Help researching 1961 Electra crash
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Lockheed did simulate a fouled aileron, and analysed force required to overcome a trapped aileron, (trapped in this case by the wing flap). A reasonable theory of entrapment could flow from a scenario where the flap, being retracted after lift off, contacted the aileron and pushed it up, creating wing down.
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I've modified the sim model to remove the forward fuselage and engines. In my prior demo the forward fuselage was there, but I'd removed its weight along with the engine weight. The fact that the fuselage was still there meant the sim calculated airflow around it, and this apparently led to the high somersault the sim showed. The sim treated it as being very long and light. With the forward fuselage missing, the plane flips much more quickly and stays lower to the ground. This might barely have showed over the trees, and may have contributed to the cartwheel myth.
It is not ignorant to be skeptical. Occasionally damage can occur on the ground prior to take off. Once in a while, a truck will damage an airframe, once in a while an aircraft will impact a tug, or food truck. Extremely rarely such damage goes unnoticed, and can affect flight.
“Both flaps at takeoff setting” is interesting. The term “both flaps” is also interesting. Here, the report takes into account the possibility that flaps may have not been set symmetrically. Hence “both flaps”. In your confidence, you have assumed what you consider to be complete knowledge. You missed that. You also missed the possibility of damage to the flap, likely impossible to ascertain post crash. Lockheed did not miss it. They spent time and not insignificant cash to exonerate fouled aileron.
I think I am within plausibility. My comments, though suggesting rarity, are not ignorant, because they do not suggest impossibility. IMO.
“Both flaps at takeoff setting” is interesting. The term “both flaps” is also interesting. Here, the report takes into account the possibility that flaps may have not been set symmetrically. Hence “both flaps”. In your confidence, you have assumed what you consider to be complete knowledge. You missed that. You also missed the possibility of damage to the flap, likely impossible to ascertain post crash. Lockheed did not miss it. They spent time and not insignificant cash to exonerate fouled aileron.
I think I am within plausibility. My comments, though suggesting rarity, are not ignorant, because they do not suggest impossibility. IMO.
Last edited by Concours77; 28th Dec 2017 at 17:12.
I’d like to offer a definition, one I post without researching, iow, from memory. Would you read it and comment? Thanks.
Safety wire: Safety wire is used extensively in aircraft applications. It is a “Fail safe” component, added to existing structure to prevent “catastrophic failure”.
Is safety wire a part of the structure it protects? Yes. And No. If a safety wire’s presence prevents a fastener from falling completely off, has it done its job? Absolutely, yes. But, is the structure safe for flight without a safety wire attached? Practically, yes. Administratively, NO. If the safety wire prevents loss of a fastener, the system is already assumed to have failed.
If a safety wire is not installed as it should be, what part of the structure secures the threads? In the case of cabling, an adjusting nut would be tightened to the correct tension, and a serrated washer and locknut would be added. This assembly is considered safe, as part of the “design consideration”. The structure is fully functional without the safety wire. Can the aircraft be released to service without the safety wire installed? Yes, but not legally, unless a waiver is secured.
Thank you again, I’m here to learn.
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Just to reinforce what megan has stated, the nuts and bolts are tightened to a design torque as specified by the manufacturer of the aircraft. The safety wire is then inserted to guarantee that the specified torque is maintained, i.e. the nut and bolt cannot slacken due to vibration or other influences such as temperature changes. The safety wire is the only indication that the nut and bolt, turnbuckle or whatever fastening is at the correct tension.
So while technically a correctly tensioned nut and bolt are theoretically capable of withstanding the physical aerodynamic stresses imposed, the slightest turn without a safety wire in place will place that connection outside the design parameters. It is then unsafe.
A browse through the air accident investigation archives will reveal many accidents caused by missing locking wires, particularly relating to engine components on light aircraft.
Vibration and thermal cycling are the main causes of threaded connections coming undone. Both are present in all aircraft during flight.
So while technically a correctly tensioned nut and bolt are theoretically capable of withstanding the physical aerodynamic stresses imposed, the slightest turn without a safety wire in place will place that connection outside the design parameters. It is then unsafe.
A browse through the air accident investigation archives will reveal many accidents caused by missing locking wires, particularly relating to engine components on light aircraft.
Vibration and thermal cycling are the main causes of threaded connections coming undone. Both are present in all aircraft during flight.
Gents,
My example is of the double nut variety, something I presume was part of the tensioning shackles on the Electra.
A turnbuckle is a different animal than a shackle. In your example you show a turnbuckle with only safety wire preventing rotation of the barrel, (not the cables). So the wire is not technically a “fail safe”. It is the primary (and only) part that prevents disaster, if the barrel rotates.
I would ask if it has been your experience that threaded ends of control cables routinely wander out, or in, disrupting tension, and potentially causing separation? Mine is that if the barrel of any cable system is fixed, stranded Stainless cable can not rotate about its own axis. If both ends are attached, the cable is rigid in respect to torsion (twisting). To rotate a cable end with its opposite end still attached is not possible, certainly not for the purpose of removal.
