AF 447 Search to resume
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Auraflyer:
Not that it's important, but your version of the French text on the wing is absolutely correct, as evidenced by the more readable picture on post #3573.
Not that it's important, but your version of the French text on the wing is absolutely correct, as evidenced by the more readable picture on post #3573.
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Hi,
Thanks to PJ2 (post #3577) for the drawings and to Machaca for the pictures, especially the second one...
.
Perhaps my first sights were misleading : looking at the structural line between the two red lines, I can't find anything compatible with rear view of the left wing : on the trailing edge near spoilers 2 and 3, stuctural wing lines aren't parallel to the area line. So, it may be front view of right wing, whose shape could be the one bertween the green lines...
With a bet changing every half day, may be I will find the truth some day: perhaps better to leave this to informed ones!
Thanks to PJ2 (post #3577) for the drawings and to Machaca for the pictures, especially the second one...
Originally Posted by PJ2
This diagram may help...as may be expected, the "Do Not Walk.." labelling would be in a number of locations along the leading and trailing edges of the wing.
Perhaps my first sights were misleading : looking at the structural line between the two red lines, I can't find anything compatible with rear view of the left wing : on the trailing edge near spoilers 2 and 3, stuctural wing lines aren't parallel to the area line. So, it may be front view of right wing, whose shape could be the one bertween the green lines...
With a bet changing every half day, may be I will find the truth some day: perhaps better to leave this to informed ones!
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Total speculation warning.
Fins have come off airbus before.
This airbus's fin was found intacto and seperate. It didn't finish up where the wreckage of the a/c was found.
If rough rudder action can snap an airbus fin off, surely a MF Cb could too.
I'll betcha that fin came off and precip'd the accident sequence.
Fins have come off airbus before.
This airbus's fin was found intacto and seperate. It didn't finish up where the wreckage of the a/c was found.
If rough rudder action can snap an airbus fin off, surely a MF Cb could too.
I'll betcha that fin came off and precip'd the accident sequence.
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Shadoko
"More often than not your first inclinations are correct" and I think in this case this is a true statement. If you refer back to your #3573 post, the attachment points of the spoilers in your picture match very well with what is seen in the crash photo. The leading edge of the wing in the crash photo isn't there. IMHO, the wing tore from root to tip, maybe as a result of the forces of the engine and pylon tearing away. The bend you see (outlined in green) may have more to do with the location and angulation of the interior structural spar in the wing. The painting of the words in English & French "Do not walk beyond this point" may vary slightly in location from aircraft to aircraft over time, but the spoiler attachment points do not.
"More often than not your first inclinations are correct" and I think in this case this is a true statement. If you refer back to your #3573 post, the attachment points of the spoilers in your picture match very well with what is seen in the crash photo. The leading edge of the wing in the crash photo isn't there. IMHO, the wing tore from root to tip, maybe as a result of the forces of the engine and pylon tearing away. The bend you see (outlined in green) may have more to do with the location and angulation of the interior structural spar in the wing. The painting of the words in English & French "Do not walk beyond this point" may vary slightly in location from aircraft to aircraft over time, but the spoiler attachment points do not.
Last edited by Jetdriver; 18th Apr 2011 at 04:21.
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I'll betcha that fin came off and precip'd the accident sequence.
.Have you been reading that A319 wake turbulence incident that SensorValidation mentioned recently? That aircraft overstressed its VS attach points but without causing permanent damage.
I found the trace of that aircraft's flight control inputs vs surface positions pretty clearly showed some control rate limiting occuring.
Unfortunately the graphic is a bit fuzzy, but if you print it out full size you can then easily read the legends along the margins.
A wake turbulence encounter is probably a good comparison with what happens inside a developed Cb, only perhaps a bit gentler.
If you look at the elevator trace, you will notice one side of the elevator lagging the other side. This is probably the result of its active hydraulic system not keeping up with the demand in that time frame. Later (after the vertical green line) you can see the rudder doing something quite different than what the pedals are commanding. Probably a good thing that the wake encounter only lasted a few seconds.
A wake turbulence encounter is probably a good comparison with what happens inside a developed Cb, only perhaps a bit gentler.
