Curious. For context, have you ever been personally involved in an actual NTSB accident investigation?
Dale Snodgrass crash in Idaho
- Thread starter Fearless Tower
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Mantis Toboggan, MD
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Albany Tom
Sherlock Holmes - Sir Arthur Conan Doyle When you have eliminated the impossible, whatever remains, however improbable, must be the truth......
Yeah, I'm familiar. But in the real world, interpretation of data generally leads to probabilities rather than absolutes. "Eliminated" and "must" sound snappier, though.
All pilots are trained and experienced in risk management, to one degree or another. So when an incident occurs that doesn't seem to fit with currently understood patterns, it's natural for that to lead to a lot of "what if's" and speculation by pilots. As long as that's respectful, it seems like a good thing to me.
Lindberg
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If this is true, then we've eliminated suicide as a cause of the accident.
PeterNSteinmetz
Ejection Handle Pulled
WWDGS ?
dtuuri
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You are in error: I haven't rendered an "analysis". Note the caveats and question marks in my statement. "Pretty sure" is not a conclusion. I didn't enter this discussion to offer my analysis, I'm here to point out the logic faults I see in others', the same thing you are doing, in fact. Sure, cameras can be deceiving—it goes without saying, so I didn't see the need to say it. However, although the flaps look retracted as the plane turns you can see they are extended. None of the other surfaces reveal themselves that way and on impact the elevator and rudder do remain neutral despite the crash forces. That might be enough for some to come to a conclusion, but I'm only "pretty sure" what they will find. Maybe they will find the controls are in fact deflected after manipulating the exposure and contrast settings. That's why I'm only "pretty sure". You, though, seem too sure about what I'm thinking.
dtuuri
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Besides that, I've eliminated Juan Brown's dismissal of the control lock, it's still in play as far as I'm concerned.
Rushie
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Rushie
Agree, that would be extremely unlikely, maybe even the only “impossible” possibility. His verbal utterance makes clear that whatever happened, was not intentional. Other than that I don’t think anyone here has reached a conclusion. People may lean strongly to one thing or another, but nobody’s claiming they’re sure.
dtuuri
Final Approach
No, and I consider that a good thing.
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Mantis Toboggan, MD
I believe you and I use 'conclusion' differently. You have stated unequivocally that the surfaces were not deflected - you have concluded that the surfaces were not deflected [edit: and that the pilot was not able to deflect them]. I don't believe it's conclusive based on the evidence available here. We're just arguing semantics at this point, and that has no bearing on what actually occurred.
Me too.No, and I consider that a good thing.
Nauga,
evidently
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dtuuri
Final Approach
Here's the first thing I said:
In the Snodgrass video I didn't see any control deflection at the 90° bank position when the airplane was aimed right at the camera. You'd think something would be deflected if it was at all possible. So, I'm pretty sure they'll find the controls were locked. ...
That isn't "unequivocal" and isn't a "conclusion". But it's a good bet.
Shouldn't you be smokin' something in your wind tunnel instead of playin' "gotcha" with me?
Ed Haywood
En-Route
Underrated post.
Ed Haywood
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I think the discussion has been reasonably intelligent. Seems like the consensus is one of 3 possible causes:
- Gust lock
- Control system jam or failure
- Shifting load
Rushie
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Rushie
- Gust lock - yes
- Control system jam or failure - a lot of rabbit holes to go down: seat falling off the rails, torn boot at the rear stick, something falling back into the tail section, trim wired backwards or otherwise malfunctioning, seatbelt around the rear stick, something broke in the system itself
- Shifting load - yes
Capngrog
Pre-takeoff checklist
I agree, but I wouldn't rule out some sort of trim problem at this point.
Fearless Tower
Touchdown! Greaser!
Don’t hold your breath.
