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Help researching 1961 Electra crash

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Help researching 1961 Electra crash

Old 8th Mar 2016, 18:31
  #41 (permalink)  
 
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Megan - I agree

Additionally, the power lines would not be insulated. The blue flash visible as the aircraft hit and shorted out the power lines confirms that the power lines were just bare conductors of the steel jacketed copper type.
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Old 8th Mar 2016, 19:04
  #42 (permalink)  
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Originally Posted by megan View Post
Additionally, the report I have quotes the railway embankment as being half the height of the power line towers.You are making the mistake of assuming the angle of bank dictates (1) radius of turn (2) its effect on the stall speed. The only time it dictates those two parameters is if the aircraft is in balanced flight. As I said earlier, the aircraft was basically on a ballistic trajectory, demonstrated by the almost straight line track of the aircraft in its later stages of flight (negligible radius of turn).
Yes, I understood what you meant, and I addressed this in my document. I went back and found the same thing for the embankment height, by the way.

To get to that location and then have the bank go vertical is not what the witnesses or the reports describe. The plane would have to be at a bank of about 45 degrees, and within a second or two it goes to 90 degrees. This is possible if the inside wing stalled, but it's not how it was described. So one way or another you have to exclude some witness reports.

This has been a very useful discussion. Having people disagree is more valuable than having them agree. I'll have to add a scale elevation of this stage of the flight in my next version.
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Old 9th Mar 2016, 00:29
  #43 (permalink)  
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Originally Posted by megan View Post
there is absolutely no reason to doubt the angles of bank at the various stages.
Piffle. There are excellent reasons for doubting the bank angles. A few posts back you said witnesses are notoriously unreliable, yet here you are saying their word is gospel.

For one, no increasing bank can get to the impact site. It will end east of the impact. That's the nature of a spiral. The plane turned through only about 130 degrees, so it's got more movement parallel to the runway axis than it has at right angles to it. The impact from the start of the turn is a greater distance orthogonal to the runway than along the axis. Simple geometry. If the plane gets there by flying, the bank must moderate.

If you depend on going ballistic to get you to the impact site, the plane has to go ballistic roughly 1500 to 2000 feet from the impact given an increasing bank, depending on when and how fast you think it increases. At 200 feet up the plane has under 2 seconds of air time before it hits, and that means it has just over 500 feet of forward movement before it hits. You can't stretch 500 feet to cover 1500 to 2000.

ETA: oops, filled in the wrong numbers. About 3.5 seconds, or 900 feet forward.

After dropping from 200 feet in ballistic mode, the plane has a downward velocity of about 70 knots. It strikes the right wing on the tracks, and then drops another 30 feet or so in the next 300 feet. In other words, the downward component goes from 70 knots to 17 knots upon striking the right wing. It defies imagination.

On the other hand, if you remember that witnesses are notoriously unreliable, and if you remember that all the witness statements are being filtered by whoever wrote the report, it's relatively easy to see what's wrong here.

Last edited by BRDuBois; 9th Mar 2016 at 01:33.
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Old 9th Mar 2016, 01:33
  #44 (permalink)  
 
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At least two of the witnesses were police officers who were relatively close to the aircraft and in a position to make an accurate assessment of the aircraft bank angle. They are trained observers who would make a report of only what they witnessed, not an assessment or a guess.

The Electra has a relatively large tail surface with a pronounced leading strake along the top of the fuselage. The tail combined with full engine power would allow for a considerable degree of aerodynamic lift despite the wings being almost vertical with respect to the ground. You only need to watch an aerobatic display to see "knife edge" flying manouvers are possible over considerable distances given sufficient initial speed and engine power.

The aircraft in this instance rolled continuously, but the roll was being resisted by rudder inputs. As the aircraft rolled through 60 degrees, the wings would have effectively stalled with respect to generating lift away from the ground, but the rudder and engine power would still have been sufficient to generate some overall lift. The inertia of the aircraft prevented the turn from tightening as you suggest would have happened as the bank angle increased through 45 degrees.

This is why the aircraft did not immediately go into a tight spiral and nose straight down into the ground as the bank angle passed some critical angle where the horizontal lift element from the wings disappeared.

The sheer number of witnesses, the bank angle estimates from the severed wires, the wing tip marks on the embankment and the witness marks from the artificial horizon all combine to provide powerful circumstantial evidence that the bank angle was around 90 degrees at initial ground contact.

The wing tip contact and propeller strikes and probable loss of engine four as the aircraft passed over the embankment could possibly have flipped the aircraft back towards a more horizontal attitude before it stuck lower ground having passed over the embankment. That would account for the wheels striking the ground rather than the roof of the aircraft at the first bounce point. The aircraft may then have continued rotating before hitting the ground a second time. A wing may then have contacted a tree or rocks, spinning the fuselage at or around the final ground contact. That combined with the continued rotation would allow for the upside down, tail forward attitude of the rear cabin area.