If you look at the elevator trace, you will notice one side of the elevator lagging the other side. This is probably the result of its active hydraulic system not keeping up with the demand in that time frame. Later (after the vertical green line) you can see the rudder doing something quite different than what the pedals are commanding. Probably a good thing that the wake encounter only lasted a few seconds.
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Originally Posted by Chris Scott
In view of the possibility that AF447 encountered sudden, severe turbulence, perhaps we should be adding another scenario to the list of possible causes of LOC and Control-Law degradation. Could it be compatible with the analysis of ACARS messages? I think it might be.
But unreliable airspeed + turbulence + no natural horizon + AP disconnect + alternate law ... could be the perfect recipe for overcontrol.
We know how easy it is to over control especially with the sidestick.
The indicated airspeed may be little, but the real true airspeed would not cope well with anything more than tiny sidestick solicitations ...
I remember being disturbed by one copilot, who moved a pedal significantly when stretching a leg that had "gone to sleep".
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Mike-wsm, do you remember the old TV game show (in the US) called "Name That Tune?" The premise was to tell the contestants something about the tune to be played. Then the contestants would hit their buzzers and suggest they could guess the tune in some number of notes. (The record is zero notes. They asked, "This is the theme from a 1940s musical that forever changed musical theater." There is only one such, "Oklahoma.")
The group of us are essentially playing "Name That Crash" with the little bits of information BEA vouchsafes us. This "tune" er Crash is strange enough I am not sure we'll all agree that a solution has been found even with CVR, FDR, and CMC (?) all recovered and readable and essentially the entire plane recovered from the bottom of the ocean.
I've learned that FDRs really do not store an exhaustive array of data that could tell us what the radar was showing, whether somebody dozed off at a critical instant, weather every outside the plane sensor froze up at about the same time, or any of dozens of other potential phenomena. So I am betting with myself that when this is all over we'll still be a few dollars short of a full set of clues. I for one am just suspicious enough of BEA's motives etc that I'd like to see their report audited by a second panel of experts. We certainly seem to have a plethora of really sharp experts here. I suspect that if this group and BEA arrive, ultimately, at different causes "I'd demand a recount" as it were bu a team of airplane accident investigators from all around the world.
This group will, ultimately, let me know of my native cynicism and paranoia should express itself.
For example, The fact that they built a 40 nm search radius for an event that went down in a violent storm in 4 minutes is just a small indictment of BEA's motives and expertise. Figure the plane's ground speed in 4 minutes. Figure it was PROBABLY (only probably) below a few thousand feet at the time of one of the last messages and guess how far the plane could be from the LKP. I am figuring 8 to 12nm. I am guessing more or less North. If they REALLY had claimed finding it 30nm South in a compact debris field I'd have raised holy heck about that.
I figure this group is providing a rather nice forum for this "reality check."
(I also love learning when not ordered to by somebody else. And I've had tremendous fun learning here. And I bet if the BEA takes good enough notes about recovery locations for specific objects some very interesting data for undersea currents in that area could be derived from the BEA data. I hope they do not waste THAT opportunity.)
The group of us are essentially playing "Name That Crash" with the little bits of information BEA vouchsafes us. This "tune" er Crash is strange enough I am not sure we'll all agree that a solution has been found even with CVR, FDR, and CMC (?) all recovered and readable and essentially the entire plane recovered from the bottom of the ocean.
I've learned that FDRs really do not store an exhaustive array of data that could tell us what the radar was showing, whether somebody dozed off at a critical instant, weather every outside the plane sensor froze up at about the same time, or any of dozens of other potential phenomena. So I am betting with myself that when this is all over we'll still be a few dollars short of a full set of clues. I for one am just suspicious enough of BEA's motives etc that I'd like to see their report audited by a second panel of experts. We certainly seem to have a plethora of really sharp experts here. I suspect that if this group and BEA arrive, ultimately, at different causes "I'd demand a recount" as it were bu a team of airplane accident investigators from all around the world.
This group will, ultimately, let me know of my native cynicism and paranoia should express itself.
For example, The fact that they built a 40 nm search radius for an event that went down in a violent storm in 4 minutes is just a small indictment of BEA's motives and expertise. Figure the plane's ground speed in 4 minutes. Figure it was PROBABLY (only probably) below a few thousand feet at the time of one of the last messages and guess how far the plane could be from the LKP. I am figuring 8 to 12nm. I am guessing more or less North. If they REALLY had claimed finding it 30nm South in a compact debris field I'd have raised holy heck about that.
