PlanesNTrains wrote:

salttee wrote:

PlanesNTrains wrote:

I hate this argument. How in the hell are we to know who is “on the payroll” somewhere? At least with one person we know exactly who they are. Who is everybody else? What are their “interests”?

Iow, it’s a big fat strawman to imply that because we know where one forum member stands that we should be concerned about them. I’m more concerned about the ones we DONT know the true intentions of.

If you hate this discussion why are you prolonging it?

I have a lot more I can say on the subject but I will only do so if invited.........................................

And I'm beginning to feel invited.

So everyone shut up and let Saltee talk? Got it.

More like let the subject drop or I'll explain my reason for being interested in the subject.
Which would divert from JT610 discussion.

salttee wrote:

PlanesNTrains wrote:

salttee wrote:

If you hate this discussion why are you prolonging it?

I have a lot more I can say on the subject but I will only do so if invited.........................................

And I'm beginning to feel invited.

So everyone shut up and let Saltee talk? Got it.

More like let the subject drop or I'll explain my reason for being interested in the subject.
Which would divert from JT610 discussion.

Sounds more like a temper tantrum to me. “Give me what I want or I’ll tell.” FWIW, you can share whatever you like. I just voiced my opinion about it.

stiphy wrote:

Lion air ends search for CVR:

https://www.cnbc.com/amp/2019/01/03/lio ... g-737.html

Smoke and mirrors, posturing for the peanut gallery, call it what you will.

The fix has been in from the get go. Why no one in the aviation community seems bothered by this cover-up is indeed troubling.

litz wrote:

Maybe the CVR, when it's found (and make no mistake, it WILL be found) will shed light on the decision making.

Post meet discredited poster...

scbriml wrote:

People said exactly the same thing about the AF447 black boxes, except it was Airbus and Air France trying to "hide the truth". The fact the search continued for the best part of two years didn't matter to those folk.

Where is your "evidence" as to why the greatest technologies and aircraft companies in the world CAN'T seem to locate a CVR in relatively shallow water and precise location? Where is your "evidence" this is an EXCEPTIONAL case of recovery? Where is your "evidence" why this recovery effort is so EXTRAORDINARY as to continue to prove unfruitful?

salttee wrote:

PixelFlight wrote:

salttee wrote:

I think it's good that someone who is a publicity agent for one of the interested parties in the JT610 accident remove himself from discussion in a forum where the rest of the posters are non-professional in the political sense and even if they appear to have an agenda, it's not really an agenda, but rather just a personal outlook.

I disagree. It's an open forum not a tribunal. There is already forum rules ( forumrules.php ).
I personally enjoy posts from professionals debating facts, regardless of there interest if there have one.

Although this is in no way a tribunal, the words here can be expected to have impact beyond this forum, so what is said here is not without consequence. To be candid PixelFlight, I have observed your point of view over many posts and it appears to me that you share the same perspective that the client(s) of the person we are discussing would like to see promoted; so I don't find it surprising that you see this particular issue the way you do. Were you to find that a poster here was being paid to post here by an entity that opposes your view, I have doubts that you would be so supportive.

If a person is really in a such situation, then this is the plain reality and this is just an another information about the reality. I see no reason to ignore it. Everyone is free to analyse the information like it want. This is an open forum, not a place where everyone have to get the same thinking. It's constructive to help someone understand (how something work for example), but if for whatever reason that person think otherwise, it's not really a problem. This is the advantage of a place like this: everyone can learn how others think.

KRI Spica, Indonesian Navy Special Ops vessel, in action...



According to multiple news sources, the NTSC & the Navy focus their search on a narrow 5M X 5M search area to locate the still missing Lion Air's PK-LQP CVR.

- https://www.marinetraffic.com/en/ais/de ... :KRI_SPICA

FlyXLsa wrote:

"The Lion Air Boeing 737 MAX 8 accident may have many specific lessons for the industry but in most respects it is likely to prove yet another casualty of the complicated relationship between pilots and highly automated systems. The pilots found themselves having to deal with what appeared to be a runaway horizontal stabiliser trim system and failed to control it."

https://www.aerosociety.com/news/lion-air-lessons/

Thanks for the link, I found a lot of good information in this article (even if most of them was know already)

Some points in my personal interest:

"The International Civil Aviation Organisation is quietly working on a new human performance manual that may hopefully, when completed, address many of the human performance issues that are obviously present in the Lion Air accident, even at this early stage in the investigation."

