Help researching 1961 Electra crash
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This is going to take a couple posts to reply to. Pardon while I use this one to vent.
With regard to faulting the investigators, my fault-finding is limited to their description of the flight and impact. I give them credit for finding the root cause and tracking down the people and practices that led to the failure.
I was raised in a flying family, and we all understood the vital need for accurate and objective analysis of accidents. It was something we discussed from time to time, and we were aware of my dad's views on the subject. Accident investigation is pretty close to sacred. We've all seen the lengths investigators now go to in retrieving recorders and salvaging wreckage from inaccessible locations.
When I realized that the investigators in this case had misreported as badly as they did, I was stunned. I didn't know they would do that; it was inconceivable. The actual statement is relatively innocuous - they said the plane slide tail-first and right side up to a stop. The pictures show it tail-first and upside down. By itself this is not vital data. Quite a few have told me, some with as much patience as they could muster, that this is irrelevant to the root cause, which of course I knew already.
What this factoid does do is tell us that they didn't much care about this aspect. I agree they were probably under pressure to close the case, but even so their work in this area (as reported officially) does not meet a minimal standard of care. I say 'as reported' because I cannot believe there weren't people focused on every aspect of the flight. The report implies several teams working on different areas, just as they do today. They did site surveys and debris mapping. There had to be people who understood the impact scene much better than did the person who wrote the report. But for some reason, what made it into the official report was wrong in this respect.
We can now say with confidence that the flight sequence in the report was flat out impossible. I'm reasonably sure that there was dissension at the time. Heck, they had 54 witnesses and it happened on airport grounds. There is a hint of witness disagreement, and the CAB clearly disagreed with Lockheed over the flight path. I'd love to see Lockheed materials, but they have not responded. I think any pilot, given a description of a vertical bank extended over a couple thousand horizontal feet at a height of 300 or so, would dismiss it out of hand. Correct me if I'm wrong.
The CAB report could have addressed this without negating the value of the conclusions. They could have said there was confusion about flight details, but not about what broke. Instead they drafted the cartwheel-and-backward-upright-slide scenario with perfect confidence on the afternoon of the crash and went public with it. I find this unconscionable. The ALPA report writer appears to have done even less work on it and written more purple prose.
Their handling of this phase left us with a blank space that we didn't know about. If I seem to take all this personally, it is because I was personally injured by their carelessness. They left us with a misunderstanding for 55 years. As I peel apart the layers, it's clear that there are things that friends and family would have liked to know, and it's too late.
Now that the lapse has become clear, I'm simply trying to fill in what they failed to address. My materials are very sparse, and the chances of more information turning up are virtually nil. So this project is now closer to its conclusion than its inception, but there's still something we can extract.
Knowing that the plane arrived at its final site nose-first and right side up tells us that the entire impact sequence was misrepresented. By back-calculating along the debris path, it tells us that the first impact was described wrong, and this says the flight itself was misrepresented. The flight simulator can not give precise numbers, but it's adequate to show patterns and trends. And reverse-engineering the flight seems to open up a window on what the crew was doing and thinking.
There are moments of this, I confess, which are extremely creepy for me.
So even though the investigators found the root cause, I fault them for their misreporting.
With regard to faulting the investigators, my fault-finding is limited to their description of the flight and impact. I give them credit for finding the root cause and tracking down the people and practices that led to the failure.
I was raised in a flying family, and we all understood the vital need for accurate and objective analysis of accidents. It was something we discussed from time to time, and we were aware of my dad's views on the subject. Accident investigation is pretty close to sacred. We've all seen the lengths investigators now go to in retrieving recorders and salvaging wreckage from inaccessible locations.
When I realized that the investigators in this case had misreported as badly as they did, I was stunned. I didn't know they would do that; it was inconceivable. The actual statement is relatively innocuous - they said the plane slide tail-first and right side up to a stop. The pictures show it tail-first and upside down. By itself this is not vital data. Quite a few have told me, some with as much patience as they could muster, that this is irrelevant to the root cause, which of course I knew already.
What this factoid does do is tell us that they didn't much care about this aspect. I agree they were probably under pressure to close the case, but even so their work in this area (as reported officially) does not meet a minimal standard of care. I say 'as reported' because I cannot believe there weren't people focused on every aspect of the flight. The report implies several teams working on different areas, just as they do today. They did site surveys and debris mapping. There had to be people who understood the impact scene much better than did the person who wrote the report. But for some reason, what made it into the official report was wrong in this respect.
We can now say with confidence that the flight sequence in the report was flat out impossible. I'm reasonably sure that there was dissension at the time. Heck, they had 54 witnesses and it happened on airport grounds. There is a hint of witness disagreement, and the CAB clearly disagreed with Lockheed over the flight path. I'd love to see Lockheed materials, but they have not responded. I think any pilot, given a description of a vertical bank extended over a couple thousand horizontal feet at a height of 300 or so, would dismiss it out of hand. Correct me if I'm wrong.
The CAB report could have addressed this without negating the value of the conclusions. They could have said there was confusion about flight details, but not about what broke. Instead they drafted the cartwheel-and-backward-upright-slide scenario with perfect confidence on the afternoon of the crash and went public with it. I find this unconscionable. The ALPA report writer appears to have done even less work on it and written more purple prose.
Their handling of this phase left us with a blank space that we didn't know about. If I seem to take all this personally, it is because I was personally injured by their carelessness. They left us with a misunderstanding for 55 years. As I peel apart the layers, it's clear that there are things that friends and family would have liked to know, and it's too late.
Now that the lapse has become clear, I'm simply trying to fill in what they failed to address. My materials are very sparse, and the chances of more information turning up are virtually nil. So this project is now closer to its conclusion than its inception, but there's still something we can extract.