I figure this group is providing a rather nice forum for this "reality check."
(I also love learning when not ordered to by somebody else. And I've had tremendous fun learning here. And I bet if the BEA takes good enough notes about recovery locations for specific objects some very interesting data for undersea currents in that area could be derived from the BEA data. I hope they do not waste THAT opportunity.)
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Machinbird, with your tab on a wing tip light example I'd suggest "imagine a maple seed." They do NOT fall straight down or deflect in breezes the same. The tab makes them "fly" more rather than sink like an avocado. And their spiral is non-trivial.
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Machinbird, with your tab on a wing tip light example I'd suggest "imagine a maple seed." They do NOT fall straight down or deflect in breezes the same. The tab makes them "fly" more rather than sink like an avocado. And their spiral is non-trivial.
Guess my forgetter is working very well.
But in water, the rotation rate of a maple seed type airfoil would be severely slowed.
shadoko wrote:
I have to say, looking closely at the shape, it really resembles a fracture line or even a tear to me. Look how it "curves" going towards the BEA logo - down, then up then down again.
Is this part of the wing skin a composite material?
Could the damage here be due to the engine being forced up against the wing on impact with the water?
Perhaps my first sights were misleading : looking at the structural line between the two red lines, I can't find anything compatible with rear view of the left wing : on the trailing edge near spoilers 2 and 3, stuctural wing lines aren't parallel to the area line. So, it may be front view of right wing, whose shape could be the one bertween the green lines...
Is this part of the wing skin a composite material?
Could the damage here be due to the engine being forced up against the wing on impact with the water?
Hi,
Perhaps my first sights were misleading : looking at the structural line between the two red lines, I can't find anything compatible with rear view of the left wing : on the trailing edge near spoilers 2 and 3, stuctural wing lines aren't parallel to the area line. So, it may be front view of right wing, whose shape could be the one bertween the green lines...
Perhaps my first sights were misleading : looking at the structural line between the two red lines, I can't find anything compatible with rear view of the left wing : on the trailing edge near spoilers 2 and 3, stuctural wing lines aren't parallel to the area line. So, it may be front view of right wing, whose shape could be the one bertween the green lines...
I'm with Turbine D on this one: Looking at the position of the supports of the plates in front of the spoilers in relation to the 'Do not step...' at the trailing edge they match perfectly. In your own post #3573 the images show it nicely.
That said it would mean everything behind the main wingbox (behind the aft spar) including the area in front of the spoilers were torn off on impact. However, as these arejust panels bolted/glued on the supports that doesn't seem too unlikely.
So I'm pretty sure you hit the nail on the head with your first assumption.
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Random question time.
In what must be one of the best ditichings ever, even conditions-wise unless the plane had floats, US1549 suffered substantial damage. What would we have seen if it had ditched +30 or 40 kts?
Anyway - since (presumably) there's some forward momentum here (??)
How does the size of the aircraft reflect damage? By that - are design loadings directly proportionate to size - in that - does a 1 tonne wing need twice the strength of a half tonne wing? (if that makes sense!)
Similarly, if a wing is longer, it has longer control surfaces - which is more area to contact water - mor drag - more 'distorting force' - a similar thing could be said for engine housings - if they are larger then they will scoop up a greater volume of water and if so - would this give 'more' damage - say it had been an A330 ditched in the Hudson at the same velocitys would there be more damage (even if only by the aircraft weight?)
Ignoring he seabed position, can much be deduced from the images beeing seen about the aircraft's dispostion at impact?
In what must be one of the best ditichings ever, even conditions-wise unless the plane had floats, US1549 suffered substantial damage. What would we have seen if it had ditched +30 or 40 kts?
Anyway - since (presumably) there's some forward momentum here (??)
How does the size of the aircraft reflect damage? By that - are design loadings directly proportionate to size - in that - does a 1 tonne wing need twice the strength of a half tonne wing? (if that makes sense!)
Similarly, if a wing is longer, it has longer control surfaces - which is more area to contact water - mor drag - more 'distorting force' - a similar thing could be said for engine housings - if they are larger then they will scoop up a greater volume of water and if so - would this give 'more' damage - say it had been an A330 ditched in the Hudson at the same velocitys would there be more damage (even if only by the aircraft weight?)
