Help researching 1961 Electra crash

[BRDuBois]

I've lurked here for some time, and recently joined so I could ask for help.

For the last year I've been researching the 1961 crash of a NWA Electra in Chicago. My dad was the captain. For background, search for N137US. A year ago I stumbled across some old press photos of the crash site, and after looking them over I realized that in certain respects the official crash reports couldn't possibly be correct.

Since then I've been digging up documentation and writing a new scenario. It's been reviewed by one person who has experience reviewing accident reports. He agrees with my reasoning and conclusions, so I think it's time to find a wider audience.

I want input from pilots, crash investigators and others in the flying community. I'm looking for critical feedback, and for ideas I haven't thought of. If I made mistakes, tell me what I got wrong.

I'm interested in hearing from anyone who has a connection to the event. My hope is that this will come to the attention of someone who has some of the original files. I'd like to find the debris maps and witness interviews and lots more pictures.

It's a 55mb PDF. If you find errors, please let me know. The link takes you to a download page, but does not start the download.

http://we.tl/4GRGZxxxEJ

Craig Hagstrom

[BRDuBois]

I'm seeing many reads, some downloads, but no responses yet.

Here's the nickel tour:

The CAB report says the plane cartwheeled, slid backward and upright to a stop, and burst into flames. Multiple pictures show the plane was upside down instead of upright. Ground scars say the plane's arrival at the final site was high-energy, not a sliding stop.

The CAB and ALPA agree that the plane was slightly nose-down and gradually descending in a 90-degree right bank. Consider the likelihood of that.

The ALPA report says the number four prop left scars across a railroad embankment, which is how they calculated ground speed. But the number four engine was left lying on the track, so it must have been the number three prop that left the scars. The wing was intact nearly to engine four, which means the ground cannot be touched by the number three prop in a bank steeper than 30 degrees.

The CAB and ALPA reports are wrong. That much is a slam-dunk. The errors are partly understandable and partly unconscionable.

The puzzle is in unraveling what actually did happen. This is a 54-year-old mystery. Part of the mystery is that no one even knew there was a gap in our understanding. The other part is to figure out what the crew was doing and how the plane really went down. To me it looks like an attempted belly landing that didn't work out.

[BRDuBois]

My project will be mentioned in the NWA History Center December newsletter. It's not out yet, but will be available at Newsletters (http://www.nwahistory.org/newsletters.html). An updated PDF will be available in a couple weeks, with two new visual aids and a newly discovered picture. The current link will still work, and will show you where the new version is.

[westhawk]

Hello Craig.

I empathize with your desire to learn as much as you can about this. I wish you the best in your quest.



westhawk

[BRDuBois]

Thanks. It's a totally fascinating project.

One editor of a flying-related newsletter was dumbfounded that I could even imagine questioning an Official Report. If there were a genuflect emoticon he would have used it. To confess, it took quite a while for me to accept that the official reports had to be wrong, having believed them for so long.

A couple well-meaning pilots have said I shouldn't even think about it, and everyone died instantly, which of course was not true. One said I must still be traumatized, but I was over that 40 years ago. This is a detective story.

I'm hoping that when this hits the NWA history newsletter it will find the right people. Many remember my dad, and remember that day. Hopefully someone still has some documentation. If not, then just finding what I have has been a terrific bit of luck.

One friend was at the airport that day, but didn't see the crash. Until he saw my write-up we had no idea our paths had crossed in this way. When he took off the plane banked toward the city instead of west as it normally did, and that caught everyone's attention. He was a veteran on that route. Apparently they banked so the passengers couldn't see the wreck. Makes sense.

Craig

[Capt_Tech]

This aircraft suffers from cracking in the wing planks, wings are not very flexible.

[BRDuBois]

Capt Tech - is that a general observation, or were you responding to my question in the document about how much the wing could contribute to the final bounce? I know the wings are stiff with regard to vertical stresses. The issue I was wondering about was how it might rebound when it hit something nose-first. As I mention in the write-up, there wasn't much wing left at that point anyway.

[BRDuBois]

Megan, thanks for your response.

You're right, the picture of something on the track is thin evidence. As I mention in the document, I try to do as little violence as possible to the official reports. I accept the reports up to the point that they are clearly wrong, and then I set that error (and that error only) aside. The ALPA report said that everything beyond engine four was finely shredded, so there cannot have been any large wing part left on the track. In the 2015_Image_03 picture there are some small fragments in the near distance, beyond and beside the guy standing on the left. These match the description in the ALPA report, but the object in 2014_Image_02 (whatever it is) does not. It's the right order of magnitude, but I can't prove what it is.

The bent railway line is evidence that a mass with sufficient kinetic energy gave it a good whack ie a 2,000 pound engine travelling at some 100+ knots.Exactly. That's the problem. The ALPA report said that it was the wing and not the number four engine that hit the track, and it was the number four prop that left the scars. If it was the wing, then it was a couple hundred pounds of fuel and aluminum that bent the track. I propose that that's not realistic. It seems that the track damage is likely to be engine four hitting the track or the ballast just short of the track, and it killed its forward momentum and left it lying there.

It's not impossible that engine four left the foreground scar in 2014-Image_05. It's not impossible that engine four parted at that point and went on to hit the track. It seems unlikely, but it's not impossible. The key event is not where engine four parted, but where it ended up. As you say, it looks like it would take an engine to bend the track, an object of about the right size was left there, and the prop scars remain unresolved unless they were from engine three. So the details of engine four are much less important than the remaining wing and the angle that WS 293 presents to us.

The prop scars across the embankment were the source of the speed calculation. This was not a throwaway line, but critical to the investigation. Yet the wing was intact out to WS 293, and it's impossible for prop three to touch the track in a 90 degree bank while the wing remains intact to WS 293. This is the strongest single piece of evidence for the shallow bank. You simply can't draw a line through WS 293 and prop 3 that is at 90 degrees to the horizontal axis.

You're right that the angle could be confirmed by measuring the broken power lines. But they were confident of the 90-degree bank, and laying out and measuring those broken lines would take probably several days and quite an investment. Who would bother, since there was no question? Nothing in either report says that power line measurements confirm the angle.

I agree that it would be best to see all this on the ground. But it's long gone, the area is now covered with warehouses, and all I have are these pictures. This is sort of like a paleontological dig. I'm looking for fossils, but fossils are statistically few and far between, so I'm trying to piece together the lineage using these scattered and blurry data points. That's why I'm hoping this document helps turn up some more old files.

What the crew actually intended, or thought they might accomplish, is the most elusive question. I think there's enough evidence to say this was close to a successful belly landing, but that doesn't mean the crew thought they could make it or even thought it was within the realm of possibility. I'm positive they were doing the best they could; I don't know what they thought the outcome might be.

[BRDuBois]

I uploaded the revision, but people are still downloading the first version. I thought the red and yellow sign on the download page pointing to the new version would be enough. :)

The new link is http://we.tl/M88emt5L4F

The revision includes a new picture of the tail wreckage, and I've been able to understand the physics there better. It has two new illustrations to show the dymamics of the last two bounces. There is also a short discussion about why the ALPA got it so wrong.

[BRDuBois]

Y'all sure are taking it easy on me. Been up a month, bunch of downloads, and no meaningful arguments. Either no one is actually reading what they're downloading, or I'm a really persuasive writer. Maybe everyone's just speechless.

[mustangsally]

An accident that occurred fifty some years ago has to be harder than solving most cold cases. The technology in the early 60's was very poor to what we can do today. The 1961 investigators, I'm sure did there best, but you are looking at it in todays time frame. I think your conclusion may be accurate, but will that ever change the historical outcome?


Frequently, in cases where the crew does not get to defend or tell their side of the story, the operators loose. The aircraft manufacture, maintenance crews and company are all there to deflect the fingers away from there possible contribution and point at the crew.


Just my couple of cents. Very sad but true.

[BRDuBois]

As I mentioned in the first post, I got a sanity check from a guy who reviews crash reports and helps with things like requests for re-examination. I don't see any value in that, because I'm not questioning the cause of the crash, only the description of the impact. I think the breakup sequence is telling, mostly as a detective story and also as archeology - uncovering a historical record that was unsuspected.

I'm getting a feel for the crash investigators, and the more I consider it the more indignant I get over the ALPA writer. Here's what I think happened:

The ALPA writer had access to CAB documents, but it was grudging access. The ALPA and CAB did not always cooperate, and in at least one case the ALPA was more or less accused of sequestering a crew so the CAB could not get toxicology results, etc.

The CAB in one document described prop hits across the railroad embankment. In another document the CAB described how the spacing between prop hits across the ground let them calculate ground speed. I'm positive those two documents described the same sequence of prop hits, but one of them explicitly mentioned the railroad embankment, and the other mentioned only the "ground". So the ALPA writer assumed those were two different sequences, but they were simply one sequence mentioned in two documents.

So with good intentions, the ALPA writer concocted a scenario that had two sets of prop hits, and obviously that had to be engine four and then engine three. And he came up with a sequence that seemed to fit that, but without doing the geometry he was wildly off base. The result of following the ALPA scenario is that the plane had to go from a 90-degree right bank to a 150-degree bank where the number three prop hit, and then reverse and go back around to a belly landing, all in 1.4 seconds. The timing comes from 380 feet between first wingtip impact and nose impact at 160 knots. The guy didn't have a clue.

What kills me about this is that all he had to do was ask. A simple conversation with the CAB guys would have cleared it up. The ALPA writer clearly never went to the crash site, never understood the physics. And because of the prickly relationship or his personal attitude he couldn't ask the question.

This is all conjecture, you understand, but this is what I see behind the scenes.

[BRDuBois]

I see nothing in your PDF that convinced me that the official report is any way in error. The CAB report says the plane slid tail-first and right side up. The pictures show the plane tail-first and upside down. Do you accept the CAB report on that item?

You agreed that the railroad tracks appear to be hit by engine four. The ALPA report says the number four prop left the scars on the tracks. Do you accept the ALPA report on that item?

The ALPA report requires a longitudinal axis rotation of 60 degrees clockwise and then 330 degrees counterclockwise all in 1.4 seconds. Do you accept that scenario? (That's in the Dec 18 version, by the way.)

For example, you contradict yourself in detailing possible 'g' forces and then assume that some pax survived these non survivable forces based on 'witness reports'. The acceleration and rotation forces were lethal in the forward fuselage. No one survived there longer than a half second, far as I can see, and no screams came from there. I put the forward fuselage and main fuselage discussions in separate sections so there would be no confusion about which I was discussing. I didn't contradict myself.

The only report I found was a woman claiming 'I swear I heard passengers screaming before the plane hit the ground'. Just not possible. It's not credible that anyone heard screaming before the forward fuselage broke off. Until then there were at least two running engines. The Morning Tribune says Mrs. Trapp heard a thump and then heard screams, so that would be after the forward fuselage broke off and there were then no engines. The plane was briefly a glider, with the fuselage front open to the air. Mrs. Trapp reported hearing screams after running out into the yard, which would have taken a few seconds. So these screams would be coming from the aft fuselage after it came to rest.

The official report is quite clear, to me, that the angle of bank was obtained/confirmed from the cut high tension lines, by saying, "severing the lines at an angle of about 70 degrees from the horizontal". The CAB report is the source of your quotation, but it doesn't assert that the lines were measured, or even strongly imply it. Whether or not they measured the lines, the wording you quoted might have been the same either way. It's not explicit.

Opposed to this position is the remaining right wing and the prop marks. It's not possible for engine three to leave prop marks while banking steeper than about 30 degrees, when the wing remains intact nearly to engine four.



I'll take geometry over witness statements any day.

[booke23]

I have been flying for nearly 20 years and work in the aviation business. I have a keen interest in aviation safety and have read pretty much every AAIB report published since the early 1980's and a fair few NTSB reports.

I have read your entire pdf and would be happy to make a few comments.

I can see you have spent a lot of time and effort in researching this topic. At first I couldn't work out what 'Axe you had to grind' (understandable by the way, I probably would in your position), then I realised that your principle issue was the lack of credit given to the crew in almost pulling off a successful forced landing (according to your theory).

But a good accident report would never do this regardless of how well the pilots did or didn't perform. A good air accident report presents the facts in a completely unbiased manor so as not to prejudice any subsequent legal proceedings.

As for your theory on the impact sequence I have a number of observations that counter your theory on maximum bank angle.

Firstly as already mentioned by Megan, the CAB report is clear that the power lines were severed about 70 degrees from the horizontal. The investigators on the ground at the time won't have just guessed this, it will have been measured and is a major piece of evidence as to the bank angle at impact.....when you then consider that the captains AI was at 90-100 degrees at impact (possibly unreliable but corroborates the power line evidence). This makes a very strong case for the bank angle.

If the aircraft did only attain a maximum bank angle of 30 degrees then the question has to be asked......why didn't they just keep on flying? Had they been able to limit bank angle to 30 degrees they could have climbed (slowly) to a safe altitude and trouble shooted the problem.

The fragmentation of the wreckage also indicates a high energy impact consistent with a high bank angle.



From the CAB report I will say this. The flight crew performed impeccably. In the very short time they had to react they managed to make a distress call and turn off the aileron boost to try to regain control of the ailerons (very impressive when you consider the pilots were very new to the Electra with a maximum of 314hrs on type). They were at very low altitude and airspeed so would in all likely hood not have been able to safely try other options like lots of rudder and/or asymmetric thrust as this would have probably led to an immediate stall/spin. (The Electra is particularly sensitive to loss of thrust with regard to lift due to the huge amount of prop wash over the wing). Your father had the control wheel at full left deflection and even had the presence of mind to close the throttles at the last minute in an effort to reduce the impact. Impeccable.

If you programmed this failure into a simulator and got 100 Electra crews to fly this flight, I'd bet all of them end in this outcome. There was nothing more the crew could do.

I don't know the full aftermath of this accident (I'd be interested to hear it if you are able to divulge it), but the 2 mechanics, Foreman and possibly the Inspector that replaced the aileron boost unit 2 months prior to this accident with complete disregard to procedure or even basic aviation engineering principles, should have ended up in jail along with their managers.

[BRDuBois]

I'm here to get my thesis tested; I want to know how robust it is. I very much appreciate your and Megan's response. I need to know how well my scenario stands up.

I can see you have spent a lot of time and effort in researching this topic. At first I couldn't work out what 'Axe you had to grind' (understandable by the way, I probably would in your position), then I realised that your principle issue was the lack of credit given to the crew in almost pulling off a successful forced landing (according to your theory). No, it's become a detective story that fell in my lap, and I was fascinated as I peeled back the layers. It's an aside that the crew did better than we knew, but it's also a guess. It might be that as Megan said they really were just along for the ride, and this is simply the attitude the plane had reached when it hit the ground despite all their attempts at control. The impact looks like an approximate belly landing, but we have no way to know that the crew thought they could make such a landing.

As I said in the document, my own case is weakened by the fact that it's so easy to say I have an axe to grind. Nothing I can do about that, since I'm the one who found the pictures.

I wouldn't expect the official reports to be particularly laudatory, though the ALPA report did mention how well they performed under the circumstances. I'm not here fishing for compliments. I just want to correct what appear to be some erroneous reports in which I have particular interest. Frankly, the more I consider the errors the more indignant I get.

Firstly as already mentioned by Megan, the CAB report is clear that the power lines were severed about 70 degrees from the horizontal. The investigators on the ground at the time won't have just guessed this, it will have been measured and is a major piece of evidence as to the bank angle at impact.....when you then consider that the captains AI was at 90-100 degrees at impact (possibly unreliable but corroborates the power line evidence). This makes a very strong case for the bank angle. I believed the angle right up until last year. I had no call to question the official reports, and accepted the 90-degree bank completely. But when the CAB says the plane was right side up and it is shown upside down, suddenly there's a legitimate call for a closer look. When the ALPA says the number four prop slashed the railroad tracks but the number four engine clearly hit the tracks, again a question is raised. If such basic issues are so clearly wrong, then how much should we trust that every single other T was crossed?

The bank angle is the biggest hurdle I have to confront, as the document says. The reports cite witnesses, some of whom probably had good views. I don't know if they were cherry-picking or not. I can't explain the artificial horizon.

In support of my thesis I have the final impacts, which indicate a high-speed forward movement, not a tumble. I have the intact wing and the prop 3 marks which cannot happen in a 90-degree bank. If you can explain this one to me, I'd appreciate it, because I can't see it.

If the aircraft did only attain a maximum bank angle of 30 degrees then the question has to be asked......why didn't they just keep on flying? Had they been able to limit bank angle to 30 degrees they could have climbed (slowly) to a safe altitude and trouble shooted the problem. I'd think so too. This is why I wanted to hear from Electra pilots. My experience is limited to sailplanes, and I don't understand why they didn't climb. So maybe they really were just along for the ride.

I don't know the full aftermath of this accident (I'd be interested to hear it if you are able to divulge it), but the 2 mechanics, Foreman and possibly the Inspector that replaced the aileron boost unit 2 months prior to this accident with complete disregard to procedure or even basic aviation engineering principles, should have ended up in jail along with their managers. I don't know the details, the punishments that might have been meted out. Many years later my sister told me that one of those held responsible committed suicide. I wasn't bitter about it and wouldn't have wished that on anyone.

As I mention in the document, one reason for putting this out is to see if I can shake some old documentation out of the tree. Some old airline employee or investigator may have something. The National Archives has nothing. Maybe some bystander with a Brownie camera has pictures. Some of this material probably still exists, but I see no path to it except this document and word of mouth.

[booke23]

Considering the report again, I guess the physical evidence at the crash site regarding the aileron cable disconnect may not have been sufficient for a criminal conviction......although possibly sufficient for a civil case.

I agree that it would be interesting to hear from a current Electra pilot......there are still around 20 Electras flying (I think nearly all in Canada in freight and fire fighting roles) so there must be a few on pprune.

There is an interesting diagram in the CAB report showing the crash site in relation to the runway....it appears the diameter of the turn the plane made was approx 5000ft. Someone with more expertise should be able to deduce average bank angle from this information.

Very best of luck in your search for further information.

[BRDuBois]

See, that's what I'm looking for. The turn radius never occurred to me.

I have several Electra manuals, but no information on turn radius.

Aircraft Turn Information Calculator (http://www.csgnetwork.com/aircraftturninfocalc.html) is a turn radius calculator.

Given the plane's takeoff weight of 93,000 lbs, the stall speed is 110 knots. I don't have a better speed to work with than the 160 knot estimated impact speed. The bank was said to be steadily increasing, so that throws a wrinkle in it.

At any rate, the calculator says a 43 degree bank would give a diameter under 5000 feet, and a 70 degree bank would give a 1660 foot diameter. So if the bank was as steep as the official reports say, the plane would have crashed closer to the runway.

This is fascinating, thank you very much. I'll have to follow this further.

[BRDuBois]

Considering the report again, I guess the physical evidence at the crash site regarding the aileron cable disconnect may not have been sufficient for a criminal conviction......although possibly sufficient for a civil case.One of the most important lessons I ever got came from this case. After the cause became known, several people told my mom she should sue NWA. But we've been an NWA family for many years, and she wouldn't do it even though it would be easy money that we really could have used in those years. She said that the fact that you could get money out of someone didn't make it the right thing to do.

Regarding finding an Electra pilot, I have a friend who's a retired NWA Electra pilot, and I can't get him to read the furshlugginer thing. It's like pulling teeth.

[BRDuBois]

Witnesses are notoriously unreliable. Your Mrs. Trapp may have heard gas bleeding off from a pressurised source.

I agree. Those who said they heard screaming before the first impact were surely hearing the turbines. That was still new technology, and those raised on piston engine sounds would not be familiar with it.

That's why I said I'll take geometry over witnesses any day.

[BRDuBois]

There was certainly no attempt at a forced landing, as I said previously, despite valiant attempts, the crew were just along for the ride.

We can't tell what they were attempting, we can only tell what they came close to. Perhaps they thought a landing was doable, perhaps not. It's reasonable to say they were trying for it, but that's as far as we can go.

In this Electra case the agency quickly found the root cause (their remit), the remaining detail, such as the rear section being upright or inverted, might be of interest to some, but is not germain.

Yes, I made that point in the document. Once they had the cause of the accident, the impact sequence became trivial. From the obvious errors, it's clear that the breakup sequence didn't rate high on their scale of importance. The impact is not relevant if you're interested in preventing future accidents. It's meaningful only if you're interested in the truth as opposed to slapdash reporting.

[BRDuBois]

We don't know what they knew. They're dead, and we can't interview them. We can only guess.

I set aside the root cause in the first few paragraphs, and explicitly said I don't take issue with that.

I take issue with a particular set of descriptions. They are not germane to the cause of the crash, but they are relevant if you care what the true story was. The errors in the CAB and ALPA reports are egregious and obvious. "Slapdash" is an appropriate term.

I don't accept that they are beyond question merely because the writers are probably now dead.

[BRDuBois]

There is an interesting diagram in the CAB report showing the crash site in relation to the runway....it appears the diameter of the turn the plane made was approx 5000ft. Someone with more expertise should be able to deduce average bank angle from this information.

Ok, this is fascinating. I've been running some numbers.

There are probably formulas that would handle all this with the ability to tweak the bank angle change rate over time, but I'm a spreadsheet guy so I did it with a spreadsheet.

I divided the flight into one-second chunks, one per line. I start the plane headed 143 at zero bank, and for each second I increment the bank by an amount. Given the bank angle, I compute the radius of the turn and the number of degrees through which it turns in that second. The degrees turned gets added to the previous line heading. I run the numbers until the heading is 270, which was the heading at impact.

I also compute the distance by which the plane moves laterally from the runway axis for each second, which is the sine of the difference of the current and initial heading, convert from knots to feet per second. I accumulate each with the prior second.

The target is to end up with a lateral movement of 5000 feet when the heading is 270. It turns out a bank that increases by 1.1 degrees per second ends on heading 270-ish and 5000 feet from the runway axis at a final bank angle of 45 degrees.

I'm going to play with the numbers some more, and see what nonlinear changes to the bank angle give us.

[BRDuBois]

I'm not saying this proves anything, ok?

This computation is highly sensitive to the way the incident starts out. If the plane starts to bank and then they get some control on it, you end up with a lower bank at the end.

So I started with the bank increasing by three degrees per second for four seconds. Then I increase it by two degrees per second for five seconds. Then I increase it by one degree per second for ten seconds. We're pretending the bank caught them by surprise and they got some control over it.

After 36 seconds they end up at 270 degrees 5000 feet from the runway at a bank of 33 degrees.

It isn't proof, it isn't even evidence, but what a totally charming result. :)

[mary meagher]

Hello DuBois -

Back when your father was pilot of the Electra, I was a housewife with 4 kids, and for the first time had to get a babysitter and fly to Boston from Philadelphia on Eastern Airlines. It was an Electra, the Eastern service was called the Shuttle.

My first time on an airliner (had a ride in a light plane in l944). So I felt relatively safe, with the pilots in proper uniforms, the cabin staff very professional. The engines started, we taxied hither and yon, and then before entering the runway, the pilots were revving the engines, then doing it again, then doing it again, and again, and they certainly made some peculiar noises.
People in the cabin looking at each other nervously. Presently after ten minutes of this, the captain came on the radio and said "You may have noticed one of the engines sounds a bit rough, so we are going back to the gate and get a different airplane.!"

And with that, we all trooped off, and over to the other gate...no further excitement at all. My only recollection of an Electra flight.

Do you fly yourself? I have 3,000 hours in gliders and light aircraft, but in my day women did not often become airline pilots. We were supposed to stay at home and raise a family.