Knowing that the plane arrived at its final site nose-first and right side up tells us that the entire impact sequence was misrepresented. By back-calculating along the debris path, it tells us that the first impact was described wrong, and this says the flight itself was misrepresented. The flight simulator can not give precise numbers, but it's adequate to show patterns and trends. And reverse-engineering the flight seems to open up a window on what the crew was doing and thinking.
There are moments of this, I confess, which are extremely creepy for me.
So even though the investigators found the root cause, I fault them for their misreporting.
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On the technical side, let me explain what I think may have happened.
We know that at 165 knots knife-edge flying an Electra is impossible. That is, a 90-degree bank is impossible, and an 80-degree is impossible, because the rudder can't lift the nose. But flying level, the rudder hard left can flip the plane over by swinging the nose left. In a shallow bank the rudder can easily overcome even extreme aileron deflection.
In a shallow bank there is some small portion of the rudder force which is actually lifting the nose, not swinging it left. The more extreme the bank, the larger is the nose vector going up and the smaller is the vector going left. At 90 degrees the entire force is trying to lift up, and it can't manage that at 165 knots.
Think of rudder deflection as a curve of decreasing effectiveness correlated to an increasing bank angle. At any given speed up to about 250 knots, there's going to be a point where the left rudder cannot lift the nose. As long as the nose can't lift (i.e. move left) the plane can't roll left by using the right wing dihedral and differential leading edge exposure. I ran some experiments with the simulator, and in an Electra at about 165 knots this point is about 55 degrees. A bank more extreme can't be countered by the hard left rudder, and less extreme can be.
A couple pilots have told me that no one trains for what happened to my dad and his crew. I've had two suggestions that they may have not called for enough left rudder or done it early enough. At the same time, I was looking at the flight as a purely mechanical problem. A hard left rudder in a right bank is an extremely unstable configuration. Either it responds quickly or not at all, and if not at all the plane crashes very fast. My goal was to figure out how the plane could get 4,000 feet from the runway, and it occurred to me that increasing the left rudder slowly rather than quickly might give an appropriate result.
Now I had a narrative suggested that would explain a slow increase, and a computer problem that seemed to favor a slow increase. So I started running trials and got a huge bunch of very close matches to the observed flight. I put one on Youtube with comments, and might try to tweak it a little and then put some more up.
See https://youtu.be/cVUta2x3pPc
Try this idea on for size: When they realized that the plane was not responding to control column left input, they first thought they had an uncommanded autopilot activation. The autopilot was carded inoperative. They spent a few seconds on this, and then started calling for left rudder.
But the left rudder input they used was appropriate to shallow banks, and by the time they started they were already at about 40 degrees. They increased the left rudder to something that would have countered a steeper bank, such as 30, but by then they were at 50. In effect they were chasing the bank down the curve of rudder effectiveness.
I'm told that pilots never train for anything like this, which suggests they are not trained that the rudder will become increasingly useless at high bank angles. (If someone can give me feedback on this, please do.) Finally in desperation they did what they should have at first but couldn't have known - they went to hard left rudder. The plane was by this time near the bank angle of no return, if I can call it that, so recovery might have been slow.
As the plane started to respond the bank lessened, but at this point they were too low and there was too much downward inertia to recover.
To put this in a larger picture, if Dad had an aileron loss of control, or if an uncommanded right bank started while they were straight and level, they would have had no trouble at all controlling it. They could have come around and landed, maybe after a big sloppy ponderous turn. Might have been a messy landing, but all doable.
Their problem came from the fact that they were already in an intentional right turn when the cable parted. This meant they didn't know they had a problem until they tried to ease the bank. There would have been some delay in figuring out what was going on and what to do. Further, this meant they were already in an attitude where the rudder would have decreasing effect. They were some way down the curve to the point where it would be useless, but they didn't know that.
The CAB report said their problem was that the cable parted at too low an altitude to recover. I think maybe that should instead read that the cable parted when they were already in a banking turn. If they had an uncommanded bank while flying level, they would have had no great trouble at any altitude. At the point they first knew there was a problem, they were already moving fast into rudder-degrade territory. I think the intentional bank was a decisive factor.
Does this make sense?
We know that at 165 knots knife-edge flying an Electra is impossible. That is, a 90-degree bank is impossible, and an 80-degree is impossible, because the rudder can't lift the nose. But flying level, the rudder hard left can flip the plane over by swinging the nose left. In a shallow bank the rudder can easily overcome even extreme aileron deflection.
In a shallow bank there is some small portion of the rudder force which is actually lifting the nose, not swinging it left. The more extreme the bank, the larger is the nose vector going up and the smaller is the vector going left. At 90 degrees the entire force is trying to lift up, and it can't manage that at 165 knots.
Think of rudder deflection as a curve of decreasing effectiveness correlated to an increasing bank angle. At any given speed up to about 250 knots, there's going to be a point where the left rudder cannot lift the nose. As long as the nose can't lift (i.e. move left) the plane can't roll left by using the right wing dihedral and differential leading edge exposure. I ran some experiments with the simulator, and in an Electra at about 165 knots this point is about 55 degrees. A bank more extreme can't be countered by the hard left rudder, and less extreme can be.
A couple pilots have told me that no one trains for what happened to my dad and his crew. I've had two suggestions that they may have not called for enough left rudder or done it early enough. At the same time, I was looking at the flight as a purely mechanical problem. A hard left rudder in a right bank is an extremely unstable configuration. Either it responds quickly or not at all, and if not at all the plane crashes very fast. My goal was to figure out how the plane could get 4,000 feet from the runway, and it occurred to me that increasing the left rudder slowly rather than quickly might give an appropriate result.
Now I had a narrative suggested that would explain a slow increase, and a computer problem that seemed to favor a slow increase. So I started running trials and got a huge bunch of very close matches to the observed flight. I put one on Youtube with comments, and might try to tweak it a little and then put some more up.
