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trnswrld
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Tue Jan 19, 2021 1:52 pm

^^^ Remember though, statistically it's usually not mechanical failure. Since your statement is just speculation, might as well go with the most likely one and say you think its pilot error.
 
washingtonflyer
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Tue Jan 19, 2021 2:24 pm

The recovery of the FDR was several days ago. Any info on the readout of the FDR? Sudden control surface changes? Thrust power setting anomalies? Conflicting control column inputs?
 
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zeke
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Tue Jan 19, 2021 2:30 pm

washingtonflyer wrote:
The recovery of the FDR was several days ago. Any info on the readout of the FDR? Sudden control surface changes? Thrust power setting anomalies? Conflicting control column inputs?


I would expect a preliminary report to be made available within a month of the accident.
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SQ22
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Tue Jan 19, 2021 5:28 pm

When posting images please provide a link to your source unleass it is clearly marked as your own one. Thanks.
 
wjcandee
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Tue Jan 19, 2021 9:53 pm

SQ22 wrote:
When posting images please provide a link to your source unleass it is clearly marked as your own one. Thanks.


Happy to do it. Not being argumentative. But I have a question: Given that we don't actually upload the images to A.net, but rather link to them in the Editor, the link to the source is embedded in the image. So, for example, if I'm using Windows, all I do is right click on the image and select either "Open Image in New Tab", which brings up the image in a new tab with the link address at the top, or "Copy Image Address", which copies the source address to the Clipboard and I can paste it anywhere. So the source is technically already there in the post. Is what we are asked to do to add an express link below the image, using the procedure I just outlined? Thank you!!
 
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Tue Jan 19, 2021 9:56 pm

PixelFlight wrote:
[Avherald:] "The KNKT have already developed a general picture of the accident, however, need further data from the cockpit voice recorder before publishing any information."


Seems to confirm, thankfully, that they're not giving up on finding the CVR and are laying the predicate to spend $$$ to find it.
 
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zeke
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Tue Jan 19, 2021 11:20 pm

wjcandee wrote:
SQ22 wrote:
When posting images please provide a link to your source unleass it is clearly marked as your own one. Thanks.


Happy to do it. Not being argumentative. But I have a question: Given that we don't actually upload the images to A.net, but rather link to them in the Editor, the link to the source is embedded in the image. So, for example, if I'm using Windows, all I do is right click on the image and select either "Open Image in New Tab", which brings up the image in a new tab with the link address at the top, or "Copy Image Address", which copies the source address to the Clipboard and I can paste it anywhere. So the source is technically already there in the post. Is what we are asked to do to add an express link below the image, using the procedure I just outlined? Thank you!!


What they are saying if for example an image is posted from an accident report, the source accident document should also be referenced. If an image is linked to avherald, the avherald page link should also be posted. Generally speaking these original “documents” be it a pdf or webpage are copyrighted, and the correct procedure is to correctly acknowledge and attribute to the source material.

Where a link would not need to be posted is if it is your own original work.
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wjcandee
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Tue Jan 19, 2021 11:32 pm

According to the citation to AvHerald above, Indonesia is ordering the inspections of all 737-300, -400, -500, while awaiting the CVR to shed light on what the FDR shows.

Do we have a clue about the terms of the inspection order? Presumably it's not just a "you should check them really, really carefully". In theory they already do that. Here, we would get maybe a clue as to what they're thinking the issue might be, broad-brush, if we know what the focus of the inspection is. It's not anything conclusive, but it would be an interesting data point.
 
OldB747Driver
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Wed Jan 20, 2021 12:06 am

Shy of the information they seek that will confirm or exonerate the aircraft systems on the CVR, we can only watch to determine if an MX issue as performed by the company may have contributed to the accident sequence (like AA191's incorrect engine removal and re-attachment that improperly stressed the mounting pylon) or if Boeing issues a broader alert, signifying a bona fide fleet-wide phenomenon...

Reading the "tea leaves", if after reading the FDR they were more certain it was mechanical (or even most likely) it would probably already be declared for legal purposes as well as self-protection from lawsuits, but unfortunately it seems to be going in a different direction. My heart goes out to those who perished.
 
trent768
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Wed Jan 20, 2021 3:53 am

2175301 wrote:
While you are partially correct - there is a substantial difference between Air France Flight 447 and this crash - which is essential in the same approximate location as the Lion Air crash.

AF Flight 447 crashed in deep water where the bottom was essentially solid or rocky, which is easy to search and find things (even if the divers are in deep diving suits). This area has meters of mud that things sink into.


Agree. I've done a scientific diving in the nearby Pramuka Island to install an acoustic current profiler during my bachelors. It was so muddy and full of seagrass. The visibility at the time was only 1-1,5M and mind you that it was on a relatively calm day. The only thing that guided me to the proper installation point was a rope that was dragged by my friend on the boat.

I have a mad respect to all the divers who are involved in the search.
 