"Discovering the cause of the AoA sensor faults is one of the subjects of the continuing NTSC inquiry."

"An experienced Southwest Airlines captain with whom AEROSPACE discussed the MCAS issues says that, in practice, the 737NG and MAX feel the same to fly. He did remark, however, that he was surprised that a single-point AoA sensor failure could be allowed to trigger what feels like a stabiliser trim runaway, venturing his personal opinion that this showed poor system redundancy design."

"Aside from the specific Lion Air lessons, the generic problem of complexity-related pilot confusion needs to be addressed. There is much study ongoing about why such crew confusion events have frequently been precursors to loss of control in flight (LOC-I) during the last 20 years, and whether there are solutions. It has already been established that pilots – the commercial air transport system’s goalkeepers – sometimes face shots they did not see coming, so they dive the wrong way."

"The information essentials for a confused pilot are those which help the crew to follow the absolute pilot priorities: aviate, navigate, communicate. The industry needs to resolve these issues to prevent pilot confusion dooming more flights."

This seem to indicate a strong motivation to evolve with the goal to make aircraft more understandable by the crew. This is the good part.
I am a bit disappointing by the fact that the redundancy issue of the AoA sensor is only raised by a captain personal opinion. I think this must be seriously addressed too.

I don't see as much complexity in this as you and your sources are postulating. Every aircraft equipped with automatic stabilizer trim, from piston driven twins to the 380 has a cutout switch available to the flight crew to either disable the automatic trim or to remove power to the auto trim motor(s). The 737 max's elevator trim cutout switches are located adjacent to the first officer's left hand: in plain sight.

Once the cloud of "complexity" is stripped away, the question remains: why were the flight crew unable to determine that the nose down condition was a result of elevator trim or why didn't they activate the elevator trim cutout switches if they understood what was causing the nose down condition?

We need the CVR before we can answer those questions.

salttee wrote:

I don't see as much complexity in this as you and your sources are postulating. Every aircraft equipped with automatic stabilizer trim, from piston driven twins to the 380 has a cutout switch available to the flight crew to either disable the automatic trim or to remove power to the auto trim motor(s).

It look like it's a bit more sophisticated on some Airbus in order to reduce crew load and increase redundancy: viewtopic.php?t=765147#p11043627 post #12 by zeke
Some others posts on the same thread are very interesting. I only chose one that summarize the best my point of view: the 737-8/-9 design is dangerous precisely because he it too simple for the critical MCAS stab trim function. Airbus, especially since the A330, (and certainly the B787, but to be verified) use a lot of redundancy in the sensors, the ADIRU, the FCC, the actuators and take a system width approach of the design. The 737 (and in part the A320) are stuck in the past in comparison. There is no reason why this very common category of aircraft is still allowed to have a underrated grade of security. Both brands are perfectly capable to upgrade there design with the most advanced ADFX avionic, more sensors and more actuators.

salttee wrote:

I don't see as much complexity in this as you and your sources are postulating. Every aircraft equipped with automatic stabilizer trim, from piston driven twins to the 380 has a cutout switch available to the flight crew to either disable the automatic trim or to remove power to the auto trim motor(s). The 737 max's elevator trim cutout switches are located adjacent to the first officer's left hand: in plain sight.

Once the cloud of "complexity" is stripped away, the question remains: why were the flight crew unable to determine that the nose down condition was a result of elevator trim or why didn't they activate the elevator trim cutout switches if they understood what was causing the nose down condition?

We need the CVR before we can answer those questions.

During recovery they deyployed the flaps. This stopped MCAS from running the trim. After they recovered and raised the flaps MCAS went into action again. This could have confused them.

In any case, single sensor failure causing this is shitty design, and that belongs to boeing 100%.

N212R wrote:

scbriml wrote:

People said exactly the same thing about the AF447 black boxes, except it was Airbus and Air France trying to "hide the truth". The fact the search continued for the best part of two years didn't matter to those folk.