The POF Northrop Flying Wing crashed in 2019 (before COVID) and it took two years for the NTSB report. Their findings? ‘Loss of control for undetermined reasons’
I wouldn’t be surprised if that’s how this one concludes.
wanttaja
En-Route
I'm aware of a similar case involving a fairly high-ranking retired military pilot involved in a solo fatal. Seemed cut-and-dried to me (engine failure, plane had been aloft to the limit of its fuel capacity, no fuel found in the tank afterwards) but they took a long time to release the factual. It was kind of like they were protecting his reputation as long as they could.
Ron Wanttaja
Fearless Tower
Touchdown! Greaser!
You referring to Lex?
Rushie
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I would put that under control system jam or failure, unless, as I think someone pointed out, the trim control is reversed from other planes he had flown, in which case it would be pilot error? I don’t have time to go find that post right now, but is that even possible?
wanttaja
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Mantis Toboggan, MD
What I find interesting is that the NTSB follows a methodical process and has access to data, facilities, and subject matter experts no one posting in this thread does...but not infrequently 'we' can figure out what happened far in advance of the NTSB or even though the NTSB could not.
Nauga,
who is not in a hurry
Kenny Phillips
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Kenny Phillips
Probably 80% of crash causes turn out to be the obvious ones.
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Mantis Toboggan, MD
I worked on one that had what people not directly involved thought was an obvious cause. Some people were absolutely convinced and very vocal that a 'loss of control and subsequent impact with terrain' was due to a failure of a major component that had failed on other airplanes of this type - and it seemed to fit the narrative. Problem was, that component was not installed on the subject airplane. That info was available to the investigation team, but not necessarily to the casual but enthusiastic observer.
In the end maybe 80% are a result of the obvious ones, but that does not mean that the less-than-obvious don't need to be assessed and ruled out. That takes time. And access.
Nauga,
and a backstage pass
Capngrog
Pre-takeoff checklist
If a pilot was unfamiliar with a particular aircraft's trim control, resulting in an accident, then, yes, I agree, that would be pilot error. It's my understanding that Snort was quite familiar with the accident airplane, and, in my opinion (ALERT, ALERT, opinion being expressed here), would not have made reversed trim inputs.
It is possible for a trim tab reversal to cause a loss of control crash which I would not characterize as pilot error. Here's a link to the Aviation
Safety Network's synopsis of a fatal crash which occurred this past May 21st
https://aviation-safety.net/wikibase/262221
It's probably just me, and I don't wish to indulge in the splitting of hairs, but I've always considered an aircraft trim system to be separate from the primary control (elevator, aileron, rudder) system because it can operate (in many aircraft) even if the primary system is jammed. I guess I'm thinking of a trimmable stabilizer such as in many aircraft ranging from the J-3 Cub to the B-727 and numerous others. If the control surfaces themselves were jammed, of course the tabs would not be effective. I'll bet I'm in the minority in this opinion, so I'll concede the trim system to be part of the primary control system.
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3G
It’s not just you and we may be in the minority, but I think the FAA agrees with that that view on page 6-8 of the PHAK.
Secondary Flight Controls
Secondary flight control systems may consist of wing flaps, leading edge devices, spoilers, and trim systems.
https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/phak/media/08_phak_ch6.pdf
Unfortunately, there is a major design difference between the Bird dog and 1019b. The Bird dog has a gust lock that is wide, and with it in place, there is very little space to fit your feet into.
The 1019B, has a "streamlined" one, very narrow to the stick, and does not interfere with having your feet comfortably on the deck or rudder peddles.
The video would support an opinion that the gust lock was in place, but other factors such as steering to the runway centerline before take off seem to make that unlikely.
If the peddles can be tilted for brakes with the lock in place, steering could be achieved, maybe.
Cargo shift seems to me the most plausible cause, and the accident investigation will determine if that is true.
In another life, in the Army, as an assistant cargo loading officer, I learned that the pilots were much more concerned that we were WELL inside balance. Weight was a less exact concern.
The 1019B, has a "streamlined" one, very narrow to the stick, and does not interfere with having your feet comfortably on the deck or rudder peddles.