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Starlionblue
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Wed Jan 20, 2021 6:12 am

btfarrwm wrote:
This accident seems to have alot in common with the 2001 crash of AA587 that happened on climbout from JFK. The PCU/rudder hard-over issue has been fixed for decades. Is the rudder on the 737 large enough cause the separation or significant damage to the vertical stabilizer if given inappropriate pilot inputs?


Any airliner rudder is strong enough to rip the tail off if mishandled. The rudder is by far the strongest flight surface, because it has to handle an engine out at max thrust. For this reason, most modern aircraft have rudder limiters that decrease max deflection with increasing speed. Note that a limiter doesn't really prevent mishandling. The rudder needs to have a lot of authority, and the pilots need to be able to use it.

Rudders are certified for one full deflection, and back. Swinging the rudder back and forth repeatedly like the FO on AA587 did is a no-no.

Checking on the Boeing 737 Technical Site, the Classic does have a rudder limiter, consisting of two systems that reduce hydraulic pressure at higher speeds. http://www.b737.org.uk/theruddersystem.htm

nicocs29 wrote:
Given the steep nosedive in so little time, is it safe to assume the engines were at max or close to max throttle? Maybe they were trying to recover from a stall?

Sent from my YAL-L21 using Tapatalk


You don't need any thrust to go very fast in a dive.

Use of thrust in a stall recovery is certainly a thing. However, if you're in a steep dive with increasing speed, you already have the energy you need to recover from the stall. You don't want to add more energy and go (further) into overspeed.


polywad6963 wrote:
Speculation here...but could have the left throttle crept back to idle causing a thrust imbalance like? TAROM 371?


It is possible.

However TAROM 371 had several additional wrinkles. A known thrust lever issue, the captain becoming incapacitated at worse possible time, IMC. And the FO didn't follow rule number one: "Fly the airplane".

The holes in the Swiss cheese certainly lined up on that one.

ryanov wrote:
wjcandee wrote:
Absolutely. And that was ET's most experienced captain. Over 10,000 hours. Hand-flying to the Flight Director, he rolled straight through the heading he was turning to and apparently only corrected because the bank angle warning went off, then held the wheel in the other direction so long that the bank angle warning went off again, because they had rolled right through wings-level and were continuing into an unsafe attitude again. Meanwhile, nothing from the PM. Zero. It's almost incomprehensible, except that we know that people are fallible.

My recollection is that ET has never accepted the report's conclusions, because to do so is super-scary (and embarrassing).


Something to remember is that humans make terrible decisions and are pretty dangerous when they’re tired. I’m not sure what the actual statistics are, but airline scheduling in generally seems to be bad for sleep, and so many accidents have had fatigue listed as a contributing factor. Last time I checked, it was still a pretty significant factor in aviation, and from that accident report under contributing factors:

* The consecutive flying (188 hours in 51 days) on a new type with the absolute minimum rest could have likely resulted in a chronic fatigue affecting the captain’s performance.
* The heavy meal discussed by the crew prior to take-off has affected their quality of sleep prior to that flight.


I’m not sure what the actual statistics are, but airline scheduling in generally seems to be bad for sleep,

Understatement of the year. :D
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
cat3appr50
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Wed Jan 20, 2021 3:41 pm

The accident flight takeoff and climb performance/metrics (reference Flightradar24 data, all altitudes PA, speeds GS) up to around 10,400 ft IMO indicate an essentially nominal takeoff and climb profile. Between 10,400' and 10,900' some anomaly occurred which resulted in stopping the climb, then maintaining 10,900' for a couple seconds, and then developing into a rapidly escalating nose down pitch. IMO there was roughly around a 55 deg +/- nose down pitch at around 7,000 ft. in steep descent. This evolved in increasing nose down pitch until at around 5,400 ft. in very steep descent, the actual GS was 115 kn, indicating an around 80 deg. +/- nose down pitch, extreme rate of descent, with around -1.0 to -1.1 G's.

Flilghtradar24 data indicates that at around 5,400 ft a pull up (nose up pitch change) began. This is confirmed by the change of GS from 115 kn at 5,400 ft to 358 kn GS at 250 ft, which also likely generated around +2.0 to +2.5 G's in the pull up before impact with the ocean.

The aircraft went from a nominal climb profile up to around 10,400-10,900 ft., and then 2 seconds later at 10,900 ft. evolved into a near vertical dive and impacted the ocean (only) 23 seconds later. No data indicates a stall at 10,900 ft.
 
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SQ22
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Wed Jan 20, 2021 5:10 pm

wjcandee wrote:
Happy to do it. Not being argumentative. But I have a question: Given that we don't actually upload the images to A.net, but rather link to them in the Editor, the link to the source is embedded in the image. So, for example, if I'm using Windows, all I do is right click on the image and select either "Open Image in New Tab", which brings up the image in a new tab with the link address at the top, or "Copy Image Address", which copies the source address to the Clipboard and I can paste it anywhere. So the source is technically already there in the post. Is what we are asked to do to add an express link below the image, using the procedure I just outlined? Thank you!!


