AF447
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Overspeed vs Stall: why not both of them ?
To me, there is no contradiction between an initial overspeed and a stall (or even two: a stall by exiting the upper limit at high altitude during the overspeed, then, after a nearly successfull recovery/flight point back again within the envelope, exiting the lower limit of the flight envelope due to an overcorrection at low altitude).
Jeff
PS) Has NTSB scheduled any report of its investigations ?
Last edited by Hyperveloce; 12th Aug 2009 at 16:24.
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Jeff
I think their opinion that the a/c remained whole is meant to include not shedding parts, a Stall and descent to the Ocean. If overspeed, and the potential for elevator failure, spoiler separation, and VS loss, well you see their problem. A kind of Reverse postulation that precludes airframe failure, which would be my goal if I had an opportunity to claim it for a principal in the accident. I think that more is included in the BEA's assessment than is justified in evidence.
I think their opinion that the a/c remained whole is meant to include not shedding parts, a Stall and descent to the Ocean. If overspeed, and the potential for elevator failure, spoiler separation, and VS loss, well you see their problem. A kind of Reverse postulation that precludes airframe failure, which would be my goal if I had an opportunity to claim it for a principal in the accident. I think that more is included in the BEA's assessment than is justified in evidence.
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BEA stance
Even if the BEA could get some clues about the impact conditions, and will get a more accurate view after the CEAT analysis, the BEA cannot know about pieces of the airframe it hasn't recovered, hence it would be difficult to understand how the BEA could suggest that the structural intergrity of the plane was not compromised at all. In my understanding, the BEA position is only that the plane had not suffered a mid-air break up or a major control surface failure (that would have rendered it uncontrollable) like a VS loss. There had been some speculation about a catastrophic structural failure in altitude. Given this, I don't think that the BEA interim report says that no spoiler was lost for example. But his was a young airframe.
Jeff
BEA interim report (page 72):
"leur examen visuel montre que l’avion n’a pas été détruit en vol ; il paraît
avoir heurté la surface de l’eau en ligne de vol, avec une forte accélération
verticale."
"their visual examination (of the debris) shows that the plane did not brake up in mid air ; .../..."
Jeff
BEA interim report (page 72):
"leur examen visuel montre que l’avion n’a pas été détruit en vol ; il paraît
avoir heurté la surface de l’eau en ligne de vol, avec une forte accélération
verticale."
"their visual examination (of the debris) shows that the plane did not brake up in mid air ; .../..."
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Hyperveloce:
quote/hence it would be difficult to understand how the BEA could suggest that the structural intergrity of the plane was not compromised at all. In my understanding, the BEA position is only that the plane had not suffered a mid-air break up or a major control surface failure (that would have rendered it uncontrollable) like a VS loss. There had been some speculation about a catastrophic structural failure in altitude./endquote
Isn't the theory of the airframe not breaking up at altitude suggested by the absence of flail-type injuries on the recovered bodies?
quote/hence it would be difficult to understand how the BEA could suggest that the structural intergrity of the plane was not compromised at all. In my understanding, the BEA position is only that the plane had not suffered a mid-air break up or a major control surface failure (that would have rendered it uncontrollable) like a VS loss. There had been some speculation about a catastrophic structural failure in altitude./endquote
Isn't the theory of the airframe not breaking up at altitude suggested by the absence of flail-type injuries on the recovered bodies?
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More Current / Wind data
Hyperveloce;
The spoiler you referred to was I think the port outer which was picked up by a merchant ship north of TASIL on 13 July. If it had detached on account of an overspeed event, then that would help to explain its recovered position not falling within the range of expectation provided by the surface current/wind data. This would also fit in with the high Gs roll/bank to port and the high speed descent toward the suspected crash site as postulated by you in a recent post.
I have extracted the Quikscat mean surface (+10m) winds from the NOAA site and determined that the mean surface wind at 3°N 30°W for the period 1 - 7 June was from 069.3°T x 11.06 knots (5.69m/sec). The vertical stabilizer has a very low profile to windage, in fact the only significant airfoil was the small piece of empennage skin rolled up and inward on the forward end. The leeway for the v/s shown on the graphic below was 221°T x 11.1NM with reference to the general position of the 5 bodies recovered on 7 June. Without knowing the precise timings for either position (which could have been any time between sunrise and sunset) there is some room for positional error.
