Help researching 1961 Electra crash
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Concours77
If we are to question the meaning of given words in the official report, reference should be made to the definitions contained in dictionaries that were contemporaneous or previous to the event and not to modern reference sources.
The archaic language used and retained in the British legal system hinges around the fact that the phrases used have a very distinct definition as established by prior court judgements.
I maintain that certain disputed parts of the official report are not deliberately inaccurate or even incomplete accounts of events. I suggest that in the light of more modern reporting standards, it is we who are drawing incorrect interpretations of what was said and meant at the time. Also we have to account for less advanced analysis techniques and methods available 55 years ago. That predates colour TV and most people having a landline phone in their home as far as the UK is concerned. Yet here I sit typing on a tablet with access to all the knowledge in the world just a few screen taps away. Okay not quite, but you get the idea.
I have absolutely no doubt that Lockheed would have dearly loved to write the accident off to pilot error. There are certain parts of the report that lead me to think the investigation was initially biased towards establishing this as a cause. That would not be considered unreasonable at the time because the majority of air accidents then were frequently down to pilot error. The increasing complexity of aircraft, lack of CRM, failure to recognise performance or weather limitations, were all contributory factors, but the pilots were frequently and unfairly given the blame in many case, in the light of more modern understanding of the issues.
Every aircraft has design flaws inherent in its construction. To my mind, the side stick controls in modern Airbus aircraft have directly contributed to quite a few accidents and near misses. Many professional pilots would vehermently disagree with my opinion and counter argue that the system is vastly superior to the older yoke design.
When I was taught to fly, the rule was to avoid thunderstorms by a minimum of ten miles. Modern aircraft with a schedule to keep are flown over, under, or through thunderstorms every single day, mostly without incident. But who or what gets the blame when things inevitably go wrong once in a while? Mostly, the pilot!
I am quite happy to accept that your version of events may lean towards being a more correct account considering the political, commercial and sociological pressures to try and play down aviation accidents at the time. I question what purpose is served in picking at these threads in the hope of unearthing some official wrongdoing though. All the people involved are undoubtably deceased and the fact is that in the light of this and other early accidents, the Electra and variants such as the Orion P3, has had a long and distinguished career as one of the most robust aircraft ever built.
I sincerely hope that the FOI request turns up more complete records of the investigation such as original notes and witness statements together with the investigators notes. Only with access to these records can any serious and legitimate attempt be made at rewriting the story of flight 706.
These records should be stored in an archive somewhere, although if they have been destroyed or disposed of and that may be considered as going some way towards pointing at a cover up or somewhat misleading account of the investigation. Of course, the documents could have been innocently destroyed by fire or other natural events, become lost in administrative clutter, eaten by vermin, or simply disposed of because there was no room to store them.
I personally don't see any evidence of conspiracy or skullduggery in the official account. There are gaps which can be filled by inference, but I doubt that these were purposefully designed to mislead in any way. I fully accept that documents could emerge that cast doubt on the official report, but until they surface I have to regard further discussion as being likely to be fruitless.
If we are to question the meaning of given words in the official report, reference should be made to the definitions contained in dictionaries that were contemporaneous or previous to the event and not to modern reference sources.
The archaic language used and retained in the British legal system hinges around the fact that the phrases used have a very distinct definition as established by prior court judgements.
I maintain that certain disputed parts of the official report are not deliberately inaccurate or even incomplete accounts of events. I suggest that in the light of more modern reporting standards, it is we who are drawing incorrect interpretations of what was said and meant at the time. Also we have to account for less advanced analysis techniques and methods available 55 years ago. That predates colour TV and most people having a landline phone in their home as far as the UK is concerned. Yet here I sit typing on a tablet with access to all the knowledge in the world just a few screen taps away. Okay not quite, but you get the idea.
I have absolutely no doubt that Lockheed would have dearly loved to write the accident off to pilot error. There are certain parts of the report that lead me to think the investigation was initially biased towards establishing this as a cause. That would not be considered unreasonable at the time because the majority of air accidents then were frequently down to pilot error. The increasing complexity of aircraft, lack of CRM, failure to recognise performance or weather limitations, were all contributory factors, but the pilots were frequently and unfairly given the blame in many case, in the light of more modern understanding of the issues.