I think the implication in the final report of 706 is that the co-pilot’s aileron command cable separated. The implication being that a safety wire’s absence prior to flight allowed the cable to rotate, unthread, and separate, causing the disaster. If safety wire was the sole retainer, that might be possible. If a true “safety wire” (fail safe) system, then it cannot have “caused” the crash. It can only be said that “it failed to prevent” the crash.
Semantic? Certainly. My assumption is that the tensioner was double nutted, a design sufficient to secure the cable. A safety wire may have been a part of the design, but my doubt is that the safety wire was the sole retainer of the cable. Hence, “fail safe”.
In any case, I believe the report mentions that none of the specific parts could be recovered, making proof impossible.
A similar cause of loss of aileron Control would be the “jammed” boost unit power arm, or seized piston. The unit was found, and showed evidence of seizure of piston or jamming of power arm. The conclusion was the seizure was caused by fire damage. What steps were taken to determine the aileron boost unit was not seized prior to launching, or final right turn?
To arrive at a probable cause involves not only supporting the theory, but eliminating all other possibilities?
Questions:
What angle of right aileron deflection was discovered on the power arm? Was it three degrees?
After unseizing and replacing the piston, the boost unit was serviceable. So the cylinder was not damaged by fire? Just the piston?
The pilot’s Control cables were found to have continuity, but lacked a safety wire. The co-pilot’s controls were not found, but they certainly must have been missing the safety wire? Why? Because there was no safety wire on the pilot’s set?
My example is of the double nut variety, something I presume was part of the tensioning shackles on the Electra.
A turnbuckle is a different animal than a shackle. In your example you show a turnbuckle with only safety wire preventing rotation of the barrel, (not the cables). So the wire is not technically a “fail safe”. It is the primary (and only) part that prevents disaster, if the barrel rotates.
I would ask if it has been your experience that threaded ends of control cables routinely wander out, or in, disrupting tension, and potentially causing separation? Mine is that if the barrel of any cable system is fixed, stranded Stainless cable can not rotate about its own axis. If both ends are attached, the cable is rigid in respect to torsion (twisting). To rotate a cable end with its opposite end still attached is not possible, certainly not for the purpose of removal.
I think the implication in the final report of 706 is that the co-pilot’s aileron command cable separated. The implication being that a safety wire’s absence prior to flight allowed the cable to rotate, unthread, and separate, causing the disaster. If safety wire was the sole retainer, that might be possible. If a true “safety wire” (fail safe) system, then it cannot have “caused” the crash. It can only be said that “it failed to prevent” the crash.
Semantic? Certainly. My assumption is that the tensioner was double nutted, a design sufficient to secure the cable. A safety wire may have been a part of the design, but my doubt is that the safety wire was the sole retainer of the cable. Hence, “fail safe”.
In any case, I believe the report mentions that none of the specific parts could be recovered, making proof impossible.
A similar cause of loss of aileron Control would be the “jammed” boost unit power arm, or seized piston. The unit was found, and showed evidence of seizure of piston or jamming of power arm. The conclusion was the seizure was caused by fire damage. What steps were taken to determine the aileron boost unit was not seized prior to launching, or final right turn?
To arrive at a probable cause involves not only supporting the theory, but eliminating all other possibilities?
Questions:
What angle of right aileron deflection was discovered on the power arm? Was it three degrees?
After unseizing and replacing the piston, the boost unit was serviceable. So the cylinder was not damaged by fire? Just the piston?
The pilot’s Control cables were found to have continuity, but lacked a safety wire. The co-pilot’s controls were not found, but they certainly must have been missing the safety wire? Why? Because there was no safety wire on the pilot’s set?
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I've put up a video showing the CAB scenario of the plane sliding backward and right side up to the final wreckage site.
This video gives some feel for the scale of the site. The trees are placed a little better than in my earlier graphic, and I used three aerial views to position them. It's increasingly clear that the plane could not slide on the ground between those trees without cutting down a significant swath of them. The backward slide, of course, was always a little nutty.
I did not try to show the damage to the plane in this series of clips - the loss of the forward fuselage and the loss of the right wing tip. You'll just have to imagine it.
This is an animation tool, not the flight simulator. I'm having a little trouble with the paint job on the plane - the tail should be red.
This video gives some feel for the scale of the site. The trees are placed a little better than in my earlier graphic, and I used three aerial views to position them. It's increasingly clear that the plane could not slide on the ground between those trees without cutting down a significant swath of them. The backward slide, of course, was always a little nutty.
I did not try to show the damage to the plane in this series of clips - the loss of the forward fuselage and the loss of the right wing tip. You'll just have to imagine it.
This is an animation tool, not the flight simulator. I'm having a little trouble with the paint job on the plane - the tail should be red.
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I would suggest that as the nose impacted the ground and broke away, the forward part of the fuselage remaining dug in and inertia carried the rest of the aircraft up and over and into an inverted backwards slide.
The important thing to realise in relatively high speed impacts is that while the forward part of a vehicle (aircraft in this case) may come to a complete rest, the remainder of the vehicle is still moving with essentially the same forward speed and inertia. It is this phenomenon that causes bullet splatter with small projectiles, crumple zones to work in motor vehicles and substantial parts of an aircraft fuselage to split away and carry along a debris track from the initial impact site.