The video would support an opinion that the gust lock was in place, but other factors such as steering to the runway centerline before take off seem to make that unlikely.
If the peddles can be tilted for brakes with the lock in place, steering could be achieved, maybe.
Cargo shift seems to me the most plausible cause, and the accident investigation will determine if that is true.
In another life, in the Army, as an assistant cargo loading officer, I learned that the pilots were much more concerned that we were WELL inside balance. Weight was a less exact concern.
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Bro do you even lift
is it possible for someone to modify the gust lock so that it locks the controls but not the brakes?
anyone know how the control stick is "attached"? like is there a pin that goes thru the rod somewhere? what if that was removed during maintenance and not put back in and the entire control stick came out? I guess 'maybe' we'd still see 'some' amount of deflection in the controls, but who knows, just a wild arse guess.
anyone know how the control stick is "attached"? like is there a pin that goes thru the rod somewhere? what if that was removed during maintenance and not put back in and the entire control stick came out? I guess 'maybe' we'd still see 'some' amount of deflection in the controls, but who knows, just a wild arse guess.
Copy of a previous post showing the gust lock, by jpskies
Note that it does not clutter the deck, and once you are in place, obscured by your legs to a large degree.
Those fore and aft tubes in the Bird dog version are wider spaced, in the center of the space where your feet should be when sitting in the cockpit. Even entering the seat is difficult with it in place. The normal procedure is to release the lock before even attempting to enter the seat.
from jpskies:
Today I finally got a chance to take pictures of a friend's Machetti SM.1019 with the gust lock engaged and disengaged. I also take a picture of the seat rail. It's so short. I don't think any pilot would have missed removing the gust lock. Nor could the seat slide too far back. Could that be another lock or seatbelt entagled in the back seat? I heard this was the first flight after the plane was delivered. And you can see the stick position is almost unchanged when the gust lock is disengaged. I hope NTSB could find out the cause. RIP Snort!
Note that it does not clutter the deck, and once you are in place, obscured by your legs to a large degree.
Those fore and aft tubes in the Bird dog version are wider spaced, in the center of the space where your feet should be when sitting in the cockpit. Even entering the seat is difficult with it in place. The normal procedure is to release the lock before even attempting to enter the seat.
from jpskies:
Today I finally got a chance to take pictures of a friend's Machetti SM.1019 with the gust lock engaged and disengaged. I also take a picture of the seat rail. It's so short. I don't think any pilot would have missed removing the gust lock. Nor could the seat slide too far back. Could that be another lock or seatbelt entagled in the back seat? I heard this was the first flight after the plane was delivered. And you can see the stick position is almost unchanged when the gust lock is disengaged. I hope NTSB could find out the cause. RIP Snort!
Capngrog
Pre-takeoff checklist
FINALLY, a picture of the SM-1019 cockpit! Thank you very much jpskies! It looks like that control lock would be difficult to miss and would make entry to the front seat very difficult unless you entered like you were mounting a horse from its right side. I can't tell from the photo if the gust lock also locks the brakes, but I would think (guess) that it has that capability. I think we can now consign the possibility of the control lock being in place to the bottom of the "Possible Cause Pile (PCP)". Of course, the controls could have been locked due to some other condition as yet unknown. The sliding seat theory may also be pushed to the bottom of the PCP; however, neither the gust lock nor the seat slide possibilities can be totally discounted, I just think that they are less likely at this point.
midwestpa24
Final Approach
NTSB Preliminary reports rarely address any issue. They are usually just a statement of the basic facts:
On this date, this aircraft had an accident during this phase of flight at this location. ## of people were on board, ## of people survived or died. The weather was sunny, rainy, snowy, or other. FAA or NTSB personal may or may not travel as part of the investigation.
No conclusions or other details are usually included in the prelim.
Ed Haywood
En-Route
Yeah, hard to see a 70+ year old man not doing the obvious thing, which is to detach the gust lock and push the stick forward to make room to get his left leg in position.