Every aircraft has design flaws inherent in its construction. To my mind, the side stick controls in modern Airbus aircraft have directly contributed to quite a few accidents and near misses. Many professional pilots would vehermently disagree with my opinion and counter argue that the system is vastly superior to the older yoke design.
When I was taught to fly, the rule was to avoid thunderstorms by a minimum of ten miles. Modern aircraft with a schedule to keep are flown over, under, or through thunderstorms every single day, mostly without incident. But who or what gets the blame when things inevitably go wrong once in a while? Mostly, the pilot!
I am quite happy to accept that your version of events may lean towards being a more correct account considering the political, commercial and sociological pressures to try and play down aviation accidents at the time. I question what purpose is served in picking at these threads in the hope of unearthing some official wrongdoing though. All the people involved are undoubtably deceased and the fact is that in the light of this and other early accidents, the Electra and variants such as the Orion P3, has had a long and distinguished career as one of the most robust aircraft ever built.
I sincerely hope that the FOI request turns up more complete records of the investigation such as original notes and witness statements together with the investigators notes. Only with access to these records can any serious and legitimate attempt be made at rewriting the story of flight 706.
These records should be stored in an archive somewhere, although if they have been destroyed or disposed of and that may be considered as going some way towards pointing at a cover up or somewhat misleading account of the investigation. Of course, the documents could have been innocently destroyed by fire or other natural events, become lost in administrative clutter, eaten by vermin, or simply disposed of because there was no room to store them.
I personally don't see any evidence of conspiracy or skullduggery in the official account. There are gaps which can be filled by inference, but I doubt that these were purposefully designed to mislead in any way. I fully accept that documents could emerge that cast doubt on the official report, but until they surface I have to regard further discussion as being likely to be fruitless.
“All the people involved are undoubtably deceased and the fact is that in the light of this and other early accidents, the Electra and variants such as the Orion P3, has had a long and distinguished career as one of the most robust aircraft ever built. “
Uh oh...
My research shows one Alan S. Boyd alive and living in Florida.
He was Chairman of the Civil Aeronautics Board during this accident investigation.
His signature appears at the top of the signature page I posted recently.
His Wiki CV reports his career summed up by this title......politician.
Uh oh...
My research shows one Alan S. Boyd alive and living in Florida.
He was Chairman of the Civil Aeronautics Board during this accident investigation.
His signature appears at the top of the signature page I posted recently.
His Wiki CV reports his career summed up by this title......politician.
Camel, straw? The direct cause is the last straw. The procuring cause is the mass of straw already borne by the poor animal’s back.....
megan, here, we are in agreement.
G0ULI
I maintain that certain disputed parts of the official report are not deliberately inaccurate or even incomplete accounts of events.
In the day, the public slavishly obeyed authority, and virtually always accepted official data as gospel. Given that power, there existed a freedom to exaggerate, embellish, ignore, and even lie on the part of a government charged with our “best interests”. This was not done necessarily for cynical reasons, but more for reasons of “protecting” the public. “Well flight crew are deceased, no good can come of chasing a different theory and hobbling an otherwise exemplary corporation with further “trouble”. “
Lockheed had contracts with the Government, and patriotism compelled a certain kind of “pass” for those boffins who almost never make fatal mistakes?
A trusting public, mostly those who accept “official probable cause” as certainty, not to be doubted....?
“Probable”. A delightful word that lets the potential culprit off the hook, and seemingly immune to a different view?
Now we can discuss some design issues that hobbled the poor Electra? A tease?
Why did Lockheed perform inspections and develop a defense of the wing area adjacent the aileron/flap? megan’s previous analysis I believe not to be accurate. “Airloads”?......please.
I think the pilots figured out what was happening. Too low, and no time to broadcast what they knew?
Oh, those pesky “chattering” ailerons? “Only in flight”? How did the aircraft “fly” four hundred feet further than contact by the wing tip at the tracks? At ninety degrees Bank? They were higher than wing tip proximity would define? So, with that, here is:
G0ULI: The only requirement for this scenario to work is that the aircraft hit the ground in a vertical bank, which is supported by the available evidence and reports.
YES! At ninety degrees Bank, the aircraft is not flying, it is falling, like a brick, at one G. Yet it stays aloft another four hundred feet? It is accelerating in the vertical at 16feet/second/second. It should have impacted the ground (a second time) no further than one hundred feet along. Probably more like fifty. Another way to envision this? When the wingtip struck, the altitude of the aircraft was already in the minus. By twenty feet...