This belongs into Site Related: We do not want the embedded link to be posted but a link to the article or website where the image is taken from. Depending on the source we are also acepting "Source ...".

Hope this explains.
 
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Wed Jan 20, 2021 7:12 pm

Starlionblue wrote:
Any airliner rudder is strong enough to rip the tail off if mishandled... Rudders are certified for one full deflection, and back. Swinging the rudder back and forth repeatedly like the FO on AA587 did is a no-no.


My recollection is that there actually were dropped jaws all over the aviation industry after AA587 at the suggestion that a puny little old pilot could tear the tail off of a large airliner just pushing on the rudder pedals. I believe they determined that the FO wound up commanding rudder deflection in one direction while the airplane was still yawing back after his previous deflection in the other direction. The resulting forces on the rudder caused the design limits for the vertical tail to be exceeded. This was not a situation anyone had previously anticipated.
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Spetsnaz55
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Wed Jan 20, 2021 9:17 pm

Interesting.... faulty throttle according to a source


https://www.bloomberg.com/news/articles ... rash-probe
 
SteinarN
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Wed Jan 20, 2021 10:11 pm

Spetsnaz55 wrote:
Interesting.... faulty throttle according to a source


https://www.bloomberg.com/news/articles ... rash-probe

Well, in that case, seems a few here already have described that situation and how it might have unfoldet fairly well.
 
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Thu Jan 21, 2021 12:14 am

hivue wrote:
Starlionblue wrote:
Any airliner rudder is strong enough to rip the tail off if mishandled... Rudders are certified for one full deflection, and back. Swinging the rudder back and forth repeatedly like the FO on AA587 did is a no-no.


My recollection is that there actually were dropped jaws all over the aviation industry after AA587 at the suggestion that a puny little old pilot could tear the tail off of a large airliner just pushing on the rudder pedals. I believe they determined that the FO wound up commanding rudder deflection in one direction while the airplane was still yawing back after his previous deflection in the other direction. The resulting forces on the rudder caused the design limits for the vertical tail to be exceeded. This was not a situation anyone had previously anticipated.


A tail should never have broken off because of rudder use unless of mechanical failure unrelated to pilot control or because of loss of control. The limiters should have been designed to handle eliminate that possibipity. Was he a knucklehead for being overly aggressive sure but that's where it should have ended with an even regain of normal un-upset flight and arrival at destination not a big hole in the ground. With FBW this should be tripley so.
AB4,6 318 319 320 321 333 342 B703 712 721 722 731 732 733 734 735 736 737 738 739 741 742 74D 744 752 753 763 764 772 773 CR2 7 9 10 D91 93 94 95 101 E135 145 170 190 L10 M80 81 82 83 87 88 M90 Q400

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wjcandee
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Thu Jan 21, 2021 12:48 am

Spetsnaz55 wrote:
Interesting.... faulty throttle according to a source
https://www.bloomberg.com/news/articles ... rash-probe


This is what happens when there's no information: you get leaks of things that are pure speculation.

Reading the whole article, it is apparent that a review of the aircraft's records show that it had had some issues with the autothrottle on previous flights. That's it. Everything else is speculation. Indeed, the article, deep within it, of course, admits that investigators say that there is no evidence that an autothrottle issue had anything to do with this crash or even that there was a malfunction of it here. The leaker said that there was apparently unequal thrust being produced, but that hasn't been confirmed.

After the TAROM crash, one would think that having a hand on the throttle handles in a climb would be SOP, particularly if it was known that this aircraft had previously had autothrottle issues. (Of course, in the TAROM accident, the tendency of the left engine to reduce to idle when switching from takeoff to climb power was known, and the captain said he would guard against that, but then became incapacitated. Weird timing. In any event, one would expect the PF to have his hand resting on the throttles in the case of a known buggy autothrottle.)

This could be something else entirely. Even the possibility that they weren't using the autothrottle because they knew it had malfunctioned and didn't hand-fly properly. In any event, a simple autothrottle malfunction, by itself, isn't going to have caused this crash. To do so would involve a big contribution of the crew in terms of failing at their duties, and there's no actual, evidence-based reason to start pointing fingers in that direction yet.

All of that said, of course, this theory neatly fits the currently-known facts: investigators saw something in the FDR that caused them to ask that other 737s be inspected (without releasing what they were looking at), and said they now had what they needed from the FDR but wanted to hear the CVR before saying anything. If this was another asymmetric thrust leading to a roll and loss of control accident due to automation complacency -- straight out of Van Vandenberg's presentation which said that TAROM wouldn't have happened if the PF had just rested his hand on the throttle levers -- then what the NTSC is doing would, sadly, be consistent with that...
Last edited by wjcandee on Thu Jan 21, 2021 1:08 am, edited 3 times in total.
 