Where is your "evidence" as to why the greatest technologies and aircraft companies in the world CAN'T seem to locate a CVR in relatively shallow water and precise location? Where is your "evidence" this is an EXCEPTIONAL case of recovery? Where is your "evidence" why this recovery effort is so EXTRAORDINARY as to continue to prove unfruitful?

Ha ha ha, good try!

You’re the one insinuating there’s some massive cover-up going on, so you’re the one that needs to provide the “evidence” to support that crackpot theory. Saying ‘They haven’t found the CVR, so there must be a cover-up’ isn’t evidence.

FlyXLsa wrote:

"The Lion Air Boeing 737 MAX 8 accident may have many specific lessons for the industry but in most respects it is likely to prove yet another casualty of the complicated relationship between pilots and highly automated systems. The pilots found themselves having to deal with what appeared to be a runaway horizontal stabiliser trim system and failed to control it."

https://www.aerosociety.com/news/lion-air-lessons/

"Boeing released a statement in response to publication of the NTSC preliminary report in which it makes this observation: 'Unlike as is stated with respect to the prior flight, the report does not state whether the pilots performed the runaway stabilizer procedure or cut out the stabilizer trim switches.'"

Sorry if I've missed something earlier in this very long thread, but is it still unknown whether or not the accident crew actually did perform the runaway stab trim procedure?

scbriml wrote:

N212R wrote:

scbriml wrote:

People said exactly the same thing about the AF447 black boxes, except it was Airbus and Air France trying to "hide the truth". The fact the search continued for the best part of two years didn't matter to those folk.

Where is your "evidence" as to why the greatest technologies and aircraft companies in the world CAN'T seem to locate a CVR in relatively shallow water and precise location? Where is your "evidence" this is an EXCEPTIONAL case of recovery? Where is your "evidence" why this recovery effort is so EXTRAORDINARY as to continue to prove unfruitful?

Ha ha ha, good try!

You’re the one insinuating there’s some massive cover-up going on, so you’re the one that needs to provide the “evidence” to support that crackpot theory. Saying ‘They haven’t found the CVR, so there must be a cover-up’ isn’t evidence.

And you're the one who responds with all too obvious dissimulation when asked simple questions.

You still have provided ZERO details which evidence why this recovery effort is still ongoing.

Until such time, my suppositions are as valid as your non-articulated ones.

Ha, ha ha

N212R wrote:

And you're the one who responds with all too obvious dissimulation when asked simple questions.

You still have provided ZERO details which evidence why this recovery effort is still ongoing.

Until such time, my suppositions are as valid as your non-articulated ones.

Ha, ha ha

The search is continuing because they haven’t yet found the CVR.

Your turn.

fsabo wrote:

During recovery they deyployed the flaps. This stopped MCAS from running the trim. After they recovered and raised the flaps MCAS went into action again. This could have confused them.
In any case, single sensor failure causing this is shitty design, and that belongs to boeing 100%.

You're wandering too deeply into this without enough knowledge and confusing the issue for yourself. It doesn't matter that MCAS ordered the trim, rather than a runaway autopilot command, anymore than it matters whether Boeing used a Motorola chip for the processor or an Intel chip: "C" coding or Python. That's buried beyond a pilot's need to know while he or she is flying an airplane. From what we know so far about JT610, the flight crew experienced down forces on the nose of the plane; to a pilot that translates to upward forces on the tail (assuming that a wing hadn't fallen off). A pilot flying a transport aircraft in this situation should know that there are two major possibilities at this point: the elevator is not following commands from the control column or the stabilizer trim has run amuck. Just looking at the trim wheel should provide evidence that elevator trim is the cause and from there the remedy is the same whether he is flying a Max or a Learjet: disable automatic trim and apply manual counter-trim.

Then as you say: During recovery they deployed the flaps - after they recovered they raised the flaps, and the plane nosed down again so they raised the flaps; and went through several cycles of this, which had actually begun before there was an evident problem, after the normal retraction of flaps post-takeoff. That defies logic as much as the pilot's failure to disable automatic elevator trim. Why couldn't they determine cause and effect here?