The effective windage factor calculated from the graphic is 0.74% which doesn't seem unreasonable. Applying the same factor to the Quikscat data provides a leeway of 249.3°T x 12.8NM over 6.5 days. Sun shadow on a photo taken at the time of the v/s recovery indicates that the sun was near or on the meridian, i.e. 1400z. However, when comparing the Quikscat data with the MSL analysis during the period in question, the wind vector should be more northerly. Putting that aside, the calculated result puts the v/s where it should be +/- a couple of miles.
mm43
The spoiler you referred to was I think the port outer which was picked up by a merchant ship north of TASIL on 13 July. If it had detached on account of an overspeed event, then that would help to explain its recovered position not falling within the range of expectation provided by the surface current/wind data. This would also fit in with the high Gs roll/bank to port and the high speed descent toward the suspected crash site as postulated by you in a recent post.
I have extracted the Quikscat mean surface (+10m) winds from the NOAA site and determined that the mean surface wind at 3°N 30°W for the period 1 - 7 June was from 069.3°T x 11.06 knots (5.69m/sec). The vertical stabilizer has a very low profile to windage, in fact the only significant airfoil was the small piece of empennage skin rolled up and inward on the forward end. The leeway for the v/s shown on the graphic below was 221°T x 11.1NM with reference to the general position of the 5 bodies recovered on 7 June. Without knowing the precise timings for either position (which could have been any time between sunrise and sunset) there is some room for positional error.
The effective windage factor calculated from the graphic is 0.74% which doesn't seem unreasonable. Applying the same factor to the Quikscat data provides a leeway of 249.3°T x 12.8NM over 6.5 days. Sun shadow on a photo taken at the time of the v/s recovery indicates that the sun was near or on the meridian, i.e. 1400z. However, when comparing the Quikscat data with the MSL analysis during the period in question, the wind vector should be more northerly. Putting that aside, the calculated result puts the v/s where it should be +/- a couple of miles.
mm43
Last edited by mm43; 13th Mar 2010 at 23:59. Reason: changed stbd outer to port outer
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While I'm neither supporting or rejecting an in-flight break up, those searching for baggage should consider that an in-flight break up can mean a rather wide variety of things. Peraps the empennage came off and the rest remained intact until impact. Perhaps a wing partially failed, but the remainder remained intact. Perhaps the horizontal tail surfaces failed downwards and the rest remained intact. In-flight break up does not necessarily translate to hundreds or even tens of tiny pieces. It just means some type of structural failure prior to impact of the whole, which precluded the ability to recover from an in-flight upset.
You all need to be as creative in your thinking about structural failure as you are about drift patterns, ocean currents, ice crystals in pitot tubes and 180 deg turns. At this point all that we have is a mystery, therefore anything is possible.
You all need to be as creative in your thinking about structural failure as you are about drift patterns, ocean currents, ice crystals in pitot tubes and 180 deg turns. At this point all that we have is a mystery, therefore anything is possible.
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Will asked a fair question, "What gives you the confidence to quote "60-120 mph" ??"
That is pure conjecture considering the terminal velocity of a human (about 120MPH) and the wings. I doubt it'd hit flat at 200 MPH with both wings present. (With only one wing it would not hit flat at all.) It might have hit faster if the pilot had been in a poorly controlled dive and managed to try to pull up as he saw the ocean. That would account for the flat or almost flat attitude, the tail breaking off as it did, and would likely give a faster velocity vector when contacting the ocean.
If I understand the construction of the pressure vessel and the interior the pressure vessel does not support much weight at all. That is all handled by an interior cabin construction. That way the pressure vessel would not be punctured by a lot of small holes supporting heavy weights. Thus it would be sort of like dropping a cigar tube on its side with the cigar in it. You'd get crumpling on the bottom that hits the ground. But the top would not crunch down. That's an extreme example. But it gives the idea behind my thinking. Mass as well as deceleration is needed to crunch the cabin.
Some evidence indicates a break near the front of the wing. That is how the galley and other parts "escaped". And it explains the crew rest facility pieces. If that happened before the rest of the fuselage crunched with its circular integrity removed you can explain the distribution for the recovered passenger bodies.
The chief arguments regarding a break-up in mid air involve getting the debris to where it was found given the ocean currents and the missing items you'd expect to see from a breakup. This would be items of luggage from the hold rather than the sparse couple things found that are generally overhead bin items.
The breakup scenario also requires the plane to remain in a relatively stable attitude until after the last message. It also requires the plane to remain enough in one piece to hit the ocean more or less flat. And you have to break off the VS in the mode seen. (Remember my demo concept of pulling pages out of a three ring binder. You can figure out how you pulled the paper out by the tear patterns. And the VS is very much like that piece of paper right down to the "three ring binder" mounting.)
I'd believe breakup in the air if you can prove God or weather could swat at a plane mashing its tail forward and up without leaving marks on its rear edges.