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Starlionblue
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Thu Jan 21, 2021 12:58 am

EAARbrat wrote:
hivue wrote:
Starlionblue wrote:
Any airliner rudder is strong enough to rip the tail off if mishandled... Rudders are certified for one full deflection, and back. Swinging the rudder back and forth repeatedly like the FO on AA587 did is a no-no.


My recollection is that there actually were dropped jaws all over the aviation industry after AA587 at the suggestion that a puny little old pilot could tear the tail off of a large airliner just pushing on the rudder pedals. I believe they determined that the FO wound up commanding rudder deflection in one direction while the airplane was still yawing back after his previous deflection in the other direction. The resulting forces on the rudder caused the design limits for the vertical tail to be exceeded. This was not a situation anyone had previously anticipated.


A tail should never have broken off because of rudder use unless of mechanical failure unrelated to pilot control or because of loss of control. The limiters should have been designed to handle eliminate that possibipity. Was he a knucklehead for being overly aggressive sure but that's where it should have ended with an even regain of normal un-upset flight and arrival at destination not a big hole in the ground. With FBW this should be tripley so.


I think no one really thought that a pilot would be so aggressive that it would lead to structural failure. However, the certification limits of tails were known, and the fact you could rip the tail off was not exactly a secret. It just wasn't properly emphasized in training.

IIRC both Boeing and Airbus had voiced concerns over AA's "Advanced Aircraft Maneuvering Program" training, which wildly exaggerated the effects of wake turbulence. In the sim, a wake turbulence encounter that would, in reality, have led to 5-10 degrees of roll, instead induced 90 degrees. This seemed done in part just to make the exercise more challenging. The result was pilots being trained to react much more aggressively than was warranted.

The basic rule in any aircraft with a yaw damper is that you never touch the rudder pedals except on the ground, takeoff and landing, or with an engine out.

The aircraft in question was not FBW, but FBW aircraft aren't really immune from this kind of failure. Both the A330 and the A350 FCTMs have cautions about aggressive pedal inputs. The rudder is perfectly fine with a full and aggressive deflection in one direction, and the limiter limits deflection at higher speeds. The limiter doesn't protect you from the effects of aggressive back and forth inputs.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
OldB747Driver
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Thu Jan 21, 2021 2:51 am

The flight track and a rolled back left engine are consistent; if in a right turn the left engine thrust is decreased, while the autopilot would continue to attempt to turn to the horizontal mode selected, the asymmetrical thrust would tend to pull the nose left and the right wing to rise in response to the yaw (dutch roll with swept wings). The combination of typical two-engine nose up angle climb with only half the thrust available, the high drag of the developing yaw angle with an autopilot trying to continue the right turn (further decreasing lift on the right wing) could set the stage for a very abrupt change in attitude when either the pilot disconnected the autopilot or the autopilot disengaged as it is designed to do with a stall warning prompt.

A similar thing happened to China Air 006 and when they disconnected the autopilot without adding any rudder for a failed outboard engine, the rapidness of the roll made both pilots believe the attitude indicators had both tumbled, when in fact, they all correctly indicated a rapid, yaw-induced roll.
Last edited by OldB747Driver on Thu Jan 21, 2021 3:08 am, edited 1 time in total.
 
iamlucky13
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Thu Jan 21, 2021 3:52 am

Spetsnaz55 wrote:
Interesting.... faulty throttle according to a source

https://www.bloomberg.com/news/articles ... rash-probe


Interesting rumor. I mentioned Aeroflot 821 upthread as an example of a crash involving spatial disorientation and a very rapid descent.

I did not see anything particularly noteworthy about the fact that thrust asymmetry was a contributing factor to the Aeroflot crash. However, combined with another poster mentioning China Air 006, and a little more learning about yaw induced roll, I'm intrigued by the idea.
 
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Thu Jan 21, 2021 10:38 am

EAARbrat wrote:
hivue wrote:
A tail should never have broken off because of rudder use unless of mechanical failure unrelated to pilot control or because of loss of control. The limiters should have been designed to handle eliminate that possibipity. Was he a knucklehead for being overly aggressive sure but that's where it should have ended with an even regain of normal un-upset flight and arrival at destination not a big hole in the ground. With FBW this should be tripley so.


Firstly the A300 of AA587 was not a FBW aircraft.
Secondly, as others point out above - the fin failed not beacuse of the effects of a single rudder deflection (which IS indeed limited), but the dynamic build up of increasing yaw due to the timing of the copilot's back-and-forth application of the rudder in opposite directions. Think about a kid on a swing in a playground - the kid makes the swing 'go' by applying force forwards and backwards against the current position of the swing. If timed correctly the swing goes higher & higher. Same with the copilots rudder inputs - the yaw got greater and greater with each swing side to side until the angle of attack of the fin reached the point where loads exceed the structural strength of the fin. This same scenario could happen to most if not all airliners if the rudder is mis-handled as it was.
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WIederling
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Thu Jan 21, 2021 11:58 am

EAARbrat wrote:
A tail should never have broken off because of rudder use unless of mechanical failure unrelated to pilot control or because of loss of control. The limiters should have been designed to handle eliminate that possibipity.