Levitation?
A reduction in power as “routine”? Just after breaking ground? At liftoff at four thousand feet down the runway, they flew another four thousand feet and managed to climb only one hundred feet? That’s a climb at two degrees. At one hundred feet the aircraft commenced a roll moment to the right? Notice that the report does not say: “Pilot commanded right turn?”
I have been reluctant to start this, pilot error is imposing, but I believe the pilots had no part in this accident. Similar to the DC10, the pilot’s were along as pax.
Last edited by Concours77; 13th Jan 2018 at 17:54.
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See Megan, that's why your contributions are important to me. When I propose an idea, I can always depend on you coming to the table with the strongest argument you can muster. Apparently that was it.
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In 1961 the control tower was 100 feet tall. The most respected witnesses would have been the tower staff, and they could use the horizon line to judge the height of the plane. So this is likely to be a relatively accurate number.
The problem started at run up, and was underway as they rolled onto the runway without stopping, cleared for an immediate departure.
They should have been at five hundred before turning but already the performance and airworthiness were deeply degraded, all the a/c could do was an anemic climb, and start an uncommanded turn, right.
Everything I propose, and the destination I have, is taken from the report itself.
Take it apart, challenge it, it would be welcome.
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The reason for the "toll road" departure was that it shortcut an extra hand-off, so this might have been part of the mindset. At any rate, that put them in a turn at very low altitude, problem or not.
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Concours77
You may wish to revisit your figures.
The acceleration of an object in free fall under Earth's gravity is 32 feet per second, per second, or approximately 9.81 metres per second per second. I will stick with imperial units here.
The wingspan of the Electra is 99 feet, putting the centre line of the aircraft 49 feet 6 inches from the wing tip.
The top of the embankment is recorded as being 25 feet above the surrounding land. The power lines would be raised above the embankment by some arbitary figure to prevent electrocultion risk to passers by.
If the aircraft wing hit the embankment at an angle of between 60 and 70 degrees, even hitting the base of the embankment would place the fuselage centre line a minimum of 30 feet above the top of the embankment. The propellor strike marks indicate that the wingtip struck the embankment significantly higher up, no more than half way. So no more than 12 feet of the wingtip was likely to have made contact. This places the centre line of the fuselage roughly 42 feet above the top embankment and therefore 77 feet above the surrounding lower ground.
The aircraft travelled 380 feet before making the first solid impact with the ground. Allowing for the descent to be in free fall, the time taken to hit the ground would be roughly 1-1/2 seconds.
380 feet travelled in 1-1/2 seconds equates to a speed of 173 mph, or around 160 knots. Exactly what we would expect to see in a take off and climb flight profile. These are the minimum speeds needed to achieve the observed results. The true speed could perhaps have been 20 mph (17 knots) higher. Any extra speed and/or air resistance opposing a free fall drop would allow for the known 5° to 10° nose downward flight path while still allowing 380 feet of flight beyond the embankment.
Naturally these figures are back of an envelope calculations, but close enough to agree with the known aircraft performance figures, the figures given in the report, and to substantiate claims that the aircraft could and did strike the ground with a wings vertical bank angle.
[I have assumed the width of the fuselage to be 10 feet to simplify my calculations.]
I don't just compose these posts without considering the maths involved. On the other hand I really can't be bothered working through all the trigonometry to give a range of figures to satisfy every possible answer to the nearest inch for every possible bank angle and velocity.
There can be absolutely no doubt that the aircraft crossed the embankment at an angle of 60° to 70° with the right wing tip making contact with the embankment. The main impact with the ground occured with the right wing aligned between 90° and 100° vertically aligned to the ground, exactly as the investigators of the time stated. What happened after that is conjecture and guesswork.
The laws of physics don't lie.
You may wish to revisit your figures.
The acceleration of an object in free fall under Earth's gravity is 32 feet per second, per second, or approximately 9.81 metres per second per second. I will stick with imperial units here.
The wingspan of the Electra is 99 feet, putting the centre line of the aircraft 49 feet 6 inches from the wing tip.
The top of the embankment is recorded as being 25 feet above the surrounding land. The power lines would be raised above the embankment by some arbitary figure to prevent electrocultion risk to passers by.