JD-EE
That is pure conjecture considering the terminal velocity of a human (about 120MPH) and the wings. I doubt it'd hit flat at 200 MPH with both wings present. (With only one wing it would not hit flat at all.) It might have hit faster if the pilot had been in a poorly controlled dive and managed to try to pull up as he saw the ocean. That would account for the flat or almost flat attitude, the tail breaking off as it did, and would likely give a faster velocity vector when contacting the ocean.
If I understand the construction of the pressure vessel and the interior the pressure vessel does not support much weight at all. That is all handled by an interior cabin construction. That way the pressure vessel would not be punctured by a lot of small holes supporting heavy weights. Thus it would be sort of like dropping a cigar tube on its side with the cigar in it. You'd get crumpling on the bottom that hits the ground. But the top would not crunch down. That's an extreme example. But it gives the idea behind my thinking. Mass as well as deceleration is needed to crunch the cabin.
Some evidence indicates a break near the front of the wing. That is how the galley and other parts "escaped". And it explains the crew rest facility pieces. If that happened before the rest of the fuselage crunched with its circular integrity removed you can explain the distribution for the recovered passenger bodies.
The chief arguments regarding a break-up in mid air involve getting the debris to where it was found given the ocean currents and the missing items you'd expect to see from a breakup. This would be items of luggage from the hold rather than the sparse couple things found that are generally overhead bin items.
The breakup scenario also requires the plane to remain in a relatively stable attitude until after the last message. It also requires the plane to remain enough in one piece to hit the ocean more or less flat. And you have to break off the VS in the mode seen. (Remember my demo concept of pulling pages out of a three ring binder. You can figure out how you pulled the paper out by the tear patterns. And the VS is very much like that piece of paper right down to the "three ring binder" mounting.)
I'd believe breakup in the air if you can prove God or weather could swat at a plane mashing its tail forward and up without leaving marks on its rear edges.
JD-EE
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IF the a/c broke up at a decent height, the main bits would then have dropped to the surface at a high speed.
*What is 'high speed'?
The surface impact would probably have been extreme and the a/c would have been reduced to smallish pieces.
Although a lot of these would have sunk, many would have floated. More than the bits that have been found..
The only real difference, is that here we'd have a few more pieces floating, due to composite construction... seems they stayed attached?
============================
We seem to be not only wantonly urinating, but to windward with a lot blowing back in our faces here...
Someone's going to be right, but probably more by chance than genuinely educated deductive reasoning
So I think BBF's conclusion is probably right, it agrees with BEAs and currently is the more likely occurrence, but some of the conjecture on kinematic and aerodynamic behaviour requires more rigorous justification.
Something may well have bent or broke at high altitude, but just as likely in thicker air at low altitude if control was compromised (which obviously it was, one way or another)....
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Harry
After the Lockerbie accident, when the a/c came apart ahead of the wing L/E , the rest of the a/c came down with enough force to dig a crater 200 feet wide and 60'- 80' deep, closing the M74 for 2 days. They found the engines........
If the AF had a similar break up, I doubt you'd find the galley a-floating on the briny.
After the Lockerbie accident, when the a/c came apart ahead of the wing L/E , the rest of the a/c came down with enough force to dig a crater 200 feet wide and 60'- 80' deep, closing the M74 for 2 days. They found the engines........
If the AF had a similar break up, I doubt you'd find the galley a-floating on the briny.
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Very early in this thread, I posted the following, but cannot find it now. This is copied from my word processor
I still think that the airplane reached the water with the fusillage together, with some failure occuring on impact. This would account for the varied distribution of bodies compared to the seating chart. Had the cabin broke at or around R & L 2, a good case can be made for the galley.
Again, I think that there is a good possibility that the airplane may have gone down intact. I based this on the thus far slow or lack of discovery of a debris footprint. Had the airplane failed at altitude, given the altitude, speed, and winds aloft, then one could reasonably expect an extended area of debris which would track with the airplane as it descended. I doubt it would have been difficult to locate.
To compare, I recall all too well the Lockerbie situation with the inflight breakup of PA and the area that was affected. The heavy portion fell in the village, and nearby area, but countless other items extended for miles. Some large, some small.
On the other hand, MS990 created only two relatively small debris field in the Atlantic. One 62 X 66 meters, and the other 83 X 73. This airplane entered the water mostly intact
To compare, I recall all too well the Lockerbie situation with the inflight breakup of PA and the area that was affected. The heavy portion fell in the village, and nearby area, but countless other items extended for miles. Some large, some small.