But I have read a few reports, when I knew the incident described, and as many above have said, witnesses do not always understand what happened.
Those who survived and were responsible for what happened tend to be economical with the truth! It can be too painful to admit responsibility when people are hurt.

[BRDuBois]

I did a little sailplane flying when I was a teenager, but had to stop so I could save money for college. Loved it, though.

The scale in the CAB site map shows the impact was about 4100 feet off the runway axis, and the CAB report says it was 3800 feet off the runway. So I'll run some more numbers through my spreadsheet. It looks like the bank can never be higher than about 42 degrees to hit that window.

[BRDuBois]

The iterations were too much like work, so I wrote a routine to do the heavy lifting. One problem is I had to add the speed calcs, which changes the turn radius continuously. Now I have a routine that calcs the flight path second by second, increments the speed until it hits 160 knots, and gives the turn diameter, time to impact, heading, all that stuff. The calc terminates when the heading goes past 270 degrees, as was reported.

V2 for this plane was about 120 knots, at a weight of 93,000 lbs. To be conservative, I'll arbitrarily use 125 knots as takeoff speed. So whatever flight time the bank rate allows us, I tweak the acceleration until it hits 160 knots before impact.

The first lesson is, you just can't realistically get to a 90 degree bank. The faster you increment the bank angle, the tighter the turn gets, and the less time you have to add more bank increments. Incrementing the turn by 10 degrees per second gets you to a 90 degree bank after about 8.5 seconds under a thousand feet off the runway axis. Any linear bank increase less than 10 per second never gets you there at all.

You can get to a 70 degree bank using a linear increment of three degrees of bank per second, but it's at less than 2500 feet from the runway. The lower the increment the farther it will get from the runway, but the farther you get from the 90 degrees reported. There doesn't appear to be any linear bank increase that gets you anywhere close to the target.

The flight time is estimated by Lockheed to be about 45 seconds. The CAB said it was two minutes from clearance to impact. We need a result that's somewhere on that order of magnitude. My computation starts from when the bank commenced, not when the plane took off, so there's some fudge factor.

We get a pretty good result if we increment the bank by 1.5 degrees per second, assuming an acceleration of 1.5 knots per second. With a steadily increasing bank, we end up with an angle of 51 degrees right at 4000 feet after 34 seconds. Problem is, we have physical evidence that the bank angle was about 30-ish degrees when it hit the railroad tracks.

Using a nonlinear bank angle, as mentioned above, we end up with a final angle of 33 degrees 4000 feet away after 27 seconds. That's the right ballpark for the angle and timing. This is based on all the bank incrementing happening in the first 8 seconds, and then the crew manages to stop the bank from increasing but are unable to immediately reduce it.

The intriguing aspect to this, of course, is that the crew must have been having an effect. If they were able to stop the bank from increasing, then they weren't without control.

[BRDuBois]

I've uploaded a new version which incorporates the discussion of turn radius. It has a map showing the path of a 90 degree bank turn and others. Experimenting with the turns leads to a fairly small range of possibilities that can get the plane to the observed impact point, and the possible bank angles range from about 33 to about 41 degrees. The bank increments cannot be linear to get the plane to the observed impact point, which means something the crew was doing was having an effect. Very interesting.

The new link is http://we.tl/B9288LJnjV and this is now the link that clicking the background will take you to.

[BRDuBois]

I took down the latest version after doing some more thinking. My turn computations were too simplistic, and they don't have the explanatory value I first thought they did.

So I'm still stuck with an intractable problem. Everything from the right wing hit on through the sequence looks like a belly landing. I can't show good evidence that the high-angle bank was wrong, but it's incompatible with the rest of the sequence. I can show that a low-angle bank is reasonable, but can't give any hard evidence for it. If the plane came down with a high-angle bank, I have no clue how it could have transitioned to the belly landing.

More work to do.

[BRDuBois]

After removing the turn radius computations, but leaving in the discussion about how the ALPA came to the wrong conclusions, I put it back up.

http://we.tl/InGXbDKkkX

I'm working on a draft that starts at the final wreckage site and works backwards. We'll see if that one works better.

The problem with the chronological approach is that it's vital to understand the bank angle, but there's not any direct evidence until the right wing impact. People seem to come to a mental halt before that, because I'm disagreeing with the official reports on what is (at that point of the crash) thin evidence. Maybe if I start with the most obvious error I'll be able to carry the reader along better.

[BRDuBois]

Uploaded a new version that reworks the turn and bank discussion. My first take at it was too simplistic.

This version is the kiss of death for the high-bank hypothesis.

Part of the new discussion uses the CAB map to determine what turn radii they were representing, and shows that their map conflicts with the witness narrative. The map constrains the maximum bank angle at impact to about 47 degrees. I also noticed a hint that at least some witnesses said the bank reduced, but the report writers chose to ignore them.

Another part takes my original computations and adds a little enhancement so I can insert the emergency during the normal expected turn. A series of calc runs shows how the flight would look and where it would end up. Turns out a final bank in the low 30's works out fine, and lower is possible.

The most interesting development in this approach is that it provides clear evidence that the bank was being moderated at the time of impact. The crew had leveled the plane from a maximum bank around 45-ish degrees to one of 35-ish, and were flattening the bank at a rate somewhere near one degree per second. In other words, they were very close to pulling out of this.

Take a look, let me know what you think.

http://we.tl/1qiw9nIJlw

[BRDuBois]

From Help Researching 1961 Chicago Electra Crash — Tech Ops Forum | Airliners.net (http://www.airliners.net/aviation-forums/tech_ops/read.main/367740/)

An interesting suggestion

Although there was no aileron control, the decreasing bank angle, the radius of the turn and the relatively shallow descent could be explained by application of left rudder, probably to the stops. Application of full left rudder would have shallowed the bank angle and decreased the turning radius thus fitting your hypothesis. Still having elevator control and throttle control the crew just might have been able to and quite possibly did set the aircraft up for a semi controlled belly landing. Had they had another hundred more feet of altitude or if not for the railway embankment they might have made it. It would still have been an ugly impact but possibly a semi successful one with some survivors.

Not being a pilot, I don't have a feel for this, but it makes sense.

when the depth of the failings of the NW maintenance staff during the replacement of the aileron boost unit on N137US became apparent all eyes and all hands rushed in that direction and the impact sequence part of the investigation was left hanging. At that time everything about the Electra was under major scrutiny and a severe cloud of suspicion hung over the aircraft. Coupled with the serious failures of the NW MSP maintenance and inspection staff uncovered during the investigation I can easily envision a scenario where all eyes and attention were diverted in that direction due to the potential for further safety concerns. The downside to that shift being an overlooking of a possibly brilliant and heroic bit of flying on the part of your father and his crew.

We were intensely aware of the focus on Electra safety in general, in addition to the work being done to figure out why my dad's plane crashed. So this certainly explains why the impact sequence was ignored when the cause was discovered. However, having an explanation does not excuse the slapdash treatment of that part of the investigation.

[evansb]

Buffalo Airways in Yellowknife, NT, has Electra pilots, as does AirSpray in AB.

[BRDuBois]

It wasn't slapdash treatment, it just wasn't pertinent to the accident. You see the same in today's accident reports. Investigators are under the pump to find the root cause and to get the message out. Wasting time on non pertinent issues delays that process.

I have no quarrel with their finding of the root cause. But their work on the impact sequence does not magically become rigorous and proper just because they got the root cause right. The work on the impact sequence was still slapdash and it's fair to call it that.

Today based on a tip from a reader I went to the Chicago Tribune archives. On the back of the Monday edition there was an artist's conception of the impact sequence. It shows the main body sliding backwards to the final site. The paper didn't make this up; it had to come from the CAB.

As an old newspaperman I can tell you that the morning edition is put to bed about 11pm. In other words, on the day of the crash the CAB had ALREADY decided that the plane slid backwards, and they never wavered from that. This goes beyond unconscionable, which is what I called it in my analysis. To put out any affirmative statement on Day One is unheard of.

At the time the CAB put their stake in the ground on the backward slide, they had absolutely no idea what the root cause was.

[BRDuBois]

And the proof is?

Evidence beyond a reasonable doubt. How many airplane crashes involve a plane sliding backwards? Ever heard of one outside of this crash? What are the odds that a reporter would make up such a story, entirely on his own? What are the odds that the CAB would match such an unlikely story with exactly the same one?

There is no need or incentive for a newspaper to posit such specifics. There's enough meat in this incident without a backward slide. Read the archives; it's dripping with pathos and tuggable heart strings.

The only way this was in the paper is because the reporter was fed it. This part, at least, I know how it works.

[G0ULI]

Having thoroughly read through the reports and reviewed the photographs, I find nothing inconsistent with the aircraft being banked at an angle of 90 to 100 degrees at the point of impact with the railway embankment.

The primary purpose of the accident report was to establish the cause and given the significant disruption and lack of flight recorder data, the investigators carried out a thorough investigation given the techniques and resources available at the time.

Given that the aircraft was at low altitude and climbing when the aileron cable detached, the description of the aircraft entering a continuously increasing bank and turn, before stalling into the ground is entirely consistant with the photographs of the scene. There is evidence that at least one control column was commanding a full left turn, presumably a full left rudder input was also commanded and the crew appear to have been attempting to control the turn with engine power, but simply didn't have the altitude to recover the situation.

I don't find anything in the official reports that suggest the crew acted inappropriately at any stage and there are definite indications that they fought to control the aircraft attitude all the way to the ground. The final radio transmission gave some pretty vital clues to the crash investigators and that is unusual in modern accidents where the emphasis is to concentrate on flying the aircraft. Perhaps one advantage of having more than two crew members in the cockpit?

The accident wasn't ever going to be survivable and I can't agree that the aircraft bank angle did anything other than continuously increase once the control cable separated.

Had the control cable separated in a high level cruise, it is possible that some measure of control over the aircraft attitude might have been regained, but I suspect that a spiral dive would probably have been the final outcome.

Given the high speed of the impact but only a modest low nose attitude, the fuselage would be expected to tumble and break up as it slid along the ground striking trees and other low level obstructions.

As far as I can tell, the crew did everything right, they just ran out of time and altitude. The official reports were as thorough as they could have been for the time. There doesn't appear to me to be any attempt to cover things up or hide any failings. It is clear that short cuts were being taken with maintenance operations, but no more than with any other similar organisations at that time. A lot of pilots and engineers had cut their teeth during World War 2 when the emphasis was in getting the job done, not getting all the boxes ticked.

Different times and different attitudes.

Sorry for your loss, but you should be proud that your dad kept trying to fly the aircraft right to the end and he was doing all the right stuff that he should to try and recover given the circumstances.

[BRDuBois]

I can't agree that the aircraft bank angle did anything other than continuously increase once the control cable separated.

It's entirely reasonable to say the bank angle in might continuously increase given the mechanical failure. But if it had continuously increased in this case, the impact would have been southeast of where it actually hit. The path would be a tightening spiral with more movement parallel to the runway and less orthogonal. For the plane to hit where it did, it required more movement orthogonal to the runway than parallel, and that means the bank must have moderated.

Given the high speed of the impact but only a modest low nose attitude, the fuselage would be expected to tumble and break up as it slid along the ground striking trees and other low level obstructions.But it didn't tumble. The right wing was obliterated just inboard of the number four engine, but the left wing's full (or very nearly full) length was present at the final impact site. The empennage was virtually undamaged, and only the forward fuselage broke off.

There doesn't appear to me to be any attempt to cover things up or hide any failings.I never suggested any ill-intent, merely carelessness. The breakup sequence just didn't matter much.

The recurring problem in this puzzle is figuring out how much we have to discard for the rest of it to make sense. Clearly not all the witnesses agree, so some of them must be in error. The question is to decide which ones.

I've been reading the Chicago Tribune stories. There is (embedded in some purple prose) a clear description of three powerful bounces, as opposed to a cartwheel. I find this fascinating because the pictures seem to show three bounces as well, and that is the scenario I present in my document.

That nugget, plus the evidence that the CAB had laid out their impact sequence on the day of the crash, is going to take a while to process before I publish a new version.

ETA: Another interesting bit in the Trib is a picture of a wing fragment lying on the west pair of train tracks. It's a small fragment no more than two feet across. But the large object lying on the east rails in my document is more like seven feet across. This adds weight to the idea that it's the number four engine lying on the east tracks in my picture, and that's a lock on the shallow bank argument.

[G0ULI]

I personally think the object lying in the track is part of the wing tip and aileron structure, rather than an engine. The metal has been twisted making it appear more three dimensional than the originally flat wing structure.

Given that it was impossible to apply any corrective aileron input due to the control cable being disconnected, the only means of moderating the bank angle would be rudder and differential engine power.

The rudder alone may have been partially successful in moderating the bank angle initially. As the bank angle continued to increase, more and more engine power would have been needed to maintain lift. Once the bank angle passed 30 degrees, differential reduction of engine power to correct the bank would not have been possible. The aircraft would have immediately stalled and fallen from the sky.

The official reports are quite firm in their estimates of bank angle when the aircraft initially struck the high tension wires and the railway embankment. The wing spar alone would have been sufficient to displace the railway tracks. Railway tracks are designed to support heavy vertical loads. The sleepers linking the tracks are designed to maintain constant spacing between the rails, not to resist horizontal displacement. A certain amount of horizontal displacement occurs naturally with constant expansion and contraction of the rails due to seasonal temperature changes. So long as the relative spacing between the tracks remains constant, trains can use the line despite some quite severe looking kinks.

So I believe the debris on the track is a twisted part of the outer wing structure and the number four engine separated after passing over the embankment.

The rear fuselage and tail section are almost completely inverted where they came to rest. Whether they rolled, tumbled or spun to arrive at this position isn't really an accurate indication of aircraft attitude at the moment of initial impact with the ground.

I appreciate that you have put a great deal of time into your research and you have made a good case that the aircraft might have been at a shallower bank angle based on your interpretation of the photographs of the scene and ground witness marks. I simply can't agree with your well presented conclusions.

Unfortunately the original investigators notes and measurements are no longer available, but almost certainly the severed high tension cable lengths would have been measured to give an estimate (and rough confirmation) of the angle at which they were severed. Detailed measurements would have been taken to order replacement cables to splice in repairs no matter what. The artificial horizon had witness marks indicating a bank angle between 90 and 100 degrees. Just two bits of physical evidence in addition to what the investigators on the scene where able to establish, such as the impact point on the rails in relation to the high tension cable breaks.

Clearly the crew had some initial measure of control over the bank angle and roll rate, probably using the rudder, but eye witness accounts and physical evidence indicates that the aircraft progessively rolled further and further until contact with the ground. There is simply no practical way that the crew could have levelled the wings or reduced the bank angle at impact given complete lack of aileron control.

[BRDuBois]

The rear fuselage and tail section are almost completely inverted where they came to rest. Whether they rolled, tumbled or spun to arrive at this position isn't really an accurate indication of aircraft attitude at the moment of initial impact with the ground.

First of all, thanks for your thoughts. This is what I came here for.

The key evidence at the final wreckage is the position of the wings. They are inverted with the leading edge pointing back along the path. So either the plane slid inverted, which the remaining rudder rules out, or it arrived upright. That, plus the ditch, tells us a lot about that final site and how the plane got there.

I didn't mean to say (in my document) that the final position was simply maintaining a position it had been in at the moment of initial impact. Many things happened in between. My point was that to arrive upright at the final site with as much energy as it had means that the plane cannot have been dissipating that energy in a cartwheel. It's the final site's energy, as much as position, that rules out the tumble.

Unfortunately the original investigators notes and measurements are no longer available, but almost certainly the severed high tension cable lengths would have been measured to give an estimate (and rough confirmation) of the angle at which they were severed. Detailed measurements would have been taken to order replacement cables to splice in repairs no matter what.

I'm following various paths to try to locate more documentation. Something may turn up.

A previous post mentioned that the cables would be measured, but there's no need to do so from the power company's point of view. If they trusted the remainder of the snapped span, they could splice new line on one of the ground-level pieces, pull it to the opposite tower by pulley, and splice it in up there. If they didn't trust the snapped span, they would pull new line up to one tower using a pulley, over and on to the next, pull taut and splice it in.

None of that demands that they know exactly where the breaks were, and determining the break point would slow them down. I suspect they would measure only if asked by the investigating authority. I'm confident that such measurements would be routine today, but have no reason to think it would have been routine then.

I also don't have a description of the power lines. The measurement would be useful only if the lines had significant vertical separation. So in the absence of any explicit statement, I don't see any reason to say that some hypothetical measurement should be presumed to exist and therefore admitted as evidence. We just don't know.

[G0ULI]

The power lines are quoted as being two sets of three wires carrying 38,000 volts. These lines would be erected at a minimum distance from the ground and away from any horizontal obstructions to avoid the risk of arc over. The power lines would have complied with electrical standards imposed at the time and are unlikely to have been "over engineered".

So it should be possible to establish from the old standards, how thick the cables were, the typical breaking strain, at what height the cables were strung above the ground and the horizontal separation from the railway tracks.

This information may help to indicate the vertical path of the aircraft as it sliced through the power lines and the wing tip contacted the railway embankment. It should at least verify the estimates of a ten degree nose down flight path.

Standards for modern high voltage power lines are probably not too dissimilar to those as the time of the accident since the same laws of physics still apply to power handling and flash over voltages.

For example, in the UK, the minimum height above ground would be in the region of twenty feet. The cable thickness would be at least two inches, or more, depending on the current carrying capability.

[BRDuBois]

Ok, thanks for seeing the power lines. The Chicago Trib says the power poles were 60 feet high and 300 feet east of the railroad embankment. This agrees very well with the map images in my document, using the scale on the left of the image.

That means the descent was very gradual, which agrees with witness reports. It also means anything steeper than 63% must have been in a stall and is not a feasible angle given the horizontal distance it had to cover to the tracks.

Once again we have to decide how much must be discarded for the remainder to make sense. The artificial horizon was treated with skepticism in the official reports. If we rule out the witness statements of the vertical bank, everything else fits.

ETA: The RR embankment was said to be the highest landform in the area. That means the power lines would have been somewhat less than 60 feet above the tracks, possibly considerably less.

[G0ULI]

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.

[BRDuBois]

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.

[BRDuBois]

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.

[G0ULI]

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.

[BRDuBois]

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.

[G0ULI]

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.

[BRDuBois]

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.

[G0ULI]

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!

[BRDuBois]

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.

[BRDuBois]

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.

[G0ULI]

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.

[BRDuBois]

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.

[G0ULI]

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.

[BRDuBois]

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.

[G0ULI]

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.

[BRDuBois]

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.

[BRDuBois]

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.

[G0ULI]

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.

[BRDuBois]

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.

[BRDuBois]

The leading edges were melted puddles.

[BRDuBois]

Looks like the rudder/aileron linkage is all in the cockpit. It's a feedback mechanism between rudder pedals and control column. So it still depended on the cables to get the rudder-induced inputs to the ailerons.

[G0ULI]

Megan, I had exactly the same idea when I woke in the night. There would have been imprints of the cables and copper flash residue on the aircraft, so the investigators would have been able to state with certainty the angle of the aircraft with respect to the cables. Any of the cable strike marks would be sufficient. It is so obvious, there was no need to explain it in the reports. The marks would have extended beyond the leading edges of the wing and/or fuselage so there would certainly be clear evidence of angle of contact. We know that the cables were carrying power and that a blue flash was seen by witnesses.

I don't know quite how litigious the US was at that time, but I suspect that whoever maintained the power lines would have made an insurance claim against the airline to repair the damage. The insurers would have insisted on full details of the damage and costs of repairs down to the last penny, judging by my dealings with such companies.

The other point that I missed in looking through the mass of documentation is that the two official reports are, in fact, merely summaries of the investigations carried out. A huge amount of detail has been skipped or glossed over because it wasn't directly relevant to the cause of the accident or avoidance of further problems.

The actual investigation documents would have filled many boxes. What has been published is just the highlights. It may well be that there is an archive in a warehouse somewhere containing all the documents generated during this investigation. That would be a treasure trove to find.

[BRDuBois]

Look at the pictures. The wings ended as pools of melted metal.

The actual investigation documents would have filled many boxes. What has been published is just the highlights. It may well be that there is an archive in a warehouse somewhere containing all the documents generated during this investigation. That would be a treasure trove to find.

As my document explicitly says, that's the reason for going public - to shake those boxes of materials out of the trees. Someone out there has something, and I'm depending on word of mouth in the flying community to bring it to light.

[BRDuBois]

whoever maintained the power lines would have made an insurance claim against the airline to repair the damage. The insurers would have insisted on full details of the damage and costs of repairs down to the last pennyLet's say I'm the power company and your plane just brought down three wires between two towers a hundred feet apart. I don't trust the integrity of the downed lines in such cases, so I'm going to replace them all. I'm going to bill you for 300 feet of wire, for the splices needed to attach it at the towers, for the payroll to cover it, for the recovery costs of the downed line that I'm sending to recycle, and for any strain damage and repair parts on the towers themselves.

The one thing that I don't care at all about is where in the line the wires were severed. I'm assuming you didn't run off with a length of it wrapped around your plane. To me it's six hunks of random length wire that are going to be lying on the ground to be spooled onto the salvage truck.

[G0ULI]

"The one thing that I don't care at all about is where in the line the wires were severed. I'm assuming you didn't run off with a length of it wrapped around your plane. To me it's six hunks of random length wire that are going to be lying on the ground to be spooled onto the salvage truck."

The on scene investgators at the time would not know whether the severed cables were significant. Every detail would have been recorded in case it became relevant at a later stage. Once the scene has been tidied up, it is impossible to go back looking for evidence, so it is vital that every detail is recorded at the time, even if it seems totally unrelated to what happened. I can speak with a certain amount of authority and personal experience on this point.

The severed cable lengths would have been measured and recorded. The copper spray contamination from the melted cables would have left marks on the outer skin of the aircraft which would have been detectable even after parts had been exposed to fire. The inner skin would be expected to display signs of copper contamination from melted wire bundles but there should not be traces of copper on the outer skin. So whether visible to the naked eye or not, the traces would be there and detectable with simple chemical testing.

Just because a full explanation doesn't appear in the official reports doesn't mean that the work wasn't carried out, simply that it wasn't considered relevant to the reasons for the accident.

Somewhere in the back of my mind I seem to recall reading about this or a similar accident being significant in influencing aircraft design by ensuring that there wouldn't be a single mode of failure in the control systems in the future. Dual paths of control were required so that failure of one system would not cause an aircraft to crash. Probably read about that 20 years or more ago, so I will have to trawl through my archives to refresh my memory.

[BRDuBois]

The power company doesn't care about the wire lengths. I stand by exactly what I said.

The crash investigators would care, if they thought about it. The power company would be happy to measure the wires if they were asked, but if they aren't asked they aren't going to do it. So it depends on the investigators. Since the CAB had already gone public with an erroneous scenario on the afternoon of the day, I don't have a lot of confidence in them.

[BRDuBois]

The accident report states the wire strike was on that portion of the wing that snapped off on striking the embankment. So the evidence would have been there.I'm not aware that the CAB report in my document includes any such information. Please give the statements that make this assertion.

they list the respective SHP and ITTI'm always impressed by people with acronyms, but for the rest of us, what does that mean? The goal here should be communication.