The fuselage may well have split, dug in and flipped over as you suggest, but I don't believe for one moment that the pilots could have had any influence in flattening the flight path or wing angles prior to the initial impact. The lack of aileron control would have prevented any such action.

If the initial impact with the railway embankment did somehow flip the aircraft into a more normal flying attitude over the second or two it took to make solid contact with the ground, then the rest of your analysis of the crash sequence makes sense.

Depending on where the power lines hit, the cockpit or some of the instruments may have been destroyed at that point, resulting in the 90 degree angle witness marks on the artificial horizon. The subsequent impacts may have shifted things around a bit resulting in more than one witness mark and generating some confusion with the investigators about which marks were relevant.

It all has to be supposition after all this time, but that is the best scenario I can arrive at that matches your analysis with the official reports at the time.

Last edited by G0ULI; 9th Mar 2016 at 01:47.
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Old 9th Mar 2016, 07:51
  #45 (permalink)  
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I would be very skeptical of the idea that just because someone's a police officer he is better suited to judge aircraft attitudes.

Knife-edge flying can be done by aerobatic planes, but in this case the nose was reported as about 10 degrees down.

There were no reported measurements from severed wires, merely the conjecture that such measurements were taken. We don't even know that the wires were hung in an arrangement that would make measurements diagnostic.

There were clearly quite a few people who were impressed by the plane's angle. That constitutes circumstantial evidence that the plane was in a steep bank. Opposing that evidence we have flight path geometry that rules out a bank steeper than the low 30's, damage to the right wing that rules out an impact at an angle higher than the mid-30's, and an impact sequence that best fits an approximate belly landing.

As Megan said, you can't trust witnesses.
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Old 9th Mar 2016, 13:41
  #46 (permalink)  
 
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I have presented a scenario that broadly fits the witness descriptions and the physical evidence yet still allows for the possibility of a mostly belly down first major impact. The only area of doubt is what happened after the wing tip hit the railway embankment and before the fuselage hit the ground.

I have also presented a mechanism where the rudder and elevators would provide some degree of lift and directional control when the aircraft developed an extreme attitude. The rudder would have controlled the nose attitude and the elevators the direction, to a certain degree.

The sudden loss of a few feet of wing tip and a couple of tons of engine could allow the intact wing to drop in the couple of hundred yards or so before the first major ground impact point. So the aircraft hits the ground in a more level attitude and everything then plays out as you have described in your analysis.

There is a faint possibility that the aircraft continued in an accelerated roll in the same direction after contacting the embankment but before hitting the ground. This might be cause for the witnesses to describe a cartwheel motion depending on their point of view.

Witnesses are commonly regarded as being unreliable in stressful situations, but taken as a whole and given a few "qualified" witnesses a good idea of what happened can be arrived at. I have personally taken hundreds, if not thousands, of witness statements and the most important aspect of the statement taking is separating what the witnesses actually saw from what they thought they saw or "invented" to fit their mental picture of what happened. Before the advent of video recording devices and DNA evidence, most court and enquiry evidence was based in eye witness testimony. The investigators at the time would have been aware of witness bias and would have conducted their interviews accordingly.

Your scenario presents a case where all the witnesses are in error, the physical evidence is treated with suspicion and an unknown mechanism allowed the pilots to level the wings before impact with the embankment.

I think I will let the jury decide which is the most plausible scenario.
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Old 9th Mar 2016, 14:11
  #47 (permalink)  
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Originally Posted by G0ULI View Post
Your scenario presents a case where all the witnesses are in error, the physical evidence is treated with suspicion and an unknown mechanism allowed the pilots to level the wings before impact with the embankment.
I very much appreciate the time and thought you have put into this. This has been invaluable.

Working from memory here, I think of the fifty-odd witnesses only four or five said the bank was essentially vertical. Several said the wing pointed right at the ground, which is ambiguous. I'm certainly not faulting all the witnesses.

I'm treating the physical evidence with considerably more respect, and not suspicion. You're conjecturing that someone measured the powerlines, and that measurements taken from those lines would have been diagnostic, and those measurements support your view. That's three big conjectures based on nothing more than the report writer guesstimating the angle when the plane hit the lines.

I don't know how the bank was moderated, I simply see evidence that it was. I'm hoping for more input from Electra pilots.

I've been reading the Chicago Trib story from the archives. It says "After the plane hit the tracks it bounced back into the air, flying another 300 feet to hit with tremendous force in a swampy slough. Then it bounced again for 100 feet before sliding to rest 800 feet west of the tracks."