Ignoring he seabed position, can much be deduced from the images beeing seen about the aircraft's dispostion at impact?
Yes. But in all cases except one this happened during the impact sequence
As is the case in almost all instances where an Airbus crashes. Even the Afriqiah Fin looked pristine compared to the rest of the plane.
The fins are simply extremely strong compared to their weight. So their own inertia is low compared to their strength.
[How do you know that, while even the investigation experts don't know it / don't agree ?
If a Cb shears something off it would rather be the HS.
That is in most cases the first control surface which fails in a dynamic overload. In the remaining cases it is the wing that fails.
Loss of VS is extremeliest rare.
Besides that I do not see giant lateral forces in a Cb, mostly vertical forces.
Where can I place my money for this bet ?
This airbus's fin was found intacto and seperate.
The fins are simply extremely strong compared to their weight. So their own inertia is low compared to their strength.
It didn't finish up where the wreckage of the a/c was found.
If rough rudder action can snap an airbus fin off, surely a MF Cb could too.
That is in most cases the first control surface which fails in a dynamic overload. In the remaining cases it is the wing that fails.
Loss of VS is extremeliest rare.
Besides that I do not see giant lateral forces in a Cb, mostly vertical forces.
I'll betcha that fin came off and precip'd the accident sequence.
While we are at speculating:
(Attention: This is all really speculation and I'm impatiently awaiting the results of the FDR /CVR analysis after they will be hopefully found soon). Will be interesting to see in hindsight where the brain farts were.
So for what it's worth:
Here comes my scenario which I have in mind based on what we know atm :
2:09:30
Being in Cb with supercooled droplets. Pitots starting to freeze over.
2:10:00 - 2:10:15
Pitot fail, unreliable airspeed.
AP A/THR disconnect.
Possibly showing overspeed causing the Pilots to reduce Thrust, leading to slow decelleration
ADR disagree, Alternate Law 2
Edit: Following comment by @Sensor_validation I agree AP /A/THR deactivation and switch to Alt2 probably occured more or less simultaneously, time delay in ACRAS only due to ACARS transmission
/Edit
2:10:15 - ~2:11:00
Pilots manually trying to keep the plane straight and level, significant turbulence being countered by significant control inputs, not being covered by protections.
Meanwhile:
2:10:34 Last position report transmitted, already in Alt 2 3nm left off course possibly indicating pilots already fighting the situation.
Probably shortly after reporting of LKP:
Manual overcontrol in pitch combined with reduced speed and strong vertical gusts leading to accelerated stall causing massive wing drop. Causing loss of spatial orientation due to severly moving Attitude indication.
2:11:30 - 2:14:30 Aircraft progressively stalled.
Heavy loss of forward velocity, decellerating from ~250kts CAS to <100 kts. Potential course reversal after initial wing drop. Pilots regaining horizontal attitude.
Heavy loss of altitude, RoD ~ 20000 ft/min. 'Falling Leaf attitude'. possiibly combined with slow rotation or erroneous heading change while dropping. In between partly recovery possible. Re-activation of AP possible while Airspeed still unreliable but consistent. Potentially followed by subsequent stall(s).
In denser atmosphere RoD decreasing to 15000 ft/min. Forward speed reduced to < 100kts.
2:14:30 - 2:15:15.
Edit:
Following Comment by @Sensor_validation I tend to agree time of crash seems more likely towards 2:14:30
/Edit
Impact on the surface: Vertical speed : 150kts, horizontal speed: 50 - 100 kts. Pitch angle: 20 - 30° Nose up, perhaps slightly less. Engines at high N1/EPR. (Does that match the pictures of the engine ?)
Heading at impact: between 090 and 180.
Is there any obvious thing which I oversaw which contradicts this sequence? Are there any obvious brain farts identifiable already now ?
Any comments ?
Please feel free to challenge/dissect it part by part.
(Attention: This is all really speculation and I'm impatiently awaiting the results of the FDR /CVR analysis after they will be hopefully found soon). Will be interesting to see in hindsight where the brain farts were.
So for what it's worth:
Here comes my scenario which I have in mind based on what we know atm :
2:09:30
Being in Cb with supercooled droplets. Pitots starting to freeze over.