On the other hand, MS990 created only two relatively small debris field in the Atlantic. One 62 X 66 meters, and the other 83 X 73. This airplane entered the water mostly intact
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Interesting the Lockerbie has been brought up. (I, unfortunately, remember it all too well.) We know for a fact that Pan Am 103 broke apart at altitude. I'd like to correlate this with the recovered bodies from 103 and AF 447. If we all remember, although 103 broke apart at altitude many of the recovered bodies were fully clothed. (Reference: "my boy", "the man in the suit", etc.) So, in answer to someone's query earlier this week: because the bodies that were recovered from AF 447 were clothed, or not, I believe is indicative of nothing as far as a break up at altitude or not.
Perhaps i"m incorrect.
Then again, this supposition does nothing toward understanding what the CAUSAL factors of AF 447's destruction were.
Perhaps i"m incorrect.
Then again, this supposition does nothing toward understanding what the CAUSAL factors of AF 447's destruction were.
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evidence - read !
Yet another dozen pages added to this thread because a few contributors refuse to read or otherwise ignore the "evidence" to date that BEA brings forward in its preliminary report which leads BEA to declare it is likely that the aircraft hit the water intact.
Allow me to paste here some quotes from pages 38 to 40 of the said report:
"The identified debris thus comes from all the areas of the plane."
"Part of the radome was found, representing approximately a fifth of its
circumference along its upper part."
"The galley, identified as G2, located at the level of door 2 on the right-hand
side, was not very distorted. Baskets and racks were compressed in the lower
part of both galley carts."
"The distortions observed in the metal vertical reinforcements of a toilet door
showed evidence of significant compressive forces."
"Fragments of the walls of the flight crew rest module were crumpled and
those of the ceiling were deformed downwards. The floor was curved under
the effect of a strong upward pressure from below. The connecting brackets
between the floor and the walls were bent backwards."
"Observations of the tail fin and on the parts from the passenger (galley, toilet
door, crew rest module) showed that the airplane had likely struck the surface
of the water in level flight, with a high rate vertical acceleration."
Assuming on what was there in terms of clues at the time of the publication of the report, I gues this sounds all perfecty plausible. To doubt the official investigating body and contrary to BEA's concrete findings speculate otherwise on NO evidence at all is irresponsible and a waste of space.
The final report will take into account all clues and evidence that has and, for now, will become available, hopefully when the wreckage and the recorders are found.
Allow me to paste here some quotes from pages 38 to 40 of the said report:
"The identified debris thus comes from all the areas of the plane."
"Part of the radome was found, representing approximately a fifth of its
circumference along its upper part."
"The galley, identified as G2, located at the level of door 2 on the right-hand
side, was not very distorted. Baskets and racks were compressed in the lower
part of both galley carts."
"The distortions observed in the metal vertical reinforcements of a toilet door
showed evidence of significant compressive forces."
"Fragments of the walls of the flight crew rest module were crumpled and
those of the ceiling were deformed downwards. The floor was curved under
the effect of a strong upward pressure from below. The connecting brackets
between the floor and the walls were bent backwards."
"Observations of the tail fin and on the parts from the passenger (galley, toilet
door, crew rest module) showed that the airplane had likely struck the surface
of the water in level flight, with a high rate vertical acceleration."
Assuming on what was there in terms of clues at the time of the publication of the report, I gues this sounds all perfecty plausible. To doubt the official investigating body and contrary to BEA's concrete findings speculate otherwise on NO evidence at all is irresponsible and a waste of space.
The final report will take into account all clues and evidence that has and, for now, will become available, hopefully when the wreckage and the recorders are found.
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DutchBru:
Is it? Are you sure? So accepting on blind faith the hastily assembled preliminary observations of the official investigators' hypotheses based on some very limited bits of evidence is ok is it? I dont see much yet that can be labelled as "concrete findings" from anyone, even BEA.
I dont mean to single you out on this DB, because your response was quite valid and yes I agree it is frustrating to read the same things coming back again and again. However, whether we like it or not, iteration is a hugely important aspect of any kind of problem solving. It is only annoying in this forum because it is inconvenient; it doesn't fit neatly into a single-thread debating format.
So, either we take the view DB alludes to that there is no point whatsoever to this thread and we should just let the investigators do their job...
...or we allow this thread to stand as a collective demonstration that the aviation community will not accept less than the highest standard of problem solving in this case.
Whether the investigators take heed of some of the additional cognitive reasoning being offered by contributors to this forum, or not, they will surely be aware that this is one of the key places at which their findings MUST stand up to criticism.
Unfortunately in the field of problem solving it is NOT sufficient to say "Oh I wish people would shut up about x,y,z because they were mentioned 130 pages ago" because unless these things churn over and get re-evaluated obvious missing links will stay missing. It took a 13 year old kid to point out the that dial-up could become DSL due to an obvious oversight by an entire industry.
