guidance at all on the point. For the Perpignan accident - even though it's the final report - the BEA just says:-
In the case of AF447, it says even less - it just tells us 'what' happened, and doesn't even tell us when it happened (i.e. which minute):-
No mention of 'why?' in either case.
So here's my 'silly question.' Despite the fact that the autopilot and autothrust had 'signed off' on AF447, and the pilot at Perpignan was most certainly seeking to get the nose down all the time, and the AF447 one much of the time - is it possible that the autotrim in both cases was still trying to regain the previously-commanded altitude?
Never flown anything with autotrim (in fact, I've only flown anything with an autopilot twice in my life). But as far as I know, that (keeping the aeroplane exactly to a given altitude) is the main 'everyday' function of an autotrim?
I'm wondering WHY the autotrim 'decided,' in both accidents, to go to 'THS full up' in the first place? And then STAY there, even though both pilots were in the end pushing the stick forward? Anyone know what the 'system logic' that could cause that reaction is?
The BEA gives us no guidance at all on the point. For the Perpignan accident - even though it's the final report - the BEA just says:-
The auto-trim system gradually moved the horizontal stabilizer to a full nose-up position during the deceleration. The horizontal stabilizer remained in this position until the end of the flight.
The trimmable horizontal stabilizer (THS) passed from 3 to 13 degrees nose-up in about 1 minute and remained in the latter position until the end of the flight.
So here's my 'silly question.' Despite the fact that the autopilot and autothrust had 'signed off' on AF447, and the pilot at Perpignan was most certainly seeking to get the nose down all the time, and the AF447 one much of the time - is it possible that the autotrim in both cases was still trying to regain the previously-commanded altitude?
Never flown anything with autotrim (in fact, I've only flown anything with an autopilot twice in my life). But as far as I know, that (keeping the aeroplane exactly to a given altitude) is the main 'everyday' function of an autotrim?
Last edited by RWA; 12th Jun 2011 at 06:17.
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Flying Basics, straight and level:
Pitch attitude controls altitude
thrust controls airspeed
This for prop, jet, rocket any type of propulsion in fixed wing aircraft, but only on the front, right side of the thrust versus speed curve.
Left side of the curve- opposite. This because of negative speed stability, where a given power setting doesn't have one but two correct speeds, and the aircraft would always fly away from the desired speed on the left side..
Pitch attitude controls altitude
thrust controls airspeed
This for prop, jet, rocket any type of propulsion in fixed wing aircraft, but only on the front, right side of the thrust versus speed curve.
Left side of the curve- opposite. This because of negative speed stability, where a given power setting doesn't have one but two correct speeds, and the aircraft would always fly away from the desired speed on the left side..
Last edited by opherben; 12th Jun 2011 at 10:54.
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GYS
Disagree... 
If you can show me a training manual clearly stating the opposite, please post it here, but for now I will extract from the Student Guide to my first Jet:
(This is actually for the PAR, but the same technique used for an ILS).
In practice either technique works to an extent, but the 2 are intertwined.
NoD
When you fly an ILS and you get a little high, you don't pull the power, you put your nose down.
If you can show me a training manual clearly stating the opposite, please post it here, but for now I will extract from the Student Guide to my first Jet: (This is actually for the PAR, but the same technique used for an ILS).In practice either technique works to an extent, but the 2 are intertwined.
NoD
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Keep it simple:
Pitch attitude IS speed control:
On a glider you adjust your speed with your pitch attitude.
On a 747 without any thrust you have a veeery big glider
. Again you adjust your speed with your pitch attitude.
(Altitude is "just" a time factor
)
The bonus by power/thrust: You are now able to maintain your altitude - even climb (in most situations
) So power/thrust IS altitude control!!!
By the way - ain't we just a little of topic??
Pitch attitude IS speed control:
On a glider you adjust your speed with your pitch attitude.
On a 747 without any thrust you have a veeery big glider
. Again you adjust your speed with your pitch attitude. (Altitude is "just" a time factor)The bonus by power/thrust: You are now able to maintain your altitude - even climb (in most situations
) So power/thrust IS altitude control!!!By the way - ain't we just a little of topic??
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complexman:
complexman:
We have a saying in my country, that goes like this:
"Presunção e água benta, cada um toma a que quer..."
(Presumption and holy water, each one takes whatever...)
What I find really scary is the way engineers are designing flying machines that are so complex that even made them think that they have created an aircraft "against pilot's mistakes".