[BRDuBois]

Not an assertion, fact. You should be on top of this stuff, given you tell us the CAB and ALPA don't have a clue. You are an aggressive little bugger. CAB page 4 and ALPA page 4 respectively.Nothing on page 4 of either report mentions the scars left from the wire strikes or says that the damage from those strikes would be in the part of the wing that was left at the tracks.

I am not impressed.

ETA: What happened to SHP and ITT?

[Stanwell]

Monsieur DuBois,
Having myself had a little exposure to crash scene investigations and forensics, I've been following this thread with interest.

It's my observation that you are fortunate indeed to have experienced, astute aviators and communicators such as GOULI and megan who have been prepared
to take the time and trouble to help you.

Please be careful and don't take them for granted.
Comments such as "The goal here should be communication" and "I am not impressed" are not going to going to help you toward YOUR goal.
And... I'm assuming that is finding out what REALLY happened, compared with what you would like to think happened.

I look forward to seeing how this turns out for you and hope you can arrive at the correct conclusions.
.

[BRDuBois]

Hi Stanwell

All inputs are welcome. If you have some experience in the field, I'd appreciate your thoughts.

My goal is to figure out what happened, which is something that the official reports clearly failed to handle. Once one comes to grips with the fact that the CAB didn't know which side was up, it gives a sort of jaundiced view of their operation.

[Stanwell]

I'm afraid my experience, fortunately or unfortunately, is not directly in the field of air accident investigation.
The principles, though, are the same.

While I've not had the time to examine the available material in minute detail, I do think, from reading the contributions to this thread,
that I've a fair grasp of what went on that fateful day.
I therefore defer to the observations, knowledge and experience of those who've had the practical experience in that particular field.

Once again, good luck and please take on board what I said earlier.
.

[BRDuBois]

I think the number four engine ended at the tracks; I thought you didn't accept that. Saying that the number four engine stopped at the tracks means the ALPA report is wrong. That would mean the number three prop left the scars on the tracks mentioned by the ALPA, and that puts the bank at no more than about 34-ish degrees.

I naturally assumed, that you being an expert in accident investigation, would have understood the lexicon of the business.

No you didn't.

Actually, the idea that wire mark evidence was left at the tracks is quite intriguing. Thanks.

[G0ULI]

At this point, it would be helpful to locate the original accident report records.

Government organisations never throw anything away, although given this was the early 60s, the records may have been committed to microfiche (microfilm).

All of the original paperwork is preserved somewhere. As far as I am aware, there are no legal reasons for the full contents of the original investigation to be witheld and suitably targetted freedom of information requests may yield results.

[BRDuBois]

At this point, it would be helpful to locate the original accident report records.

I'd love to. The National Archives tells there's nothing on file except the official reports. Everything from the CAB was turned over to them. I'm hoping my NWA contacts may turn up something. And as I mentioned it's possible someone involved in the investigation still has records, which is the reason for going public with what is a work in progress.

[BRDuBois]

what with you continually telling us the CAB, ALPA and posters here don't know crap.

Don't misquote me. I don't question the root cause of the accident, and didn't accuse anyone of not knowing crap.

What I said was that the CAB misinterpreted the breakup sequence, probably because it wasn't very important to them. I think the ALPA followed the CAB lead. In the course of this I've discovered the Chicago Tribune graphic which shows they went public on the day of the crash with a bogus scenario. That's the bit about the plane being upside down, which you dismissed as not germane.

As I say in my document, I don't know that I have the real scenario but there is enough information to show the official scenario is wrong. To be precise, I said

It's clear enough that the ALPA and CAB were wrong about the breakup, but that alone does not prove my reconstruction is correct.

That doesn't sound like someone saying that no one else knows crap.

[BRDuBois]

A couple more snippets from my document

Not being a pilot, there are things I don't understand. I want to know what Electra pilots would do in this situation. I would like to find more pictures and perhaps debris maps, to verify details I've had to guess. Given the limited documentation I stumbled on, an attempted belly landing seems like the best explanation. Even so, for most of this effort I'm beyond my depth.

I've tried to present it in as much detail as possible, to show the ways in which it is either congruent or conflicting with the evidence. I've shown my conclusions and also how I got there, because there may be errors in my method as much as my results.

Doesn't sound like I'm claiming to be the source of all knowledge.

[G0ULI]

From the Lockheed Martin website

"Every so often employees at Lockheed Martin Aeronautics are asked to clean house. They go through their desk drawers and file cabinets to discard old and unnecessary materials to make space for the new.
This process often results in unearthing items of historical significance. This was the case in 1990 and again 2006, when concepts or advanced design drawings, reports, and other documents dating back to the 1940s and ’50s were found.
When the Lockheed facility in Burbank, California, was shutting down in the early 1990s, all the commercial aircraft data for aircraft such as the Constellation, L-188 Electra, and L-1011 TriStar was moved to Marietta, Georgia.
The file cabinets of data were placed in a warehouse for distribution to various groups. The Field Service group (now known as Technical Operations) inherited a large number of cabinets, including those for the L-188. While searching through the contents of those cabinets, three ring binders were found that were chock full of preliminary aircraft designs numbered CL-xxx, which stood for California-Lockheed.
Bill Slayton, a Burbank customer support employee, realized the historical importance of data available to him through the Advanced Design group. Slayton gathered descriptions, three-view drawings and isometric drawings and compiled these into a remarkable collection of the Lockheed advanced designs.
Slayton stored the data in the L-188 cabinets, most likely because the cabinets happened to have an empty drawer. Most of the CL-xxx collection has never seen the light of day."

Seems like a good place to make enquiries for a start. They will certainly have had an interest in the accident report.

Even if the documents are no longer with Lockheed Martin, they are likely to have gone to a university, aviation library, or some other organisation or individual with a particular interest in the history of avaiation. They should certainly be able to provide you with some clues as to where to continue your searches.

[BRDuBois]

Thanks, great idea. I'll pursue that.

[G0ULI]

For those who don't want to trawl through all the documentation, some basic information about the Lockheed Electra.

The aircraft is a four engine turboprop which first entered service in January 1959. The aircraft had a very good power to weight ratio with short wings and huge propellers giving very good short field performance.

Two notable accidents in September 1959 and March 1960 were attributed to wing failure caused by the gyroscopic forces from the propeller disks causing the engine mounts to fail. This whirl mode failure was addressed by strengthening the wing and engine mounts and by altering the mountings to run the engines at an angle of three degrees in relation to the wings.

Four other accidents could be attributed to crew handling errors and one to bird strike where three of the four engines were affected.

The seventh accident (this one) occured in September 1961 at Chicago O'Hare airport as the aircraft climbed after take off. The aileron control cable separated leaving the aircraft with a full right wing low input. The aircraft initially climbed but the roll command could not be counteracted by the crew and the plane eventually crashed.

At present, only summary reports of the accident and press photos appear to be available to re-examine what happened. The summary reports appear to have some conflicting information regarding the final few seconds of the flight and the final disposition of the wreckage.

Did the pilots have any measure of control over the aircraft?
Did they somehow manage to attempt a belly landing?

The documents available so far, do not support this idea, but some of the data in the accident summaries has been given without context or supporting data.

There is no evidence that the investigators at the time took any shortcuts in the investigation, or that a less than thorough job was carried out. It is an unfortunate fact that no comment on the pilot's performance appears in the documents currently available.

Public confidence in the Lockheed Electra was severely damaged by this series of accidents and no further airframes were built after 1961.

It is significant that remedial upgrades and strengthening of the aircraft were so successful that it was not until 1971 that another incident involving structural failure of a Lockheed Electra in a thunderstorm occured.

Out of a total of 170 airframes built, 58 remain in service or could be restored to flying condition. The US Navy anti submarine patrol aircraft and NASA storm chaser aircraft are based on the Lockheed Electra airframe, which gives a measure of just how successful and robust the aircraft became.

[booke23]

This may seem glaringly obvious, but I assume you have approached the NTSB regarding any original files or evidence relating to this accident? It was only a few years after this accident that the CAB became the NTSB.

[BRDuBois]

Thanks, yes, the NTSB told me all the CAB files were turned over to the National Archives. The National Archives said the only CAB files they got on this incident were the final reports.

[BRDuBois]

I've uploaded a new version to http://we.tl/TvTrucG3Ak

This incorporates the material I found at the Chicago Tribune. It has a couple graphics to discuss the trajectory at the end of the flight.

Based on input here and from some emails I think my understanding of the situation has improved, and I'm characterizing the crash not as a failed attempt to make a belly landing, but more as an attempt to manage a descent that they couldn't stop.

This draft also has an explanation of the mechanism that can explain the leveling of the bank. The CAB discounted this, because they thought the bank was always increasing. Once the calculations showed that it couldn't always increase, suddenly this return-to-neutral makes much more sense.

[G0ULI]

Interesting.

I see you have incorporated some of the suggestions from the forum.

The only point of contention is that you seem to equate bank angle with a given rate of turn. While this in broadly true, it only applies in a balanced turn with ailerons and rudder acting together.

Given that there was no effective aileron control, the turn became progressively more unbalanced as the roll increased. So the aircraft was effectively skidding sideways through the air (in a horizontal axis).

That kind of makes a nonsense of any attempt to calculate a turn rate based on the angle of bank of the aircraft. That is to say, an aircraft in banked or even knife edge flight, may have no turning moment whatsoever. Or alternatively there may be a considerable initial rate of turn that then progressively reduces as bank angle increases, due to the ailerons and rudder becoming increasingly out of balance.

That would account for the impact site being where it was, despite calculations suggesting that this would not have been possible with progressively increasing bank angle and rate or turn. The rate of turn didn't increase linearly with increasing bank angle. In fact it may well have reduced somewhat.

[BRDuBois]

I see you have incorporated some of the suggestions from the forum.

Of course. That's what I came here for. I've also been in email discussions with pilots.

Yes, I understand the turn and bank calculations can be off, and I don't yet know how much off. I need to play with a simulator. So for the time being this is an approximation.

[BRDuBois]

New version posted at https://we.tl/beXUsgYPvX

Two significant additions to this release.

The first is discussion of an Argentine Navy Electra crash in '89. Video is available at http://www.youtube.com/watch?v=1OezfOROS6o The video shows what an Electra actually does in a high bank right wing impact, compared to what the CAB said of Flight 706. I use a bunch of frame grabs to show how this contrasts with Flight 706 regarding trajectory, crash dynamics, and survivability. Very useful lessons.

The second is a series of posed images to show what N137US would have looked like in different bank angles. My most encouraging supporter (a retired NWA pilot) gave me a big metal Electra model, and I posed it on a stand to replicate perspectives. The most important is the view from the control tower, presented as a storyboard in correct scale.

[G0ULI]

The Argentinian accident invites a lot of interesting comparisons with the original crash. The scale representations of the aircraft as it would appear in flight are a great idea. It is possible to appreciate how difficult it is to estimate bank angle from any significant distance and without a clearly defined reference. Well done.

I am still uneasy at your criticism of the original accident reports. The investigators at the time identified a disconnected aileron cable as the component commanding full right wing down. The aircraft was effectively uncontrollable from this point onwards, so no matter what action the flight crew performed, the crash was inevitable.

It is possible to run thousands of different scenarios through a modern computer and come up with several possible solutions to explain how the aircraft ended up at the final crash position and with the wreckage arranged as found. At the time of the accident, such tools simply didn't exist and imvestigators were forced to rely on experience and rules of thumb to arrive at a conclusion.

So while your scenario may indeed be more accurate in terms of describing the flight path and sequence of events during impact, it doesn't actually serve to improve flight safety, which is the primary purpose of any accident investgation.

I continue to have no doubts whatsoever that the flight crew on that day did everything they could to save the aircraft, but the physical evidence, photographs and contemporary reports do not indicate a nearly successful attempt at belly landing.

That is my interpretation of the evidence, yours is different and backed up by computer modelling and comparison to other incidents. I am happy to accept that what you propose is a possibility but not the most likely probability as to the exact sequence of events.

You have collected a mass of data from various sources and you are now probably the best informed person on the planet with regards to this accident. You are entitled to express your opinion as an expert after all that research and to be taken seriously. The experts who investigated the accident at the time were also doing their best but with the added constraint of needing to find the cause as soon as possible and without the benefit of modern technology. The truth probably lies between both sets of conclusions.

I shall be studying your latest report in more depth over the coming weeks.

[G0ULI]

I'm impressed that they all got out alive from that crash. What is clear is that there was a lot of disturbance of the wreckage during the search and freeing of casualties. The same is probably true for most crashes where there might be the possibility of survivors. That makes any reconstruction of the incident more difficult for investigators.

Where I saw a possible similarity is in initial contact by a wing with the ground. Also the increasing angle as the aircraft climbed out from the runway and control was lost.

While it might not be possible to make direct comparisons between the two crashes, the video gives an indication of the sorts of time scales involved and what a witness to the original crash might have seen.

Other than that, I agree with you megan.

[BRDuBois]

G0ULI, you're correct that my fault-finding has nothing to do with the cause of the crash. Megan had made the same point earlier. But my whole subject is the impact sequence, and I explicitly say that I don't question the cause of the crash. With regard to that part of the investigation I have nothing to criticize.

My subject is the impact sequence and plane attitude, which was investigated so badly as to qualify for my term "slapdash". If I seem harsh, it's because I lived through that and watched others live through it as information trickled in. There were many people who cared very much what happened. After over 50 years we can see that the news we waited for was misreported badly. It makes me indignant, I confess.

I've adjusted my phrasing and my understanding, based on quite a few conversations with pilots. In the document I now characterize it as not so much an attempt to make a belly landing as an attempt to manage a descent. With more altitude they might have had much better results. They were headed for the ground and were hoping not to hit too hard, rather than having the goal of putting it on the ground.

I'd be delighted if someone had the computational tools to re-enact the possibilities and see how it plays out. I don't have the equipment for it. As I say in the document, I can show that the CAB/ALPA reports are wrong, but I can't prove that I'm right. I'm confident of being pretty close, but that's about it.

A couple pilots have discussed the flight with me. They agree that this maneuver would never be tried at all (at a safer height) and there will be no data on it or first person reports. They suggest I try a flight simulator and see what results I get, and I've started on that project.

I presented the Argentine crash not because it was like the Chicago crash, but because it's like the CAB said the Chicago impact started but the Argentine crash played out differently from the first impact. No two crashes are going to be alike, but finding this one gives us the chance to draw a couple lessons from it.

I agree that the crew did all they could, and we knew that since '61. I get a lot of drive-by psychoanalysis out of this. People think I'm trying to salvage reputations that don't need salvaging, or trying to deal with trauma that I was over at least 30 years ago.

Being the best-informed person on the planet on this particular crash is setting a fairly low bar, considering that everyone who studied it in person is probably dead. I'd rather be known for my book The Passionate Ape. :)

[BRDuBois]

Hi Megan, glad you're still here. I have valued your input on this thread. Thanks for the video link.

As I said, the Argentine crash is not a match for the Chicago crash. The similarity starts and ends with the right wing impact.

But three things can be taken away from the Argentine crash: The trajectory of a plane with no lift, the rotational effect on an Electra when the right wing hits, and the survivability of a moderately low-angle Electra impact. These are all highly relevant to understanding the dynamics of the Chicago crash and how close they came to a survivable incident.

ETA: Your video has much better quality. The clip I found was passed through some steadying software and was electronically zoomed, and lost a lot of detail. I'll be able to redo my graphics with better quality next release.

[BRDuBois]

Oh yeah, that's a major reason why the Argentine crash is so interesting. N137US ended up tail-first and upside-down, and the Argentine plane ended tail-first and right side up.

It seems highly likely that the CAB investigators had in mind something like the Argentine impact sequence when they viewed the wreckage. It sort of fits the description of cartwheel, in a sloppy way. And the tail section being upside-down apparently didn't faze them. But being upside-down is the kiss of death to their model, because it means N137US arrived at the final site with high energy and nose-first, and then flipped over.

I presented the Argentine crash for contrast, not to show the similarity. The Argentine plane crashed just how the CAB said N137US crashed, but the Argentine plane behaved in a completely different manner. That's why (as I said in my document) the Argentine crash refutes the CAB model. If N137US crashed as the CAB said, a backward slide would be normal. But being upside-down, N137US obviously didn't crash that way.

Do you see the implication?

ETA: One of my pilot friends read the CAB report and busted out laughing at the description. He said "so it hit the right wing, and then defied the laws of physics for 800 feet."

[BRDuBois]

Several pilots have said that any information about the flight dynamics will have to come from a simulator. I've loaded X-Plane, which is the best one for my purposes, and am using a L188C model written by David Starling. The manual says the Electra at the conditions for Flight 706 should stall about 110 knots, and the model does. The maintenance manual says the rudder can deflect 30 degrees right and 25 left, and the model has it exactly.

The model appears to be an accurate representation, and we can probably take its behavior to be correct within a smallish percentage of error. I'd be interested in hearing from pilots about the feel of the model.

One of the questions is whether an Electra can knife-edge fly. Turns out it can at any speed over about 250 knots. At lower speeds there isn't enough airflow over the rudder to get the nose up. I've run a number of tests, all starting at 1k feet over Puget Sound, since Flight 706 got to 300 feet tops and ORD elevation is 680 feet. My tests start at 160, 200, 250 and 300 knots, and I throttle up as needed as soon as the bank goes vertical. At 160 knots the plane has no chance, and is essentially in free-fall for the first 500 feet. At a starting 200 knots after a few tries I could get to 250 knots about 50 to 150 feet over the water. Starting at 250 or faster the plane had no trouble at all.

There will be some discussion of this in the next version. The answer for now is that knife-edge flying was not possible for Flight 706 because it was about 100 knots too slow.

My next step is to write a program harness for X-Plane so I can run turn and bank trials and collect more rigorous numbers. The questions to address are (1) what bank can the rudder induce, or what unwanted bank can it counter, and (2) what do rudder inputs do to turn radius calculations.

Hand-flying suggests that the rudder alone can turn the plane completely over, which impressed me. I'll be interested in seeing how the data turns out.

[G0ULI]

Excellent idea to get a feel for how the aircraft handled and the effectiveness of the rudder. Even though sustained knife edge flight is not possible at speeds below 250 knots, the rate of descent is presumably reduced somewhat, even at the slower airspeeds? Inappropriate use of rudder can certainly turn an aircraft inverted and/or induce a spin.

[BRDuBois]

I'm certain that there's at least some lift from the side of the fuselage, but I haven't measured the exact rate of descent to determine how much. I hope to do that when I develop some firmer numbers. My first goal is to program the harness for running the simulator, and that is unfortunately a little ways away due to competing demands for my time.

[BRDuBois]

Other commitments have taken me away from this project for the last month. I don't yet have the program harness working. Programming is my field, and I understand the problem, but don't have a solution yet.

Meanwhile I've been trying to get some useful information out of the simulator. Bear in mind that the simulator results are all that's available, but they can only be considered an approximation. I covered the fact that knife-edge flying is not possible at 160 knots. Two other questions are answerable by hand-flying: What are the behavior characteristics of an Electra banking right under full left rudder, and what attitude would result in a five degree descent slope.

Several pilots have agreed that the rudder must have been hard left. This would be an instinctive response, it would have an immediate effect, and they would have maintained it until they regained level flight. So we have an airspeed of about 160 knots and hard left rudder in a right bank. The first issue is to determine what this does to the turn radius. All my illustrations are based on balanced turns, because no one could estimate what the rudder inputs would do to the radius.

We have evidence that the bank angle at impact was near 34 degrees, so I used that angle when collecting a representative radius value, but I'm not saying this radius calc is itself evidence for a 34 degree bank. A balanced turn at 160 knots and 34 degrees gives a turn radius of 3370 feet. A 35 degree bank at 160 knots and hard left rudder in the simulator gives a turn radius of 5275 feet. I'll be running more trials to get an average, but it's in this ballpark. The left-rudder turn radius is around 1.5 times that of a balanced 35 degree turn, give or take.

In my illustration on page 20 of the 160602 document, I said that the red-dotted path was the most extreme possible, but that was based on a balanced turn. That path would have resulted in an impact bank angle of about 22 degrees, which made it unrealistic. Given the new unbalanced turn radius estimate, that path becomes much more reasonable. The plane could have reached the 271 heading with considerably more bank than 22 degrees. So the initial emergency probably started with a higher bank farther southeast than I had thought.

The second question is: What attitude would result in a 5 degree descent slope. At 160 knots a 90 degree bank results in free-fall, as discussed earlier. When this project showed me that they weren't in a 90 degree bank as reported, I wondered why they didn't climb. The simulator says at a 34 degree bank and 160 knots with hard left rudder it's easy to climb. So I'm looking for a bank angle extreme enough that the plane has insufficient lift to stay up, but not yet stalling.

As the bank increases, the elevator angle has less and less effect vertically, and starts to serve only to tighten the turn. Meanwhile the rudder has more responsibility for keeping the nose up, but it's going too slow to do that. N137US weighed 93,000 lbs and would have stalled at about 63 degrees in a balanced turn at 160 knots. My numbers are rough, but it appears that the simulator is giving stall warnings just above 55 degrees. Pulling back on the yoke increases the stall likelihood by lifting the nose, while not pulling back keeps the plane descending.

The exact rate of descent is highly sensitive to airspeed and bank angle, but a descent of 1400 to 2000 feet per minute seems within reach. The 5 degree slope Lockheed estimated would be 1400 feet per minute. The simulator run suggests they were at the stall boundary and unable to stop descending. My latest report characterizes their effort as just trying to manage an unstoppable descent, but seeing the stall warning makes it clearer.

This view, rough as the numbers are, is the best evidence I've seen that my 34 degree impact bank angle estimate is too low. This gives about a 20 degree gap between the simulator's result of a maximum 55 degree bank in flight and physical evidence of a mid-30 bank at impact. I can see a couple possibilities. One is that the flight bank and impact bank are both somewhere in the middle, and computation errors in the simulator are showing a steeper bank than they actually could have had.

The other is that in the last two or three seconds the bank angle was changing, perhaps as the aileron boost unit was returning to neutral. If the second one is the case, then the turn radius was decreasing and the elevators would have been able to pull the nose up. In other words, it's possible the impact was actually a flare that they were unable to initiate until too late.

The idea that the bank was changing rapidly in the last couple seconds feels conceptually awkward, a bit too close to magical thinking. I'm inclined to think the first possibility is the better one.

The rate-of-descent data is very rough because I have a really tight window to get into position and collect data, and I'm no pilot. I wasn't able to collect turn radius data at this extreme bank. If I can get the harness working it will give better numbers.

Meanwhile, I'm always interested in feedback.

[BRDuBois]

I've uploaded a proof-of-concept video to my weTransfer page. This is intended to show the kind of data I'll capture using the X-Plane simulator. This is a 15 mb MP4 video. The frame rate is low, but the goal here is to capture data, not to make a smooth video experience. https://we.tl/GU7wQaiDOZ

I envisioned three levels of testing with the simulator. The first was to test basic handling characteristics of an Electra. One of the objections raised to my analysis has been the proposal that Flight 706 not in a shallow bank but was knife-edge flying when it hit, and this explains the slow descent. Hand-flying the simulator shows that this is impossible because Flight 706 was going about 100 knots too slow for knife-edge flying. Hand-flying is sufficient for this proof, but that's about my limit as a pilot.

The second is to determine the characteristics of an Electra in a banked turn. Turn radius is critical to understanding how Flight 706 got to where it impacted on the airport grounds, and the angle of attack it could have had. So the next set of tests involves putting the simulated plane into turns of varying angles and different rudder deflections and measuring the turn radius of each. A pre-requisite was to write a simulator-controlling harness, which now is showing basic functionality. The first job in this test series is to calibrate the simulator and ensure that it accurately reflects what we could expect of an Electra. The link shows part of such a calibration step.