See https://youtu.be/cVUta2x3pPc
Try this idea on for size: When they realized that the plane was not responding to control column left input, they first thought they had an uncommanded autopilot activation. The autopilot was carded inoperative. They spent a few seconds on this, and then started calling for left rudder.
But the left rudder input they used was appropriate to shallow banks, and by the time they started they were already at about 40 degrees. They increased the left rudder to something that would have countered a steeper bank, such as 30, but by then they were at 50. In effect they were chasing the bank down the curve of rudder effectiveness.
I'm told that pilots never train for anything like this, which suggests they are not trained that the rudder will become increasingly useless at high bank angles. (If someone can give me feedback on this, please do.) Finally in desperation they did what they should have at first but couldn't have known - they went to hard left rudder. The plane was by this time near the bank angle of no return, if I can call it that, so recovery might have been slow.
As the plane started to respond the bank lessened, but at this point they were too low and there was too much downward inertia to recover.
To put this in a larger picture, if Dad had an aileron loss of control, or if an uncommanded right bank started while they were straight and level, they would have had no trouble at all controlling it. They could have come around and landed, maybe after a big sloppy ponderous turn. Might have been a messy landing, but all doable.
Their problem came from the fact that they were already in an intentional right turn when the cable parted. This meant they didn't know they had a problem until they tried to ease the bank. There would have been some delay in figuring out what was going on and what to do. Further, this meant they were already in an attitude where the rudder would have decreasing effect. They were some way down the curve to the point where it would be useless, but they didn't know that.
The CAB report said their problem was that the cable parted at too low an altitude to recover. I think maybe that should instead read that the cable parted when they were already in a banking turn. If they had an uncommanded bank while flying level, they would have had no great trouble at any altitude. At the point they first knew there was a problem, they were already moving fast into rudder-degrade territory. I think the intentional bank was a decisive factor.
Does this make sense?
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Without a doubt this is the closest simulation run yet to approximate the flight path. That really is quite an impressive run. I think you may have cracked it.
Any pilot will tell you that control inputs, particularly on large aircraft, need to be made in a considered manner otherwise you will tear the wings or tail off. The aerodynamic forces really are large enough to cause instant failure of the tail if full rudder is commanded suddenly. Smooth, measured, control inputs are generally one of the marks of a good aviator. The Airbus crash in New York shortly after 9/11 was caused by a relatively inexperienced pilot violently applying full rudder inputs when they hit wake turbulence from a preceding aircraft. The tail broke away and the aircraft crashed.
Something must have convinced the investigators that the aircraft hit the ground the right way up and facing in the direction of travel. Most likely witness marks on the ground from equipment in the lower part of the aircraft or detatched parts from landing gear, etc.
At some point after that initial impact the fuselage rolled and rotated, ending up facing the wrong way and upside down. My best guess would be a wing snagging the ground and the rotation taking place about that point. Indeed there may have been a couple of rotation points with perhaps the nose digging in flipping the fuselage upwards and then a wing snagging and dragging the fuselage around before the wing broke off and the fuselage rotated upside down and backwards. It would all have happened extremely rapidly, one or two seconds at most, so plenty of room for confusion about the exact sequence.
I am begining to come to the conclusion that the description of the impact sequence was hastily written and not revised because it was not strictly relevant to the root cause of the accident or its' survivability. The investigators found the root cause of the mishap, with the broken aileron cable and were then able to account for the flight path and impact point. After that, the investigators were not too concerned with the break up sequence other than points that affected their investigation as to the cause. There was a need to be able to demonstrate the aileron cable broke in flight, for instance. Having effectively backed themselves into a corner with an early publicity release about the likely impact sequence, perhaps the investigators decided to just leave that as the official record, rather than go through the trouble and embarrassment of issuing a retraction. Such a correction might have cast doubt on the investigator's abilities or accuracy, certainly in the public's eye. I don't think there was any malicious purpose behind the inaccuracies.
To summarise, I think that you have arrived at a reasonable simulation of the flight path, one that reasonably matches the witness reports and investigators findings. You have demonstrated that the impact sequence, break up and final disposition of the aircraft wreckage were not accurately described by investigators after the initial impact point of the main fuselage. The aircraft may have slid for some distance relatively upright, but clearly it rotated upside down and end for end. The investigators did not accurately describe that sequence, but may have been constrained by a too hastily released press report. They left their report written to agree with the early press release so as not to cast any doubts on the investigation. The root cause of the accident was established and amending the accident report to more accurately account for the final position of the aircraft wreckage would not materially affect any of the findings.
I think that is possibly the most accurate account that can now be written after all these years and without new evidence coming to light.
Any pilot will tell you that control inputs, particularly on large aircraft, need to be made in a considered manner otherwise you will tear the wings or tail off. The aerodynamic forces really are large enough to cause instant failure of the tail if full rudder is commanded suddenly. Smooth, measured, control inputs are generally one of the marks of a good aviator. The Airbus crash in New York shortly after 9/11 was caused by a relatively inexperienced pilot violently applying full rudder inputs when they hit wake turbulence from a preceding aircraft. The tail broke away and the aircraft crashed.
Something must have convinced the investigators that the aircraft hit the ground the right way up and facing in the direction of travel. Most likely witness marks on the ground from equipment in the lower part of the aircraft or detatched parts from landing gear, etc.
At some point after that initial impact the fuselage rolled and rotated, ending up facing the wrong way and upside down. My best guess would be a wing snagging the ground and the rotation taking place about that point. Indeed there may have been a couple of rotation points with perhaps the nose digging in flipping the fuselage upwards and then a wing snagging and dragging the fuselage around before the wing broke off and the fuselage rotated upside down and backwards. It would all have happened extremely rapidly, one or two seconds at most, so plenty of room for confusion about the exact sequence.