AA587:
A300 is not an FBW design.
Airline procedures already exceeded Airbus recomendations.
"Grobmotoriker" High Amplification pilot strongly exceeded Airline procedures.

Really kicking the rudder back and forth. limiters don't have memory. out of scope.
Murphy is an optimist
 
trnswrld
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Thu Jan 21, 2021 12:54 pm

Regarding AA587, to this day the final findings still boggles my mind. I mean if that's what the FDR shows it's what it shows, but I just cant imagine a professional pilot doing what that pilot did as far as the rudder goes. I'd imagine most pilots would really just sit there and monitor the situation and let the plane fly out of it, or if anything just make small corrections with the ailerons. Ok so the pilot did use the rudder for whatever reason...how the heck was it enough to snap it off? Bizarre stuff.
 
ucantbme
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Thu Jan 21, 2021 1:11 pm

The search for victims & aircraft parts has ended today, even though the CVR CSMU still hasn’t been found yet.

Source - https://nasional.sindonews.com/read/309 ... 1611226908

However, the Indonesian Navy will continue searching for the CVR CSMU.

Source - https://nasional.sindonews.com/read/309 ... 1611223271
 
Flaps
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Thu Jan 21, 2021 3:39 pm

"Instead of shutting off the system",

How many more times do we have to see this? I really hope this doesn't turn out to be another case of a crew relying on the automation to substitute for their judgement instead of supplementing their judgement.
 
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CrewBunk
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Thu Jan 21, 2021 4:12 pm

Flaps wrote:
"Instead of shutting off the system",

How many more times do we have to see this? I really hope this doesn't turn out to be another case of a crew relying on the automation to substitute for their judgement instead of supplementing their judgement.

If an auto thrust malfunction is where they are looking, then it appears so.

Let’s face it, if the autothrust commands idle on one engine, it’s no different than the engine failures we do 10 times every six months in the simulator. There are few more forgiving aircraft than the 737-500. Autopilot and autothrust off, level the wings, match the thrust, put the nose on the horizon ..... and it’s as easy to fly as a Cessna 172!

But, there appears to be a reluctance among some pilots to switch off the automation and just fly the damned aircraft.
Last edited by CrewBunk on Thu Jan 21, 2021 4:13 pm, edited 1 time in total.
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morrisond
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Thu Jan 21, 2021 4:13 pm

CrewBunk wrote:
Flaps wrote:
"Instead of shutting off the system",

How many more times do we have to see this? I really hope this doesn't turn out to be another case of a crew relying on the automation to substitute for their judgement instead of supplementing their judgement.

If an auto thrust malfunction is where they are looking, then it appears so.

Let’s face it, if the autothrust commands idle on one engine, it’s no different than the engine failures we do 10 times every six months in the simulator. There are few more forgiving aircraft than the 737-500. Autopilot and autothrust off, level the wings, match the thrust, put the nose on the horizon ..... and it’s as easy to fly as a Cessna 172!

But, there appears to be a reluctance among some pilots to switch off the automation and just fly the damned aircraft.


Oh - then even I could fly it!
 
WIederling
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Thu Jan 21, 2021 4:34 pm

morrisond wrote:
Oh - then even I could fly it!


With your philosophic stance you are probably
better served with a glider :
no automation, no electrics, nothing but all the leeway one needs
to show up as the perfect pilot sitting on a bag of air :-)) .
Murphy is an optimist
 
morrisond
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Thu Jan 21, 2021 4:50 pm

WIederling wrote:
morrisond wrote:
Oh - then even I could fly it!


With your philosophic stance you are probably
better served with a glider :
no automation, no electrics, nothing but all the leeway one needs
to show up as the perfect pilot sitting on a bag of air :-)) .


Actually I think all Pilots would benefit from time in a glider so they actually feel what it is like to actually fly and not hope the automation never fails.

Both Sully and the Captain of the Gimli Glider had glider experience. If you want to lump me in with them - I'm good with that.
 
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PixelFlight
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Thu Jan 21, 2021 8:36 pm

morrisond wrote:
Both Sully and the Captain of the Gimli Glider had glider experience. If you want to lump me in with them - I'm good with that.