Think in terms of dropping an extended slinky spring onto the ground. The bottom of the spring hits the ground and comes to a stop, while the top, or tail end of the spring is still travelling and accelerating downwards.
It takes a finite time for energy to propogate through a structure. In the case of the slinky spring demonstration, the majority of the energy is actually provided by gravity, not by the spring attempting to contract.
The nose breaking away is an indication that this section stopped almost instantly while the inertia of the remainder of the fuselage was sufficient to flip and slide a considerable distance further on.
Your video assumes and essentially wings level initial impact of the fuselage section with the ground. I suggest this is inaccurate and a substantial bank angle was maintained after contact with the railroad embankment. That is the only way the aircraft profile would have been able to pass between the trees. It is also more likely to result in the tail section being upside down and facing the direction of travel.
The aircraft could have impacted wings level, the nose broke away and then the remainder bounced and flipped over the trees, but this is a more complex scenario and therefore less likely to have occured.
The important thing to realise in relatively high speed impacts is that while the forward part of a vehicle (aircraft in this case) may come to a complete rest, the remainder of the vehicle is still moving with essentially the same forward speed and inertia. It is this phenomenon that causes bullet splatter with small projectiles, crumple zones to work in motor vehicles and substantial parts of an aircraft fuselage to split away and carry along a debris track from the initial impact site.
Think in terms of dropping an extended slinky spring onto the ground. The bottom of the spring hits the ground and comes to a stop, while the top, or tail end of the spring is still travelling and accelerating downwards.
It takes a finite time for energy to propogate through a structure. In the case of the slinky spring demonstration, the majority of the energy is actually provided by gravity, not by the spring attempting to contract.
The nose breaking away is an indication that this section stopped almost instantly while the inertia of the remainder of the fuselage was sufficient to flip and slide a considerable distance further on.
Your video assumes and essentially wings level initial impact of the fuselage section with the ground. I suggest this is inaccurate and a substantial bank angle was maintained after contact with the railroad embankment. That is the only way the aircraft profile would have been able to pass between the trees. It is also more likely to result in the tail section being upside down and facing the direction of travel.
The aircraft could have impacted wings level, the nose broke away and then the remainder bounced and flipped over the trees, but this is a more complex scenario and therefore less likely to have occured.
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The important thing to realise in relatively high speed impacts is that while the forward part of a vehicle (aircraft in this case) may come to a complete rest, the remainder of the vehicle is still moving with essentially the same forward speed and inertia. It is this phenomenon that causes bullet splatter with small projectiles, crumple zones to work in motor vehicles and substantial parts of an aircraft fuselage to split away and carry along a debris track from the initial impact site.
Your video assumes and essentially wings level initial impact of the fuselage section with the ground. I suggest this is inaccurate and a substantial bank angle was maintained after contact with the railroad embankment. That is the only way the aircraft profile would have been able to pass between the trees. It is also more likely to result in the tail section being upside down and facing the direction of travel.
The aircraft could have impacted wings level, the nose broke away and then the remainder bounced and flipped over the trees, but this is a more complex scenario and therefore less likely to have occured.
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Re: your video and your comment, "...the CAB scenario of the plane sliding backward and right side up to the final wreckage site."
OK, even I have to chime in here, frustrated with your continued insistence that the CAB report says something it doesn't.
Yes the CAB report says the aircraft "...landed right side up".
Yes, the report says it "...then slid tail first."
But the report does NOT say the aircraft slid tail first AND right side up throughout the entire path. Nowhere does it claim the aircraft remained right side up for the whole slide. What it says, quoted exactly, is: "...landed right side up. It then slid tail first another 820 feet. The aircraft disintegrated throughout its path, and wreckage was strewn over an area 200 feet wide and 1,200 feet long."
The actual sequence may not be as clearly described and in as much detail as you would wish. And that portion of the report is poorly worded, so it would be easy to draw the inference you did initially. However, an inference is all it is, and "disintegrated through its path" and "wreckage was strewn" do actually cover the final disposition of all parts of the aircraft.
Remember also, as noted in the ALPA report, there was a wreckage distribution chart available to the investigators, so they actually knew the exact final location of each part of the aircraft.
With all the best will in the world, I'd also note multiple people on at least two forums have responded to your questions and theories about the CAB report and the accident sequence, and most don't see that the report contains any gross or egregious errors either - and please note my emphasis on those adjectives. No, it doesn't contain every single scrap of data used to reach the final determination, but neither do NTSB final reports today - and at the time, technology did not make it easy to distribute to the public what might have been as many as 20,000 pages of documents, hand- or type-written ones at that.
Last, you'll recall you started a similar thread over on airliners.net, which I read before I started my research. One comment in particular seems worth reviewing at this point, from user Flaps, who wrote:
And I think we all agree with that. The CAB's primary obligation was to public safety, and their primary objective to find the actual cause of the accident. But the last couple of weeks' comments here seem to be veering toward questioning the CAB's overall probity, and some commenters appear to be questioning whether or not they even got the cause of the accident right.