I am begining to come to the conclusion that the description of the impact sequence was hastily written and not revised because it was not strictly relevant to the root cause of the accident or its' survivability. The investigators found the root cause of the mishap, with the broken aileron cable and were then able to account for the flight path and impact point. After that, the investigators were not too concerned with the break up sequence other than points that affected their investigation as to the cause. There was a need to be able to demonstrate the aileron cable broke in flight, for instance. Having effectively backed themselves into a corner with an early publicity release about the likely impact sequence, perhaps the investigators decided to just leave that as the official record, rather than go through the trouble and embarrassment of issuing a retraction. Such a correction might have cast doubt on the investigator's abilities or accuracy, certainly in the public's eye. I don't think there was any malicious purpose behind the inaccuracies.
To summarise, I think that you have arrived at a reasonable simulation of the flight path, one that reasonably matches the witness reports and investigators findings. You have demonstrated that the impact sequence, break up and final disposition of the aircraft wreckage were not accurately described by investigators after the initial impact point of the main fuselage. The aircraft may have slid for some distance relatively upright, but clearly it rotated upside down and end for end. The investigators did not accurately describe that sequence, but may have been constrained by a too hastily released press report. They left their report written to agree with the early press release so as not to cast any doubts on the investigation. The root cause of the accident was established and amending the accident report to more accurately account for the final position of the aircraft wreckage would not materially affect any of the findings.
I think that is possibly the most accurate account that can now be written after all these years and without new evidence coming to light.
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Megan, you are correct. The point I was trying to make is that pilots are generally predisposed not to make large and sudden control inputs, particularly in commercial aircraft. It makes the passengers feel uncomfortable.
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Two interesting wrinkles turned up. Been going through all my Electra manuals looking for anything on control surfaces and problems.
An Eastern and a Qantas manual both mention that in the event of a loss of authority over any control surface, the best course is to engage the autopilot. The autopilot communicates directly with the boost units, bypassing all the cabling, which of course is where their problem was. But in this incident the autopilot was tagged inoperative. I don't know if that means it was completely nonfunctional with parts yanked, or was in need of adjustment and was considered not trustworthy, so I don't know what would have happened if they turned it on. Investigators suspected that the crew thought the autopilot had engaged and were trying to turn it off, which suggests it was in fact operational but not trustworthy. In any case, they weren't able to take the one recommended course, perhaps because they thought it was the problem.
The second factoid is that in the event of a control surface problem (and only when the autopilot is not available) the default action should be to disconnect the boost for that surface. The Qantas manual says that they can safely cut all boost units in such a case, and recommends it. In a normal flight attitude this would be no problem, but they were in a bank that was getting steeper by the second. Cutting the boost increases the force needed at the flight station, and also reduces considerably the range of movement of the surface, leaving enough movement for what the manuals refer to as normal needs. But in this instance they needed to do full left rudder. So if they followed the manual instructions (presuming NWA specified something along these lines) they were inadvertently crippling their ability to counter the bank using the rudder.
ETA: Just found it in another manual. The movement range with boost off is approximately half for all control surfaces.
An Eastern and a Qantas manual both mention that in the event of a loss of authority over any control surface, the best course is to engage the autopilot. The autopilot communicates directly with the boost units, bypassing all the cabling, which of course is where their problem was. But in this incident the autopilot was tagged inoperative. I don't know if that means it was completely nonfunctional with parts yanked, or was in need of adjustment and was considered not trustworthy, so I don't know what would have happened if they turned it on. Investigators suspected that the crew thought the autopilot had engaged and were trying to turn it off, which suggests it was in fact operational but not trustworthy. In any case, they weren't able to take the one recommended course, perhaps because they thought it was the problem.
The second factoid is that in the event of a control surface problem (and only when the autopilot is not available) the default action should be to disconnect the boost for that surface. The Qantas manual says that they can safely cut all boost units in such a case, and recommends it. In a normal flight attitude this would be no problem, but they were in a bank that was getting steeper by the second. Cutting the boost increases the force needed at the flight station, and also reduces considerably the range of movement of the surface, leaving enough movement for what the manuals refer to as normal needs. But in this instance they needed to do full left rudder. So if they followed the manual instructions (presuming NWA specified something along these lines) they were inadvertently crippling their ability to counter the bank using the rudder.
ETA: Just found it in another manual. The movement range with boost off is approximately half for all control surfaces.
Last edited by BRDuBois; 20th Oct 2016 at 17:20.
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Without any artificial boost, the control surfaces could only be moved as far as the physical strength of the pilots would allow against the aerodynamic forces. About 50% of the full range assisted movement seems reasonable.
It would be interesting to know what the problem with the autopilot was and the process for disabling it when it was inoperative. Just a circuit breaker pulled, a fuse removed from a panel, or switched off with a placard placed over it.
If the autopilot was capable of operating the ailerons independently of the manual flight control cables, then this aircraft should never have been allowed to fly. With the auto pilot inoperative, the cable presents a single point failure mode where maintenance of normal flight becomes impossible.
A bit like taking off in a modern jet with only one generator operative and the other generator and APU flagged inoperative. It shouldn't ever happen, but it does.
One question to consider is whether when the cable broke, did the controls lock in position because the broken ends of the cable jammed and snagged preventing movement? That would certainly give the impression that the autopilot had somehow engaged and was fighting the crew for control. Under the circumstances it is probably reasonable to first assume that the autopilot has engaged somehow. Something as vital and simple as a mechanical control cable breaking would probably not be the first item to spring to mind, especially in what was a complex aircraft for those times.
So perhaps the root cause was that the aircraft was despatched with an inoperative autopilot, removing the only possibility of maintaining control in event of a mechanical failure of the flying control cables.
It would be interesting to know what the problem with the autopilot was and the process for disabling it when it was inoperative. Just a circuit breaker pulled, a fuse removed from a panel, or switched off with a placard placed over it.
If the autopilot was capable of operating the ailerons independently of the manual flight control cables, then this aircraft should never have been allowed to fly. With the auto pilot inoperative, the cable presents a single point failure mode where maintenance of normal flight becomes impossible.