Fact is that Sully was saved from stall by the automation of the A320. Read the US1549 official report about that point:
Page 89: "However, FDR data indicated that the airplane was below green dot speed and at V LS or slightly less for most of the descent, and about 15 to 19 knots below V LS during the last 200 feet."
Page 98: "The flight envelope protections allowed the captain to pull full aft on the sidestick without the risk of stalling the airplane."
:stirthepot: 737-8 MAX: "For all speeds higher than 220 Kts and trim set at a value of 2.5 units, the difficulity level of turning the manual trim wheel was level A (trim wheel not movable)." :stirthepot:
 
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zeke
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Thu Jan 21, 2021 9:18 pm

RogerMurdock wrote:
Investigators suspect malfunctioning engine controls and pilot efforts to troubleshoot the problem likely played a major role in an Indonesian airliner’s fatal plunge into the Java Sea earlier this month, according to people familiar with the details.

Information downloaded from the Sriwijaya Air jet’s flight-data recorder, the people said, points to pilots trying to deal with a problem affecting an automatic throttle system on the twin-engine, 1990s-era Boeing Co. 737. The recorder, which is one of the plane’s two black boxes, was retrieved a few days after the crash.

The data indicates the so-called autothrottle system—which automatically adjusts fuel flow and thrust to maintain the path set by pilots—wasn’t operating properly on one engine at some point during the Boeing 737-500’s climb away from the nation’s capital, Jakarta, on Jan. 9, according to some of the people familiar with the matter.

Instead of shutting off the system, they said, the flight-data recorder indicates pilots tried to get the stuck throttle to function.


https://www.wsj.com/articles/indonesia- ... 1611214371


There is more known about this than has been made public, some of what is being put in the media is not consistent with the 737 system design, or what was known before the FDR was found.

There are multiple sources of information that need to be put together by the investigators to get the full understanding of the scenario.

Please be guided accordingly, no need to jump to conclusions with every piece of news.
“Don't be a show-off. Never be too proud to turn back. There are old pilots and bold pilots, but no old, bold pilots.” E. Hamilton Lee, 1949
 
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Starlionblue
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Thu Jan 21, 2021 11:57 pm

trnswrld wrote:
Regarding AA587, to this day the final findings still boggles my mind. I mean if that's what the FDR shows it's what it shows, but I just cant imagine a professional pilot doing what that pilot did as far as the rudder goes. I'd imagine most pilots would really just sit there and monitor the situation and let the plane fly out of it, or if anything just make small corrections with the ailerons. Ok so the pilot did use the rudder for whatever reason...how the heck was it enough to snap it off? Bizarre stuff.


The structural failure is the easiest part to understand. No rudder limiter or envelope protection measure is designed to deal with repeated strong back and forth inputs. As mentioned above, it is out of the scope of their function.

I guess some posts were deleted, so I'll repost this very interesting article from IFALPA. It contains excellent illustrations regarding repeated back and forth inputs. (It is about Boeing but would apply to any airliner.)


Boeing aircraft are designed to withstand the structural loads generated by a full rudder input out to the aircraft’s maximum
operating airspeed, Vmo/Mmo. Some Boeing aircraft meet these requirements out to the design dive speed. This means the structure
has at least a 50% safety margin over the maximum load generated by this kind of manoeuvre. As previously mentioned, Boeing
aircraft vertical fins can also sustain loads if the rudder is rapidly returned to neutral from the over yaw sideslip or the rudder is fully
reversed from a full steady state sideslip.
Boeing aircraft are not designed to a requirement of full authority rudder reversals from an “over yaw” condition. Sequential full
or nearly full authority rudder reversals may not be within the structural design limits of the aircraft, even if the airspeed is below
the design manoeuvring speed. There are no Boeing Procedures that require this type of pilot input. It should also be pointed out
that excessive structural loads may be generated in other areas of the aircraft, such as engine struts, from this type of control input.
In addition, large sideslip angles may cause engine surging at high power settings. It is important to note that use of full rudder for
control of engine failures and crosswind takeoffs and landings is well within the structural capability of the aircraft.


https://ifalpa.org/media/2029/12adobl02-use-of-rudder-on-boeing-aircraft.pdf
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
ucantbme
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Fri Jan 22, 2021 12:29 am

morrisond wrote:
Actually I think all Pilots would benefit from time in a glider so they actually feel what it is like to actually fly and not hope the automation never fails.


In that case, it would please you to know that the PIC of this accident aircraft started out as a glider pilot.

zeke wrote:
There is more known about this than has been made public, some of what is being put in the media is not consistent with the 737 system design, or what was known before the FDR was found.

There are multiple sources of information that need to be put together by the investigators to get the full understanding of the scenario.

Please be guided accordingly, no need to jump to conclusions with every piece of news.


Can’t agree with you, more. Any B737 rated pilot will know that there is really nothing to troubleshoot in the A/T system of the aircraft.

The QRH in fact instructs the pilots to continue the flight normally by trying to reengage the A/T or using manual thrust for the remainder of the flight.
 
morrisond
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Fri Jan 22, 2021 1:34 am

PixelFlight wrote:
morrisond wrote:
Both Sully and the Captain of the Gimli Glider had glider experience. If you want to lump me in with them - I'm good with that.