Non-Techies skip this part: The internal control is via a Lua plugin running inside Gizmo. Gizmo is a Lua/X-Plane interface plugin. This Lua script is a dumb plugin; it passes simulator data (eztracted by Gizmo) to the external program and the external program passes data values for the plugin to stuff into the sim through Gizmo. The plugin makes no decisions. The external program is a Delphi 10 (Pascal) program that has rudimentary flying abilities. Delphi 5 was my last installed version, and it's the best IDE I ever used, but it's unable to deal with W10. Embarcadero is giving away an intro-level Delphi 10 for free for the next four or five days, so it you ever want it this is a great opportunity. The intro level has plenty horsepower for this job.

The uploaded video shows the level of control needed to establish Electra flight characteristics. The harness can hold the sim plane within about a half a degree of bank angle, and within very few meters of height. There is a ringing effect, so the longer it runs the smoother it gets. With this harness I can put the plane into a stable state and then mess with rudder inputs and the like. The large readout shows the time it takes to make a circle, control surface deflections, headings, etc. It's not all wired up yet. The goal at this point is to calibrate the simulator and refine the Delphi flight controller so it smoothes more quickly. The video shows the Electra (in 1960's livery) circling over Elliot Bay and Bainbridge Island.

Not shown in the readout are the longitude and latitude values that determine exact coordinates. These are captured in a log file with other data, and I use those to compare to the speed and timing, which determines circumference, to check on the circle dimensions. There is a distortion in these measurements due to the way the simulator handles the 'flat earth problem', so I'll have to do the real measurement flights in Jakarta, not Seattle. Circles flown near Seattle turn out to be north-south-elongated ellipses, buit circles flown near the equator are circles.

The third set of tests will be to replicate possible flight paths for Flight 706. I won't be able to work on this until I have more data, a feel for how the sim handles, and a better Delphi flight controller. If the sim cannot be shown to be a good representation of Electra handling, then more work would be wasted. Even if the sim is only a marginal flight model, there should be some useful information about how rudder deflections alter the turn radius. If the sim turns out to have a dependable flight model, then there may be more useful data forthcoming. At this point I can't be sure the sim will generate anything useful beyond disproving the knife-edge flying conjecture.

[G0ULI]

All good stuff. Obviously you need to concentrate on one set of data at a time to establish the correct control responses. Don't forget to consider the effect of various engine power and propeller pitch settings once you have your basic data established. For initial analysis, assuming the engines were developing full power at lift off would be reasonable, but changes to engine power settings may have been made as the bank developed. This would change the airflow and therefore the effectiveness of the flight control surfaces on the wings and tail. If you don't get reasonable results from your initial simulations, this may prove to be the cause of the problem.

[BRDuBois]

I've put five videos on Youtube, illustrating flight dynamics for an Electra using the X-Plane simulator.

https://youtu.be/2JiGSJ5xPQg shows knife-edge flying, which was proposed as an explanation for the slow descent of N137US. It shows it at about 250 knots and about 150, which was the actual speed of Dad's plane. This is the only clip where I hand-flew the plane. The rest were all run by my harness, for consistency and repeatability.

https://youtu.be/kwVrHJ1obSk shows how I validated the simulator's turning circle calculations. Turn radius accuracy is critical in using the simulator for this research. I ran the plane in circles at bank angles from 10 to 35 degrees and varying speeds and heights. At each setting I ran five or more circles and averaged them for accuracy. The time required for each circle, along with the speed, gives me the circumference and therefore the radius. The bank angle and speed gives me the radius using the standard formula. The extremes of latitude and longitude gives the diameter and therefore the radius. These all agree to a high degree of accuracy. The elongation of circles at a distance from the equator turns out to be a computational pleat used by the simulator to cope with the "flat earth" problem, and has no effect on the short distances involved in my Flight 706 reconstruction.

https://youtu.be/62nRO2VFyGM shows the planned departure of Flight 706, with a gradual turn toward the west. This is shown for contrast with other videos, and describes where the turn starts in relation to the tower and runway.

https://youtu.be/R3ytdwRsxUM shows the increasing bank described in the CAB and ALPA reports, and shows what the result would be of such a bank. All the trial runs end at least 2,000 feet from the known impact point, and none of the runs ends in a 90 degree bank. These runs presume that the ailerons remain at the deflection used to initiate a smooth turn somewhat less emphatic than a standard rate turn.

https://youtu.be/9z_zaW5MvOU shows what it takes to achieve the 90 degree bank described in the CAB and ALPA reports. All these trials end from 2,700 to over 3,000 feet from the known impact point, and their final heading is 90 degrees off from what was surveyed.

I am tagging all these videos with N137US, which is not otherwise used on Youtube. When Youtube gets their indexes updated, that search term should bring up all these.

I have two more sets of simulation runs in mind. One is to explore what would be required for the plane to end in a 90-degree bank at the 4,000 foot distance. The other is to recreate what I think Dad's plane did. Based on the simulation results so far, it appears possible that I'll be able to propose a causal factor that has not been mentioned before. It will be very interesting to see whether this pans out.

[G0ULI]

One thing that occurs to me while watching your videos is that the ailerons are functional throughout the simulation run. You can vary the aileron inputs to attempt to duplicate the actual flight path taken by the original accident aircraft, but does that actually represent the true aileron positions during the accident flight?

Once the aileron drive cable broke, the ailerons may have been held in a fixed position for a time by powered assistance until the pressure bled away or the power boost was turned off. Alternatively, the ailerons may have moved due to airflow over the wing and prop wash from the engines.

Because of this, it is difficult to conclude that the turning circle was continuous or at a constantly and steadily increasing bank angle. Clearly the aircraft banked to the right after take off and that bank increased to a point where the aircraft could no longer remain in the air. There is the possibility that the bank angle increased in a series of 'jumps' as the crew struggled to regain control and as the aileron deflection altered due to crew inputs such as turning off powered assistance and changing airflow patterns over the wing.

Rather than assuming a steadily and smoothly incresing bank angle, you might want to try increasing the bank in a series of steps that might correspond to attempts to regain directional control.

The initial cable break would require a left rudder deflection to try and correct the bank. The ailerons would progressively become more susceptible to aerodynamic forces, and propwash effects as engine power levels were adjusted and the bank angle increased.

It seems clear from your tests so far that this wasn't a nice neat curving climb and descent with a steadily increasing bank. You have already concluded that this simply wasn't possible if the aircraft was to finish up at the actual crash site.

Perhaps a take off with a gentle 5° bank which then increases steadily to perhaps 30° bank at the highest point in the flight, followed by a jump to 45° increasing to 60° over perhaps 5-10 seconds, then a further roll to 70+ degrees to the impact point. I feel this would more accurately reflect the possible flight profile and allow the turning radius to agree with the results recorded in the accident investigation as to impact point in relation to the runway and airfield.

The problem is that once the aileron cable broke, it is very difficult to establish the position of the ailerons between that point and the moment of impact, when witness marks would reveal the deflections with reference to the wings. Did the ailerons remain in one fixed position, did they flutter in the slipstream, were they influenced by the engine power settings, or did they move in response to control power boost devices being cycled off and on, perhaps repeatedly?

Considering the flight as a series of step changes which temporarily mitigated the situation, but then failed is probably the way to go in understanding this accident.

[BRDuBois]

Well, I CAN alter the aileron settings, but I don't. Once the turn is initiated I leave the ailerons in that position for the remainder. I use a variety of settings in different runs, but it's stable within each run. There's a little jiggling out past the second decimal, but that's generated by the sim and I can't control it. For this series of tests and examples, I'm presuming the ailerons aren't moving after the cable parted. I've been doing some other runs using a scenario where the ailerons return to neutral, but no useful results yet.

It's possible the ailerons were moving significantly after the break. In order to test possibilities, I need a backstory to justify the exploration. I can't presume they were moving at random and find all the outcomes. Statistically such research is impossible because the permutations are endless. Logically it becomes meaningless because I could concoct any movements I like in order to bolster my case.

If there's a solution (and there's no guarantee I'll find one) it needs a rational scenario for a framework. The system returning to neutral is one. The idea that they were doing something that resulted in some sudden movements is interesting, but I'm not sure how to approach it. The most accessible premise is that there was no movement, since the deflection noted in witness marks is a reasonable deflection to start a moderate turn.

Take a look at https://www.youtube.com/watch?v=MDc4fHJFchY

That's a demo I did to illustrate ideas in an email thread I've got going with a couple pilots. I've been exploring the reaction when the left rudder is initiated at different points after the cable failure using different rates of change and different degrees of aileron deflection. I'm not getting satisfactory results, but it's getting closer.

I've been doing some experiments with hand-flying the simulator in high-angle banks with hard left rudder, to see how it behaves and to see at what point it can't maintain altitude. It's possible that the real answer lies in a higher bank than I'd previously considered, maybe in the mid-50 range, with a rapid left rotation on first impact.

The damage geometry says the plane was banked no more than the mid-30's when the prop left scars on the embankment, but the embankment actually had several strikes. I'm impressed with how fast the plane rotates counter clockwise about its longitudinal axis and right about its vertical axis when it hits the right wing a glancing blow, and then straightens again under rudder influence. Perhaps the answer is that it hit the embankment at a mid-50 bank, and left prop marks while in a mid-30 posture within a matter of a few dozen feet.

I don't know how much weight we can put on impact behavior in the sim, since it's a flight sim and not a crash sim. It's very doubtful that we can trust the plane model to accurately reflect the effect on the plane from tearing off half a wing.

[G0ULI]

The videos certainly demonstrate that flight is considerably prolonged with the application of left rudder to counteract aileron deflection.

The question of the aileron positions during flight can perhaps be simplified somewhat by considering that the aircraft maintained a constant turn to the right. This suggests that the aileron position at the point the cable broke was at the very least maintained.

Application of left rudder failed to rectify the situation, so on the balance of probability, the ailerons appear to have moved somehow to a position where they became even more effective at rolling the aircraft despite the application of full left rudder. The aircraft would have been flying in an unbalanced sideslip. Would the disrupted airflow over the wings have been enough to move the ailerons, sucking them further from a neutral position?

It is probable that the engines on the right wing would have had the power pulled back at some point in order to try and get the wing to drop. The left engines would be left at full power to try and prevent an incipient spin developing which would have led to an immediate crash.

As you say, the closer you look at all the variables and interactions that could have been involved, the more difficult the problem becomes in arriving at a credible solution, rather than one that just happens to fit.

This is why I suggest that the flight needs to be considered as a series of events with the aircraft reacting to the failure and the crew's attempts to corect the problem.

Aircraft takes off a bit long and low on the runway, not necessarily a problem.
Aircraft begins a standard banked departure turn.
Aircraft climbs in a banked turn.
Aileron cable breaks.
Crew are unable to adjust the angle of bank using ailerons.
Bank increases.
Up elevator commanded to maintain height?
Progressive application of left rudder to the limits.
Further movement of aileron due to disrupted airflow over the wings in sideslip?
Aircraft starts to descend.
Crew reduce engine power to right wing engines, maintain full power on the left.
Does the application of differential engine power move the ailerons still further out of the neutral position and increase the bank angle?
Aircraft continues to roll and descend.

I have a hunch that doing the right thing in reducing engine power on the starboard engines while leaving the port engines in full power may have resulted in the ailerons being moved out into a more effective, rather than reducing to a neutral, position in the slipstream. Flight training would have taught that applying more power to the port (left) wing should raise the wing and turn the aircraft to the right. So while the flight crew reacted correctly and in accordance with their training and experience, it is possible that the "correct" course of action would have been to completely and counter intuitively reduce engine power, particularly on the port wing first. This would inevitably have resulted in a crash landing, but just possibly in a more wings level attitude.

As I say, this is just purely supposition and it is possible that the crew did finally take a counter intuitive approach to control of rhe aircraft when it became obvious that a crash was inevitable. That could certainly account for the apparent reduction in bank angle before the initial impact, which is what you have been trying to explain all along if I have my facts straight.

I doubt that these possible elevator control inputs, aileron positions, engine power settings and rudder inputs can be duplicated using personal computer flight simulation software, but approximations can be made to test the ideas. As you have already demonstrated, just applying a hard rudder against increasing bank angle dramatically prolongs the flight.

I think you are making genuine progress in explaining what actually may have happened. You are certainly building a fairly strong case that tends to support and explain your version of events.

I don't think the accident investigators at the time were at fault in any way. They had to work with the resouces available to them at the time and no doubt with considerable commercial and government pressure to produce a result quickly.

You have the benefit of being able to review and model potential scenarios over and over without any constraints. I would be surprised if you don't eventually arrive at a better solution to this tragedy, one that demonstrates that your theory is correct and also agrees with the results recorded at the time, if not the conclusions.

[BRDuBois]

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.

[BRDuBois]

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?

[G0ULI]

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.

[G0ULI]

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.

[BRDuBois]

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.

[G0ULI]

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.

[BRDuBois]

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.

[BRDuBois]

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.

[G0ULI]

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.

[BRDuBois]

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.

[G0ULI]

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.

[BRDuBois]

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.

[BRDuBois]

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.

[G0ULI]

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.

[BRDuBois]

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.

[G0ULI]

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.

[BRDuBois]

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.

[BRDuBois]

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

[G0ULI]

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.

[Concours77]

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?

[BRDuBois]

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.

The overall site image from the impact end (page 41 of my latest version) appears to show a thin white line going off to the upper left with people along that line. The tracks are blocked, and they were reported cleared on the first day. Shadows indicate this image is about noon. I take that while line to be a measuring tape, so it suggests they were mapping on day one very soon after the smoke was gone.

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.

That was my guess, and how I described it in my cockpit resources document mentioned above, but I have no practical experience.

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.

That's the kind of feedback I'd really like to get. I'm frustrated by an acquaintance who lives near me. He's a retired Northwest Electra (among other types) pilot, and he refuses to look at this project or discuss it in any way. Mumph.

[BRDuBois]

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?

PM sent.

Whirl mode was brought up in passing, but never seriously considered. The more curious question has to do with airspeed and height. The official reports say the plane was "somewhat low" or words to that effect, but when it passed the tower it was about half the normal height. It was only doing about 165 knots when it hit and should have been doing 225 if I recall right.

There was extensive investigator discussion of engine failure as a cause as reported in the papers, but then in the official reports there is not a word about the low and slow path. My simulation says that just a little more speed would have saved them, and the official report concludes that they were too low to effect recovery, but there's no hypothesis given to explain the flight path.

[G0ULI]

I have looked in vain for a detailed cutaway drawing of the wing showing the routing of the aileron and engine controls. I was wondering if the aileron control cables or turnbuckle could have recoiled and interfered with the engine controls, rolling the power back a bit on that side. That would certainly increase the bank angle by reducing propellor wash across the wing. It all rather depends on whether all the control cables were routed along a single channel in the wing, something I have been unable to establish.

If this was possible and did occur, that would suggest that the aileron cable parted during the takeoff run while the aircraft was still on the ground. The reduced power available could account for the slow acceleration and climb characteristics observed.

That does give rise to all sorts of questions as to whether such a power rollback would be reflected in the cockpit controls or be detectable by the crew.

[BRDuBois]

I have looked in vain for a detailed cutaway drawing of the wing showing the routing of the aileron and engine controls. I was wondering if the aileron control cables or turnbuckle could have recoiled and interfered with the engine controls, rolling the power back a bit on that side. That would certainly increase the bank angle by reducing propellor wash across the wing. It all rather depends on whether all the control cables were routed along a single channel in the wing, something I have been unable to establish.

The cabling ends at the boost unit which for ailerons is midship. The actuating force to the ailerons is carried within the wings by push-pull tubes. I presume that's one reason the emergency response to a cable failure is to switch to autopilot. The autopilot controls the boost unit hydraulically, bypassing all cabling.

[Concours77]

Whirl mode ending in fatal impact was well described in the two accidents I reviewed. My experience as pax in the Electra involved seated portside abeam the engines and witnessing it first hand. It is impressive. In my case the aircraft was short, and full power added whilst level at one hundred feet. The two port engines were wobbling and the aircraft was shaking so bad the passengers were alarmed. There were a couple of screams as I recall.

In the takeoff roll, at rotation, the stresses are at max on the mounts, and whirl mode is one loose motor mount away.

Have you the logs and maintenance records? I would consider whirl mode, especially as one engine left the airframe before the others?

[BRDuBois]

Whirl mode ending in fatal impact was well described in the two accidents I reviewed. My experience as pax in the Electra involved seated portside abeam the engines and witnessing it first hand. It is impressive.

I never saw it while flying in an Electra. After my dad's crash I was probably on one three or four times. Thought it was a good plane. A friend shared that he'd noticed it on at least one occasion. All I can say is that after the wing geometry changes there were no more catastrophic instances, and of course the P3 is still going strong.

Have you the logs and maintenance records? I would consider whirl mode, especially as one engine left the airframe before the others?

I have almost nothing. Got a whole bunch of manuals supplied by a few retired NWA pilots and from downloads. Got the press photos that triggered this whole thing. Got the official reports and a bunch of newspaper archive stories.

A friend has an in with some Lockheed folks; he hopes to shake something loose. Lockheed has a reputation for saving documentation, but they've never answered my requests. One reason for putting this project out in front of the public is to get some buzz going, and maybe a FOAF will come forward with some musty folders. Small hope, but that's about all I have.

[woptb]

Been a while since I worked on the Electra as a maintainer. A few practical notes I can add; when we would deactivate the Autopilot, we would do so by depowering via a three phase ganged circuit breaker. The AP amp & cb were in the avionics rack on the flight deck at floor level,just behind & to the right of the FE's position. I flew many times on the flight deck & as the Electra was prone to Dutch roll,we would pull & reset the AP cb. It is extremely (impossible) unlikely for the flight controls and engine power controls to mechanically interfere. The engine controls being routed along the wing leading edge & flying controls along the trailing edge. They are also physically separated on the flight deck & within the fuselage.

[G0ULI]

woptb

Thanks for the info. Another possible issue eliminated in determining exactly what happened and the sequence of events.

[cordwainer]

Dear Mr. Hagstrom:
On YouTube there is a video that contains an amateur film of the crash site. I'm not allowed to post URLs, but you can find it easily by knowing the title is "Chicago O'Hare Takeoffs and Landings From 1961 Video 1" and it was uploaded by davidevo2

Crash scene footage begins at 3:42. The camera work is absolutely horrible, but it does briefly show, for example, workmen up on the power lines who appear to be inspecting things rather than doing repairs. A large amount of the footage is shots of the power lines, in fact.

I can't make heads nor tails of most of it it's so shaky, blurry, and constantly shifting...except I could tell the flowers in one shot are sunflowers because I know sunflowers well enought to recognize them no matter how lousy the filming. Which is my optimistic way of expressing the very faint hope, since you know the scene so well, that you might likewise spot something recognizable that would help answer some of your questions. And even if it's no help at all, I thought you might want to know about it. Wishing you all best with your research, c

[BRDuBois]

Wow, that's incredible, thank you very much.

The photographer must have been very excited, because it's just all over the place. I presume the scaffold near the powerline is something to support the slack wires over perhaps a road or a railroad line until they are tightened, but that's a guess. I'll freeze-frame it and see what I can see.

He's got an excellent frame or two of the initial impact, showing wing fragments left on the east side of the track. There's some clue to the depth of the impact hole where I suspect engine four hit. The sequence as a whole gives me a much better feel for the terrain than I had before. It looks like the photographer was on the access road and on an embankment east of the tracks. It's going to take a little time to map this out.

This must have been several hours after the crash, possibly the following day. That scaffold wouldn't go up instantly, but it looks like a portable rig that would be pretty quick to handle.

It's going to take some time to process this. Thank you.

[BRDuBois]

The entire sequence was just over 2900 frames. About 820 of those were clear enough and stable enough to be useful. He appeared to shoot from three locations - (1) close to the main fuselage first impact site in the trees, about 300 feet west of the tracks, (2) just east and below the tracks and virtually under the high tension line, and (3) on a hill east of the tracks, elevated above them and slightly southwest of position #2. Since he was panning I should be able to map his location pretty closely.

The scaffolding looks like a permanent installation, not a temporary structure. It appears to have concrete footings. It doesn't seem to have any equipment. It's possible the platform on top supports lights that aren't obvious from this angle.

Three panoramas made from these sequences might be instructive.

[cordwainer]

Very glad if it ends up helping at all.

Also, I didn't see any mention of this in this forum or your PDF, so forgive me if I'm telling you something you already know. And I don't want to get you all excited about what may be nothing.

However, ALPA's archives are not with NARA. Instead they chose Wayne State University as their repository. As before, I can't post a URL, but try

reuther[dot]wayne[dot]edu[slash]taxonomy[slash]term[slash]9

and if that's incomprehensible look for the Walter P. Reuther Library site, Collections.

I didn't see a direct reference to this crash in the (admittedly few) collection descriptions I skimmed through. But there are a lot of records, with a descriptive PDF for each sub-collection within the ALPA group. And there are definitely documents and correspondence from 1961 and 1962, though the catalog is not necessarily specific enough to trust with regard to details of every document in every box. And none of it appears to be digitized, so you'd be in for a long, dusty slog through a ton of old paper.

Still, on the off chance it might help.

Cheers,
c

[BRDuBois]

Wow, thanks again. I found the crash records in Box 12 folder 1. Now I need to contact a human.

Meanwhile, I've finished two composites. One is practically standing on top of the impact site. He was probably chased away from there pretty quickly. That they didn't have perimeter control at that point tells me he was shooting on the afternoon of the crash. The second is from his final shooting location, a hill southeast of the railroad track first impact point.

https://ibb.co/nasY7b

https://ibb.co/g83Fnb

I'm working on a third, taken under the power lines. There are fewer visual cues to tie the images together, and he took two sequences from slightly different locations.

Pretty amazing to see this after all these years.

[G0ULI]

Astonishing! I never expected to see colour images after all this time.

I note that there are regular poorly focused vertical and horizontal markings spread across the still frames. I initially thought that suggested filming through a wire fence, but watching the video reveals these are apparently just scratch marks on the film. I would guess the lens as being the equivalent of a 200 or 400mm modern zoom lens. Pretty hard to get steady hand held shots and probably no compensation in the viewfinder from more normal wide angle lenses. I believe the other aircraft shots were made with a tripod support if they are all by the same photographer.

I think the chaotic panning was simply an effort to try and include all of the scene, shooting handheld while not having a decent viewfinder to confirm what was being filmed.

Truly remarkable what turns up on the Internet.

[BRDuBois]

Astonishing! I never expected to see colour images after all this time.

I note that there are regular poorly focused vertical and horizontal markings spread across the still frames. That suggests filming was through some form of wire fencing, perhaps installed to keep wildlife and people off the railroad track. That might help to establish the camera position exactly.

I think the vertical lines are scratches on the film. This was 8mm, and probably converted to digital form after at least 35 years of being played mechanically. There's a very curious horizontal line in the foreground on the left side of the composite done near the crash site. I really don't know what to make of that. There is also a wire draped higher up in that image, which suggests the plane managed to go entirely underneath it.

I've heard back from Wayne State U, and they'll be looking for the crash materials next week. The ALPA never answered my emails, so I had pretty much no hope of getting their stuff. This is a real gift, but as I told my wife it will make for a long weekend! Lockheed-Martin also never answered, and Delta couldn't begin to care about NW history. Next week should be interesting.