2:10:00 - 2:10:15
Pitot fail, unreliable airspeed.
AP A/THR disconnect.
Possibly showing overspeed causing the Pilots to reduce Thrust, leading to slow decelleration
ADR disagree, Alternate Law 2
Edit: Following comment by @Sensor_validation I agree AP /A/THR deactivation and switch to Alt2 probably occured more or less simultaneously, time delay in ACRAS only due to ACARS transmission
/Edit
2:10:15 - ~2:11:00
Pilots manually trying to keep the plane straight and level, significant turbulence being countered by significant control inputs, not being covered by protections.
Meanwhile:
2:10:34 Last position report transmitted, already in Alt 2 3nm left off course possibly indicating pilots already fighting the situation.
Probably shortly after reporting of LKP:
Manual overcontrol in pitch combined with reduced speed and strong vertical gusts leading to accelerated stall causing massive wing drop. Causing loss of spatial orientation due to severly moving Attitude indication.
2:11:30 - 2:14:30 Aircraft progressively stalled.
Heavy loss of forward velocity, decellerating from ~250kts CAS to <100 kts. Potential course reversal after initial wing drop. Pilots regaining horizontal attitude.
Heavy loss of altitude, RoD ~ 20000 ft/min. 'Falling Leaf attitude'. possiibly combined with slow rotation or erroneous heading change while dropping. In between partly recovery possible. Re-activation of AP possible while Airspeed still unreliable but consistent. Potentially followed by subsequent stall(s).
In denser atmosphere RoD decreasing to 15000 ft/min. Forward speed reduced to < 100kts.
2:14:30 - 2:15:15.
Edit:
Following Comment by @Sensor_validation I tend to agree time of crash seems more likely towards 2:14:30
/Edit
Impact on the surface: Vertical speed : 150kts, horizontal speed: 50 - 100 kts. Pitch angle: 20 - 30° Nose up, perhaps slightly less. Engines at high N1/EPR. (Does that match the pictures of the engine ?)
Heading at impact: between 090 and 180.
Is there any obvious thing which I oversaw which contradicts this sequence? Are there any obvious brain farts identifiable already now ?
Any comments ?
Please feel free to challenge/dissect it part by part.
Last edited by Jetdriver; 18th Apr 2011 at 16:00.
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Originally Posted by JD-EE
For example, The fact that they built a 40 nm search radius for an event that went down in a violent storm in 4 minutes is just a small indictment of BEA's motives and expertise. Figure the plane's ground speed in 4 minutes. Figure it was PROBABLY (only probably) below a few thousand feet at the time of one of the last messages and guess how far the plane could be from the LKP. I am figuring 8 to 12nm. I am guessing more or less North. If they REALLY had claimed finding it 30nm South in a compact debris field I'd have raised holy heck about that.
Which bit of F-GZCP knocked the tail off F-GTAM on 17.08.2006 ?
The attachment points of the A330 do look like the are specially reinforced compared to similar early designs?
Photos: Airbus A330-203 Aircraft Pictures | Airliners.netThe natural feature was then incorporated into AF's paint job.
Perhaps they should start to search for the remains of half of it "UNDER THE FOOT OF THE BEAR" (Nevil Shute)
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henra said "As is the case in almost all instances where an Airbus crashes. Even the Afriqiah Fin looked pristine compared to the rest of the plane. The fins are simply extremely strong compared to their weight. So their own inertia is low compared to their strength."
On the contrary, the fin was quite thoroughly damaged, and was mixed up with the remainder of the empennage and HS in a tangled mess.
Libya crash's boy survivor doing well | World | News | Toronto Sun
On the contrary, the fin was quite thoroughly damaged, and was mixed up with the remainder of the empennage and HS in a tangled mess.
Libya crash's boy survivor doing well | World | News | Toronto Sun
Where do you see damage to the rest of the fin structure (apart from the TE as said) ?
Have you looked at the remainder of the aircraft and what has been left of it compared to the fin ? It is a 10 million item 3d puzzle.
Can't you see a pattern there ?
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What I see is that a belly flop on the hard desert pan of sufficient violence to completely destroy the aircraft, did not separate the fin from the empennage or from the HS, but that the rudder was torn all to hell.