Fact is that Sully was saved from stall by the automation of the A320. Read the US1549 official report about that point:
Page 89: "However, FDR data indicated that the airplane was below green dot speed and at V LS or slightly less for most of the descent, and about 15 to 19 knots below V LS during the last 200 feet."
Page 98: "The flight envelope protections allowed the captain to pull full aft on the sidestick without the risk of stalling the airplane."


No he knew it was there and used it to his advantage - I doubt Sully would have stalled it in the glide without FBW or anyone else with Glider training like reportedly SJ182 had in the same situation. SJ182 alas does not appear to be the same as the Miracle on the Hudson or Gimli Glider where loss of thrust was more gradual in both.

Actually if you read up on Sully's comments he was quite critical of the FBW system as it would not allow him to stall it right before splashdown as that could have materially cut forward velocity and increased the odds for a successful landing. He thought they were going to flip.

And I'm not the one who Brought up gliders. Based on what we think we know so far having glider experience doesn't seem like it would have helped in SJ182.
 
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PixelFlight
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Fri Jan 22, 2021 6:44 am

morrisond wrote:
PixelFlight wrote:
morrisond wrote:
Both Sully and the Captain of the Gimli Glider had glider experience. If you want to lump me in with them - I'm good with that.

Fact is that Sully was saved from stall by the automation of the A320. Read the US1549 official report about that point:
Page 89: "However, FDR data indicated that the airplane was below green dot speed and at V LS or slightly less for most of the descent, and about 15 to 19 knots below V LS during the last 200 feet."
Page 98: "The flight envelope protections allowed the captain to pull full aft on the sidestick without the risk of stalling the airplane."

No he knew it was there and used it to his advantage - I doubt Sully would have stalled it in the glide without FBW.

Read the report. There was a difference in how he perceived the speed and the actual speed recorded by the FDR, due to the "tunnel effect" in high stress situation. Managing the speed was difficult without to worry about the pitch. Adding the task of managing the pitch in that situation increase the risk of an error witch would have been almost impossible to recover. Automation, done the right way, are very good, far better than human, at managing precisely and reliably just at the limit of the protection.

Actually if you read up on Sully's comments he was quite critical of the FBW system as it would not allow him to stall it right before splashdown as that could have materially cut forward velocity and increased the odds for a successful landing. He thought they were going to flip.

Fact proved that the splashdown angle provided by Airbus was a good choice. A higher angle would have damaged more the aft of the A320, increasing the water intake.
:stirthepot: 737-8 MAX: "For all speeds higher than 220 Kts and trim set at a value of 2.5 units, the difficulity level of turning the manual trim wheel was level A (trim wheel not movable)." :stirthepot:
 
wjcandee
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Fri Jan 22, 2021 6:54 am

Does anybody feel that there is MASSIVE thread drift here? I know we're bored waiting for actual information, but the extensive discussion way off topic kind of crowds out the few posts containing either (1) new information or (2) discussion of the actual accident and/or theories and analysis directly-relating thereto.
Last edited by wjcandee on Fri Jan 22, 2021 7:18 am, edited 1 time in total.
 
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PixelFlight
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Fri Jan 22, 2021 7:06 am

morrisond wrote:
I agree Automation has overall made things safer - but pilots still have to know how to fly without it and always assume it's about to fail even if you are flying the latest and greatest aircraft or you decide to turn off the automation yourself.

Things break and/or wear out.

Humans makes errors more often than automation. This is exactly why automation (done the right way) have contributed to a big safety improvement. The idea of the pilots that can do everything, especially in high load and high stress situation is not how recent aircraft designs are done. The actual trend is to provides reliable automation as far as possible outside the nominal operation, to help the pilots and to reduce the risk of error.
:stirthepot: 737-8 MAX: "For all speeds higher than 220 Kts and trim set at a value of 2.5 units, the difficulity level of turning the manual trim wheel was level A (trim wheel not movable)." :stirthepot:
 
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CrewBunk
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Fri Jan 22, 2021 1:32 pm

WIederling wrote:

Apropos:
737 throttles are back driven, right?

What happens when the back drive motors go crazy?


You hold the thrust levers where you want them. It doesn’t take much to overpower them.

Then, you shut down the autothrust system, starting with the disconnect on the thrust levers themselves, or the FCU, or as a last resort, pull the circuit breaker.
If you respond with a two page answer, obviously pre-prepared, I’m not going to bother reading it. Odds are, no one else is either!
 
JayinKitsap
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Sat Jan 23, 2021 7:44 am

any word on the CVR recovery?
 
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SQ22
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Sat Jan 23, 2021 7:48 am

Please keep this thread on topic and do not turn it into a B vs. A discussion. Feel free to start a separate thread about crash rates of B737 and A320, but please do not derail this thread by discussing it here. Thanks.
 
ucantbme
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Sat Jan 23, 2021 10:22 am

This law firm plans to sue Boeing due to faults with the auto throttle, with the support of 4 victims’ families. They have also drawn comparisons with the Asiana crash in SFO.