[G0ULI]

In the first panoramic composite, the power lines can be seen descending at the extreme right side of the image. There are two parallel lines clearly visible.

The second composite would appear to have been framed looking between the two power lines that are descending from left to right across the image.

The angles and spacings look very similar considering the difference in scale caused by changing the filming position.

[booke23]

This is quite a development. Some amazing information from cordwainer. It'll be very interesting to see what Wayne State University have in their archives.

[BRDuBois]

I'm still trying to nail down where he was. He shows no sign of zooming, but he could have had something like a 3-lens turret, pretty common for a movie camera of the era. If you compare the AtImpact image with the press photo that I use for my overhead view in my document (page 41), He's somewhere on a line roughly between point Y and the lower left corner of the image. He could conceivably be filming through the railroad wires running beside the tracks.

His second shooting position was down below that structure I mentioned earlier, and if you view the video its footing is clearly quite a bit above him. Also note in the OverTrack image that there's a power pole on his near side of the track almost between him and the impact site (the red spot in the distance), and the next power pole to the left is on the opposite side of the track. So the low-voltage line crosses the track at that point, and presumably the high-tension line does as well. The highest two frames of the OverTrack image show the bottom conductor of the high-tension line. On page 70 of my document you can just barely pick out a couple poles at the bottom of the picture, and see that the power lines are crossing the tracks.

At the pole in front of him, the lines drop down quite quickly but are parallel and under some tension at least. It appears that the string of poles is dropping down into the lower elevation from which he filmed up at the structure (landing lights?). So the droop on the right side of the OverTrack image is not severed lines, and if they were cut it was beyond a following pole off to the right.

I'll work on a composite from that lower vantage some more. It's pretty terrible film.

booke23 - this is what I keep begging for, and the reason I release my research in stages. I ask people to pass it around in the hopes that it will come to the attention of someone who knows where to find documentation.

[BRDuBois]

I've uploaded an aerial photo of O'Hare from 1961. Forgot I had the thing.

https://ibb.co/krms0w

[cordwainer]

Truly thrilled the ALPA archive may be of help.

I should be clear, I'm not a pilot. But your project is exceptionally intriguing from the standpoint of accomplishing a kind of time travel - creating a window into the past where you can view the scene as it was on the dates of and surrounding the crash.

So while I'm of no use when it comes to analysis of the flight sequence, I can at least try to locate other information out there useful for purposes of identification, mapping, and orientation around the site.

I'll also keep working on ferreting out other sources where photos, documents, or footage are hiding.

BTW, I don't want to clog the thread, so please let me know if you'd prefer PMs to posts.

A few last notes though: with regard to nailing down exact locations, have you done any comparisons with topo maps from the time period? Or with the various City of Chicago planning documents for O'Hare ? Together they might provide clues to structures and features for orientation, are drawn exactly to scale, and in the case of the topos and one engineering report provide info on elevation and terrain.

There are USGS historic maps available for free, none from 1961 , but I can point you to a 1957 Chicago quadrangle and a 1963 Elmhurst map with enough detail they may be of use.

Several O'Hare master-plan documents are available in the Internet Archive. They contain quite a number of maps, diagrams, and photos potentially relevant to your re-creation...though you'd be the best judge of that, of course. 1958 master plan volumes are avaiable, including the first-stage Engineering report, also the 1960 fueling system agreement and the 1962 Revenue Bond Improvement plan which probably contain the most contemporaneous look at the airport and area.

I can also look, if you like, for surveys and documents from public utilities, and from the rail companies tangentially involved (if I'm reading the maps and reports correctly those would be the Chicago and North Western or the C.M.St.P&P or both). It's possible their files might even include information from the crash and/or related repairs.

Um...nonetheless, if any of these are way off the mark, please let me know. Likewise if there is anything in particular you think would be useful. I actually enjoy historic research, and would be pleased to be of assistance wherever possible.

Cheers,
c

[BRDuBois]

cordwainer,

This project is like an electronic archeological dig. It comes with a big chunk of emotional load, obviously, and I get a lot of free psychoanalysis out of that. But mostly it's a puzzle.

I've talked with the Chicago & Northwestern historical museum. They have all the archives but nothing to the level of detail I need. If you've read the missing-engine puzzle you can see that they might have provided a key bit of evidence in their job ticket journal.

I'd be very interested in topo maps for the area as of that date, if for nothing more than locating our photographer. Topo maps would give power and phone lines. Maps from 57 and 63 would be close enough to be useful. A man who was a pastor at a church near the crash site told me that the area was virtually untouched for many years after the crash, and the scattered homes visible in the panorama suggest it was pretty stable for some years before. The whole area is now warehouses. When I was recreating the flight with a simulator, I kept crashing into warehouses. By the way, my videos are on Youtube and can be found searching for N137US.

[BRDuBois]

I've loaded the third composite. It's several sequences, explained in the notes.

https://ibb.co/gYGsHb

[cordwainer]

Just sent you a PM with some links to topos and 2 planning reports
c

[BRDuBois]

After looking at his other three videos, it's clear he had a zoom lens and uses it A LOT. Probably too excited to use it for the crash scenes. There's a bunch of great clips there; love those old planes.

[BRDuBois]

Big thanks to cordwainer for the information. One of the topo map links he sent was pure gold. I've clipped out the O'Hare portion of it, overlaid it with the CAB report map showing the flight path as a half-transparent image. The landmarks line up exactly, validating the CAB cartographer.

https://ibb.co/e4n1dG

Turns out the impact point was virtually on top of the A from my other image. I had guessed it was farther north.

[cordwainer]

1) The corporate records of Northwest Airlines are archived at the Minnesota Historical Society

www2[dot]mnhs[dot]org[slash]library[slash]findaids[slash]00110.xml

The 1961 O'Hare crash is specifically noted in the Accident Files, which also references a section of general info on accidents between 1929 and 1974.

2) There was also a Coroner's Jury inquest held October 4, 1961, for which a transcript theoretically exists. The Cook County Medical Examiner's office is responsible for warehoused inquest archives, which are public documents. BUT: be forewarned there are no end of complaints about how difficult, time-consuming, and expensive it is to get those records. Numerous genealogy researchers have expressed frustration with obtaining even simple reports, or cited charges of $5 per page of sworn testimony from inquests.

One researcher's attempts to obtain a large inquest file are detailed in this article, which gives you an idea of what you might be facing:
www[dot]chicagonow[dot]com[slash]chicago-history-cop[slash]2016[slash]02[slash]cook-county-medical-examiners-office-is-a-joke-especially-on-valentines-day

I did find a few articles about the inquest that discussed some of the witness testimony - will PM a Dropbox link for you to access the clippings. Though you've probably already seen them...

c

[BRDuBois]

I'm frankly amazed that the MNHS has records, because retired NWA people and the NWA History Center told me that Delta would have everything, and Delta won't answer me. At any rate, I see the entry in the MNHS index and have asked my sister in St Paul if she's willing to go look at it. Thank you very much for the lead. How do you know this stuff?

As for Cook County, I'd heard about that, and the obvious records to get from them are autopsy files, and I'm not real sure I'm ready for that. It's only been 55 years, after all. Give it some time. :)

Thank you for the clippings. I think I have most of that after searching newspaper archives, but I'm going through them.

[cordwainer]

I definitely wasn't suggesting you obtain autopsy records - that would be too grim, and I wouldn't be so insensitive.

Instead, the suggestion is to obtain the transcript from the Coroner's Jury hearing. That would contain the verbatim statements from the eyewitnesses and first responders, as well as from some of the investigators at the scene.

The point of the Coroner's Jury hearing was primarily to determine whether the deaths were accidental or if some person or party bore responsibility (e.g., were there grounds for manslaughter or negligence charges). The verdict was the crash was an accident.

My impression was that the Coroner's role at that time was similar to that of the Coroner in British jurisprudence. This is no longer true, but in 1961 Coroner was an elected position, and didn't actually require any medical knowledge or background.

A lot of the testimony and evidence are probably identical to that given at the CAB's separate hearing 6 days later. Since thus far it is proving impossible to locate any of the CAB transcripts or detailed investigation files, it seemed the Coroner's Jury hearing transcript would be the next best thing. If you could actually get it, which as noted is the problem.

Cheers,
c

[BRDuBois]

Got the ALPA files. They are mostly clippings. A quick scan shows several items of significant interest.

First, there's a cover letter for the ALPA report being sent to the CAB in August '62. I mentioned in my document that the ALPA seemed to be in a rush to get their report out, and the cover letter suggests that the reason is so the ALPA could put a stake in the ground regarding the crew. As a union voice, this is a major role for the ALPA, and they wanted to get the ALPA view into the CAB report. I blamed this rush for the apparent errors in the ALPA report.

Second, the Chicago Trib carried a graphic on their last page showing the CAB scenario of a right wing hit, the plane spinning around and sliding backward some 800 feet. As I demonstrated, the plane had to have slid forward until it flipped at the end. I called it unconscionable that the CAB would put this out on the afternoon of the crash. The CAB never walked back this scenario, and the ALPA clippings include a much better image than the one I got from the Trib microfilm conversion.

Finally, there is a closeup of a piece of debris on the railroad tracks. If I can identify its location in the wing, this will tell us that the wing was destroyed at least to that station at the tracks. My maintenance manuals may or may not allow me to identify it.

This is an exciting development, and thanks again to cordwainer.

[BRDuBois]

I've assembled the back page scans. These scans are informal and low-res, intended for review. I'll have them redone as high-res. You can see the power line at the bottom of the picture. The positions of people on the track exactly match their positions on page 41 of my document, so this is a wider-framed version from the same exposure. Page 70 of my document shows the terrible quality that came from the Trib microfilm.

https://ibb.co/hMoFA6

Note that it shows the right wing breaking off at the tracks. In my opinion, the break should be shown between engines three and four. I suspect the reporter conveyed the CAB story to the artist wrong, but having worked at a newspaper I can attest that it's sometimes more important to be finished than to be correct.

This is the same image which under higher resolution shows a large object on the tracks, but no large object was there by the time a photographer got to the tracks.

[G0ULI]

Whatever the object was on the tracks, it probably wasn't that heavy. The apparent speed with which it was removed suggests something that could be shifted using just manpower. So probably some part of the wing structure rather than an engine or other massive part.

[BRDuBois]

It's an interesting puzzle.

If the object was light enough that a half dozen guys could pick it up, I could see them doing that and putting it on the west (unused) set of rails. But they wouldn't carry it away entirely; that's the job of the crash investigators. When a news photographer got there later that day and shot the scene, the papers carried a picture of an unimposing chunk of aluminum sheet between the rails, looking like twenty pounds tops. If an engine had been there to shoot, they sure would have taken that. And the chunk of aluminum sheet was way too small to be the object lying on the east tracks in the overhead shot.

The railroad guys are experts at clearing tracks, picking up stuff and moving it. Probably have a small flatcar with a jib boom on it, the railroad equivalent of a pickup truck, for jobs like this. Once they had the go-ahead from investigators, it was probably a ten or twenty minute job.

When you add in the whole missing-engine conundrum as I laid it out in an upcoming chapter and uploaded standalone as https://we.tl/2iOuz04If7, the simplest explanation is that the number four engine was blocking the track. But the evidence is thin.

[G0ULI]

The photo that shows a chunk of debris lying between the railroad tracks looks to me like a highly crushed and distorted wing rib with some additional components attached. Given that the aircraft wing is assumed to have made first contact with the ground in the vicinity of the raised embankment, that sort of debris is to be expected. That is why propose that the large object on the tracks was part of the outboard wing.

Contact with the embankment is undoubtably responsible for the loss of the outboard engine but where I can see a large chunk of wing breaking off and remaining on the rails at the top of the embankment due to snagging and air resistance, the engine is an altogether different matter. The engine and gearbox are a compact mass of metal travelling at over a hundred miles an hour. There is absolutely no way it would have remained on top of the embankment. Sheer inertia would have carried it a considerable distance and/or buried it in the ground on the far side of the embankment.

We know that propellor strikes were evident across the embankment, so it is reasonable to assume that a section of the wing outside of the outer engine broke away as the aircraft struck the rising embankment. The propellor strikes them shattered the propellor of the outer engine and shock loaded the engine to the extent it too broke away from the wing structure. The remainder of the aircraft with three engines continued in flight until making contact with the ground some distance from the embankment. This would certainly account for three of the engines being found relatively close to each other with the fourth some distance away.

The inertia contained in the engine and gearbox components can be estimated by the depth to which some penetrated the ground, eight feet deep in at least one case if I recall correctly from your report.

The extent to which the railroad tracks were apparently distorted in the crash is a matter of inches. Pretty much what you might expect from contact with a high speed but relatively light weight structure such as a wing. Solid contact with a gearbox or engine block would surely have broken or severely dented the rails, not just shifted them sideways a bit. Apart from the apparent track movement, there is remarkably little obvious damage to the tracks at all.

That is why I am absolutely convinced that whatever the large object was on the railroad tracks, it was not an engine. Even railway engineers of the time would know that an engine was a significant part of the crash sequence and that it would not be moved without the specific instructions of one of the air crash investigators. A large piece of wing alloy skin flapping in the breeze would be another matter and probably treated far more casually. Shifting that off the lines and down the embankment would seem a sensible idea for those entrusted with clearing and examining the tracks.

[BRDuBois]

There's certainly room for disagreement here, and I understand what you're saying. I discuss the physics of the impact at some length, but not being an engineer it's no more than an attempt to get my head around it.

I wouldn't expect propeller strikes to detach the engine on an Electra or any other plane. I've put up an image of the damage when an Electra prop makes a substantial ground strike at https://ibb.co/knWn8R. There is no visible damage to the engine or nacelle. I'm not suggesting that prop four hit the tracks and that this was sufficient to tear off the engine. The prop strikes across the tracks were from prop three.

I contend that the plane was at about a 35 degree bank and the wing hit the track just inboard of engine four. So engine four wasn't skittering along the tracks, it was stopped pretty much dead by a direct impact with the embankment. It then bounced more or less vertically off the sloped embankment, and landed on the rails.

The best reason for saying the large object imaged on the tracks was the engine is precisely what you pointed out earlier. A bunch of guys could pick up a mass of aluminum and move it out of the way. If they had done so, that mass would have been what the papers ran instead of the ten or twenty pound chunk that they showed as the first impact debris. The reports note that the wing was reduced to small fragments at the embankment. In the various pictures there are bits of metal all over the area.

As I say elsewhere, the question is not to determine the odds of a torn off engine landing on the track. The question is, given a large object lying on the track, what are the odds it's engine four? If it's not, then it's an amazingly large piece of wing considering the shreds that the rest of the wing was reduced to in that area.

Whether it was an engine or other debris, I'm confident the railway workers had permission to move whatever they moved. As I wrote in the engine puzzle chapter, it sounds like there was miscommunication among the investigators, but I'm pretty sure the rail staff got what they thought was an authoritative ok from someone.

[BRDuBois]

Holy Toledo. My sister just sent me the contents of a NWA folder at the Minnesota Historical Society that cordwainer suggested.

The most important single document is a letter from Don Nyrop dated Dec 21 '62, discussing the CAB report that was released Dec 13. Nyrop says the report was "issued prior to the availability of all of the scientific data and tests necessary to establish a probable cause for the accident. The Board has been notified that there are at least 22 specific errors in the report it released on December 13. In our opinion, the Civil Aeronautics Board's findings are based on incomplete data, an unfinished analysis, and on conjecture."

Nyrop's letter was under a cover note that said it was clearly not intended for public consumption, but could be used as the basis for private responses.

I said elsewhere that it felt like the Lockheed engineers thought the CAB guys were a bunch of fools. Turns out NWA thought so too.

Holy Toledo.

[BRDuBois]

My goodness, brought that thread to a screeching halt didn't I?

I have said that the CAB investigators seem to have been held in low regard by Lockheed and Northwest. Evidence for Northwest's view is documented in Don Nyrop's letter. Evidence for Lockheed's view comes from the flight path map. I owe Lockheed a word of appreciation here.

When a reader first suggested I look at turn and bank calculations, I started by overlaying the CAB map with circles to measure the turn radius at different points. I said that not all who drew the map would have been thinking of my reverse-engineering their work. When the CAB report said that Lockheed held the inner curve to be the only possible path, it didn't dawn on me until much later what that signified.

To say that this was the only possible path is a remarkably assured statement. It does not sound like Lockheed was simply more discerning in its choice of witnesses to believe, which might have resulted in a statement of heightened confidence but certainly not one of such bald certainty. And no other means of recording the flight path is mentioned in any report.

The only reasonable explanation for Lockheed's statement is that the team calculated the path. I have no direct evidence, but I will assert this. With slipsticks and pencils they ran iterations just as I did with an Excel spreadsheet, and they kept on until they had derived a path that ended at the impact point.

When they had finished the path calculation, they said they had found the only possible one. When I ran the Excel routine I came close to the same path. When I flew the simulator I came up within a wingspan of the same path. Lockheed knew it was the only path not because witnesses agreed but because they ran the math.

This means that Lockheed knew the plane hit at much less than a vertical bank. The Lockheed team would have known how debris was distributed, and if I am correct that engine four was left at the tracks then Lockheed knew the plane hit at no more than 35 degrees.

The inner curve on the map was not something drawn by a draftsman with a French curve, nudging and tweaking while a bunch of guys looked over his shoulder until they had a consensus. It is the plot of their turn and bank calculations. The CAB's giant looping flight path range, trowelled on top of Lockheed's calculations, must have been like a slap in the face.

The inner curve is like a hand print in cement; it memorializes Lockheed's presence. It is evidence that due care was taken by at least some of the investigators, and it's a permanent record of what the Lockheed team was thinking.

[G0ULI]

Lockheed had all the design parameters and design flight characteristics of the aircraft. While their conclusions may match your findings, you both have a significant stake in trying to prove that neither the aircraft nor the flight crew were inherently at fault. Lockheed would be particularly keen to eliminate any suggestion that the aircraft was inherently unsafe and to a certain extent it would have been ideal from their point of view if mishandling of the emergency by the flight crew was contributory to the crash.

The accident investigators on the other hand were required to consider all possibilities and not just the ones that conveniently fitted a certain conclusion. While they might have to accept the findings of Lockheed's engineers, they would certainly treat that information with suspicion, because of vested interests in the company.

The fault in the aileron rigging was clearly something that needed to be addressed, but it exonerated Lockheed from direct responsibility for the accident.

The most common finding of pilot error could not be attributed to this accident either, because the aircraft became uncontrollable once it left the ground since the ailerons did not function as they were effectively disconnected from the flight controls. It certainly seems that some attempt was made to discredit the pilots by suggestions that the autopilot controls could have been used to control the aircraft. Had the autopilot not been flagged inoperative and the breakers pulled, I have a strong suspicion that this would have been the finding of the investigation. Such a finding would have been grossly unjust given the time constraints the crew had to find a solution to the problem, it is unlikely that such action to regain control would have been considered in the time available.

I am inclined to believe that the aircraft struck the embankment at an angle greater than 35° of bank, possibly as much as 60°, but certainly a lot less than wings vertical. The flatter angle of 35° would, I think, have resulted in a less damaging impact with the ground and perhaps the possibilty of some survivors. The damage to the aircraft points towards a much heavier impact with the ground which is why I theorise a steeper angle of bank on impact with the railway embankment. I am aware of course of your arguments for the shallower angle of bank supported by ground and other witness marks.

As to the engine being left on top of the embankment, this would have to have been recorded somewhere in the paperwork. The fact that no statement of any sort record the engine being found there, or moved from there, suggests that whatever was on the embankment, it wasn't the engine.

Because of the solidity and physical inertia of the engine and gearbox, in order for them to be deposited across the railroad tracks without damaging the tracks, the engine would have to have struck the embankment lower down, broken away and lost inertia before bouncing up in the air and landing on the tracks. While there is nothing inherently impossible with this scenario, it would have left hugely obvious marks on the approach side of the embankment and does not fit with the propellor strike marks found across the embankment.

Additionally, there should have been considerably more shrapnel and bits of metal and oil scattered across the tracks, which surely would have been photographed, officially or otherwise. It simply doesn't make sense that the engine ended up lying across the tracks given everything else that has been revealed.

[BRDuBois]

I wouldn't expect the CAB to take outside advice without qualification. If someone pointed out that the plane was upside down instead of right side up as the CAB said, I'd think they'd at least look at it again.

We have no idea what size hole was left in the embankment; we have no good images of it. There's a hint in this new film, but the quality is too poor to have any confidence in it.

We don't know whether there was paperwork showing engine four came off at the tracks. We have no paperwork. That's why this is a puzzle. There were probably hundreds of pictures, but the files are gone. News photographers may have taken dozens more. News photogs burn through an enormous amount of film. But they discard what's unusable, and I don't have access to their archives.

I've uploaded a chart of my simulator flight overlaid on the CAB map. The red dots show the approximate size of the plane and represent about half second intervals. The map shows that my flight agrees with Lockheed's path within 50 or 75 feet.

https://ibb.co/fKZcF6

[BRDuBois]

Hi Megan, thought you gave up on me.

As I discuss on page 54, I'm trying to relate ground marks to the airplane structure to figure out how it made the final bounce. The bounce seems to have been driven by the main gear and the ground is somewhat soft. The C indicates what looks to me like the right gear dent.

[BRDuBois]

Not having any luck identifying this piece of debris, so I'll put it out here and see if anyone has an inspiration.

https://ibb.co/c8oKoR

I could imagine a piece of piping going through the holes, and being ripped out when the plane hit. But piping never bears against a hard edge like that in plane construction. It would be cradled in a saddle and strapped down. Maybe the holes are for lightening, and whatever it supported was bolted at what is here the top ends of the legs, and when it ripped apart it gave way at the holes.

Alternatively, since the holes seem to have a distinct concavity toward the right, perhaps this was some kind of guide meant to trap and lead something being inserted. The only possibility that occurs to me is in replacing the fuel scavenge pump, which is roughly the right size. But I don't find that at all convincing.

At any rate this is another example of the size of debris at the tracks. Compare this to the image I published last release:

https://ibb.co/kCQQ7m

The newspaper editor would have selected the most impressive image the photog brought back. So these can be taken to be representative samples, and it matches the reports saying the track debris was in shreds.

The plane had a 67% fuel load. The wing tank would have exploded like a water balloon when it hit the embankment, and the planking would have torn into individual sheets or partial sheets.

By elimination, all I can come up with to explain the large object on the tracks is to say it's engine four.

[Concours77]

As to first pic, I would say motor mount. The relief holes are needed because the casting is heavy, and the two "attach points" just seem consistent with motor mount.

The second pic looks like nacelle. The Electra nacelle is quite long, and the structure looks like longeron and skin structure.

[BRDuBois]

I wasn't able to get a good enough view into a nacelle to see it. Motor mount makes sense. The reduction gearbox is supported by two struts on each side, but I don't know what's directly under the power unit.

If we can identify it as that, then it's proof engine four was left at the tracks and therefore the 35 degree bank.

[BRDuBois]

I uploaded an image from the LEAP program, showing the new engine mounts. I don't see anything that looks right, but this is not a real detailed illustration. The back upper mount seems like the best match.

https://ibb.co/c2Gh3R

[G0ULI]

The piece of debris being examined appears identical to that next to the standing man in your earlier pdf upload. I suspect it is part of a wing rib from near the wing tip. I appears heavily distorted and folded into three by impact and tearing forces.