So it seems time to pull back to the greater objectivity with which you began your own investigation. An awful lot of conjecture, and assumptions have been creeping in - you yourself have used the phrase, "This is pure conjecture...". Theories based on evidence are one thing, but narratives created seemingly out of surmise alone with nothing to back them up? That's the opposite of investigation.
Further to the crash records: I won't have time to get back to research until fairly late in January, but at that time I'm hopeful of being able to track down some more of the CAB and Lockheed documentation on this accident. Keep your fingers crossed :-)
All best,
cordwainer
OK, even I have to chime in here, frustrated with your continued insistence that the CAB report says something it doesn't.
Yes the CAB report says the aircraft "...landed right side up".
Yes, the report says it "...then slid tail first."
But the report does NOT say the aircraft slid tail first AND right side up throughout the entire path. Nowhere does it claim the aircraft remained right side up for the whole slide. What it says, quoted exactly, is: "...landed right side up. It then slid tail first another 820 feet. The aircraft disintegrated throughout its path, and wreckage was strewn over an area 200 feet wide and 1,200 feet long."
The actual sequence may not be as clearly described and in as much detail as you would wish. And that portion of the report is poorly worded, so it would be easy to draw the inference you did initially. However, an inference is all it is, and "disintegrated through its path" and "wreckage was strewn" do actually cover the final disposition of all parts of the aircraft.
Remember also, as noted in the ALPA report, there was a wreckage distribution chart available to the investigators, so they actually knew the exact final location of each part of the aircraft.
With all the best will in the world, I'd also note multiple people on at least two forums have responded to your questions and theories about the CAB report and the accident sequence, and most don't see that the report contains any gross or egregious errors either - and please note my emphasis on those adjectives. No, it doesn't contain every single scrap of data used to reach the final determination, but neither do NTSB final reports today - and at the time, technology did not make it easy to distribute to the public what might have been as many as 20,000 pages of documents, hand- or type-written ones at that.
Last, you'll recall you started a similar thread over on airliners.net, which I read before I started my research. One comment in particular seems worth reviewing at this point, from user Flaps, who wrote:
I'm doing some digging. I had done some research on this accident many years ago in college. I do believe based on memory at this point, that it was entirely possible that the accident sequence as was described in the report is largely accurate. The initial impact points were known from the point of first contact with the power lines as the lines themselves were ripped out followed by further impact marks, ground scars and debris propagation. The fact that the empennage is upside down in the photo does not in any way indicate that the aircraft did not initially slide right side up and backward.
There was considerable energy acting on the fuselage as it disintegrated along its ground path and the post impact explosion. The empennage could easily have rolled over into its final position indicated in the photo late in the accident sequence. The damage to the left horizontal stabilizer indicates exactly that. Nearly half of it is missing in the photo. The right horizontal stabilizer however is nearly intact. This indicates a roll to the left as it came to rest. The minimal damage to the vertical stabilizer solidly supports this hypothesis. If the aircraft were upside down the vertical stabilizer would have been destroyed. Instead it is nearly intact.
If you want to see some good similar instances of pieces of wreckage ending up in surprising positions relative to the impact sequence and path, reference Southern 242 and Eastern 401. Both of these aircraft were under control and close to wings level at impact yet major sections spun off and rolled in multiple directions as a result of impact energies and striking trees/objects along the way.
I'm not totally discounting your theory but I have done extensive research on hundreds of accidents over the years. The methodology of the NTSB and CAA is thorough, sound and well proven. Everything is thoroughly analyzed, checked, rechecked and verified by multiple experts before any final report is issued. I'm not saying that they never make a mistake. I am saying that it is highly unlikely that one of such magnitude would end up in a final report. Furthermore the photos of the empennage do support the statements in the accident report. The photos do not support the fuselage being upside down until very late in the impact sequence.
To be fair, Flaps wrote more later, including:There was considerable energy acting on the fuselage as it disintegrated along its ground path and the post impact explosion. The empennage could easily have rolled over into its final position indicated in the photo late in the accident sequence. The damage to the left horizontal stabilizer indicates exactly that. Nearly half of it is missing in the photo. The right horizontal stabilizer however is nearly intact. This indicates a roll to the left as it came to rest. The minimal damage to the vertical stabilizer solidly supports this hypothesis. If the aircraft were upside down the vertical stabilizer would have been destroyed. Instead it is nearly intact.
If you want to see some good similar instances of pieces of wreckage ending up in surprising positions relative to the impact sequence and path, reference Southern 242 and Eastern 401. Both of these aircraft were under control and close to wings level at impact yet major sections spun off and rolled in multiple directions as a result of impact energies and striking trees/objects along the way.
I'm not totally discounting your theory but I have done extensive research on hundreds of accidents over the years. The methodology of the NTSB and CAA is thorough, sound and well proven. Everything is thoroughly analyzed, checked, rechecked and verified by multiple experts before any final report is issued. I'm not saying that they never make a mistake. I am saying that it is highly unlikely that one of such magnitude would end up in a final report. Furthermore the photos of the empennage do support the statements in the accident report. The photos do not support the fuselage being upside down until very late in the impact sequence.