A bit like taking off in a modern jet with only one generator operative and the other generator and APU flagged inoperative. It shouldn't ever happen, but it does.
One question to consider is whether when the cable broke, did the controls lock in position because the broken ends of the cable jammed and snagged preventing movement? That would certainly give the impression that the autopilot had somehow engaged and was fighting the crew for control. Under the circumstances it is probably reasonable to first assume that the autopilot has engaged somehow. Something as vital and simple as a mechanical control cable breaking would probably not be the first item to spring to mind, especially in what was a complex aircraft for those times.
So perhaps the root cause was that the aircraft was despatched with an inoperative autopilot, removing the only possibility of maintaining control in event of a mechanical failure of the flying control cables.
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I went back and looked at the report. The CAB said the autopilot was tagged inoperative pending a required modification. This suggests that the parts may all have been there and functional, but there's no indication what exactly the crew would have known. The report did mention that the autopilot switch was accessible.
My comment about wondering if the crew thought they were fighting an autopilot that had activated uncommanded comes from recollections of what we discussed at the time. We had a lot of conversations with NWA pilots and some contact with investigators, which is why the ALPA report is a carbon we were given. The CAB report doesn't directly address that.
The CAB report said spark damage indicates there was power in the autopilot, but they couldn't rule out something happening in the impact sequence.
The CAB also said the boost units were in the engaged position for the elevator and rudder, and disengaged for the ailerons. This is the ideal configuration, but they also said they didn't rule out that the impact forces acted to engage or disengage something that was set the other way during the flight.
This whole incident has really started to flesh out for me now. My next document version is going to have a section covering these systems and how they're intended to (and perhaps did) interact.
My comment about wondering if the crew thought they were fighting an autopilot that had activated uncommanded comes from recollections of what we discussed at the time. We had a lot of conversations with NWA pilots and some contact with investigators, which is why the ALPA report is a carbon we were given. The CAB report doesn't directly address that.
The CAB report said spark damage indicates there was power in the autopilot, but they couldn't rule out something happening in the impact sequence.
The CAB also said the boost units were in the engaged position for the elevator and rudder, and disengaged for the ailerons. This is the ideal configuration, but they also said they didn't rule out that the impact forces acted to engage or disengage something that was set the other way during the flight.
This whole incident has really started to flesh out for me now. My next document version is going to have a section covering these systems and how they're intended to (and perhaps did) interact.
Last edited by BRDuBois; 21st Oct 2016 at 17:18.
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I've uploaded another video to Youtube. This is my best sketch so far of the plane's flight.
https://www.youtube.com/watch?v=D4_b1ekxKkY
The video includes several camera angles, simulating views by witnesses in different locations. It becomes abundantly clear why witnesses disagreed, and why the CAB and ALPA got the bank angle wrong.
Earlier I thought the shallow bank meant they should have been able to recover, but eventually I acquiesced to the consensus and agreed they couldn't. Now that I look at a simulation that ends in the shallow bank evidenced by the impact damage, it looks more than ever like it was close to recoverable. The video makes that clear as well.
I can't swear the video portrays the real flight, but it matches the site survey and the impact damage, and clarifies witness statements. I'm putting this out as an approximation of what the real flight must have been, with a certain degree of slop in all directions. My video matches the site survey within 1.5%, which feels pretty good.
I'm grateful to all who both agreed and disagreed with me. You've helped me clarify my thinking about this.
https://www.youtube.com/watch?v=D4_b1ekxKkY
The video includes several camera angles, simulating views by witnesses in different locations. It becomes abundantly clear why witnesses disagreed, and why the CAB and ALPA got the bank angle wrong.
Earlier I thought the shallow bank meant they should have been able to recover, but eventually I acquiesced to the consensus and agreed they couldn't. Now that I look at a simulation that ends in the shallow bank evidenced by the impact damage, it looks more than ever like it was close to recoverable. The video makes that clear as well.
I can't swear the video portrays the real flight, but it matches the site survey and the impact damage, and clarifies witness statements. I'm putting this out as an approximation of what the real flight must have been, with a certain degree of slop in all directions. My video matches the site survey within 1.5%, which feels pretty good.
I'm grateful to all who both agreed and disagreed with me. You've helped me clarify my thinking about this.
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Craig,
Excellent video and simulator work. You clearly demonstrate that it is virtually impossible to estimate bank angle accurately unless the aircraft is flying directly towards or away from the observer. From a side on viewpoint, as soon as both wings are visible, the brain sees the aircraft in a more severe bank than it actually is.
This psychological effect doubtless contributes to popularity of airshows. The spectators see spectacular manouevers from the ground which are relatively benign from the pilot's seat.
Bank angles of up to 30 degrees are part of flying a normal instrument holding pattern, so are not normally of much concern to pilots, but it would look like a much steeper bank from many points on the ground.
Your reconstructed flight path and bank angles do indeed seem to match the accident report very closely. I doubt that anyone will ever be able to do a better job of recreating the flight path than this. Impressive work. Well done.
Excellent video and simulator work. You clearly demonstrate that it is virtually impossible to estimate bank angle accurately unless the aircraft is flying directly towards or away from the observer. From a side on viewpoint, as soon as both wings are visible, the brain sees the aircraft in a more severe bank than it actually is.
This psychological effect doubtless contributes to popularity of airshows. The spectators see spectacular manouevers from the ground which are relatively benign from the pilot's seat.
Bank angles of up to 30 degrees are part of flying a normal instrument holding pattern, so are not normally of much concern to pilots, but it would look like a much steeper bank from many points on the ground.
Your reconstructed flight path and bank angles do indeed seem to match the accident report very closely. I doubt that anyone will ever be able to do a better job of recreating the flight path than this. Impressive work. Well done.