If the aircraft wing hit the embankment at an angle of between 60 and 70 degrees, even hitting the base of the embankment would place the fuselage centre line a minimum of 30 feet above the top of the embankment. The propellor strike marks indicate that the wingtip struck the embankment significantly higher up, no more than half way. So no more than 12 feet of the wingtip was likely to have made contact. This places the centre line of the fuselage roughly 42 feet above the top embankment and therefore 77 feet above the surrounding lower ground.
The aircraft travelled 380 feet before making the first solid impact with the ground. Allowing for the descent to be in free fall, the time taken to hit the ground would be roughly 1-1/2 seconds.
380 feet travelled in 1-1/2 seconds equates to a speed of 173 mph, or around 160 knots. Exactly what we would expect to see in a take off and climb flight profile. These are the minimum speeds needed to achieve the observed results. The true speed could perhaps have been 20 mph (17 knots) higher. Any extra speed and/or air resistance opposing a free fall drop would allow for the known 5° to 10° nose downward flight path while still allowing 380 feet of flight beyond the embankment.
Naturally these figures are back of an envelope calculations, but close enough to agree with the known aircraft performance figures, the figures given in the report, and to substantiate claims that the aircraft could and did strike the ground with a wings vertical bank angle.
[I have assumed the width of the fuselage to be 10 feet to simplify my calculations.]
I don't just compose these posts without considering the maths involved. On the other hand I really can't be bothered working through all the trigonometry to give a range of figures to satisfy every possible answer to the nearest inch for every possible bank angle and velocity.
There can be absolutely no doubt that the aircraft crossed the embankment at an angle of 60° to 70° with the right wing tip making contact with the embankment. The main impact with the ground occured with the right wing aligned between 90° and 100° vertically aligned to the ground, exactly as the investigators of the time stated. What happened after that is conjecture and guesswork.
The laws of physics don't lie.
Last edited by G0ULI; 14th Jan 2018 at 04:13.
G0ULI,
Here:
The aircraft travelled 380 feet before making the first solid impact with the ground. Allowing for the descent to be in free fall, the time taken to hit the ground would be roughly 1-1/2 seconds.
Uh oh... you assume no vertical velocity at RR embankment? I give the vertical vector a value of 2000 fpm. At Impact.
The angle of Bank and the lack of lift did not begin at RR impact.
You assume no vertical velocity at the tracks? The a/c also accelerated radially, turning the left wingtip toward Earth at close to the aircraft’s horizontal speed, which negates your fuselage centerline as reference. The fuselage did the same. It’s ASPECT relative to the Earth changed, downward, with a component of what had been forward velocity. IOW, its flight path was altered, dramatically, and that changes your very basic calculation? It didn’t continue along pointed where it had been.
Falling at one hundred forty feet per second, the Electra should have hit the ground in one half second. Not counting for the added acceleration to which you refer?
That is approximately one hundred feet beyond the impact with the tracks....
Here:
The aircraft travelled 380 feet before making the first solid impact with the ground. Allowing for the descent to be in free fall, the time taken to hit the ground would be roughly 1-1/2 seconds.
Uh oh... you assume no vertical velocity at RR embankment? I give the vertical vector a value of 2000 fpm. At Impact.
The angle of Bank and the lack of lift did not begin at RR impact.
You assume no vertical velocity at the tracks? The a/c also accelerated radially, turning the left wingtip toward Earth at close to the aircraft’s horizontal speed, which negates your fuselage centerline as reference. The fuselage did the same. It’s ASPECT relative to the Earth changed, downward, with a component of what had been forward velocity. IOW, its flight path was altered, dramatically, and that changes your very basic calculation? It didn’t continue along pointed where it had been.
Falling at one hundred forty feet per second, the Electra should have hit the ground in one half second. Not counting for the added acceleration to which you refer?
That is approximately one hundred feet beyond the impact with the tracks....
BRDubois
Their haste may have contributed to the problem. If they had to wait a bit for clearance they might have noticed an issue. If already rolling and the issue wasn't waving a red flag in their face, they might not have addressed it as carefully as they should.
The Electra’s ailerons “droop” at less than flying speed, it isn’t until they gain authority from airflow that they nest to fair in chord. They are sloppy on the roll.
Turning (nose wheel, Rudder) and lining to centerline from a rolling entry takes skill and may cause a bit of distraction.