Your analysis of the turn and the bank angles definitely make more sense in explaining the photos and debris patterns than the CAA or ALPA reports. I agree that once the cause was found the investigation into the impact sequence ended right there.
And I think we all agree with that. The CAB's primary obligation was to public safety, and their primary objective to find the actual cause of the accident. But the last couple of weeks' comments here seem to be veering toward questioning the CAB's overall probity, and some commenters appear to be questioning whether or not they even got the cause of the accident right.
So it seems time to pull back to the greater objectivity with which you began your own investigation. An awful lot of conjecture, and assumptions have been creeping in - you yourself have used the phrase, "This is pure conjecture...". Theories based on evidence are one thing, but narratives created seemingly out of surmise alone with nothing to back them up? That's the opposite of investigation.
Further to the crash records: I won't have time to get back to research until fairly late in January, but at that time I'm hopeful of being able to track down some more of the CAB and Lockheed documentation on this accident. Keep your fingers crossed :-)
All best,
cordwainer
Last edited by cordwainer; 31st Dec 2017 at 05:56.
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Your video shows the plane landing on its belly almost immediately after the railway embankment. The report notes the entire wreckage path, from first impact with the wires to final rest was 1200 feet.
Did you allow for the additional 380 feet of distance before the second impact (1200ft-820ft)? It appears that would have been enough to put the beginning of the slide beyond the trees in your video. That also makes more sense of some witnesses describing a "cartwheel" and some describing a "bounce", i.e., if the plane were more or less still airborne for that 380 feet.
Cheers,
c
Did you allow for the additional 380 feet of distance before the second impact (1200ft-820ft)? It appears that would have been enough to put the beginning of the slide beyond the trees in your video. That also makes more sense of some witnesses describing a "cartwheel" and some describing a "bounce", i.e., if the plane were more or less still airborne for that 380 feet.
Cheers,
c
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Your video shows the plane landing on its belly almost immediately after the railway embankment. The report notes the entire wreckage path, from first impact with the wires to final rest was 1200 feet.
Did you allow for the additional 380 feet of distance before the second impact (1200ft-820ft)? It appears that would have been enough to put the beginning of the slide beyond the trees in your video. That also makes more sense of some witnesses describing a "cartwheel" and some describing a "bounce", i.e., if the plane were more or less still airborne for that 380 feet.
Did you allow for the additional 380 feet of distance before the second impact (1200ft-820ft)? It appears that would have been enough to put the beginning of the slide beyond the trees in your video. That also makes more sense of some witnesses describing a "cartwheel" and some describing a "bounce", i.e., if the plane were more or less still airborne for that 380 feet.
That makes the distance between wires impact and RR embankment critical. Unless the wires and RR embankment were co-located?
Surely the distance between RR first impact and final pos. Is 1200 feet?
megan: I am having difficulty explaining my presumption re: safety wire, and jammed Boost power arm, (or, piston).
Is it your presumption that the “safety wire” is the sole source of thread lock?
Also, in the time between right turn and impact, one assumes the controls were manipulated with some passion, including rapid reversals. I can demonstrate that the tension available in manual manipulation of aileron command cabling is approximately twelve hundred pounds. Not the 2000 pounds Lockheed reports to severe the cable, (in tension), but a very respectable amount of force. Given inertia of fluid, it is conceivable that reversal can cause piston “stall”, or “bind”.
Thanks for your comments.
Your video shows the plane landing on its belly almost immediately after the railway embankment. The report notes the entire wreckage path, from first impact with the wires to final rest was 1200 feet.
Did you allow for the additional 380 feet of distance before the second impact (1200ft-820ft)? It appears that would have been enough to put the beginning of the slide beyond the trees in your video. That also makes more sense of some witnesses describing a "cartwheel" and some describing a "bounce", i.e., if the plane were more or less still airborne for that 380 feet.
Cheers,
c
Did you allow for the additional 380 feet of distance before the second impact (1200ft-820ft)? It appears that would have been enough to put the beginning of the slide beyond the trees in your video. That also makes more sense of some witnesses describing a "cartwheel" and some describing a "bounce", i.e., if the plane were more or less still airborne for that 380 feet.
Cheers,
c
Also, I am confused about the 380 foot gap in ground contact. If at ninety degree bank, at ground level on first ground collision, and falling at one gee, how could the aircraft have stayed aloft almost four hundred feet? This to me infers a fair amount of lift, no? Lift that is simply not available if first impact is as described elsewhere? Tends to support the theory of roughly level flight post embankment, IMO.
That is one hell of a “bounce”
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It's clear from the CAB report that they considered the right wing impact with the embankment to be the first impact, and the distance to the final site was 1200 feet. You or I might consider the wires to be the first impact, but the CAB apparently did not, and we're relying on their measurements.
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This incident is a puzzle. It's not a crusade to enshrine my father's reputation, despite Megan's assessment. It's not a jihad against the CAB, and I accuse the investigators not of dishonesty but of sloppy work. I'm not trying to crucify long-dead investigators, I'm trying to determine what they got wrong and why. I'm amused by all the free psychoanalysis, but this is simply a puzzle. Because I have a stake in it, I intend to solve it.