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A brand new puzzle has turned up. It's almost charming.
I've been scanning newspaper archives online. The best source has been the Chicago Trib. They followed the story closely, and they carried the graphic (morning after the crash) showing the rotation and erroneous backward slide.
On Tuesday they reported that one engine was found buried eight feet deep in mud and one other engine had been located, with two still missing. On Wednesday they reported that all had been found, with three of them (2, 3 and 4) 'close together' on open ground. It seems very odd that they could find one of those three on the day after the crash, and it took another day to see two more that were close to it. Since their frame of reference was that these were about 30 feet from the forward fuselage, we may take 'close' to mean something on that order of magnitude, as opposed to (say) a hundred feet apart.
This was open ground with no other wreckage in the area except the forward fuselage. In my document I pointed out two objects in photographs which were candidates to be engines, in the area the Chicago Trib described. An Electra engine is about 12 feet long and 29 inches high lying on its side. If you think of a Jaguar F-type, you're not far off. There were (per the Trib) three of these within about three car-lengths of each other, but they couldn't find two of those for a day.
Further, the one buried in mud was said to be number one. There is a distinct line in the aerial views where something went zooming off to the southwest from near the tracks, which I strongly suspect but can't prove was an engine. But if this was engine one, then it separated before the left wing or nose touched the ground. This seems as unlikely as not seeing two engines lying on the ground within a dozen yards or so.
This was not the CAB report; this was the Trib reporter relating what he thought the CAB rep said. I'm familiar with terrible reporting, and this sounds like something was garbled in the communication. These two Trib stories, taken together, are invalid on their face. I suspect two engines on open ground near the forward fuselage were just as I described in my document - engines one and two, which separated just east of their final location.
The irreducible core of this report is that the CAB said they could not account for the full complement of engines until Tuesday, and on Monday they were puzzled by this.
This is not something a reporter is just going to make up; it had to have come from the CAB. So why was there difficulty accounting for all of them? As in several other pieces of this documentation, the question is how much we have to discard before the rest makes sense.
Nothing was moved from the crash scene under official auspices until Wednesday at the earliest, when mapping was done. The Bridgeport Post reported on Monday that the rail line was out of service 'for a time', so the track was reopened to traffic on the day of the crash. The question is then to ponder what might have put it out of service.
The track was clearly shifted about a foot, but the distortion is over about 40 feet, and is within the range of normal distortion for poorly maintained track. The railroad could have simply stopped rail traffic while the site was surveyed for damage. There may have been some broken ties that either needed replacing or at least needed review before they allowed rail traffic to resume. There may have been some sheet metal and other wing material on the track, which could have been moved by several people lifting it off. Or it might have been engine four.
I have said that it looks like engine four was left lying on the railroad tracks. Two pictures show an object on the rails that looks to be the right size, with a couple people standing near it.
The railroad would have been the ones to move engine four off the tracks, if that really was engine four in the pictures. They had the rail-mounted equipment and know-how to pick it up and hand it off to the CAB at a convenient intersection perhaps.
I'm intrigued by the possibility that they did this without coordinating with the CAB, thus resulting in a missing engine until it was located sitting on a flatcar. It seems more likely that they did get some kind of ok from a CAB investigator at the tracks, and then this wasn't communicated to the CAB site coordinator. Either way, the CAB investigators were left thinking an engine was missing, and this impression lasted long enough for the spokesperson to brief the Trib reporter, who then got it a little garbled in retelling.
This small puzzle feels almost parenthetical. The odd story of the missing engine does not by itself prove that engine four was left at the tracks. But if engine four did indeed land on the rails, my confusion scenario explains how an engine could be reported as missing for a day, and therefore constitutes circumstantial evidence which is admittedly thin but entertaining.
I've been scanning newspaper archives online. The best source has been the Chicago Trib. They followed the story closely, and they carried the graphic (morning after the crash) showing the rotation and erroneous backward slide.
On Tuesday they reported that one engine was found buried eight feet deep in mud and one other engine had been located, with two still missing. On Wednesday they reported that all had been found, with three of them (2, 3 and 4) 'close together' on open ground. It seems very odd that they could find one of those three on the day after the crash, and it took another day to see two more that were close to it. Since their frame of reference was that these were about 30 feet from the forward fuselage, we may take 'close' to mean something on that order of magnitude, as opposed to (say) a hundred feet apart.
This was open ground with no other wreckage in the area except the forward fuselage. In my document I pointed out two objects in photographs which were candidates to be engines, in the area the Chicago Trib described. An Electra engine is about 12 feet long and 29 inches high lying on its side. If you think of a Jaguar F-type, you're not far off. There were (per the Trib) three of these within about three car-lengths of each other, but they couldn't find two of those for a day.
Further, the one buried in mud was said to be number one. There is a distinct line in the aerial views where something went zooming off to the southwest from near the tracks, which I strongly suspect but can't prove was an engine. But if this was engine one, then it separated before the left wing or nose touched the ground. This seems as unlikely as not seeing two engines lying on the ground within a dozen yards or so.
This was not the CAB report; this was the Trib reporter relating what he thought the CAB rep said. I'm familiar with terrible reporting, and this sounds like something was garbled in the communication. These two Trib stories, taken together, are invalid on their face. I suspect two engines on open ground near the forward fuselage were just as I described in my document - engines one and two, which separated just east of their final location.
The irreducible core of this report is that the CAB said they could not account for the full complement of engines until Tuesday, and on Monday they were puzzled by this.
This is not something a reporter is just going to make up; it had to have come from the CAB. So why was there difficulty accounting for all of them? As in several other pieces of this documentation, the question is how much we have to discard before the rest makes sense.
Nothing was moved from the crash scene under official auspices until Wednesday at the earliest, when mapping was done. The Bridgeport Post reported on Monday that the rail line was out of service 'for a time', so the track was reopened to traffic on the day of the crash. The question is then to ponder what might have put it out of service.