That is exactly the sequence I've been describing.
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Old 9th Mar 2016, 15:44
  #48 (permalink)  
 
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I wish you all the best with your research. I know you have made enquiries with more US centric forums, so hopefully you will get some more positive responses from people who actually built and flew the Electra. It was certainly an interesting, if tragic, time in the development of modern aviation.

I came across some fascinating footage on YouTube from those times. It is amazing how the aircraft manufacturers of the time were allowed to play down the seriousness of the problems they faced. Severe structurally destructive vibrations in the airframe became a program to reduce cabin noise levels and increase passenger comfort after the marketing departments had done their job.

Simply incredible!
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Old 9th Mar 2016, 22:33
  #49 (permalink)  
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I wrote a little Excel table to calc drop speeds if the plane went ballistic, using the power line as the point of first impact. I'll put the graphics in my next version.

If the plane stalled and essentially went ballistic just as it hit the power lines, it would barely clear the embankment after losing some wing, but wouldn't make it to the first recorded impact in the swamp. If it stalled at 75' it would impact the embankment directly. If it stalled at 150 feet or higher it wouldn't even make it to the embankment.
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Old 10th Mar 2016, 01:12
  #50 (permalink)  
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That's fine, let's just say it was a ballistic object and had no significant lift from any surfaces. It's still going to accelerate downward at 32f/sec/sec.
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Old 10th Mar 2016, 03:08
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The engines were generating thrust throughout the impact sequence and aerodynamic forces on the aircraft lift and control surfaces, irrespective of attitude, mean that the aircraft was never following a ballistic trajectory at any point while in flight.
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Old 10th Mar 2016, 11:07
  #52 (permalink)  
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the aircraft was never following a ballistic trajectory at any point while in flight.
I never thought it was. But for those who suggest that inertia was going to carry it through the last few hundred feet while it was in a vertical bank and generating no lift, calculating the trajectory is a good enough approximation of the possibilities.
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Old 10th Mar 2016, 11:25
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Megan - Absolutely right. The point being that the aircraft was descending, but not necessarily accelerating towards the ground at 32 fps squared.

My interpretation of the control inputs was along the lines of;

Aircraft lifts off from the runway. Witnesses claim it was a longer ground run than usual. Did the pilots detect some slop in the controls and consider aborting the takeoff?

Once airborne, a right bank is initiated and a balanced turn commenced.

A left aileron input is made to adjust the turn and the control cable separates.

The bank angle increases and a left rudder input is made to counter the bank. The crew discover that the control column is not responding to aileron control inputs, but the aircraft is still in a climbing turn.

Progressively more left rudder inputs are made in an effort to control the bank angle and the control column turned fully to the left, to no effect.

As the bank angle increases through 30 degrees, the aircraft begins to lose height.

Bank angle approaches 40 degreees and the control column is pushed forwards to try and reduce the rate of turn. The elevators are now acting in place of the ailerons and rudder as a crude directional control. The rudder is now acting to keep the nose up.

As the bank angle continues to increase, the nose drops through the horizon and the aircraft descends clipping the embankment and shedding several feet of wing tip and engine four. The inertial kick from propeller strikes and the engine breaking away level the aircraft somewhat before the fuselage strikes the ground.

The aircraft was under some measure of control throughout the sequence and the crew performed the only actions that they could to mitigate the effects of the inevitable crash. Unfortunately, their efforts were in vain.

Had the aircraft not struck the railway embankment first, I would expect the fuselage to have made initial ground contact virtually fully inverted.

Given the speeds involved and the design of aircraft at that time, the accident would not have been survivable due to break up of the cabin interior and the physical stresses imposed on the passengers and crew during deceleration, even if the aircraft had simply flopped on its belly and slid to a stop.

If the aircraft had struck the embankment at a shallower angle of 30 degrees rather than the 90 degrees submitted in the official reports, I would expect both of the engines to break away from the wing and a much wider area of damage and debris crossing the railway embankment. There would also be two distinct parallel sets of propeller strike marks running over the embankment, which does not appear to have been noted at the time.
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Old 11th Mar 2016, 16:28
  #54 (permalink)  
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An interesting quotation from the CAB report:

"... tension on the right wing down cable imparts an immediate signal to the aileron boost unit for a right wing down control movement. These tests also disclosed that if the forces on the boost quadrant were released, the propensity of the system would be to return the ailerons to neutral in approximately seven seconds, provided no part of the system hangs up or binds. However, the tests involving cable separation further showed a tendency of the cable connectors ... to bind with airframe structure. Because of the mechanical advantage of the system, only a small hang-up force would hold against in-flight airloads and would prevent the aileron boost unit from returning to the neutral position."