I think they may not have noticed aileron issues until the ailerons “came alive” and their flat climb may actually indicate that they considered an abort. Once the roll issues presented as critical, they were past the opportunity to land. Pilot would have known Roll was creepy almost instantly. I think the Roll right was uncommanded, and was not part of the aileron issue blamed for this crash.
Lockheed designed an experiment to test airflow at the aileron/flap merge. They removed the flap outboard jackscrew before measuring various airflows. Any idea why? I have a theory.
Their haste may have contributed to the problem. If they had to wait a bit for clearance they might have noticed an issue. If already rolling and the issue wasn't waving a red flag in their face, they might not have addressed it as carefully as they should.
The Electra’s ailerons “droop” at less than flying speed, it isn’t until they gain authority from airflow that they nest to fair in chord. They are sloppy on the roll.
Turning (nose wheel, Rudder) and lining to centerline from a rolling entry takes skill and may cause a bit of distraction.
I think they may not have noticed aileron issues until the ailerons “came alive” and their flat climb may actually indicate that they considered an abort. Once the roll issues presented as critical, they were past the opportunity to land. Pilot would have known Roll was creepy almost instantly. I think the Roll right was uncommanded, and was not part of the aileron issue blamed for this crash.
Lockheed designed an experiment to test airflow at the aileron/flap merge. They removed the flap outboard jackscrew before measuring various airflows. Any idea why? I have a theory.
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Concours77
Fair points, but the aircraft did strike the ground 380 feet past the embankment and back of an envelope calculations are sufficient to prove that this is possible and reasonable without invoking some violation of the laws of physics. The aircraft was in a relatively shallow descent through most of the curved flight path and it was only after the angle of the wings exceeded 60° that the wings stalled and gravity became the predominant force. The rate of descent was not constant.
Of course the aircraft was in nothing like free fall...
So 100 feet past the embankment in a vacuum, maybe.
Fair points, but the aircraft did strike the ground 380 feet past the embankment and back of an envelope calculations are sufficient to prove that this is possible and reasonable without invoking some violation of the laws of physics. The aircraft was in a relatively shallow descent through most of the curved flight path and it was only after the angle of the wings exceeded 60° that the wings stalled and gravity became the predominant force. The rate of descent was not constant.
Of course the aircraft was in nothing like free fall...
So 100 feet past the embankment in a vacuum, maybe.
Concours77
Fair points, but the aircraft did strike the ground 380 feet past the embankment and back of an envelope calculations are sufficient to prove that this is possible and reasonable without invoking some violation of the laws of physics. The aircraft was in a relatively shallow descent through most of the curved flight path and it was only after the angle of the wings exceeded 60° that the wings stalled and gravity became the predominant force. The rate of descent was not constant.
Of course the aircraft was in nothing like free fall...
So 100 feet past the embankment in a vacuum, maybe.
Fair points, but the aircraft did strike the ground 380 feet past the embankment and back of an envelope calculations are sufficient to prove that this is possible and reasonable without invoking some violation of the laws of physics. The aircraft was in a relatively shallow descent through most of the curved flight path and it was only after the angle of the wings exceeded 60° that the wings stalled and gravity became the predominant force. The rate of descent was not constant.
Of course the aircraft was in nothing like free fall...
So 100 feet past the embankment in a vacuum, maybe.
That is what I wanted to establish, that the impact evidence is as observed. The flight path, not so much.
What do you make of the Lockheed experiment regarding possible conflict of expected airflows over the aileron, as influenced by the wing flap, without its jackscrew?
What it says to me is quite interesting. Why remove the jackscrew? At first blush, to simulate a deformation of the wing flap that affected roll? We must assume they don’t care a fig about what happened post impact, so is their surmise that the flap jumped its canoes inflight?
Wouldn't The consideration of drag embellish my point, and serve to conflict with a greater distance from first impact?
Interesting?
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I think the tests were undertaken to eliminate fouling between the flaps and the ailerons as a possible cause of the accident. The investigators needed to consider all possible causes of the uncontrolled bank, in addition to an aileron roll, an asymmetrical extention or retraction of the flaps, could and probably would have produced forces that could not be controlled by the ailerons. It has happened on other aircraft designs. I well remember my flying instructor insisting that a visual check to both sides of the aircraft be made whenever the flap lever was operated. One of the things I used to regularly forget, especially selecting final stage flap just before landing. I knew the flaps on either side were mechanically connected, what could go wrong? Well they were connected with a joint that was capable of sliding and rotating. Copies of accident reports in the office soon persuaded me that it was a vital safety precaution to carry out a visual check in a small aircraft. Larger aircraft are not much different, things just happen at a different pace and control surfaces may not be visible from the cockpit, so you have to rely on other telltales.