The track was clearly shifted about a foot, but the distortion is over about 40 feet, and is within the range of normal distortion for poorly maintained track. The railroad could have simply stopped rail traffic while the site was surveyed for damage. There may have been some broken ties that either needed replacing or at least needed review before they allowed rail traffic to resume. There may have been some sheet metal and other wing material on the track, which could have been moved by several people lifting it off. Or it might have been engine four.
I have said that it looks like engine four was left lying on the railroad tracks. Two pictures show an object on the rails that looks to be the right size, with a couple people standing near it.
The railroad would have been the ones to move engine four off the tracks, if that really was engine four in the pictures. They had the rail-mounted equipment and know-how to pick it up and hand it off to the CAB at a convenient intersection perhaps.
I'm intrigued by the possibility that they did this without coordinating with the CAB, thus resulting in a missing engine until it was located sitting on a flatcar. It seems more likely that they did get some kind of ok from a CAB investigator at the tracks, and then this wasn't communicated to the CAB site coordinator. Either way, the CAB investigators were left thinking an engine was missing, and this impression lasted long enough for the spokesperson to brief the Trib reporter, who then got it a little garbled in retelling.
This small puzzle feels almost parenthetical. The odd story of the missing engine does not by itself prove that engine four was left at the tracks. But if engine four did indeed land on the rails, my confusion scenario explains how an engine could be reported as missing for a day, and therefore constitutes circumstantial evidence which is admittedly thin but entertaining.
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There doesn't appear to be a plan showing the position of the major components in the official reports, although it would seem essential for a thorough investigation. Interesting that no such document has shown up in the records.
The four engines are probably the most concentrated blocks of mass in the entire airframe, but they are not that large when cowlings and accessories are stripped away from them.
The ground was relatively soft, so all the engines were probably partially buried in ground that was pretty chewed up by the crash and response vehicles. I don't think it is too much of a suprise that it took a couple of days to get everything found and mapped out.
I suspect only the wing tip broke away in contact with the embankment and perhaps one engine on first contact with the ground beyond. The remaining engines separated more or less together at a later stage of the impact sequence. That would account for them all being found close together, with one engine a distance away.
I'm pretty sure there would have been a lot more damage to the railroad track and embankment if an engine had made contact at that point.
If an engine had been left on the railroad tracks or the embankment, that would have made for a terrific news photograph. Someone would have documented something as dramatic as that for sure. So the debris on the railroad track is most likely bits of wing and perhaps a propellor tip.
The four engines are probably the most concentrated blocks of mass in the entire airframe, but they are not that large when cowlings and accessories are stripped away from them.
The ground was relatively soft, so all the engines were probably partially buried in ground that was pretty chewed up by the crash and response vehicles. I don't think it is too much of a suprise that it took a couple of days to get everything found and mapped out.
I suspect only the wing tip broke away in contact with the embankment and perhaps one engine on first contact with the ground beyond. The remaining engines separated more or less together at a later stage of the impact sequence. That would account for them all being found close together, with one engine a distance away.
I'm pretty sure there would have been a lot more damage to the railroad track and embankment if an engine had made contact at that point.
If an engine had been left on the railroad tracks or the embankment, that would have made for a terrific news photograph. Someone would have documented something as dramatic as that for sure. So the debris on the railroad track is most likely bits of wing and perhaps a propellor tip.
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The engines possibly breaking up is certainly a valid issue. The CAB report said that in only one case did they fail to get torquemeter readings from an engine, which suggests that only one engine broke apart at the drive shaft. One newspaper article mentioned that the investigators were surprised at how well the engines held together.
They mapped the site, of course, and all that documentation existed once. But when the CAB moved their records to the FAA all that was discarded. There's nothing in the National Archives and I haven't been able to turn up anything else. If I had a debris map all this would be easily settled. That's what makes this a detective story.
The energy of an engine hitting the embankment is one of the things I've wrestled with. I've tried to find experienced crash investigators to give me some feedback, but haven't found any yet. I go into that at some length in my document, but it's all guesswork.
You're right about the photographer getting that shot if he could. That plus the Bridgeport Post article suggests that whatever was on the track was moved really quickly. Something was there in the aerial view, but not when he was at the tracks. I have a faint hope of hearing more from the Chicago & Northwestern Historical Society, which maintains a lot of unsorted old journals and records, but their first response was not encouraging.
They mapped the site, of course, and all that documentation existed once. But when the CAB moved their records to the FAA all that was discarded. There's nothing in the National Archives and I haven't been able to turn up anything else. If I had a debris map all this would be easily settled. That's what makes this a detective story.
The energy of an engine hitting the embankment is one of the things I've wrestled with. I've tried to find experienced crash investigators to give me some feedback, but haven't found any yet. I go into that at some length in my document, but it's all guesswork.
You're right about the photographer getting that shot if he could. That plus the Bridgeport Post article suggests that whatever was on the track was moved really quickly. Something was there in the aerial view, but not when he was at the tracks. I have a faint hope of hearing more from the Chicago & Northwestern Historical Society, which maintains a lot of unsorted old journals and records, but their first response was not encouraging.
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The ALPA report says that engine power indications came from the engine torquemeter itself, not from the cockpit instruments. The CAB report said that the only cockpit instrument with anything on it was the captain's artificial horizon, and they didn't trust the reading.
The ALPA said the engine power indications were read off of engines one through three, but no reading could be obtained from number four. It also said that engine four separated at the embankment. As I've said, engine four hitting the embankment is an excellent reason for not being able to recover the torquemeter value.
The ALPA said the engine power indications were read off of engines one through three, but no reading could be obtained from number four. It also said that engine four separated at the embankment. As I've said, engine four hitting the embankment is an excellent reason for not being able to recover the torquemeter value.