[Concours77]

From your image, I may want to revise. The structure being observed by the kneeling man might by one of the gear box side mounts. If first impact was made at the tracks, Right wing low, it is likely the propellor contacted first, tearing away the gearbox, mounts, and nacelle skin. I don't see a wing tip in the second image. Ribs and skin, but oriented in longitudinal, not horizontal aspect, suggesting nacelle, not wing (tip). Also, I see a robust, cast object that has a circular attach point showing, something I would associate with a torque link, amidst some torn skin. We might be looking at the ring that constitutes the forward (circular) frame, mounting the gear box/propellor assembly. With its mass, though, and energy, how could it have remained in the area it first struck at 150 knots?

The holes in the skin (in the second image) have a square shape, and are likely inspection panels, something I would associate with an engine bay/gearbox.

[BRDuBois]

appears heavily distorted and folded into three by impact and tearing forces.

I considered that too. If it's folded, it's an awfully symmetrical fold. The two legs (for want of a better term) appear to have ribs or folds in them as if to strengthen them without too much weight.

We really need an Electra/P3 airframe guy to weigh in here.

[BRDuBois]

how could it have remained in the area it first struck at 150 knots?

Because it hit a sloped embankment, killing forward momentum and translating any remaining inertia into a more or less vertical bounce.

[BRDuBois]

Ok, what about the womans purse and stretcher on page 41, what is the source for those?

Good catch on the purse. I had originally included an image that I later left out. I've uploaded it.

https://ibb.co/gQ5aOR

It was probably done as a human interest shot.

The stretcher is the one on page 72.

I noted these images on the Site image just to give the reader some context, to help them relate the images to the overall surroundings.

[BRDuBois]

If I were to hazard a guess I'd say your first image in post #187 is a piece of spar with the partial remains of two ribs attached, the holes in the ribs being lightening holes. Anyone is just shooting in the dark trying to assess what such an object may be, and mine is similarly nothing but a wild ass guess on which I would not place money.

That was my initial thought. The ribs are 7.5" OC, and that looks about right to be the distance between those uprights. The only place in the ribs that has holes of any kind appears to be the leading edge, with holes for the de-icing piping. The remainder of the ribs have diagonal bracing all the way back. But the cutout for de-icing is much larger and not at all circular. It's really up for grabs, which is why I put it out for opinions.

Here's a drawing of the leading edge.

https://ibb.co/b1k1f6

Re the object on the tracks that you suggest is an engine - I'm in complete agreement with G0ULI that it definitely is not an engine, but a piece of wing skinning.I understand that finding engine four there seems pretty unlikely; I don't fault anyone for thinking it's something else. Paraphrasing Sherlock, if you rule out the impossible you're left with the truth even though it seems improbable.

Looking at the impact scar (page 41) and the scar across the railway tracks could you please explain what it means in terms of angle of bank. The video supplied by cordwainer is illustrative in this regard as well.Nothing on page 41 says anything to me about the bank angle. Proving the bank angle from the railroad track comes from solving the riddle of engine four. The speed was judged from prop strikes on the track. If engine four was lost at the track, the prop must have been number three. Since the right wing was intact nearly to engine four, prop three can't touch the ground at anything more than about 35 degrees.

[BRDuBois]

I was corresponding today with Omar Hayat Khan in Pakistan, who has done some really nice T56/501D illustrations. He doesn't think this looks like a motor mount.

[Concours77]

I utilize a device in forensics that promotes theory, no matter the fallout.

Investigations take too long. Why? Generally because they proceed based on fossilized methods of inquiry.

Instead of waiting until the conclusion is "inescapable", the use of imminent analysis encourages all present to think, quickly, and forensically.

The piece is quite obviously ribs, likely because of their proximity to each other, outboard on the wing, and may be in the leading edge domain.

The piece has other characteristics. The gross shape suggests a symmetry found in mountings, "U-shape". Relief of material to save weight, but depending on the resolution of the photography, it also appears heavier than rib material (thicker).

In considering and rejecting discussion, not only is progress attained, but an encouragement to think outside the "box" is instructive.

We do round tables, no opinion is judged, instead it is objectively evaluated.

Many opportunities to find the truth are lost in waiting for the solution to "appear". It is a process, not magic.

[BRDuBois]

It's much too heavy for ribs. The only place that makes sense (to me) in the leading edge would be directly under the engine. The rest of the leading edge needs large cutouts to let de-icer air recirculate and exhaust. This object has one small hole below that large broken hole on each leg, too small for much air to move. Compare that to the material removed in the leading edge image I posted above.

Under the engine it might support the de-icing duct that makes a Y there, or support the overwing cooling duct. Neither of those feels right, as I said earlier, because the pipe would be passing through the hole.

Here's a head-on view of an Electra showing landing lights. It might be a bracket for those. That would be right at the edge of the wing destruction.

https://ibb.co/fvc4Hm

It feels like some kind of bracket or stand-off. Something related to ailerons perhaps, but I don't have the relevant manual sections.

Not sure whether you're funnin' us with your forensic theory diagnostic tool description. Got a name for that?

[Concours77]

On the LEAP image showing the new braces. Give the side mount for gearbox a long look. I can almost see the Delrin doughnuts. Look again, visualize the brackets and brace with snubbed bolted beds, and see if you don't like the similarities?

[BRDuBois]

I see what you're saying; it's not a bad fit. Problem is, that's in the forward cowling and they don't open that for routine work. I can't find a picture anywhere. Got lots of pictures with the side cowl doors up.

ETA: Here's a fairly poor image from a training manual. The trainee drew in the LEAP modifications. I don't know if LEAP changed the mounts, never saw a mention of it. Anyway, you can see the structure is a possible fit.

https://ibb.co/etY8Sm

[Concours77]

I am thinking the debris is the forward vibration isolate. Are you saying it is aft? Also, isn't there a bottom cowl panel to allow drainage for gearbox servicing?

Something to consider also, whatever it is, the shorn remnants were subject to extreme loads. My supposition is that from the data, the impact was borne by the propellor and transmission? Is it your belief that the blade ruts were from number three?

[G0ULI]

What if the wing tip outboard of engine four was the object left lying across the railroad tracks and the prop strikes were from engine four before it too broke away?

Would that significantly affect your calculations of bank angle as the aircraft crossed and came into contact with the embankment?

That seems a more probable chain of events.

[BRDuBois]

Concours77 - I was agreeing it looks sort of like the forward vibration isolator. They can get into the cowl from several directions. From the maintenance images I've seen, and from the manuals, the sides are what they always open up. Going further might require just some more quick screws, but the garden variety maintenance always shows the sides up. I've never seen the forward cowl off an engine that's sitting on its mounts.

I am strongly persuaded that the prop hits on the railroad track were from prop three. There is a bunch of circumstantial evidence that four was torn off at the railroad, and what I'm looking for now is the smoking gun. Evidence includes the missing engine puzzle referenced earlier, the amount of damage to the tracks which looks to my novice eye like more than a wingtip would do, the large object on the track, etc.

G0ULI - I frankly don't recall whether the engine four or the turning radius epiphany came to me first. Evidence for the 35 degree bank is in the Lockheed map of the path, in my attempts to reach anything higher that were fruitless with respect to that location on the field, and in the forward sliding scenario as opposed to the impossible CAB cartwheel. Finding engine four somewhere else, and finding that prop four made the divots, doesn't change the bank angle. But finding that engine four was torn off at the track would certainly be the kiss of death to the high bank.

The best evidence against the large object being wingtip is that it would have been featured in the papers. They went with the most spectacular bit they had, and that was something the size of a crumpled rug. If the wingtip were left on the track, a team of half a dozen guys could move it to the idle track and the RR would be back in business. If the engine were left on the track, the RR would have called in a crane and flatbed and loaded it up and rolled it away, leaving small stuff for the photog to find.

[G0ULI]

Which is kind of the point I was making. A largish object is photographed across the tracks and appears to have been removed from that location very quickly. There does not appear to be any photographic evidence of the type of heavy equipment used to lift rails, repair or realign the track being used. That would have taken a while to get to the scene and remained for some time while any work was completed. This does not appear to have happened, which suggests that the damage done to the track was insignificant as far as affecting trains running along the lines. Railway repair work and the heavy equipment involved generates some good photo opportunities which would not have been missed by journalists at the time.

So we are left with the conclusion that whatever was left lying on the tracks was fairly large, yet relatively light weight. The tracks suffered no damage sufficient to cause them to be relaid, so impact with the angine and gearbox can effectively be ruled out.

We can be certain that some part of the aircraft struck the embankment because of debris left on top. Prop marks show that at least one of the engines was turning and developing power.

I suggest that the evidence indicates that it was engine four that created the marks and that the force of the propellors striking the embankment in addition to stresses caused by the wing tip being torn away, caused the engine to separate from the wing in advance of the rest of the aircraft impacting the ground. That would account for the engine being found away from the rest of the aircraft. Everything else could be exactly as you have described it. The bank angle would have been significant, certainly in excess of 30°, but likely less than 60° because the aircraft would have stalled into the ground earlier at that angle of bank.

[BRDuBois]

Picking up a hunk of debris and hauling it away is a matter of twenty minutes or so for the RR guys. They do this kind of thing all the time. As for straightening the track, here's an example of what trains can manage:

https://ibb.co/cBrdUb

You've seen the picture of the Chicago and Western track after the crash. The distortion is about 6 or 9 inches to one side. Pretty trivial. It registers the amount of force involved, but as soon as the RR inspectors have had a look they realize this is navigable, if one can say that of a RR track. They'd tell the trains to reduce speed a bit until they fixed the track.

As long as they got the engine hauled away before the photog got there, what's to take pictures of? Alternatively, where are the pictures of the relatively intact wingtip?

The plane's stall angle in a bank was about 63 degrees that day, by the way. They were descending not because they were in fact stalled, but because they were feeling the shaking in the controls and knew a stall was near, and they were fighting to keep the speed up by keeping the nose down. Rolling left, close to recovery, they ran out of air.

[BRDuBois]

It's far from incontrovertible, but I understand your point. There's not enough detail on that embankment to be sure where the wingtip hit.

If it was indeed prop four that left the tip strikes across the track, I agree the engine could not have been left lying there.

[Concours77]

megan: "From information provided I calculate the point of wing tip contact is some 14 feet below the top of the embankment. The impact scar from the wing is as near vertical as can be estimated (ignoring dihedral), and the scar across the railway lines is vertically above the wing tip point of contact ie the angle of bank was pretty much 90°, and backs up the CAB statement, “about 85°”.

Haven't seen the wing impact evidence on the embankment, and apologize for being late to the discussion. If the impact scar was caused by a wing, the angle would depend on the velocity of the wing tangential to the obstruction, no? An embankment has a grade, what was it? A wing has dihedral, and a heading, plus a velocity of its own. Those are a lot of factors to be considered to arrive at a conclusion "the wing had a ninety degree aspect at impact".

I may be way too behind to merit comment here, but my initial queries would include:

Did the pilots have aileron command? Was the Rudder operating as designed? Were the pilots trying to gain directional control by differential thrust? If there was a severe vibration before impact, was its origin determined? Collecting serial numbers of each propellor blade, was it possible to recreate the path of each?

Having experienced Whirl Mode on an early Electra as pax, abeam the wing, I can testify to the alarming behavior of wing/power plant. It would have been an extremely difficult recovery in normal flight, let alone one hobbled by inop ailerons. What about walk around, controls checks? Depending on the orientation of the prop strikes, would it be possible to determine if the power plants were even still attached prior to impact? Had one separated prior to impact would certainly explain inversion of the airframe.

[Concours77]

Hi Megan,

Incontrovertible. No such thing, sorry. Maybe in 101.

From the aerial, I can make a supposition subject to evidence re the embankment scar.

1. If the wingtip, there is no possibility propellor ruts would be symmetrical. (allowing a GS calc...)

2. If the wingtip, there is not enough mass to disrupt the rails to such an extent.

3. If the wingtip, the width of the scar would be much narrower, the scar is too wide.

4. Supposition. Number four experienced catastrophic mount failure, was hanging low, and tore up the embankment prior to wing contact.

From the audio: "have you...." (Feathered four?) "we cannot recover the right roll"

5. How were the aileron cables and boost reconstructed to determine a "fatal flaw"

6. What was the argument that supported two months of aileron duty as serviceable until the fatal launch?

7. Could Lockheed have survived another aircraft loss due to engine mount flaws?

8. Clear your mind, look closely at the scar, and give your consciousness respite from "incontrovertible".....

Best regards,

Concours

Craig: "The plane's stall angle in a bank was about 63 degrees that day, by the way. They were descending not because they were in fact stalled, but because they were feeling the shaking in the controls and knew a stall was near, and they were fighting to keep the speed up by keeping the nose down. Rolling left, close to recovery, they ran out of air."

The aircraft was crossing the ground at 160 knots. What was the wind? If you dismiss the radical roll angle, you should question your consideration of Stall? If so, we need a source for "shaking in the controls...." "Rolling Left, close to recovery...." Does this contradict the CVR "cannot recover the right roll...." Final words, "have you...." (?) this interrogatory suggests a belief in recovery, however remote. My best guess given the controversy here as to roll angle might be "have you feathered four?"

BTW. If Propellor hit first, and included the powerplant (it would), it becomes clear the wing tip may have risen immediately. Why? Once integrity of the spar is lost, all the lift being generated by the wing outboard of #4 instantly lifts the outer wing, clear of the embankment...

[BRDuBois]

Craig: "The plane's stall angle in a bank was about 63 degrees that day, by the way. They were descending not because they were in fact stalled, but because they were feeling the shaking in the controls and knew a stall was near, and they were fighting to keep the speed up by keeping the nose down. Rolling left, close to recovery, they ran out of air."

The aircraft was crossing the ground at 160 knots. What was the wind? If you dismiss the radical roll angle, you should question your consideration of Stall? If so, we need a source for "shaking in the controls...." "Rolling Left, close to recovery...." Does this contradict the CVR "cannot recover the right roll...." Final words, "have you...." (?) this interrogatory suggests a belief in recovery, however remote. My best guess given the controversy here as to roll angle might be "have you feathered four?"

Wind was negligible - 6mph out of the south, so crossways to the flight path. The mental model I've been developing is that the plane was in a fairly high bank which they were getting under control in the last few seconds. By no means do I dismiss the radical angle; I just think they weren't still at that angle when they hit. My somewhat long explanation for this is at

http://www.pprune.org/accidents-close-calls/571018-help-researching-1961-electra-crash-7.html#post9539907

I will be expanding on this premise in the next release. I think the physics are a little like an engine coming over top dead center. If there's pressure in the cylinder it moves very slowly until it gets a few degrees from TDC and then it can snap very fast. Same thing with a rock rolling off the flattish top of a hill - once it hits the slope it goes fast. I suspect the plane was sort of balanced in a high bank until the rudder started to bite, but once it bit the plane was rolling left fast. The flatter the plane got, the faster it would flatten. 35 degrees was totally flyable, after all, and not even close to a stall at that point.

My video attempting to recreate this is at https://www.youtube.com/watch?v=D4_b1ekxKkY

With the 93,000 gross weight the stalling speed in that temperature and altitude was about 110 knots. At 63 degrees the stall speed hits 160 knots. There is no stick shaker; the Electra crew sensed turbulence on the elevators as the wing airflow starts to separate. So they would have felt a mushy response and shaking, and they were guiding down to try to keep the speed up.

There was no CVR. The voices were captured on the tower radio recording.

[Concours77]

Whatever the flight path, it is secondary to momentum. Mass continues in its path unless acted upon or hitting an obstacle. The "acted upon" (command) seems to be without sufficient authority to alter the flight path, but in this case, the momentum seems to have been consistent with obstacle, or impact.

The recent example of low speed, near Stall grief is Asiana at SFO. It is remarkable how quickly an airframe can respond, but remember size and mass are deceptively at odds in large aircraft.

The triple seven rotated immediately in the horizontal when the right main gear hit rocks at threshold. This acceleration of the aircraft caused a violent wing over, and these folks were immeasurably luckier than those on your Electra.

Another exemplar might be FedEx at Norita. The MD11 oscillated emphatically until the right wing spar collapsed, and the aircraft rotated violently with the (resultant) massive asymmetric increase in AoA.

Prolly no yaw damper on the Electra? I certainly agree most crew would be actively on the Rudder to control heading and roll.

So you mesh pre Stall buffet with control yoke oscillation? At ninety degrees roll, there is no lift at all, save that reserved for heading! Rudder becomes elevator at knife edge. I don't see that, there is far too much forward travel. Dropping at that rate I would expect a smoking hole, not so much linear advance?

BTW, thank you for such a measured and intelligent discussion.

[BRDuBois]

At ninety degrees roll, there is no lift at all, save that reserved for heading! Rudder becomes elevator at knife edge. I don't see that, there is far too much forward travel. Dropping at that rate I would expect a smoking hole, not so much linear advance?

That's my opinion, but I'm not a pilot. That's why you're here!

The Electra can't knife-edge fly until it gets to about 250 kts. My simulator video is at https://www.youtube.com/watch?v=2JiGSJ5xPQg So at 90 degrees and 160-ish kts we're talking about pure ballistics, and it would drop like a rock. I graphed that on page 24. But Lockheed measured a 5 degree slope from the power lines to the embankment. That sounds like a landing with no flare.

[Concours77]

Flight 706 in knife edge? The eyewitness claims he saw a wing fall out of the clouds, then seconds later, a fuselage with wing attached?

A five degree glide slope is survivable. And impossible with the reported roll angle. At a ground speed of close to 200 mph (I find that hard to believe), we are talking pure fantasy.

If 90 degrees roll angle and Stalled, she has also already spun, and wants to get on her back. That is completely incompatible with the debris trail. IMO.

Cartwheel? Certainly possible, but I am missing some important evidence.

[cordwainer]

Um, not sure if these will help in identifying the debris, but I came across PDFs of a few Lockheed L-188 Electra Field Service Digests (from 1958, '59 and '61), containing detailed descriptions, drawings, and photos of airframe, flight control system, power plant, etc. The originating Brazilian site is ad-infested and somewhat sporadic, so I've copied the files to:

https://www.dropbox.com/sh/7zhhl0jxu78eg9x/AACHsYcT0wjAZErJtjxxnEeWa?dl=0

for easy download.

c

[BRDuBois]

Thanks cordwainer, but none of them will open, Acrobat says they're invalid or broken. What's the site? I'm willing to wade through the ads.

[G0ULI]

The documents open just fine using an iPad.

[booke23]

Opened fine in Google Chrome too.

[BRDuBois]

I see what happened. My initial downloads were interrupted, so the files were unreadable. Downloaded again, got everything fine. Unfortunately, it turns out to be three I already had! Thanks anyway cordwainer for your work, I appreciate it.

[Concours77]

Craig, If you have the time, I'd like to ask some questions.

1. Your video. During T/O roll, Did you intend to show the aircraft drifting off centerline to the right? If asymmetrical thrust, would that explain? Aileron would not have caused this drift, IMO.

2. Never more than 300 feet AGL, why did the aircraft initiate a turn so soon? If related to the aileron issue, wouldn't the crew have input left Rudder immediately? If in an unrecoverable right bank, and the immediate turn has to do with this, I would expect an immediate mayday? If a thrust issue, the pilots may have been satisfied trying to sort it before making a call?

3. Is there additional discussion, either in the report or elsewhere about "there was a change in the sound of the engines?"

4. Could you direct me to any data relative to the impact on the railway berm? Was there exhaustive inspection of the area between power line sever and wing tip contact on the gravel ballast? Were carbon tracks found anywhere on the debris material indicating high voltage contact?

5. Is there professional analysis of the presence of internal engine bay material so close to initial impact?
It would seem unprofessional to leave out identification of the telltale piece we think might be motor mount/vibration snubber?

6. Wouldn't you consider the collision with power lines to be "initial point of impact"?

7. If the a/c was incontrovertibly in ninety degree bank, and falling rapidly, why would the debris field not be closer to the tracks, but displaced further forward? This would tend to put in jeopardy the "ninety degree bank" conclusion?

Though these questions may have been answered in the report, my purpose is not to correct or defend a flawed report, but to seek the truth.

[BRDuBois]

Concours77,

1. The slight drift is an artifact of the way it's flown, no meaning intended. The simulator does not fly the aircraft in a goal-seeking process, guiding up to reach a desired altitude, banking right to a desired bank. The simulator is under the control of a scripting program I wrote which simply replays control inputs that were recorded from a prior run. I wrote an editing interface, and I tweak the script until I get the results I want. The simulator has a built-in randomizer to make the world seem more realistic, so each flight has tiny variations. It's the electronic equivalent of launching paper airplanes. The result is like a shotgun - a closely grouped set of results, no two quite the same.

2. The turn was planned that way. They had no idea they had a problem until they tried to flatten the bank. By the time they saw there was a problem, they were in a bank somewhere over 20 degrees. This was I think a fatal circumstance not mentioned as a contributing factor in the reports. If the aileron had become unresponsive in level flight, they would have been fine.

3. There were several comments in newspaper reports. At the time this was a subject of intense discussion. It is baffling to me that it was never addressed in the reports, considering the contemporary discussion. The reports say the engines were turning and delivering power, but there's no confidence that it was full power. Still, the speed was about right for that point in the takeoff, and it was the excessive bank that made the speed critically low. Equally interesting is how low they were. The reports say they were slightly low, but they were about half the normal altitude, which is also never really addressed.

4 and 5. I have no other information on the berm or debris. This is why I keep looking for investigation documents. My sister has some experience with document retention policies, and she's sure the investigation documents are still around. But no one gains a thing by releasing them to me, or acknowledging to me that they exist. There's always the possibility of liability issues. A reopening of the investigation would shake them loose, of course.

6. Don't see that the label matters. It's possible the power lines interrupted what may have been an incipient recovery. None of the power line pictures show indicator globes between the poles, planes weren't supposed to be there, and it's probably a safe bet that the crew never saw them.

7. The debris should have been closer and the right wing should have been obliterated. Compare to the Argentine crash on page 63 and watch the video linked there. I don't think a near-vertical bank is credible for several reasons.

I'm currently working on some CGI software to help visualize all this.

[Concours77]

I would have wanted more attention paid to the powerlines in the day. If the poles are at sixty feet, how high were the lines? (Sag). This is important, it bears directly on the fligh path and impact orientation....

For obvious reasons, a departure turn can't be initiated until deemed safe, or by rule (noise abatement). Was there "maintain Runway heading to "x feet" then make right turn to _____?" From the video, the turn was early, very. Even if well known to the crew, ATC would be required to command the proper procedure. I would have been alerted to a problem before the non responsive left inputs, due to lack of climb rate? Unfamiliar with Electra, but wouldn't right rudder have accompanied right aileron? Any tendency to skid would have been noticed immediately, and the unfamiliar (Un-co-ordinated inputs) controls would also have been an alert (sluggish response in roll "correction?")

From the photographic evidence, the displaced second impact argues strongly against extreme bank angle. Simply balancing the (reported) ballistic calcs would be fatal to the ninety degree value postulate, IMO.

What persuades you to suggest pilot input Nose Down? If no extreme roll, no pre Stall buffet? Hence no need for nose down. I am intrigued by the "shaking control column". How do we know this?

I am aware that if the aircraft did not experience extreme right bank, and the impact is the tip of the right wing, we are obligated to entertain a wing already broken?

[BRDuBois]

The tower had already approved what they called a "toll road departure" which is apparently local jargon for an early right turn. Probably because it lines up with Irving Park Drive being the tollroad in question, but that's a pure guess. So they were turning as permitted.