So you are correct when you say that a flap fault could have produced similar results, but the solution is to return the flap lever to the position it was in before the flight upset started in order to restore a balance. Takeoff flap settings are usually only a few degrees and designed to increase the effective wing area while keeping drag at a low level. If one of the flaps had dropped completely, commanding full flaps would have rebalanced the aircraft to a level attitude and given the impressive power to weight ratio of the Electra, it should have been capable of maintaining altitude even with full flaps set.
Witness marks on recovered components suggested that takeoff flap was set and maintained throughout the flight and that the flaps were not set asymmetrically before impact.
All the additional tests were conducted to eliminate other possible causes before settling on a break in the aileron control cables as the cause of the accident. Of course the root cause was the incorrect actions of the maintenance engineers on the ground.
Were there indications of a potential problem during the takeoff run?
The rolling takeoff is significant in that it is usual to stop, verify runway heading and compasses are aligned and that all controls are free and move to their full extent. There is mention in the report that a test pilot felt virtually no change in the feel of the controls when the aileron cable was deliberately severed on a test rig.
If the full and free control movements were conducted on, or just coming off the stand, perhaps the aileron cable separated during this test. The trip along the taxiway to the runway would not have involved movement of the ailerons, just toe brakes, throttles and rudder.
The first indication that the pilots might have had that something was not quite right would probably been just before V2 when they were already committed to takeoff. Up until that point, the rudder would have been the sole directional control in use. Perhaps the aircraft did not respond correctly at that point to aileron input to counter a slight crosswind. At that point it could have been dismissed as slop in the control rigging, since the aircraft had a history of poor aileron response. It was only once the right bank on departure was initiated and could not be countered, that it became obvious that this was a critical failure in the control system. The accident report suggests that the pilots would not have been aware of the cable disconnect through any difference in feeling of the control yokes, only that the aircraft failed to respond to aileron control inputs.
The general rule is that once an aircraft has reached flying speed it is safer to lift off and try and solve problems once airborne than to attempt to stop. This was one of the exceptions to that rule.
The rolling takeoff may have contributed in some way to the accident, but that would rely on a visual check of the aileron movements being conducted from the cockpit and the lack of proper movement being noticed. I suspect that wing visibility from the cockpit is very limited if possible at all, like most larger aircraft.
So you are correct when you say that a flap fault could have produced similar results, but the solution is to return the flap lever to the position it was in before the flight upset started in order to restore a balance. Takeoff flap settings are usually only a few degrees and designed to increase the effective wing area while keeping drag at a low level. If one of the flaps had dropped completely, commanding full flaps would have rebalanced the aircraft to a level attitude and given the impressive power to weight ratio of the Electra, it should have been capable of maintaining altitude even with full flaps set.
Witness marks on recovered components suggested that takeoff flap was set and maintained throughout the flight and that the flaps were not set asymmetrically before impact.
All the additional tests were conducted to eliminate other possible causes before settling on a break in the aileron control cables as the cause of the accident. Of course the root cause was the incorrect actions of the maintenance engineers on the ground.
Were there indications of a potential problem during the takeoff run?
The rolling takeoff is significant in that it is usual to stop, verify runway heading and compasses are aligned and that all controls are free and move to their full extent. There is mention in the report that a test pilot felt virtually no change in the feel of the controls when the aileron cable was deliberately severed on a test rig.
If the full and free control movements were conducted on, or just coming off the stand, perhaps the aileron cable separated during this test. The trip along the taxiway to the runway would not have involved movement of the ailerons, just toe brakes, throttles and rudder.
The first indication that the pilots might have had that something was not quite right would probably been just before V2 when they were already committed to takeoff. Up until that point, the rudder would have been the sole directional control in use. Perhaps the aircraft did not respond correctly at that point to aileron input to counter a slight crosswind. At that point it could have been dismissed as slop in the control rigging, since the aircraft had a history of poor aileron response. It was only once the right bank on departure was initiated and could not be countered, that it became obvious that this was a critical failure in the control system. The accident report suggests that the pilots would not have been aware of the cable disconnect through any difference in feeling of the control yokes, only that the aircraft failed to respond to aileron control inputs.