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I agree, the torque settings would have been inferred from the position of components within the engines, rather than cockpit instruments. The position of fuel feed and oil feed valves, or witness marks, would provide an approximate indication of the power settings on the engines.
If engine four separated on or shortly after contact with the top of the embankment and then tumbled some distance to a final resting position, the disruption and damage to the engine might cause several sets of witness marks which would be difficult or impossible to accurately decode.
If engine four separated on or shortly after contact with the top of the embankment and then tumbled some distance to a final resting position, the disruption and damage to the engine might cause several sets of witness marks which would be difficult or impossible to accurately decode.
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Thanks Megan.
I hadn't found documentation on how that works and was curious about it. See, that's what I come here for!
Ok, the missing torquemeter value doesn't tell us anything useful. Good to know.
I hadn't found documentation on how that works and was curious about it. See, that's what I come here for!
Ok, the missing torquemeter value doesn't tell us anything useful. Good to know.
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Megan
An impressive amount of detail in your post. I had no idea that engine monitoring technology had advanced to that stage when the Electra was produced. I was thinking of the mechanisms within the engine that controlled the power output rather than the instrumentation side of things. I think your explanation is the correct one. Thank you.
An impressive amount of detail in your post. I had no idea that engine monitoring technology had advanced to that stage when the Electra was produced. I was thinking of the mechanisms within the engine that controlled the power output rather than the instrumentation side of things. I think your explanation is the correct one. Thank you.
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I tracked it down in a pile of manuals dated '56 and '58 sent by my biggest supporter. The pickup circuitry was vacuum tube technology. It's all transistors now, I presume. This is very cool, and just as Megan described.
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I'm way behind schedule on this project. Taking off a few months was intentional; this thing really wears on me for personal reasons and I needed a break. I had hoped to finish the write-up on the flight simulator, but it's at least a couple months away.
In addition, I'm exploring the prospects of animating the breakup, as contrasted to simulating the flight. The flight simulator was intended to play out real physics in a virtual world, to give my best approximation of the flight. But I have no access to the kind of tools it would take to simulate the impact and breakup. This would require vast amounts of structural data and probably a supercomputer to run the sim. But I should at least be able to use an animation tool to show what I think happened and make it more accessible to the reader/viewer. A side-effect of importing from the flight sim into an animation tool is that I can redo all my fairly crude line drawings with much better images. So I may delay the next version in order to at least do the import and redo images, before I get into the animation itself.
Meanwhile I've posted two interim files, which I've been circulating among my contacts since February. The first of these is a write-up of the missing engine puzzle discussed here in the thread. It will become a chapter in the next version. https://we.tl/2iOuz04If7
The second is an attempt to understand what was going on in the cockpit. This was pretty creepy, and is why I took a break from the project. This discusses the resources they had to work with, and I try to fit what they might have been doing into the time they had. A pilot friend said he'd forward this to an Electra instructor, but I don't have results yet. I would be very grateful to pilots for their feedback on this write-up and on whether I've come anywhere near the pacing of what would be going on under stress conditions like this. https://we.tl/x0L59Bpfmj
In addition, I'm exploring the prospects of animating the breakup, as contrasted to simulating the flight. The flight simulator was intended to play out real physics in a virtual world, to give my best approximation of the flight. But I have no access to the kind of tools it would take to simulate the impact and breakup. This would require vast amounts of structural data and probably a supercomputer to run the sim. But I should at least be able to use an animation tool to show what I think happened and make it more accessible to the reader/viewer. A side-effect of importing from the flight sim into an animation tool is that I can redo all my fairly crude line drawings with much better images. So I may delay the next version in order to at least do the import and redo images, before I get into the animation itself.
Meanwhile I've posted two interim files, which I've been circulating among my contacts since February. The first of these is a write-up of the missing engine puzzle discussed here in the thread. It will become a chapter in the next version. https://we.tl/2iOuz04If7
The second is an attempt to understand what was going on in the cockpit. This was pretty creepy, and is why I took a break from the project. This discusses the resources they had to work with, and I try to fit what they might have been doing into the time they had. A pilot friend said he'd forward this to an Electra instructor, but I don't have results yet. I would be very grateful to pilots for their feedback on this write-up and on whether I've come anywhere near the pacing of what would be going on under stress conditions like this. https://we.tl/x0L59Bpfmj
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My impression from the sparse documentation at the time is that the initial efforts were devoted to recovering the casualties from the crash. Mapping of the wreckage wasn't initially seen as a priority, hence the confusion about the engine location(s). Nobody bothered to map it all out until the third day, when reports indicated that all the major parts of the airframe and engines were accounted for.
Cockpit resource management was in its relative infancy in those days. The crew would most likely be looking to the Captain to direct attempts to recover the aircraft, so probably not a lot of discussion, rather orders to perform certain actions.
With regards to the initial response and air accident investigation, there would have been very little organised communication initially between the first responders and agencies attending the scene. Undoubtably a scene of utter confusion for a day or two until proper lines of communication and assignment of responsibilities had been organised.
I wonder whether any of the current generation of P3 Orion pilots can give any insights considering that the two aircraft types are closely related.
Cockpit resource management was in its relative infancy in those days. The crew would most likely be looking to the Captain to direct attempts to recover the aircraft, so probably not a lot of discussion, rather orders to perform certain actions.
With regards to the initial response and air accident investigation, there would have been very little organised communication initially between the first responders and agencies attending the scene. Undoubtably a scene of utter confusion for a day or two until proper lines of communication and assignment of responsibilities had been organised.
I wonder whether any of the current generation of P3 Orion pilots can give any insights considering that the two aircraft types are closely related.
Have you tried 'Failure Analysis' in Menlo Park, California? They might be of some help in (forensic) animation? PM me for contact info on a P-3 Navy Pilot.
Was whirl mode (investigation or AD) in play at the time of the crash?
Was whirl mode (investigation or AD) in play at the time of the crash?