Also, as I've repeated several times, every tailwheel pilot is trained as a reflexive action to pull that stick back to plant the tail when starting the aircraft and taxiing. Unless you want this to happen when you tap the brakes:
IMO just no way he would not know the gust lock was on. But I've been wrong before.
dtuuri
Final Approach
It was there before you joined the discussion. Here's the accident airplane's front cockpit, posted on Kathryn's Report. I don't see a stop on the visible seat rail. Pretty sure that's where the seat rail theory comes from:
Compare to the back cockpit of the same plane:
EDIT: Perusing Kathryn's Report I was reminded by a post that IF the controls are locked and you attempt controlling via the elevator trim — it works backwards.
ALSO: Someone who seems to know the Marchetti 1019 says the control lock does NOT control the brake. There's a handle on the panel for that.
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Capngrog
Pre-takeoff checklist
The first link furnished by you above, is of a photo used by Juan Brown, and as previously pointed out, doesn't show the gust lock very well. As you stated, the SM-1019 gust lock system does not lock the brakes. I found the below photo linked in a post on yesterday's (Aug. 16, 2021) Kathryn's Report. The parking brake is set by pulling and twisting the T-handle located at the lower left corner of the panel.
"FINALLY, a picture of the SM-1019 cockpit!" I guess I should have used the term "useful picture" of the SM-109 and added "front" to my reference to the cockpit. The photo of the "front" cockpit previously found in several locations on the 'net and in Juan Brown's presentation is useless in providing details of the SM-1019 gust lock system. I was praising the photos posted elsewhere by jpskies for showing clear images of the gust lock system. I should also have thanked geezer for posting the photos on this thread. Photos of the rear cockpit of the SM-1019 are not relevant to a discussion of its gust lock system. I assumed everyone knew this.
Kenny Phillips
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I have such a propeller in the corner of my music room, but I Q-tipped it in a different manner.
Rushie
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I agree. I also can’t see someone that well trained in aerobatics loading unsecured cargo and not be acutely aware of the consequences of a CG shift. Unless it was secured but got loose. I can however see where anyone would not think about a torn boot leaving an opening for some small item to get in there and jam the rear stick pivot mechanism. Was the stick removed to allow cargo?
For some reason I put a lot of weight on the fact that the tail assembly seems to show no deflection after the crash, and that is a clearer picture than when it’s in the air but still not totally clear. But I’m not ready to draw a conclusion as to why or what it means.
In any case, I have also been known to be wrong.
A Martin
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I had been considering that as well .... (pin removed from control stick) .... I know rear stick is removable ... not sure if front is.
If electrical wiring passes thru the stick some pilots or techs will take a quick look once in a while to make sure no wires are chafing etc.
A Martin
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Just to throw another wrench into the works .... if indeed it was a rearward cargo shift that upset the CofG it is unlikely the investigation could determine that with certainty.
Any loose cargo would have shifted forward in the dive and the impact would drive it even farther forward.
Does that aircraft even have a baggage area behind the rear seat ???? .... someone said they think it does but still some uncertainty. thanks.
.
Any loose cargo would have shifted forward in the dive and the impact would drive it even farther forward.
Does that aircraft even have a baggage area behind the rear seat ???? .... someone said they think it does but still some uncertainty. thanks.
.
sourdough44
En-Route
Yes, any ‘cargo shift’ would of went back firmly forward as the nose hit. There could still be witness marks or similar if it happened.
So now is it gonna be silence for 2+ years until a final report is issued? It seems often these investigations are very tight lipped.
So now is it gonna be silence for 2+ years until a final report is issued? It seems often these investigations are very tight lipped.
Rushie
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Yes I suppose if it was cargo shift they’d have to arrive to the conclusion after ruling out other causes. If they can get an idea of the mass of the cargo if it hadn’t been too destroyed in the fire, determine it wasn’t anchored, do some math involving friction factor, angle of climb and so on, you could reasonably show the likelihood it might have shifted. But maybe never conclusively prove.