Source - https://bisnis.tempo.co/read/1426011/pe ... page_num=1
https://bisnis.tempo.co/read/1425982/4- ... ll&view=ok
 
Aseem747
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Sat Jan 23, 2021 10:32 am

ucantbme wrote:
This law firm plans to sue Boeing due to faults with the auto throttle, with the support of 4 victims’ families. They have also drawn comparisons with the Asiana crash in SFO.

Source - https://bisnis.tempo.co/read/1426011/pe ... page_num=1
https://bisnis.tempo.co/read/1425982/4- ... ll&view=ok

lol what!? How do they know if the auto throttle failure was due to a design flaw or poor maintenance to sue Boeing for this?
Last edited by Aseem747 on Sat Jan 23, 2021 10:35 am, edited 1 time in total.
 
bennett123
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Sat Jan 23, 2021 10:34 am

Given how long the B737 Classic has been flying....

I assume that Autothrottle design has not changed recently.
 
bennett123
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Sat Jan 23, 2021 10:53 am

Not sure that the Asiana crash at SFO will help them.

Firstly, that was a B777.

Secondly, it was on landing.

Thirdly, iirc the issue was pilot error.

Apart from that...
 
WIederling
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Sat Jan 23, 2021 1:37 pm

bennett123 wrote:
Not sure that the Asiana crash at SFO will help them.

Thirdly, iirc the issue was pilot error.


Foreigners crashing a Boeing and invariably the sole cause must be pilot error.

re the Asiana crash:
See the substantial list of tasks set for Boeing to improve the 777 in the NTSB report.
Murphy is an optimist
 
bennett123
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Sat Jan 23, 2021 1:51 pm

https://en.wikipedia.org/wiki/Asiana_Ai ... Flight_214

The NTSB reached the following final conclusion:

The National Transportation Safety Board determines that the probable cause of this accident was the flight crew's mismanagement of the airplane's descent during the visual approach, the pilot flying's unintended deactivation of automatic airspeed control, the flight crew's inadequate monitoring of airspeed, and the flight crew's delayed execution of a go-around after they became aware that the airplane was below acceptable glidepath and airspeed tolerances. Contributing to the accident were (1) the complexities of the autothrottle and autopilot flight director systems that were inadequately described in Boeing's documentation and Asiana's pilot training, which increased the likelihood of mode error; (2) the flight crew's nonstandard communication and coordination regarding the use of the autothrottle and autopilot flight director systems; (3) the pilot flying's inadequate training on the planning and executing of visual approaches; (4) the pilot monitoring/instructor pilot's inadequate supervision of the pilot flying; and (5) flight crew fatigue, which likely degraded their performance.[1]:129

An awful lot of this is still down to the pilots, rather than Boeing.

The fact that the pilots were 'foreigners' is neither here nor there.
 
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Polot
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Sat Jan 23, 2021 1:51 pm

WIederling wrote:
bennett123 wrote:
Not sure that the Asiana crash at SFO will help them.

Thirdly, iirc the issue was pilot error.


Foreigners crashing a Boeing and invariably the sole cause must be pilot error.

re the Asiana crash:
See the substantial list of tasks set for Boeing to improve the 777 in the NTSB report.

Basically every crash attributed to pilot error has suggested improvements for OEM to minimize risk of similar error in the future.
 
WIederling
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Sat Jan 23, 2021 3:10 pm

bennett123 wrote:
https://en.wikipedia.org/wiki/Asiana_Airlines_Flight_214

The NTSB reached the following final conclusion:
........ <selective quote> .


See: Accident Report NTSB/AAR-14/01 PB2014-105984 "4. Recommendations" p148ff

Quite a number of "Require Boeing to ..."
Murphy is an optimist
 
Flow2706
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Re: Sriwijaya Air 737-500 (SJ182 CGK-PNK) crashes shortly after takeoff

Sat Jan 23, 2021 3:23 pm

Even if this accident was indeed related to the autothrottle system, it is most likely not comparable to the Asiana accident. The Asiana accident was mostly the result of poor system knowledge resulting in mode confusion and finally lack of monitoring (probably due to complacency). Even if the design of the auto flight system was not perfect it was only a contributing factor. The Asiana accident happened during the approach, this accident happened at FL100. A simple auto throttle malfunction would not lead to this kind of accident on its own. A trained crew should recognize the abnormal behavior of the auto throttle and correct the situation before it becomes critical. Even if the situation is allowed to deteriorate to a stall or (in case of asymmetric thrust) a beginning spiral dive it should be possible to recover with 10000ft of altitude. So while the auto throttle may have been a contributing factor (either due to a technical malfunction or simply due to mishandling of the system by the crew) it is most likely not the only cause of the accident.

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