Right rudder would have been automatic, due to an interlock between the rudder and control yoke. It's spring-loaded so it can be overcome. I'm told it's common to not touch the pedals on many flights/planes because this interlock gives the right degree of rudder for turns. There was no hint of unresponsive left input until they actually tried a left input when turned far enough right, and then nothing happened. At that point they had about 22 seconds left in the air.

I think they were experiencing pre-stall buffet and that's why the nose was down (as witnesses reported). The stall angle at 160-ish knots was about 63 degrees and they were close to 60, so (speaking as a non-pilot) my understanding is they would have felt the shaking. What I look for here is feedback from pilots to tell me if I'm on the right track.

They were absolutely in an extreme bank, in my view, and were rapidly recovering from that when they ran out of altitude. When they hit the embankment at about 35 degrees, that was a highly transient state.

[Concours77]

What I meant in the rudder/aileron coordination would be as the roll kept increasing, the rudder would not have kept up, since the ailerons were locked in a certain position? As the roll kept increasing, the aileron setting would not have matched with yoke position, and the uncoordinated controls would have felt "skid dish" on the cheeks. IOW, the airplane would have signaled an aileron problem before they tried to recover. Also, they would have selected a specific roll angle, the aircraft roll would need to be "stopped" at a certain value, and held in neutral aileron to acquire a smooth and consistent turn rate. I don't buy that the pilots were unaware of the problem prior to excessive roll, they would have known something was wrong when they selected an angle to sustain, tried to stop roll, and the bank kept increasing....follow? But even before that, the skid would have alarmed them.

If unresponsive in roll, the Captain would have instantly retarded the thrust levers on the two port side power plants. There would have been a very powerful turn to the left, and any rudder selected by the Commander would have easily overpowered the "linked springloaded" roll design....problem solved.

He May have also selected Nose Down, but the immediate roll left would eliminate the pre stall buffet?
At one hundred feet, Nose Down would be a last resort?

Unless, the starboard power was compromised in some way, by engine failure. If power (thrust) on the right side was compromised, any turn to the right is trouble.

[cordwainer]

As always, this may be data you've already found, but just in case not:
Though NTSB does not have CAB archives prior to about 1965, there is a section of CAB Records in the National Archives at College Park, MD, details at
https://www.archives.gov/research/guide-fed-records/groups/197.html
197.3.5 Records of the Office of the General Counsel references "aircraft accident investigations, 1952-64", as well as some contemporaneous records related to liability and litigation which, though a longer shot, might include pertinent material.

By the way, concerning the existence of retained records, I noticed you wrote above in one post, "...no one gains a thing by releasing them to me, or acknowledging to me that they exist. There's always the possibility of liability issues. A reopening of the investigation would shake them loose, of course."

As someone whose work involves quite a lot of research, I think you are right to be cynical...but I think you're cynical about the wrong thing.

Realistically, none of these agencies or companies has anything to lose by releasing archived records from a closed, 55-year-old, well-publicized public investigation. But I began my research from a point of cynicism as to whether some of the people you contacted for information really knew what they were talking about. Or if they pointed you in another direction just because they didn't want to be bothered. Both are a lot more likely than them trying to hide something or stonewall you.

To be fair, I'm sure the intentions of most were good, and they genuinely believed they were giving you accurate information. But as you've seen, some of those records exist in public archives despite assertions to the contrary.

Loss of institutional knowledge is endemic, especially after half a century. Most likely there's just no one left at the agencies/companies or their successors who has first-hand knowledge of where old records ended up. And there's more stuff out there no doubt in collections of personal papers and correspondence of the various executives and investigators. The Chicago Tribune now sells old photos from its archives, so you may be able to get a clear print of the track debris photo...albeit not for free. Lockheed's website contains references to all documents from California being moved to their warehouses in Marietta, GA when the CA facilities closed. Someone must know what's in those warehouses, given the number of scholars, researchers, and scientists still writing about Lockheed's role in aviation history, and those interested in every aspect of the various Electra versions. Etc., etc., etc.

In other words, your sister is right. Don't give up. We have not yet begun to search :-)

[cordwainer]

These 3 files together may clarify the early right turn and the meaning of "toll road departure":

https://www.dropbox.com/s/gkc2m29h0kjjdm5/departure_routing_description.jpg?dl=0
https://www.dropbox.com/s/724jm9z8mgpzlci/arrival%20departure%20chart.jpg?dl=0
https://www.dropbox.com/s/uurh7m9oatzrcxm/Expressways_1961_OHare.jpg?dl=0

The "departure routing description" is from an April 1962 O'Hare master plan analysis, based on operations information from "...late Fall or early Winter of 1961."

Note the paragraph beginning, "Departures to the south...", particularly the last sentence: "Formerly, this routing was circuitous--aircraft proceeded via Victor 172, Victor 429, and Victor 38 to Peotone."

If I'm reading the chart correctly, in September 1961 the "circuitous" routing might have been the reason for initiating the right hand turn - toward V172 in the direction of V429, and thus toward the Northwest Tollway which V172 roughly parallels. Irving Park Rd/Route 19 is not a toll road, the Tri-State Tollway is in the other direction, and the newer "direct southerly routing through the Midway vector area..." surely wouldn't require first turning that much to the right?

Could the circuitous routing have been changed partly as a result of the accident, considering the investigation would still have been in its early stages? I.e., was the early turn itself, at some point, implicated as a causal factor?

As always, hesitant to interpret or make suppositions, as a non-pilot, so please feel free to swat me if all this is irrelevant.

c

[BRDuBois]

Thank you for the routing information. I'd wondered about it, but never heard that the turn itself was thought to be a contributing factor.

The National Archives did a search of the CAB documents. They said all they had was the final report.

I've been working on a graphic/animation tool to help illustrate and visualize. I installed an Electra and am exploring how to use it. Right now it's bare metal, still working on getting the NWA paint on it. I intend to replace some of my pretty primitive drawings with better ones.

My initial project was to pose it in proper scale on the picture of the RR tracks. Boy, now that I see it in scale it's real hard to imagine anything more substantial than the wingtip hitting. The software has not yet output an image. When I get that working I'll post it.

[BRDuBois]

Concours - I understand what you're saying. This is why I want to hear from pilots. The interlock between the ailerons and rudder doesn't actually link them directly, it's a linkage at the flight station. So if the ailerons deflection doesn't match the control inputs, the rudder won't hear about that, so to speak.

[BRDuBois]

I've put up a composite image of a low and high bank impact at the tracks, with a computer model Electra approximately to scale.

https://ibb.co/ctkqEb

This isn't evidence or anything, just intended to help visualize.

[Concours77]

Hi cordwainer.

Here: "Realistically, none of these agencies or companies has anything to lose by releasing archived records from a closed, 55-year-old, well-publicized public investigation. But I began my research from a point of cynicism as to whether some of the people you contacted for information really knew what they were talking about. Or if they pointed you in another direction just because they didn't want to be bothered. Both are a lot more likely than them trying to hide something or stonewall you."

I must disagree. No matter the length of time involved, any reopening of a "cold case" brings with it the possibility of civil and criminal litigation.

Why? Because in the US, there is no limit to prosecution or litigation IF it can be reasonably demonstrated that there was fraud in any official testimony related to the incident. Fraud can be demonstrated easier than one may think, since even an "innocent" representation that is false might be construed as fraud.

I most certainly am not trying to suggest there was any thing improper in this investigation.

[Concours77]

Concours - I understand what you're saying. This is why I want to hear from pilots. The interlock between the ailerons and rudder doesn't actually link them directly, it's a linkage at the flight station. So if the ailerons deflection doesn't match the control inputs, the rudder won't hear about that, so to speak.

They couldn't be locked directly, that would involve a "disable" switch and in an emergency, no one wants to create risk because Lockheed thinks the aircraft needs to have co ordinated turns "at all times"....any deviation from expected turn behavior would have alerted the crew to a problem, perhaps it was the initial clue for your Dad?

I brought up the early turn earlier. I base my thought on your video, which shows the aircraft turning at extremely low altitude, and since the Electra never exceeded 300 feet AGL as testified to by ATC, one could conclude it initiated a turn at an altitude barely equivalent to its wingspan. "Wind Shear" was not well understood in 1961, but subjecting a passenger transport to ground contact due to an itinerant "down draft" was on every pilot's mind.

BTW, such a shallow climb on departure would catch ATC attention, for sure. More evidence the flight path was not actually consistent with the reported "understanding" of it by the report. More evidence of that reposes in the ALPA statement the Electra was "nearly inverted".... Were there witnesses who saw the actual impact?

[BRDuBois]

The rudder and aileron aren't locked, it's just a spring-loaded link that takes fairly moderate force to overcome. Somewhere in my manuals I probably have more detail.

They were very low, and the reports' glossing over this puzzles me. They were at about half the typical altitude when they passed the tower. I understand the Electra takes off like a reusable rocket, compared to piston planes of the day. Speaking as a veteran Electra simulator pilot, it was hard to keep the thing low and slow. :)

I'm confident the CAB was cherry-picking witness statements. At the point where I say the bank started reducing, the CAB concedes that the rate of increase might have briefly stopped. I think that was their concession to voices who they decided to more or less dismiss. In my simulator run I showed what the same flight would have looked like from different viewpoints, and only someone pretty straight-on to the path would have seen the flattening from a distance. No one in the immediate crash area was quoted in the papers.

I don't know how thick the trees were between the RR impact site and the tower. Page 172 shows a clear line between the tower and the and the RR track in the direction of the final wreckage, but I don't know that they could see the RR impact site. My 1960 construction picture https://ibb.co/krms0w seems to match the ground appearance on page 172, and it shows a block of possible trees just east of the impact site. So the visual contact might have been lost to the tower there.

[BRDuBois]

Starting to work on modeling the site, using the elevation lines to contour it. Figured out in the model where the Trib page 19 picture was taken from by trial-and-error on the model. The Trib picture, my recreation, and a shot of my work surface are at https://ibb.co/cR1GAG (https://ibb.co/cR1GAG)

This will let me precisely locate trees and wreckage on the topo map. You can validate the result by clipping the recreation view, making it half transparent, and floating it over the Trib image. In the image of my work surface, the camera is the orange triangle thing. I have a couple other images to use in the same way.

Found a couple errors in my document. On page 35 I thought the station wagon was on the train tracks and we were looking at a berm on the embankment. I realized after modeling the site that there is no berm, the vehicle was on the access road, and the picture was taken from the west side of the top of the embankment.

On page 41 I thought a white line running diagonally from the service road to the center left was a measuring tape, with investigators apparently standing along it. I suspect it's a crowd control tape, and the people there are onlookers.

[BRDuBois]

I've been curious about the space between the trees on the sides of the crash path. It didn't look wide enough for the plane to get through, but I presumed it was an artifact of my perspective. So plotting those trees was a primary interest in doing this virtual scene.

I've posted an image at https://ibb.co/kjvsvR

This shows the trees plotted using the graphic mentioned in the last post. The airplane is to scale and is positioned at ground level. There's not enough room for the plane to fit through there either nose- or tail-first, even lacking a substantial part of the right wing. It could conceivably fit through sideways, since the forward fuselage was missing by that time. Interesting.

ETA: image https://ibb.co/g83Fnb is a close-up of the gap, composed from film frames. No trees appear to be lying down or damaged. No obvious branches on the ground.

[G0ULI]

Two points to mention regarding trees. The first is that any reasonably stout tree will resist any vehicular impact with the only damage being some stripped bark which regenerates in a few months. I have personal experience of this, revisiting the same tree to write up multiple accident reports over several years,

Secondly, if the aircraft was already banked over at a significant angle, it would pass through the gap in the trees without making contact with either side. That would be in agreement with the findings of the original crash investigators who believed the aircraft hit the railroad embankment with a very high angle of bank.

Perhaps this is the basis of the somersault speculation.

Your investigations have certainly helped to fill in vital gaps in the investigation reports curently available, but they also increasingly tend to support the findings of the original investigators in many ways. I find that rather reassuring in the sense that the crash investigation appears to have been conducted with all the care and diligence expected given the tools, methods, and equipment available at the time. Professionalism at its best. Just like today, the press reports appear to be full of inaccuracies, speculation and a certain amount of sensationalism. Gilding the lily a bit to sell more papers perhaps.

The true story may not be ending quite how you wish it to be, but it is certainly proving to be a most interesting journey through aviation history.

[BRDuBois]

I don't want it to end any particular way, though I understand people think I do. It's obvious the CAB got it wrong, and I want to know what happened. My goal is to come up with a scenario that survives criticism by apparently knowledgeable people and fits what facts we have or can reasonably deduce.

The significant bank is possible. In my document I suggested the plane was in a right bank due to the loss of part of the right wing. A bounce high enough to clear the lower trees, particularly on the north side of the crash path, is possible. Too soon to say, at this point.

If the wing spar could shift a pair of railroad tracks six to nine inches over a distance of twenty feet or whatever, I think it could take out a nontrivial tree trunk. The Constellation crash tests chopped phone poles. Beyond that, don't know about the tree damage. My working assumption is that the plane didn't hit them.

I've got a decent NWA paint job on the plane, so I can do some better illustrations for the next version. I'm working on additional vantage reconstructions to nail down locations on the map.

[G0ULI]

From the photograph, I think it is safe to say that no substantial part of the aircraft contacted the trees on either side.

There are three possible reasons;
the aircraft was at a high angle of bank as it passed between the trees
the aircraft bounced over the trees after initial impact
the aircraft somersaulted and pivoted around the trees in some way

A fourth option that should technically be considered for the sake of completeness is that the trees were not in the path of the aircraft. I think this can be safely ignored after fairly cursory examination of the evidence.

A high angle of bank would be the the simplest conclusion that fits the other observations at the scene. A turning (twisting) and bouncing somersault would also fit with the final disposition of the wreckage, especially with the nose section broken away. Certainly a combination of the two is possible, accounting for the tail ending up facing the direction of travel.

A simple wings level bounce over the trees is the least likely scenario.

A lesson learned from accident investigation, avoid hitting earth banks and trees. Neither will give an inch in a collision so if the structural damage doesn't get you, the instant deceleration forces certainly will.

[BRDuBois]

The CAB got it right, and you're barking up a tree I'm afraid.

The CAB said the plane slid right side up and tail first. The plane was upside down and tail first. The CAB got it wrong. Simple as that. Your steadfast refusal to confront that fact tells me much. The questions then are: What else did they get wrong? How did the plane get into that position? How much of what the CAB said do we have to discard before the remainder makes sense?

Orientation of the aircraft at initial impact is obvious, but it doen't fit with your object of making your Father a hero by nearly pulling off a forced landing narrative.My object is to find out what happened. My dad is my hero regardless what this accident turns out to be. That's pretty normal, actually. He was a terrific guy. The drive-by psychoanalysis is typical and boring, but I understand it and am not offended. It's a pity that the instant psychoanalysis often cuts off thinking about the actual issues. I'm willing to follow the evidence wherever it leads. Your snap judgment makes that impossible for you to do.

All my previous posts deleted, and this is the last.That's unfortunate.

You've contributed two substantive ideas. First, that the bank angle would have left a mark on the wing when it hit the power line and that the power line breaks if measured would also tell the angle. Neither is mentioned in the reports, and your conjecture doesn't make them evidence. Second, you said the wingtip would have left a mark in the embankment. Since the image quality is too poor to make it out, we don't know what that mark was.

Beyond that, you object to this project because I'm not a licensed crash investigator, which is quite true. My most intense familiarity with big planes comes from paying part of my college by polishing the bellies of NWA jets. This put me on intimate terms with the underside of an airplane, which is probably why I could detect that the plane was upside down, a factoid that eluded the professionally trained CAB investigators.

You also objected because the people who wrote the report are no longer here to defend it. Presumably this would forbid the study of history as a whole, and I dismiss that objection entirely.

You're my favorite contributor. You've hated this project from the start, and if anyone was going to find flaws in it that person would be you. You've never posted anything here that I wasn't pleased to see.

"Nothing in life is so exhilarating as to be shot at without result." Winston Churchill

[akaSylvia]

I don't want it to end any particular way, though I understand people think I do. It's obvious the CAB got it wrong.

I find it amazing that you can't see the contradiction in your own posts.

[BRDuBois]

I find it amazing that you can't see the contradiction in your own posts.

Please state a contradiction.

[BRDuBois]

For those who haven't read my report, I'll make it easy.

https://ibb.co/d7dk26 is page four of the CAB report, saying the plane slid tail first and upright until it stopped.

https://ibb.co/kvz8N6 is a press photo of the main wreckage, showing the plane is upside down. If it's not immediately obvious to you, note the position of the main gear. It retracts forward from the main spar, and the brake lines which are behind the wheels end up below the main strut when retracted. You're looking at the bottom of the wing, and the leading edge is to the left.

There it is, real simple. Either the plane is NOT upside down, or the CAB is wrong. Take your choice.

Once you accept that the CAB is wrong, the questions are: How did the plane get there? What else did the CAB get wrong? How much of the official reports do we have to discard before what's left makes sense?

[BRDuBois]

For the purposes of this discussion, let's say it rotated in some fashion about its vertical axis as it slid. This of course means the CAB was wrong in saying it slid tail first the final 820 feet.

So now it's at a stop after sliding 820 feet upright. How did it flip over? Note that the leading edge is facing back the way it came and it's still tail-first. If it slid tail-first and upright, when it flipped over the wings had to swap left-for-right. If it slid nose-first and upright, what flipped it after it stopped? Any guess how that was done?

I appreciate your enthusiastic defense of your fellow investigators, but at some point it seems like reality should start to impinge.

[Concours77]

From the final position of the a/craft.

The wingbox is intact, the main spar is intact from outboard #2 to outboard #3.

The tail section appears to have remained partially attached.

The V/S is intact save for crumpling at its peak. The HS are intact.

And the structure is upside down. I don’t see any ruts consistent with “slide”.

There is a long rut at a bias of about sixty degrees to the structure, but it is continuous on both sides, and appears to be man made.

There is wing structure visible outboard of both MLG, and upper cowling of #3 is present next to the wheels of Starboard landing gear.

“Sliding” would appear to be not supported by the photographic evidence IMO. The tail cone would be corrupted extensively, and the orientation of wing box/tail would similarly have been less suggestive of structural continuity.

What I see would suggest that this wreckage had been airborne just prior to impact at this location. In other words, it flopped onto the ground, it did not slide.

As to CAB, I think it is a reach to have concluded the cause of this accident within hours of its occurrence. Their text on page four suggests that a turn was initiated while the aircraft was still on the ground. It also suggests a climbing turn. For that to have occurred as they describe, the maximum altitude attained would have had to have been at least twice that of what ATC testified to.

Also, from page four, it states five witnesses report a change in “engine noise” as the turn was initiated.
There would be NO reason to change thrust this early in take off, unless there was something else going on. “Noise abatement”? Doubt it.

The Electra has thrust levers, not throttles. Engines maintain approx. 13000 rpm. What they heard is likely a change in propellor pitch. Most turboprops make far more noise with the propellors than engines.

Five witnesses? Remarkable. If the aircraft was on runway heading when the turn initiated, and altitude was as low as reported, Why the concurrent noise change? A change in heading absent aileron means a thrust problem. Gearbox? Pitch pressure? The aircraft would be at takeoff power, so a change in noise might indicate engine trouble. Not even addressed by CAB.

My first inclination having this data would not be aileron malfunction. Loss of thrust on the right side? In any case, without discussion, CAB concluded the cause virtually immediately. Right side aileron was determined to be in three degree up, (wing down) post crash. Three degrees is one third of aileron deflection available without boost, in manual. Maximum aileron in boost mode is over thirty degrees.

Pretty weak in roll command. At first blush, not nearly enough to have caused this accident...

[Concours77]

Short of rejecting CAB’s conclusion, what is important is conduct, incomplete analysis, and a rush to judgment. How many cable sets command boost? What is suggested by testimony of change in noise level? It doesn’t take a dunce cap to associate change in noise level with lackluster climb. Why is boost off done by mechanically pulling a handle, which loops a continuation of pressure? Why not switch off the electric pumps? No chance of jamming the boost off handle, no need to move the wheel to alleviate a stalled piston?

Not exactly an exhaustive investigation.

[BRDuBois]

Some thoughts on interpreting the final wreckage image at https://ibb.co/kvz8N6

When I first noticed the crossways ditch, I thought it was something the farmer dug. This was some kind of squash/pumpkin patch, and the reports mention the wreckage among the squash. But the ditch doesn't seem to collect from anywhere or debouch to anywhere. There are no other ditches in the area.

Perhaps the farmer dug a ditch that has a slight dogleg that matches an Electra dihedral. Perhaps he dug it where a plane would crash a few days later. I can't prove it one way or another. If anyone wants to weigh in on that, have at it.

But let's hypothesize for the moment that this was an artifact of the crash, and let's see where that hypothesis leads us. This is how science is done.

Let's say the plane was sliding nose-first to its final destination, and as it slowed it was digging into the soft ground. As dirt built up ahead of it it would tend to dig in even more. As the weight of ground slowed it, the tail would start to kick up, sort of like a car hitting a retaining wall. At some point the tail would pitch over.

If the ditch were dug by the leading edges, it would have roughly the plan it does. But it shows no sign of dirt scooping from the left side. Instead the ditch is quite symmetrical, near as we can judge. So if the ditch was caused by the leading edge, the leading edge was coming down from some height. It need not have been coming down vertically, but it must have been coming down at not much more than the slope angle of the left wall of the ditch. Let's say 30 degrees for convenience.

Here's an experiment you can safely do at home. Take a kleenex box and put it on the desk in front of you, and imagine some line at which the sliding plane would scoop enough dirt that it would hit the retaining wall and start to pitch over. The box long side is the fuselage long dimension; the short side is the fuselage width. Slide the box until it hits the retaining wall point and tilt it over. It briefly stands on its short side, and then tilts on over to rest on the cabin roof.

The box is now as far from your retaining wall line as the box is tall. If you assume some skidding it might be farther, but it can't be less. The top of the cabin is a fulcrum on which the fuselage will rotate, and the more intact the cabin the farther from the ditch it will land.

If you like, chop a bevel in your kleenex box to simulate a partially collapsed cabin. The box will end up not quite so far away, but still well clear of the ditch. If you don't want to tear up your kleenex box, it's all illustrated on page 54 of my document. https://we.tl/beXUsgYPvX

In the image in question, the only way for the plane to end up athwart the ditch is for it to bounce into the air. The cabin height is 13 feet. This means (if the ditch is an artifact of this crash) that the plane bounced at least 13 feet into the air.

What drove this bounce? Electra wings are notoriously stiff vertically. This plane had been through the LEAP program so they were even stiffer. I have no data on fore-and-aft elasticity of Electra wings, but I'm prepared to say they had virtually none. But the main gear was present, the inboard nacelles were stripped, and the main gear seems to my untutored eye like an adequate explanation for the bounce.

So I conjecture that the plane came down at an angle, the wings cut the visible ditch, the main gear bounced the plane back up at least 13 feet, as it continued to pitch over.

I don't know the angle it came down at. It might have been near vertical, it might have been anything down to the slope angle of the ditch left wall. I doubt it could have been much less, but depending on the dirt collapse it is unclear. The issue here is not how high the plane was as it descended, but how much energy it had. It need not have come down from more than 13 feet in order to bounce 13 feet.

This tells me the plane arrived at the final site not by sliding but by some aerial trajectory of mostly unknown specifics.