I have not questioned the root cause, and see no call to. I question things in the CAB and ALPA reports only when they make no sense. All I'm working on is the impact and breakup sequence. I don't question that the CAB fulfilled their basic role of explaining the incident and helping to correct the system that led to it. I accept that an unsafetied fitting was the cause.
Within the scope of the CAB's charter, a poor description of the impact sequence is probably not a gross or egregious error. I suspect it was an afterthought, and once the root cause was known the impact sequence description may have been banged out by a flunkie. But my scope is not the entire incident; my scope is the impact sequence because that's where I took issue. And within the scope of the impact sequence, the description error is gross and egregious.
The CAB report makes a clear statement about the sequence, and the simplest reading of it is that the plane slid tail first and right side up to the final wreckage site. The CAB was clear that the plane went tail first the final 820 feet. I'm delighted that people seem to be coming to grips with the fact that this didn't actually happen. What you are doing is what I did three years ago when I had to digest the same uncomfortable reality.
My family always took investigation reports as Holy Writ. There are no mistakes there. When upon studying the images I found that the plane was upside down, I had to square this with the report. I tried imagining the plane breaking apart approximately at that final site, the tail flipping over near the wings. https://ibb.co/jSVpsG is a picture of the aft fuselage before fire has consumed much of it. From the length of fuselage at that point, and comparing to the overhead view at https://ibb.co/kvz8N6, it's clearly in contact with the wings but has partly collapsed. Notice the apparently extreme damage to the belly. It took a helluva pounding.
I tried to imagine the tail breaking off and rolling independently. The closeness to the wings makes that unlikely. The aft fuselage as seen in the overhead view is within half a dozen feet of correct alignment with the wing root, and if the aft fuselage rolled over it would be half a fuselage circumference away. I tried persuading myself that I was misreading the image, until I studied the landing gear structure which confirms the wing is upside down. I tried to imagine the wings, having broken from the tail, flipping on their latitudinal axis. But the leading edge faces east, meaning that from an upright slide the wings must have flipped on their longitudinal axis. That means the tail and wings are in the same orientation and in contact, and the main body ended at that site upside down. To suggest that the wings and aft fuselage parted, gyrated each in some independent way, and ended up back in their correct relative orientation but both rotated 180 degrees, is beyond belief.
It probably took me a couple weeks to accept that the CAB report was simply wrong. It was a Holy Toledo moment, I assure you. Saying that the plane slid tail first to the final site is by itself so woefully inadequate that "wrong" is an appropriate term to apply, so I do, because "woefully inadequate" is tedious to key in. If I told my wife I drove to the store and came home, and she later found I came home by taxi because I totalled the car, she would make it clear that my statement was so woefully inadequate as to be simply wrong.
So the questions present themselves. Why did the CAB leave us with such a woefully inadequate statement? What really happened? This is the puzzle. People making excuses for the woeful inadequacy of the CAB report is a good indicator that people are ready to consider the puzzle. If you're looking for wiggle room, you're starting to grasp the issue.
The CAB explicitly said the plane slid tail first the last 820 feet, though it doesn't explicitly say the plane was upright the whole way. The total path from first embankment impact was 1200 feet, the second impact was at 380 feet, and from then the plane slid. So although the CAB report doesn't say the plane slid tail first until it stopped, it also doesn't say the plane slid 821 feet and it does say it was tail first for 820 feet. Megan took issue with this, but the simplest reading is that the plane stopped. So the plane slid upright or inverted, but per the CAB it slid tail first until it didn't slide any more.
The vertical stabilizer is mostly intact, and the plane did not slide on it. As Cordwainer quoted Flaps: " If the aircraft were upside down the vertical stabilizer would have been destroyed. Instead it is nearly intact." This leaves us with a conundrum. The plane did not slide inverted, and it could not slide upright and tail first and leave us with inverted tail-first wreckage. Therefore it could not have slid tail first the final 820 feet.
This constitutes an error on the part of the CAB. The common term for this is "wrong". It doesn't mean the investigators were dishonest or evil. I have no doubt some or most of them knew exactly what happened. But what got into the final report is a wrong statement, and it's the same wrong scenario that the CAB gave to the Chicago Trib on the day of the crash. This is the puzzle. Why was the CAB spokesman so sure so early? Why was that not walked back?
I didn't start this project with an agenda to demonstrate a belly landing. I started with the overhead picture and bafflement. After due consideration, the arrival at the final wreckage looks like a high-energy nose-first approach. I can't square this with a backward slide of any kind. What looks like an agenda to someone reading this for the first time is merely the product of three years' hypotheses, testing, discarding, and starting over. Concours77 just shot down my scenario of a forward pitchover at the final site, by noticing the post in the ditch. So I have to start over and form a new hypothesis, which led to my very interesting flight sim of the damaged plane at
.
This is how solutions are found. You start with a conjecture, a hypothesis, and look for evidence that either supports or refutes it. I challenge anyone to describe a mystery that was solved without any conjectures. I try to keep the reader clear on my level of confidence in the various statements that I propose for others to critique. That's how conversations work. Steel is sharpened against stone; people sharpen against people. Read the title of the thread.