Man/machine interface was relegated to a status of "get used to it". Adapt yourself to your new role: flight management.
Fortunately for us, things are not all black and white. Engineers are not perfect, nor are we pilots...
But one thing is for sure, pilots are open to debate, open to new ideas, open to other professional classe's meddling and scrutinizing opinions.
In favor of flight safety, we do need to continue to open ourselves to our own scrutiny and open ourselves to other's opinions. I have learned a lot in this forum. There are a lot of great professionals with whom I love to exchange ideas and comments.
What we don't need is that sort of sleaze and arrogance, especially when coming from someone who should behave as an invited guest and therefore adopt more urban manners.
I am an aircraft engineer with nearly two decades of experience in the industry. I am not a pilot. What I find SHOCKING is that many professional pilots in this thread disagree so strongly on such basic issues as flight dynamics or what a variation of throttle will do to you in level flight. This is really scary. I know quite a lot about airframe design as well as flight control system design having done both for many years. But this thread is proving that as automation proceeds flying IS going to become more and more dangerous. And if that were not enough, they've now started to make airplanes from plastic!
We have a saying in my country, that goes like this:
"Presunção e água benta, cada um toma a que quer..."
(Presumption and holy water, each one takes whatever...)
What I find really scary is the way engineers are designing flying machines that are so complex that even made them think that they have created an aircraft "against pilot's mistakes".
Man/machine interface was relegated to a status of "get used to it". Adapt yourself to your new role: flight management.
Fortunately for us, things are not all black and white. Engineers are not perfect, nor are we pilots...
But one thing is for sure, pilots are open to debate, open to new ideas, open to other professional classe's meddling and scrutinizing opinions.
In favor of flight safety, we do need to continue to open ourselves to our own scrutiny and open ourselves to other's opinions. I have learned a lot in this forum. There are a lot of great professionals with whom I love to exchange ideas and comments.
What we don't need is that sort of sleaze and arrogance, especially when coming from someone who should behave as an invited guest and therefore adopt more urban manners.
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Quote, "With the greatest respect to some: On Approach,
1) light aircraft use pitch for speed
2) Heavy Jets use thrust for speed
Too many light aircraft pilots here who obviously have no experience in heavy aircraft operations "
By George,
I beg to differ. Since you are on the thrust curve backside, adding thrust will not necessarily regain target airspeed, but lowering attitude will. No different from light aircraft.
The differentiation of light from heavy aircraft flying technique is an error in understanding aircraft flight mechanics and resulting handling qualities, even if the chief flight instructor taught this way. What matters are design parameters like wing loading, thrust over weight, lift over drag, and the CL vs Alpha and thrust vs airpseed curves. The B747 at any landing weight isn't substantially different in approach handling qualities from a Cessna 206, even though the Boeing wing is swept, and has more tires and Lbs. Their greatest handling qualities differences are in the flight control system mechanical characteristics, irrelevant to the above quoted issue.
The writer served as chief experimental test pilot since the 70's.
1) light aircraft use pitch for speed
2) Heavy Jets use thrust for speed
Too many light aircraft pilots here who obviously have no experience in heavy aircraft operations "
By George,
I beg to differ. Since you are on the thrust curve backside, adding thrust will not necessarily regain target airspeed, but lowering attitude will. No different from light aircraft.
The differentiation of light from heavy aircraft flying technique is an error in understanding aircraft flight mechanics and resulting handling qualities, even if the chief flight instructor taught this way. What matters are design parameters like wing loading, thrust over weight, lift over drag, and the CL vs Alpha and thrust vs airpseed curves. The B747 at any landing weight isn't substantially different in approach handling qualities from a Cessna 206, even though the Boeing wing is swept, and has more tires and Lbs. Their greatest handling qualities differences are in the flight control system mechanical characteristics, irrelevant to the above quoted issue.
The writer served as chief experimental test pilot since the 70's.
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For those questioning the auto-trim on the airbus - this is a function of the FBW system.
On a conventional aeroplane (PA28 or 737) the pilot pitches up using the control column and manually trims the pressure off using the trim wheel or electric trim switch (same thing).
On the airbus this happens automatically. The pilot pitches the aeroplane up with sidestick inputs and the computer trims off the resulting "pressure" (you can still see the trim wheel rotating back during this process).
If the pilot applies sufficient back stick for a sufficient amount of time then the trim will wind fully back to the stop. This is what happened during the deceleration phase of the Perpignan Accident and almost certainly what happened during the Air France 447 tragedy.