The general rule is that once an aircraft has reached flying speed it is safer to lift off and try and solve problems once airborne than to attempt to stop. This was one of the exceptions to that rule.
The rolling takeoff may have contributed in some way to the accident, but that would rely on a visual check of the aileron movements being conducted from the cockpit and the lack of proper movement being noticed. I suspect that wing visibility from the cockpit is very limited if possible at all, like most larger aircraft.
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I've uploaded a Youtube video of my animation of the crash at
.
There are two reasons for doing this. First, the flight sim run, and creating a virtual chunk of O'Hare, told me I'd drastically misunderstood what the plane must have done after the initial impact. I incorporated that sim run in this video. I put together the animation to help me understand the physics involved.
Second, the narrations I've given are an imprecise way to communicate what I envision happening.What I've posted isn't proof or evidence, just an artist's conception to help get the picture across.
There are two reasons for doing this. First, the flight sim run, and creating a virtual chunk of O'Hare, told me I'd drastically misunderstood what the plane must have done after the initial impact. I incorporated that sim run in this video. I put together the animation to help me understand the physics involved.
Second, the narrations I've given are an imprecise way to communicate what I envision happening.What I've posted isn't proof or evidence, just an artist's conception to help get the picture across.
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Interesting. Following this page link it's marked as removed by the user, but it plays fine. The link without the https is youtu.be/zfBQHyuPXGg Try that.
As a test, I'll create a fresh link on this post to the same video.
Hmm, seems happy. If you mouse over the yellow box in the preceding post where the video URL is shown, your nav status will show a different URL. Might be a board hiccup. So clicking the prior post's video was sending you off into never-never land.
As a test, I'll create a fresh link on this post to the same video.
Hmm, seems happy. If you mouse over the yellow box in the preceding post where the video URL is shown, your nav status will show a different URL. Might be a board hiccup. So clicking the prior post's video was sending you off into never-never land.
Last edited by BRDuBois; 30th Jan 2018 at 18:46.
Hi.
In the air, even in extremis, aerodynamic surfaces do not lead, they follow. It is highly unlikely, IMO, that the remainder of the aircraft travelled at any time inverted and tail first. An intact tail will be feathers to the arrow, always. I continue to think the aircraft swapped ends and aspect late in the energy trail.
Your impact depiction is first rate.
In the air, even in extremis, aerodynamic surfaces do not lead, they follow. It is highly unlikely, IMO, that the remainder of the aircraft travelled at any time inverted and tail first. An intact tail will be feathers to the arrow, always. I continue to think the aircraft swapped ends and aspect late in the energy trail.
Your impact depiction is first rate.
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I sure wouldn't have thought of it if I hadn't seen it in the sim. It's like a hydrofoil flipping over. Once the plane's longitudinal axis was vertical, it's all ballistics and not much in aerodynamics, I'd think. At that point everything is in stall, and the rotational momentum from the pitch-up continues until the tail is first.
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Excellent work with the potential break up sequences.
I have difficulty accepting that the tail section could have flown up and flipped vertically, landing upside down. Such a scenario would surely have crushed or badly damaged the vertical stabiliser. From the photographs, that appears the one piece of the aircraft that survived virtually intact.
Whatever mechanism inverted the tail section therefore had to be at a relatively low energy, just enough to flop over into the inverted position without destroying the vertical stabiliser.
This suggests a largely horizontal movement of pieces of the aircraft along or parallel to the ground, rather than cartwheeling high into the air.
I have difficulty accepting that the tail section could have flown up and flipped vertically, landing upside down. Such a scenario would surely have crushed or badly damaged the vertical stabiliser. From the photographs, that appears the one piece of the aircraft that survived virtually intact.
Whatever mechanism inverted the tail section therefore had to be at a relatively low energy, just enough to flop over into the inverted position without destroying the vertical stabiliser.
This suggests a largely horizontal movement of pieces of the aircraft along or parallel to the ground, rather than cartwheeling high into the air.
Two tail slides and a gentle Lomcevak. Flying tail first takes a lot of skill. Those maneuvers are all under complete control.
Even ballistic, drag and momentum have a part to play in trajectory. Your work is very skilled.
Even ballistic, drag and momentum have a part to play in trajectory. Your work is very skilled.