Rescue workers examine debris from Afriqiyah Airways flight 8U771 at Tripoli airport May 12.
Rescue workers examine debris from Afriqiyah Airways flight 8U771 at Tripoli airport May 12.
PF Transition from AP with Normal Law to AP-OFF with ALTN 2 Law
I wrote (currently post #3556), in the light of the TSB of Canada’s report[FONT=Verdana][SIZE=2] of an A319 wake-turbulence encounter:
"In view of the possibility that AF447 encountered sudden, severe turbulence, perhaps we should be adding another scenario to the list of possible causes of LOC and Control-Law degradation. Could it be compatible with the analysis of ACARS messages? I think it might be."
Was the original fault that led to the degradation from Normal Law to Alternate-2 (ALTN2) Law either:
(a) AoA-probe anomalies caused by pilot-induced yaw;
or
(b) pitot-probe anomalies caused (perhaps) by icing?
CONF iture points out:
"...the message related to the pitot tubes which, in my opinion, is absolutely central in the AF447 ending."
So (a) looks less likely than (b).
However, CONF iture continues:
"We know how easy it is to over control especially with the sidestick.
The indicated airspeed may be little, but the real true airspeed would not cope well with anything more than tiny sidestick solicitations ..."
During the minute from 0210z, for whatever reason, the PF undoubtedly found himself in Alternate Law (probably ALTN 2), sans-AP, trying to keep the wings level (or fly a safe turn) and control the pitch. ALTN 2 does not apply in the case of the A320 family, but the DFDR trace (reproduced above by Machinbird) shows an experienced PF trying to cope with the transition from AP to sidestick and Alternate Law in moderate-severe turbulence on an A319.
Again in the light of the TSB of Canada’s report, I also wrote:
Should rudder ever be used in cruise-flight, apart from the asymmetry case?
If the answer to that is in the negative, there is now more than anecdotal evidence that some pilots do use rudder at any speed, and that undesired yaw-cycling can be the result. This may compromise aerodynamics and/or structure; and even the quality of sensor-data in the ADRs.
"In view of the possibility that AF447 encountered sudden, severe turbulence, perhaps we should be adding another scenario to the list of possible causes of LOC and Control-Law degradation. Could it be compatible with the analysis of ACARS messages? I think it might be."
Was the original fault that led to the degradation from Normal Law to Alternate-2 (ALTN2) Law either:
(a) AoA-probe anomalies caused by pilot-induced yaw;
or
(b) pitot-probe anomalies caused (perhaps) by icing?
CONF iture points out:
"...the message related to the pitot tubes which, in my opinion, is absolutely central in the AF447 ending."
So (a) looks less likely than (b).
However, CONF iture continues:
"We know how easy it is to over control especially with the sidestick.
The indicated airspeed may be little, but the real true airspeed would not cope well with anything more than tiny sidestick solicitations ..."
During the minute from 0210z, for whatever reason, the PF undoubtedly found himself in Alternate Law (probably ALTN 2), sans-AP, trying to keep the wings level (or fly a safe turn) and control the pitch. ALTN 2 does not apply in the case of the A320 family, but the DFDR trace (reproduced above by Machinbird) shows an experienced PF trying to cope with the transition from AP to sidestick and Alternate Law in moderate-severe turbulence on an A319.
Again in the light of the TSB of Canada’s report, I also wrote:
Should rudder ever be used in cruise-flight, apart from the asymmetry case?
If the answer to that is in the negative, there is now more than anecdotal evidence that some pilots do use rudder at any speed, and that undesired yaw-cycling can be the result. This may compromise aerodynamics and/or structure; and even the quality of sensor-data in the ADRs.
Last edited by Jetdriver; 18th Apr 2011 at 15:59.
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henra
Given only the photos of the engine remains, it is impossible to tell if the engines were operating at high N1, there is nothing to go by at the moment. Usually one can tell this by visually observing the fan blades or compressor blades which would be bent in the opposite direction of rotation.
I am thinking the upward pitch angle would be less, more like 5°
Impact on the surface: Vertical speed : 150kts, horizontal speed: 50 - 100 kts. Pitch angle: 20 - 30°. Engines at high N1/EPR. (Does that match the pictures of the engine ?)
I am thinking the upward pitch angle would be less, more like 5°