Over those three years the thin evidence at hand has coalesced to suggest a low-bank initial impact. Megan's dismissal aside, I see no evidence against a low bank and considerable evidence for it. The investigators had a wealth of data that is unavailable to me. They had debris maps and internal memos and hundreds of pictures, no doubt. They might have taken measurements of the broken electrical lines, and those might have shown the bank angle. Megan wanted me to take her conjecture on this as if it were evidence, but it's only conjecture.
I point out the CAB error not to take satisfaction trumpeting it from the rooftops, but because recognizing the error is the first step in solving the puzzle. Something went wrong in this investigation. The official reports describe an impact and breakup scenario that does not correspond to the pictures.
People working only from the narrative have a harder time seeing this, so I did the animation. If you look at an animation and say "Well THAT didn't happen" then the puzzle gets clearer. When I started the animation I had to build the virtual site, and until then I didn't know it would show how tight the gap was between the trees. That lack of space, along with Concours77 pointing out the post in the ditch, is moving the solution along.
Sylvia apparently thought my statements conflicted when I said it was obvious the CAB was wrong but I had no target solution in mind. There's no conflict there. It is becoming clearer to several here that the CAB was wrong, soften the word however you like. And I still don't know what happened and am ready to give up any holding that has evidence to disprove it.
I have not questioned the root cause, and see no call to. I question things in the CAB and ALPA reports only when they make no sense. All I'm working on is the impact and breakup sequence. I don't question that the CAB fulfilled their basic role of explaining the incident and helping to correct the system that led to it. I accept that an unsafetied fitting was the cause.
Within the scope of the CAB's charter, a poor description of the impact sequence is probably not a gross or egregious error. I suspect it was an afterthought, and once the root cause was known the impact sequence description may have been banged out by a flunkie. But my scope is not the entire incident; my scope is the impact sequence because that's where I took issue. And within the scope of the impact sequence, the description error is gross and egregious.
The CAB report makes a clear statement about the sequence, and the simplest reading of it is that the plane slid tail first and right side up to the final wreckage site. The CAB was clear that the plane went tail first the final 820 feet. I'm delighted that people seem to be coming to grips with the fact that this didn't actually happen. What you are doing is what I did three years ago when I had to digest the same uncomfortable reality.
My family always took investigation reports as Holy Writ. There are no mistakes there. When upon studying the images I found that the plane was upside down, I had to square this with the report. I tried imagining the plane breaking apart approximately at that final site, the tail flipping over near the wings. https://ibb.co/jSVpsG is a picture of the aft fuselage before fire has consumed much of it. From the length of fuselage at that point, and comparing to the overhead view at https://ibb.co/kvz8N6, it's clearly in contact with the wings but has partly collapsed. Notice the apparently extreme damage to the belly. It took a helluva pounding.
I tried to imagine the tail breaking off and rolling independently. The closeness to the wings makes that unlikely. The aft fuselage as seen in the overhead view is within half a dozen feet of correct alignment with the wing root, and if the aft fuselage rolled over it would be half a fuselage circumference away. I tried persuading myself that I was misreading the image, until I studied the landing gear structure which confirms the wing is upside down. I tried to imagine the wings, having broken from the tail, flipping on their latitudinal axis. But the leading edge faces east, meaning that from an upright slide the wings must have flipped on their longitudinal axis. That means the tail and wings are in the same orientation and in contact, and the main body ended at that site upside down. To suggest that the wings and aft fuselage parted, gyrated each in some independent way, and ended up back in their correct relative orientation but both rotated 180 degrees, is beyond belief.
It probably took me a couple weeks to accept that the CAB report was simply wrong. It was a Holy Toledo moment, I assure you. Saying that the plane slid tail first to the final site is by itself so woefully inadequate that "wrong" is an appropriate term to apply, so I do, because "woefully inadequate" is tedious to key in. If I told my wife I drove to the store and came home, and she later found I came home by taxi because I totalled the car, she would make it clear that my statement was so woefully inadequate as to be simply wrong.
So the questions present themselves. Why did the CAB leave us with such a woefully inadequate statement? What really happened? This is the puzzle. People making excuses for the woeful inadequacy of the CAB report is a good indicator that people are ready to consider the puzzle. If you're looking for wiggle room, you're starting to grasp the issue.
The CAB explicitly said the plane slid tail first the last 820 feet, though it doesn't explicitly say the plane was upright the whole way. The total path from first embankment impact was 1200 feet, the second impact was at 380 feet, and from then the plane slid. So although the CAB report doesn't say the plane slid tail first until it stopped, it also doesn't say the plane slid 821 feet and it does say it was tail first for 820 feet. Megan took issue with this, but the simplest reading is that the plane stopped. So the plane slid upright or inverted, but per the CAB it slid tail first until it didn't slide any more.
The vertical stabilizer is mostly intact, and the plane did not slide on it. As Cordwainer quoted Flaps: " If the aircraft were upside down the vertical stabilizer would have been destroyed. Instead it is nearly intact." This leaves us with a conundrum. The plane did not slide inverted, and it could not slide upright and tail first and leave us with inverted tail-first wreckage. Therefore it could not have slid tail first the final 820 feet.
