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. 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]

Lockheed L-188C Electra

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]

Hard to solve.

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 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.