- I agree it is frustrating to read all the repitition though, particularly in such a complicated case. I would propose to the moderators that AF447 should temporarily occupy its own section within Pprune - with seperate sub-threads for the main debating issues, general news and a summary; until such a time as the evidence, reporting, speculation and debate of each nuance begin to gravitate towards something conclusive.
To doubt the official investigating body and contrary to BEA's concrete findings speculate otherwise on NO evidence at all is irresponsible and a waste of space.
I dont mean to single you out on this DB, because your response was quite valid and yes I agree it is frustrating to read the same things coming back again and again. However, whether we like it or not, iteration is a hugely important aspect of any kind of problem solving. It is only annoying in this forum because it is inconvenient; it doesn't fit neatly into a single-thread debating format.
So, either we take the view DB alludes to that there is no point whatsoever to this thread and we should just let the investigators do their job...
...or we allow this thread to stand as a collective demonstration that the aviation community will not accept less than the highest standard of problem solving in this case.
Whether the investigators take heed of some of the additional cognitive reasoning being offered by contributors to this forum, or not, they will surely be aware that this is one of the key places at which their findings MUST stand up to criticism.
Unfortunately in the field of problem solving it is NOT sufficient to say "Oh I wish people would shut up about x,y,z because they were mentioned 130 pages ago" because unless these things churn over and get re-evaluated obvious missing links will stay missing. It took a 13 year old kid to point out the that dial-up could become DSL due to an obvious oversight by an entire industry.
- I agree it is frustrating to read all the repitition though, particularly in such a complicated case. I would propose to the moderators that AF447 should temporarily occupy its own section within Pprune - with seperate sub-threads for the main debating issues, general news and a summary; until such a time as the evidence, reporting, speculation and debate of each nuance begin to gravitate towards something conclusive.
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I would propose to the moderators that AF447 should temporarily occupy its own section within Pprune - with seperate sub-threads for the main debating issues, general news and a summary; until such a time as the evidence, reporting, speculation and debate of each nuance begin to gravitate towards something conclusive.
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"So accepting on blind faith the hastily assembled preliminary observations of the official investigators' hypotheses based on some very limited bits of evidence is ok is it?"
Yes. The time constraint was 30 days and they only posted the basic knowned facts or what they observed at that 30-day period. They specifically stated that they were not making any hypothesis.
Yes. The time constraint was 30 days and they only posted the basic knowned facts or what they observed at that 30-day period. They specifically stated that they were not making any hypothesis.
This document has been prepared on the basis of the initial information gathered during the investigation, without any analysis and - given the continuing absence of wreckage, the flight recorders, radar tracks and direct testimony - without any description of the circumstances of the accident. Some of the points covered may evolve with time. Nothing in the presentation of this interim report or in the points that are raised therein should be interpreted as an indication of the orientation or conclusions of the investigation.
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Until such time as new facts or evidence emerges, perhaps this thread should be closed, as it is, anyhow, vanishing up its own ass with constant rehashing and repetition based on very little known & no new evidence.
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captplaystation, with all due respect, sir, who is forcing you to read this if you so intensely dislike it? 
It appears to be popular with others.
JD-EE
It appears to be popular with others.JD-EE
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I am not forced to read it, but, like so many others I look here for new information or perhaps a "new" angle on what has happened. At the moment I have (and feel free to disagree) the distinct impression that like most threads following an accident this one is now going round in circles chasing it's own tail.
It is frustrating to have to wade through pages of speculative suggestions recycled & regurgitated ad infinitum, to only find that there is nothing new of any value.
It is frustrating to have to wade through pages of speculative suggestions recycled & regurgitated ad infinitum, to only find that there is nothing new of any value.
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Captplaystation, mate I completely agree with you!
I fly the A332 (and A343/5), so I am obviously keen to find out what happened, however the thought of wading through 4000 posts of speculative drivel (as is often the case on these hallowed forums) fills me with dread and fear, and frankly I can't be arsed!
So please guys, why don't we make a new pact (or thread) that only brings NEW relevant information to the fore that actually may be of some use to us buggers that actually fly the things.
Cheers
I fly the A332 (and A343/5), so I am obviously keen to find out what happened, however the thought of wading through 4000 posts of speculative drivel (as is often the case on these hallowed forums) fills me with dread and fear, and frankly I can't be arsed!
So please guys, why don't we make a new pact (or thread) that only brings NEW relevant information to the fore that actually may be of some use to us buggers that actually fly the things.
Cheers