This constitutes an error on the part of the CAB. The common term for this is "wrong". It doesn't mean the investigators were dishonest or evil. I have no doubt some or most of them knew exactly what happened. But what got into the final report is a wrong statement, and it's the same wrong scenario that the CAB gave to the Chicago Trib on the day of the crash. This is the puzzle. Why was the CAB spokesman so sure so early? Why was that not walked back?
I didn't start this project with an agenda to demonstrate a belly landing. I started with the overhead picture and bafflement. After due consideration, the arrival at the final wreckage looks like a high-energy nose-first approach. I can't square this with a backward slide of any kind. What looks like an agenda to someone reading this for the first time is merely the product of three years' hypotheses, testing, discarding, and starting over. Concours77 just shot down my scenario of a forward pitchover at the final site, by noticing the post in the ditch. So I have to start over and form a new hypothesis, which led to my very interesting flight sim of the damaged plane at
This is how solutions are found. You start with a conjecture, a hypothesis, and look for evidence that either supports or refutes it. I challenge anyone to describe a mystery that was solved without any conjectures. I try to keep the reader clear on my level of confidence in the various statements that I propose for others to critique. That's how conversations work. Steel is sharpened against stone; people sharpen against people. Read the title of the thread.
Over those three years the thin evidence at hand has coalesced to suggest a low-bank initial impact. Megan's dismissal aside, I see no evidence against a low bank and considerable evidence for it. The investigators had a wealth of data that is unavailable to me. They had debris maps and internal memos and hundreds of pictures, no doubt. They might have taken measurements of the broken electrical lines, and those might have shown the bank angle. Megan wanted me to take her conjecture on this as if it were evidence, but it's only conjecture.
I point out the CAB error not to take satisfaction trumpeting it from the rooftops, but because recognizing the error is the first step in solving the puzzle. Something went wrong in this investigation. The official reports describe an impact and breakup scenario that does not correspond to the pictures.
People working only from the narrative have a harder time seeing this, so I did the animation. If you look at an animation and say "Well THAT didn't happen" then the puzzle gets clearer. When I started the animation I had to build the virtual site, and until then I didn't know it would show how tight the gap was between the trees. That lack of space, along with Concours77 pointing out the post in the ditch, is moving the solution along.
Sylvia apparently thought my statements conflicted when I said it was obvious the CAB was wrong but I had no target solution in mind. There's no conflict there. It is becoming clearer to several here that the CAB was wrong, soften the word however you like. And I still don't know what happened and am ready to give up any holding that has evidence to disprove it.
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The reports of the time were not wrong. They just do not contain the level of detail regarding the sequence of events after the initial impact with the railroad embankment that you wish to know.
The purpose of any accident investigation is to discover how the accident happened. The investigators established that the ailerons became effectively disconnected and the aircraft entered an uncontrollable bank after takeoff which led to a turn and descent.
The impact sequence was never something that was of primary concern to the original investigation teams as it had no bearing on the cause of the accident.
As far as the investigators were concerned, the cause was known. The next stage was to ensure the same circumstances could never again cause a similar accident.
The purpose of any accident investigation is to discover how the accident happened. The investigators established that the ailerons became effectively disconnected and the aircraft entered an uncontrollable bank after takeoff which led to a turn and descent.
The impact sequence was never something that was of primary concern to the original investigation teams as it had no bearing on the cause of the accident.
As far as the investigators were concerned, the cause was known. The next stage was to ensure the same circumstances could never again cause a similar accident.
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Instead the CAB said the aft fuselage slid tail first the final 820 feet. This is an erroneous statement. It is not lacking detail that I seek, it provides detail that does not match the photo evidence. It is wrong. Hence it gives rise to the puzzle.
Hi cordwainer,
Here, “....Originally Posted by cordwainer View Post. Your video shows the plane landing on its belly almost immediately after the railway embankment. [B]The report notes the entire wreckage path, from first impact with the wires to final rest was 1200 feet.[B]
Did you allow for the additional 380 feet of distance before the second impact (1200ft-820ft)? It appears that would have been enough to put the beginning of the slide beyond the trees in your video. That also makes more sense of some witnesses describing a "cartwheel" and some describing a "bounce", i.e., if the plane were more or less still airborne for that 380 feet.”
Can you help with this? The report measures “wires to final position at 1200 feet?”?
Thank you for your work....
Here, “....Originally Posted by cordwainer View Post. Your video shows the plane landing on its belly almost immediately after the railway embankment. [B]The report notes the entire wreckage path, from first impact with the wires to final rest was 1200 feet.[B]
Did you allow for the additional 380 feet of distance before the second impact (1200ft-820ft)? It appears that would have been enough to put the beginning of the slide beyond the trees in your video. That also makes more sense of some witnesses describing a "cartwheel" and some describing a "bounce", i.e., if the plane were more or less still airborne for that 380 feet.”
Can you help with this? The report measures “wires to final position at 1200 feet?”?
Thank you for your work....
Last edited by Concours77; 31st Dec 2017 at 22:15.