In other words, the CAB is fairly confident in conjecturing that the aileron boost did not return to neutral, but realized that such return-to-neutral was possible. In the absence of affirmative control by the crew, the flight path geometry provides reason to think that this returning to neutral was happening during the latter part of the flight.

This, along with the rudder inputs and evidence from trim settings, provides a mechanism that can explain the observed flight characteristics.

The CAB ended by concluding that this return-to-neutral did not happen, partly based on witness reports and partly on the debris recovered.
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Old 11th Mar 2016, 17:22
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The cable binding kept the right aileron raised into the airflow over the wing by six degrees, effectively commanding full right wing down. The cable remained snagged until the aircraft hit either the power cables or the embankment. The shock of impact on the wing structure released or forced the snag to run free. Unfortunately that was too late to save the aircraft, but it would have removed the wing down aileron input and could help account for the aircraft seeming to level before the primary ground contact by the fuselage.

So a combination of factors were likely at work, a sudden release of the fouled aileron cable, loss of the wing tip, two ton weight reduction by loss of engine four, and some inertial kick from propeller strikes as the engine broke away from the wing. All of these factors seem to have acted to reduce the bank angle combined with the pilot's control inputs.

But, I don't see anything that indicates that the pilots were directly able to influence or affect the ultimate outcome. As Megan pointed out, once the cable broke, they were simply along for the ride.

Every indication is that this crash was inevitable and although chance most likely moderated the bank angle before the fuselage hit the ground, it was just that, sheer luck.

What is apparent is that the pilots flew the aircraft to the best of their ability all the way to the ground. They didn't give up, even though they doubtless knew that their efforts would be futile. Can't ask for any more than that.
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Old 11th Mar 2016, 17:29
  #56 (permalink)  
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I don't see anything that indicates that the pilots were directly able to influence or affect the ultimate outcome.
I think that's a fair statement. I think it was you who earlier commented that the most they could do was manage the descent to some degree. The best they could possibly get out of this was bound to be very messy.
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Old 12th Mar 2016, 01:23
  #57 (permalink)  
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I get a lot of drive-by psychoanalysis from this project. I'm used to it.

The first published version was actually draft 13, so by the time I released a version there was a lot of evolution behind it. I'm a writer; I do many drafts. It took quite a bit of writing before I realized what the CAB/ALPA errors implied about the flight and therefore the crew. It started just as I stated in the document - with no expectations.

The wire strike evidence that you allude to does not exist. There was a bare statement in a report saying the plane was at about a 70 degree angle when it hit the wire. From that you deduce that it was measured from the breaks, with absolutely no evidence of that and good reason to doubt it. And you treat that conjecture as if it were evidence itself. This is ludicrous.

I understand that you differ in interpreting the object on the tracks. It's very hard to make out, and it's only by some reading between the lines that we can make a determination. Evidence on that point is pretty good, but clearly circumstantial.

It falls to me to rewrite history because the CAB and ALPA did such a crappy job of it. The errors in the official reports are obvious and egregious. You have said that they don't go to the cause of the matter, which is true. But they are nonetheless evidence of a slapdash approach that treats the physical evidence in an almost offhanded manner. This gives me all the permission I need to state the obvious truth. They got almost everything except the root cause wrong.

As I say in the document, you should treat with suspicion any relative who says the crew did better than was reported. You should probably treat with suspicion any claim at all by a relative. But it landed in my lap so I have to do the job. The evidence was out there for 55 years and no one else did it.
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Old 12th Mar 2016, 01:38
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Megan

We all need our dreams and the past isn't always how we thought it was.

I was proud that my Polish father trained as a commando in Scotland in WW2. He was an expert marksman and demolition trained.

It wasn't until a couple of years before he died that I found out that he had also served for three years in the German Army as a conscript and was trained by them as a sniper, before deserting and escaping to Britain.

it has been fascinating to go through the records of this accident and try to arrive at a conclusion as to what actually happened. I think we have reached a point where we can agree that the aircraft did in all probability level out somewhat before it hit the ground. From the evidence available to us, it appears that the pilots were unable to initiate that levelling out, but something clearly did. There is no need to rewrite history and I am grateful for the opportunity to examine these records.
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Old 12th Mar 2016, 02:00
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From the evidence available to us, it appears that the pilots were unable to initiate that levelling out, but something clearly did.
Today I discovered an Electra manual that discusses a rudder/aileron linkage. Apparently rudder movements affect the ailerons independent of the control wheel. It's part of a mechanism to help make balanced turns. There's some exploration to do here.

This project is far from over. I'll have a new version out in a couple weeks, covering the Chicago Tribune materials and some ideas developed from our conversation here.
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Old 12th Mar 2016, 10:32
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The leading edges were melted puddles.
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