In some conditions the auto-trim disconnects (abnormal attitude and direct law) and the trim setting and therefore wheel and stabiliser will remain in that final position until either
a) auto-trim is restored
or
b) the pilot moves the trim wheel manually!
On a conventional aeroplane (PA28 or 737) the pilot pitches up using the control column and manually trims the pressure off using the trim wheel or electric trim switch (same thing).
On the airbus this happens automatically. The pilot pitches the aeroplane up with sidestick inputs and the computer trims off the resulting "pressure" (you can still see the trim wheel rotating back during this process).
If the pilot applies sufficient back stick for a sufficient amount of time then the trim will wind fully back to the stop. This is what happened during the deceleration phase of the Perpignan Accident and almost certainly what happened during the Air France 447 tragedy.
In some conditions the auto-trim disconnects (abnormal attitude and direct law) and the trim setting and therefore wheel and stabiliser will remain in that final position until either
a) auto-trim is restored
or
b) the pilot moves the trim wheel manually!
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Man Flex
Fair enough, Man Flex - except that I can't recall (unless I missed it) any reference to the Perpignan pilot applying 'up stick'? Please correct me if I'm wrong?
And secondly, the ('vestigial)' BEA 'note' about AF447 does indeed refer to the PF applying 'up stick' in the early stages of the accident -but it ALSO says, in the next paragraph:-
So it appears, on the face of it, that the PF 'did the right thing,' recovered control, and restored the aeroplane to a stable flightpath and a sensible attitude? But - important point - the THS didn't respond?
If the pilot applies sufficient back stick for a sufficient amount of time then the trim will wind fully back to the stop. This is what happened during the deceleration phase of the Perpignan Accident and almost certainly what happened during the Air France 447 tragedy.
And secondly, the ('vestigial)' BEA 'note' about AF447 does indeed refer to the PF applying 'up stick' in the early stages of the accident -but it ALSO says, in the next paragraph:-
"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."
So it appears, on the face of it, that the PF 'did the right thing,' recovered control, and restored the aeroplane to a stable flightpath and a sensible attitude? But - important point - the THS didn't respond?
On the airbus this happens automatically. The pilot pitches the aeroplane up with sidestick inputs and the computer trims off the resulting "pressure" (you can still see the trim wheel rotating back during this process).
If the pilot applies sufficient back stick for a sufficient amount of time then the trim will wind fully back to the stop. This is what happened during the deceleration phase of the Perpignan Accident and almost certainly what happened during the Air France 447 tragedy.
In some conditions the auto-trim disconnects (abnormal attitude and direct law) and the trim setting and therefore wheel and stabiliser will remain in that final position until either
a) auto-trim is restored
or
b) the pilot moves the trim wheel manually!
Entirely acceptable in after-dinner parlour games. But NOT, IMO, on airliners travelling at around 400 knots at well under 10,000 feet......
OK, I'll stick my neck out. I think that it's high time that aviation (Airbus, but also Boeing if appropriate) adopted a principle called 'failsafe.' At one time (I'm actually ancient enough to know 
) it was new to my own industry - but it was a 'blinding light' at the time, and (in my own experience) started saving lives within months.......
) it was new to my own industry - but it was a 'blinding light' at the time, and (in my own experience) started saving lives within months.......What it would have amounted to, in aviation terms, is that the 'systems' should have reverted to neutral settings after they signed off - so that the autotrim, for example, would not have just signed off and left the THS at an unheard-of 13 degrees up or so, but would have reduced the angle to a conventional setting (say 3 degrees up or so).
But even that 'begs the question' of how long the THS actually TAKES to adjust. From the BEA 'note,' it appears to have taken the best part of a minute to go from 3 degrees to 13 degrees - presumably it would have taken most of another minute to go back from 13 degrees to any sort of reasonable angle? Considering that the whole accident happened within not much more than three minutes, that still wouldn't have given the pilots much chance?
OK - as just a 'seat of the pants' amateur pilot from many years ago (who mainly flew sailplanes because I couldn't afford powered aeroplanes) I'll stick my neck out.
And say that, in my (genuinely-humble) opinion, both manufacturers should actively consider whether such 'new' features as slow-acting, but enormously powerful THS's - as opposed to old-fashioned, under-powered, but quick-acting trim-tabs -are 'a step too far'.........
Last edited by RWA; 12th Jun 2011 at 15:37.