If anyone would like to propose an alternate explanation for what we see, I'd be delighted to hear it. This is simply what the picture says to me.

[Concours77]

Hi....

But there is a fence post in the ditch six feet East of the landing gear. At the bottom, and vertical. It even has a sign on it.

The ditch is a gulley, with a neat and narrow trench at its bottom. The trench is six inches wide, the spar is almost two feet.

The trench was supposed to get a pipe laid in it, likely for water.

The gulley is almost two hundred feet long. What was left of the wing at this location was no more than fifty feet in span. How did the wreckage miss the fence post but carve a continuous gulley through it?

The wreck may have slid. If it did, it was heading whilst upright, heading forward. The wheels fell into the gulley, and the assembly “pitch poled”, landing upside down, “facing” South. Tail on its VS.

In the last fifty feet of its journey, there was little energy left, that disappeared as it rotated end for end. Then it caught fire.

[BRDuBois]

I took it for a piece of debris embedded in the ground. Hard to see someone digging a ditch and then putting a post in the middle of it, or digging a ditch and leaving the post. No other posts in the area.

https://ibb.co/dixuVR is a closeup of it. No sign.

If it predates the crash it shoots down my hypothesis, of course.

[BRDuBois]

Gotta go run errands, back later.

https://ibb.co/nN6UVR is an image of the left wing. The report said it was broken in two places but was present at the final site.

[Airbubba]

The Electra has thrust levers, not throttles. Engines maintain approx. 13000 rpm.

Actually, on the L-188 they are power levers with output measured by torquemeters. And the constant speed props had synchronizing and syncrophasing. They were all the same speed and rotated with each blade crossing the wing at about the same time to reduce harmonic effects in normal operation.

So, as you observe, a change in acoustic pitch of the prop noise would be unusual in normal operation.

[Concours77]

Gotta go run errands, back later.

https://ibb.co/nN6UVR is an image of the left wing. The report said it was broken in two places but was present at the final site.

Hi.

It appears to be a 4” x 4” post, quite old, given the checking at the top. Very old lumber. Perhaps a property marker, or old enough to warrant saving it as a “signpost”. I swear I saw a metal sign at the top, bent in two....

[Concours77]

I took it for a piece of debris embedded in the ground. Hard to see someone digging a ditch and then putting a post in the middle of it, or digging a ditch and leaving the post. No other posts in the area.

https://ibb.co/dixuVR is a closeup of it. No sign.

If it predates the crash it shoots down my hypothesis, of course.

See my response above, with the left wing pic.

[BRDuBois]

It appears to be a 4” x 4” post, quite old, given the checking at the top.

You're right, it does. It looks like charring, actually.

[Concours77]

You're right, it does. It looks like charring, actually.

It does, and likely from sloshed fuel as the aircraft flipped.

Airbubba:

Thanks for the clarification.... the witnesses report seems important, and should have been chased down and examined.

1. “At 8-9000 feet down the runway, the sound changed...”

2. Where were these people located? Doppler may have made a difference.

3. If a mile away, there could have been a five second delay in sound travel.

4. The aircraft may have been at 5-6000 feet down the runway.

5. At 160 knots, how much distance need we allow for?

6. Never having climbed to three hundred AGL, any turn that low would have been important, and when associated with power level changes, the initial “turn” may not have been aileron inspired?

7. Looking at pictures of the aileron command cabling. As shown, these cables can not “unthread”, they are retained by a threaded collet, which prevents twisting either direction. The collet itself is threaded, pinned, clipped and safetied.

8. A loss of boost, or locked boost, in and of itself, can be overcome manually after disabling the pumps.

9. Surely switching off the electric pumps should have been on the memory items?

10. If the aileron was indeed at three degrees on impact, when did it return? Was it under manual control? At what point?

[Concours77]

“As I mention in the document, one reason for putting this out is to see if I can shake some old documentation out of the tree. Some old airline employee or investigator may have something. The National Archives has nothing. Maybe some bystander with a Brownie camera has pictures. Some of this material probably still exists, but I see no path to it except this document and word of mouth......”. BRDubois.

Wasn’t the CAB folded into the FAA? If so, it was, is a Federal agency....

Records of this type of accident are not allowed to be destroyed, IMO.

The FAA will almost certainly have all the data. To get the data requires a filing of FOIA request. “Freedom of Information Requests” are not difficult to file. If the FAA demures, a lawsuit will encourage the release.

I state this in the interest of explaining that our government works for the people. One needn’t demonstrate a need for the data, it must be made available to those who request it.

[BRDuBois]

The cable was threaded into a turnbuckle of some kind, but the safety wire was never inserted. They found it after the crash with no wire and no soot marks indicating a wire had been there. I can't attest that this was a valid finding of the root cause, but I'm not at this point questioning it.

As I went through the simulator runs I was increasingly questioning the crew's response. That's an uncomfortable feeling. It seems to me that faster left rudder would have gotten them out of it. I'm still pondering this. The next release will have a lot of material about simulating the flight.

When the CAB was folded into the FAA, all the CAB files went to the National Archives. The Archives verified this, and did a search for all records on this crash. They said there was nothing but the final report. I'm not averse to filing legal motions as needed ...

[BRDuBois]

Ok, I submitted an FOIA request. Huh, never did that before. :)

[Concours77]

I see the assembly not as turnbuckle, but shackle, there is a difference. A turnbuckle is used to take up slack, not necessary when the cabling is constructed as “lockclad”. In any case, one lead loosening in a turnbuckle tightens it’s counterpart. I have a picture in the manual.

The attachment of the command cable is made by threading a swaged terminus into a collet, which is placed into the opening of a shackle. The collet is then locked into the leaves of the shackle with a pin. The end of the cable can not rotate. If you are familiar with “push pull” controls, you would know that the cable resists “spinning”. The entire length of the cable would “Flemish” into a coil, which is not possible.

Cable slack is addressed specifically by Lockheed with this (patented?) cladding.

[Concours77]

With the testimony of five separate witnesses as to noise, we assume something of importance was happening as early as liftoff. It may have been a closing of the power levers, an attempt to reject takeoff. That this noise signature apparently coincided with a “turn” is potentially the key to what happened. Losing boost, or boost locked controls are trained in this type exhaustively, that is why the unlocking/relocking of boost levers is at the base of the pedestal, with the takeoff checklist demanding the access flip door be open on launch. I am wondering why the pumps are not shut down as part of the procedure?

[BRDuBois]

After the main body impact, which detached the engines that hadn't already gone, I guesstimate the plane was about 25,000 lbs lighter and the CG was moved aft maybe twenty feet. I'm tinkering with the simulator (which has a provision for designing your own planes) to see if I can model this.

[Concours77]

Hi. After loss of #4 and the wing area with it, wasn’t the next impact the remainder of the right wing? The main wing spar excavated a ditch deeper than the surrounding wing structure? Next impact was the forward fuselage?

Not sure what CG change would do. Why is that important? The structure is not an airplane any longer? All control lost, everything is ballistic?

I understand your investment in establishing an accurate debris propagation. To support your theory of “reducing bank and attempting a belly landing”, I draw attention to the orientation of the right aileron in its pocket when the right wing tip impacted the rising portion of RR embankment.

There was a crushing scar on the outboard face of the inboard pocket rib. Since the embankment was the first ground impact, we can say that the evidence found is at least as worthy as the gyro horizon face, indicating ninety degrees Bank. It is legend to invest sacred truth to obliterated structure, “it impacted at 9:01, that’s where the hands of the clock were....”.

This scar was left by the Alclad hem of the lower skin of the right aileron. It showed the aileron was deflected three degrees in the up (wing down) position. That tells me that not only was roll control regained, but the ailerons were deflected manually, with the three to one mechanical advantage the design afforded. If CAB theory is correct, no such finding can be made. Aileron Control was not totally lost, and they were not “along for the ride”.

Somebody show me a turnbuckle. Make a case for “unthreaded cable”.

I do know Lockheed designed the tankage to minimize CG variation with fuel consumption. The fuel was oriented span wise.

The Electra was a groundbreaking design. I don’t buy the theory that absence of a safety wire brought this aircraft down.

http://dotlibrary.specialcollection.net/Document?db=DOT-AIRPLANEACCIDENTS&query=(select+732)

Instructive, but still “the cable unscrewed”. I believe this is a myth. Aircraft cables are robust, and cannot rotate, twist, or unscrew from a threaded connector.

[BRDuBois]

I've wavered on what they might have been attempting. A pilot friend said the plane was doomed to hit, given the aileron deflection. But the rudder can easily counter that aileron, at least per my sim runs. I've phrased it as trying to moderate a descent, trying to at least manage a belly landing. My latest sim runs tell me the 35 degree bank is a highly transient state, and at their speed it should have been easily manageable even with the ailerons still stuck at three degree deflection.

My take on it at this point is that they were descending to keep from stalling, which they would have felt in the higher bank angle. As they got the bank reduced, the danger of stall would have dropped to nothing. So they were trading height for speed when they needed to, and were transitioning to level flight and climbing right about the point they hit the high tension lines. This is what my flight recreation shows.

https://youtu.be/D4_b1ekxKkY

The point is, they were not trying to do a belly landing, they were trying to stay in the air. It merely LOOKS like a belly landing gone bad, because they ran out of altitude, possibly exacerbated by hitting the power lines.

[BRDuBois]

I've discussed this before, but let me recap the rudder issue and knife edge flying. The Electra can knife edge fly at about 250kts IAS. At anything less, the rudder cannot depress the tail against the airflow to lift the nose and cause the fuselage to act as an airfoil.

For any given speed under 250kts, there is some angle at which the rudder can just barely hold its own against the airflow. At any lower angle the rudder can counter the bank and roll the plane level. At any higher angle the rudder is insufficient and the plane will drop its nose. Sim runs tell me this angle is about 60-65 degrees at 160-ish kts. In contrast to knife-edge flying, I call this bevel-edge flying.

My Dad was at about a 57 degree bank at about 160 kts with a rudder whose bank-countering functionality was degraded to just about nothing. They didn't know that; they never trained for it; no one trains for this. But once the rudder took hold and the bank started to flatten, the rudder would have increasing effect. A full left rudder at a 60 degree bank is nothing at all like a full left rudder at 35 degrees. Once the bank starts to flatten, the effect of the rudder will increase exponentially.

This is a little like rolling a ball along the crest of a berm. Once it starts to move to one side or the other, it will accelerate quite quickly. As long as it's on the crest, it might stay there. And simulating this particular instance requires quite a long run along the crest, which then exponentially cascades. I hope that's not too obscure. What it means is that my chances of replicating this with the simulator are virtually nil. I can animate it, but I doubt I can simulate it.

[Concours77]

I’ve run across some text in the report that raises some questions, potentially very important.

At what point along the trail did the cockpit area separate from the main structure(s)?

I don’t think the aircraft can fly without its right wing, and if #4 plus its supporting wing area impacted at the RR tracks (at an angle) and separated, the next structure to impact would likely be the forward fuselage? Did the fuselage separate? At what station?

Thanks

edit. The video and your description of the Rudder activity show a forward slip. Without aileron, the Rudder must be accompanied with reduction in power on the port wing. The forward slip is a maneuver generally used to lose altitude.

edit’. From the doc. “......Although both mechanics testified that they checked each other's work after completion of the installation, neither one could recall having made a specific cheek (sic) to insure that the previously loosened cable connectors were properly threaded into the slack absorber terminal blocks, the cable tension checked, or the connectors resafetied.....”

Edit’’. From the report, no actual separation of cable from Boost Quadrant was found on pilot’s side. On Co-pilot’s side, “the cables and pertinent structures were not recovered.”

Conclusion: no actual evidence of command cable separation was found. That makes the CAB’s implied finding a THEORY, not a finding of fact....

[BRDuBois]

The nose hit about 380 feet past the railroad embankment. The cockpit was crushed and the forward fuselage broke off just in front of the wings. The forward fuselage traveled perhaps a couple hundred feet. What arrived at the final site was the entire left wing (badly fractured), the remains of the right, and the empennage complete.

[BRDuBois]

Here's a very informal demo. https://youtu.be/QG83qxtxLnw

I've subtracted 25,000 lbs and moved the CG 20 feet aft to adjust for the loss of the engines and the forward fuselage.

I have not actually altered the graphic to show the forward fuselage or engines as missing.

It starts in level flight at 140 kts. It travels roughly 800 feet past the starting point. This is not an animation, it's the flight simulator.

[Concours77]

The nose hit about 380 feet past the railroad embankment. The cockpit was crushed and the forward fuselage broke off just in front of the wings. The forward fuselage traveled perhaps a couple hundred feet. What arrived at the final site was the entire left wing (badly fractured), the remains of the right, and the empennage complete.

I thought that was how it developed. I have a remarkable postulate, but I need to spend some time assembling it. I think I have CAB in another gross blunder.

[BRDuBois]

Wish I had the list of the 22 errors NWA sent to the CAB. Even allowing for corporate efforts to minimize legal or face damage, there must have been something there.

[Concours77]

It is likely N137US was released to service with aileron slack. The stainless threaded connector on the pilot’s side was “backed out” of its attachment to the brass junction. Nevertheless, the CAB found all cables attached on the pilot’s side, even though the tensioner side of the flexible cable had but 1/2 inch engagement. Lockheed's test of tension on the aileron connections produced a severed Stainless cable, at 2,000 pounds.

No information on the (connections) valve side of the tensioner, but it was continuous. Loose cabling is suggestive of removal of boost valve and boost unit in the shop. The valve end, a swaged ball fitting, is assumed to have its keeper in place, or the CAB would have noted it.

Without more information, including shop logs, boost unit assembly replacement protocol, and other schematics, we are left to critique the CAB. The actual work in design, maintenance, repair, and design considerations of aileron systems cannot be judged, no data to support any criticism is available.

Lockheed did simulate a fouled aileron, and analysed force required to overcome a trapped aileron, (trapped in this case by the wing flap). A reasonable theory of entrapment could flow from a scenario where the flap, being retracted after lift off, contacted the aileron and pushed it up, creating wing down. If the flap then jammed, the wing is producing a right turn, and the flap is creating chronic drag, perhaps the cause of low angle of climb, and lackluster airspeed. The flap would have contributed to right yaw, especially if the left flap had stowed.

[BRDuBois]

Lockheed did simulate a fouled aileron, and analysed force required to overcome a trapped aileron, (trapped in this case by the wing flap). A reasonable theory of entrapment could flow from a scenario where the flap, being retracted after lift off, contacted the aileron and pushed it up, creating wing down.

Would entrapment necessarily mean physical contact, or do you envision the possibility of flap airflow impacting a somewhat slack aileron and pushing it to a wing-down position without directly contacting it?

[Concours77]

The ignorance on display here is staggering.

Well. Lockheed thought it important. Had I known of your experience surviving an impact with power lines, I’d have embellished your rank. My comment had to do with post impact “realignment” of aircraft wing structures.

[BRDuBois]

I've modified the sim model to remove the forward fuselage and engines. In my prior demo the forward fuselage was there, but I'd removed its weight along with the engine weight. The fact that the fuselage was still there meant the sim calculated airflow around it, and this apparently led to the high somersault the sim showed. The sim treated it as being very long and light. With the forward fuselage missing, the plane flips much more quickly and stays lower to the ground. This might barely have showed over the trees, and may have contributed to the cartwheel myth.

https://youtu.be/YKQES3UJiiM

[Concours77]

It is not ignorant to be skeptical. Occasionally damage can occur on the ground prior to take off. Once in a while, a truck will damage an airframe, once in a while an aircraft will impact a tug, or food truck. Extremely rarely such damage goes unnoticed, and can affect flight.

“Both flaps at takeoff setting” is interesting. The term “both flaps” is also interesting. Here, the report takes into account the possibility that flaps may have not been set symmetrically. Hence “both flaps”. In your confidence, you have assumed what you consider to be complete knowledge. You missed that. You also missed the possibility of damage to the flap, likely impossible to ascertain post crash. Lockheed did not miss it. They spent time and not insignificant cash to exonerate fouled aileron.

I think I am within plausibility. My comments, though suggesting rarity, are not ignorant, because they do not suggest impossibility. IMO.

[Concours77]

No it doesn't, it just says the outboard flap jack was removed, presumably to see if the twist imposed by airloads was sufficient to cause interference with the aileron.

Thanks megan.

I’d like to offer a definition, one I post without researching, iow, from memory. Would you read it and comment? Thanks.

Safety wire: Safety wire is used extensively in aircraft applications. It is a “Fail safe” component, added to existing structure to prevent “catastrophic failure”.

Is safety wire a part of the structure it protects? Yes. And No. If a safety wire’s presence prevents a fastener from falling completely off, has it done its job? Absolutely, yes. But, is the structure safe for flight without a safety wire attached? Practically, yes. Administratively, NO. If the safety wire prevents loss of a fastener, the system is already assumed to have failed.

If a safety wire is not installed as it should be, what part of the structure secures the threads? In the case of cabling, an adjusting nut would be tightened to the correct tension, and a serrated washer and locknut would be added. This assembly is considered safe, as part of the “design consideration”. The structure is fully functional without the safety wire. Can the aircraft be released to service without the safety wire installed? Yes, but not legally, unless a waiver is secured.

Thank you again, I’m here to learn.

[G0ULI]

Just to reinforce what megan has stated, the nuts and bolts are tightened to a design torque as specified by the manufacturer of the aircraft. The safety wire is then inserted to guarantee that the specified torque is maintained, i.e. the nut and bolt cannot slacken due to vibration or other influences such as temperature changes. The safety wire is the only indication that the nut and bolt, turnbuckle or whatever fastening is at the correct tension.

So while technically a correctly tensioned nut and bolt are theoretically capable of withstanding the physical aerodynamic stresses imposed, the slightest turn without a safety wire in place will place that connection outside the design parameters. It is then unsafe.

A browse through the air accident investigation archives will reveal many accidents caused by missing locking wires, particularly relating to engine components on light aircraft.

Vibration and thermal cycling are the main causes of threaded connections coming undone. Both are present in all aircraft during flight.

[Concours77]

Gents,

My example is of the double nut variety, something I presume was part of the tensioning shackles on the Electra.

A turnbuckle is a different animal than a shackle. In your example you show a turnbuckle with only safety wire preventing rotation of the barrel, (not the cables). So the wire is not technically a “fail safe”. It is the primary (and only) part that prevents disaster, if the barrel rotates.

I would ask if it has been your experience that threaded ends of control cables routinely wander out, or in, disrupting tension, and potentially causing separation? Mine is that if the barrel of any cable system is fixed, stranded Stainless cable can not rotate about its own axis. If both ends are attached, the cable is rigid in respect to torsion (twisting). To rotate a cable end with its opposite end still attached is not possible, certainly not for the purpose of removal.

I think the implication in the final report of 706 is that the co-pilot’s aileron command cable separated. The implication being that a safety wire’s absence prior to flight allowed the cable to rotate, unthread, and separate, causing the disaster. If safety wire was the sole retainer, that might be possible. If a true “safety wire” (fail safe) system, then it cannot have “caused” the crash. It can only be said that “it failed to prevent” the crash.

Semantic? Certainly. My assumption is that the tensioner was double nutted, a design sufficient to secure the cable. A safety wire may have been a part of the design, but my doubt is that the safety wire was the sole retainer of the cable. Hence, “fail safe”.

In any case, I believe the report mentions that none of the specific parts could be recovered, making proof impossible.

A similar cause of loss of aileron Control would be the “jammed” boost unit power arm, or seized piston. The unit was found, and showed evidence of seizure of piston or jamming of power arm. The conclusion was the seizure was caused by fire damage. What steps were taken to determine the aileron boost unit was not seized prior to launching, or final right turn?

To arrive at a probable cause involves not only supporting the theory, but eliminating all other possibilities?

Questions:

What angle of right aileron deflection was discovered on the power arm? Was it three degrees?

After unseizing and replacing the piston, the boost unit was serviceable. So the cylinder was not damaged by fire? Just the piston?

The pilot’s Control cables were found to have continuity, but lacked a safety wire. The co-pilot’s controls were not found, but they certainly must have been missing the safety wire? Why? Because there was no safety wire on the pilot’s set?

[BRDuBois]

I've put up a video showing the CAB scenario of the plane sliding backward and right side up to the final wreckage site.

https://youtu.be/yJa8yue_B7U

This video gives some feel for the scale of the site. The trees are placed a little better than in my earlier graphic, and I used three aerial views to position them. It's increasingly clear that the plane could not slide on the ground between those trees without cutting down a significant swath of them. The backward slide, of course, was always a little nutty.

I did not try to show the damage to the plane in this series of clips - the loss of the forward fuselage and the loss of the right wing tip. You'll just have to imagine it.

This is an animation tool, not the flight simulator. I'm having a little trouble with the paint job on the plane - the tail should be red.

[G0ULI]

I would suggest that as the nose impacted the ground and broke away, the forward part of the fuselage remaining dug in and inertia carried the rest of the aircraft up and over and into an inverted backwards slide.

The important thing to realise in relatively high speed impacts is that while the forward part of a vehicle (aircraft in this case) may come to a complete rest, the remainder of the vehicle is still moving with essentially the same forward speed and inertia. It is this phenomenon that causes bullet splatter with small projectiles, crumple zones to work in motor vehicles and substantial parts of an aircraft fuselage to split away and carry along a debris track from the initial impact site.

Think in terms of dropping an extended slinky spring onto the ground. The bottom of the spring hits the ground and comes to a stop, while the top, or tail end of the spring is still travelling and accelerating downwards.

It takes a finite time for energy to propogate through a structure. In the case of the slinky spring demonstration, the majority of the energy is actually provided by gravity, not by the spring attempting to contract.

The nose breaking away is an indication that this section stopped almost instantly while the inertia of the remainder of the fuselage was sufficient to flip and slide a considerable distance further on.

Your video assumes and essentially wings level initial impact of the fuselage section with the ground. I suggest this is inaccurate and a substantial bank angle was maintained after contact with the railroad embankment. That is the only way the aircraft profile would have been able to pass between the trees. It is also more likely to result in the tail section being upside down and facing the direction of travel.

The aircraft could have impacted wings level, the nose broke away and then the remainder bounced and flipped over the trees, but this is a more complex scenario and therefore less likely to have occured.

[BRDuBois]

The important thing to realise in relatively high speed impacts is that while the forward part of a vehicle (aircraft in this case) may come to a complete rest, the remainder of the vehicle is still moving with essentially the same forward speed and inertia. It is this phenomenon that causes bullet splatter with small projectiles, crumple zones to work in motor vehicles and substantial parts of an aircraft fuselage to split away and carry along a debris track from the initial impact site.

Yes, I describe it this way in my document.

Your video assumes and essentially wings level initial impact of the fuselage section with the ground. I suggest this is inaccurate and a substantial bank angle was maintained after contact with the railroad embankment. That is the only way the aircraft profile would have been able to pass between the trees. It is also more likely to result in the tail section being upside down and facing the direction of travel.

This is my attempt to show what the CAB explicitly posited as the impact sequence. I think it's ridiculous. The CAB said it pancaked and slid. I agree that it couldn't fit between the trees that way.

The aircraft could have impacted wings level, the nose broke away and then the remainder bounced and flipped over the trees, but this is a more complex scenario and therefore less likely to have occured.

I would not have suggested it, but for the tightness of the gap and the simulator run showing what a simulated Electra minus the forward fuselage did. I probably wouldn't have thought of it, had Concours77 not shown me the error of my own hypothesis. It's remarkable that the sim plane landed in the right attitude and within fifty or so feet of the observed location.