Is it going too far to say that these two didn't know how to fly a plane but had just memorized myriad procedures to operate a piece of complex machinery?
How can you pin that on Boeing?

salttee wrote:

fsabo wrote:

During recovery they deyployed the flaps. This stopped MCAS from running the trim. After they recovered and raised the flaps MCAS went into action again. This could have confused them.
In any case, single sensor failure causing this is shitty design, and that belongs to boeing 100%.

You're wandering too deeply into this without enough knowledge and confusing the issue for yourself. It doesn't matter that MCAS ordered the trim, rather than a runaway autopilot command, anymore than it matters whether Boeing used a Motorola chip for the processor or an Intel chip: "C" coding or Python. That's buried beyond a pilot's need to know while he or she is flying an airplane. From what we know so far about JT610, the flight crew experienced down forces on the nose of the plane; to a pilot that translates to upward forces on the tail (assuming that a wing hadn't fallen off). A pilot flying a transport aircraft in this situation should know that there are two major possibilities at this point: the elevator is not following commands from the control column or the stabilizer trim has run amuck. Just looking at the trim wheel should provide evidence that elevator trim is the cause and from there the remedy is the same whether he is flying a Max or a Learjet: disable automatic trim and apply manual counter-trim.

Then as you say: During recovery they deployed the flaps - after they recovered they raised the flaps, and the plane nosed down again so they raised the flaps; and went through several cycles of this, which had actually begun before there was an evident problem, after the normal retraction of flaps post-takeoff. That defies logic as much as the pilot's failure to disable automatic elevator trim. Why couldn't they determine cause and effect here?

Is it going too far to say that these two didn't know how to fly a plane but had just memorized myriad procedures to operate a piece of complex machinery?
How can you pin that on Boeing?

I pin the single sensor causing MCAS to act incorrectly as shitty design by boeing. Could the pilots have saved the aircraft? Clearly yes. Does that alter the fact that boeing's design is shitty? No.

delete

salttee wrote:

A pilot flying a transport aircraft in this situation should know that there are two major possibilities at this point: the elevator is not following commands from the control column or the stabilizer trim has run amuck. Just looking at the trim wheel should provide evidence that elevator trim is the cause and from there the remedy is the same whether he is flying a Max or a Learjet: disable automatic trim and apply manual counter-trim.

Yes, and this is in fact what the JT610 crew did: the automatic trim was disabled because the AP was disconnected and there apply manual counter-trim.
There didn't know that a another hidden MCAS system was erratically acting in manual flight mode.

PixelFlight wrote:

Yes, and this is in fact what the JT610 crew did: the automatic trim was disabled because the AP was disconnected and there apply manual counter-trim.
There didn't know that a another hidden MCAS system was erratically acting in manual flight mode.

Here is a picture of a 737-200 cockpit. Notice that the stab trim cutout switches existed and were located in the same place in this 1965 model 737. The method of killing runaway trim has been the same on 737s for over 50 years. Long long before MCAS.

salttee wrote:

PixelFlight wrote:

Yes, and this is in fact what the JT610 crew did: the automatic trim was disabled because the AP was disconnected and there apply manual counter-trim.
There didn't know that a another hidden MCAS system was erratically acting in manual flight mode.

Here is a picture of a 737-200 cockpit. Notice that the stab trim cutout switches existed and were located in the same place in this 1965 model 737. The method of killing runaway trim has been the same on 737s for over 50 years. Long long before MCAS.

Again yes. But does exists documented incident on a 737 not MAX over 50 years where the crew faced a runaway stab trim that was still correctly responding to the electrical manual stab trim ?

PixelFlight wrote:

does exists documented incident on a 737 not MAX over 50 years where the crew faced a runaway stab trim that was still correctly responding to the electrical manual stab trim ?

I don't have any knowledge or data on previous trim failures. But I don't see how they would have any bearing on what occurred here. Conceivably,there may have been erroneous flight director commanded stabilizer trim pitch downs, but I don't know if there actually were any. Boeing made provision for that type of failure by placing stab trim cutout switches in a prominent position in the cockpit. We know that much.

salttee wrote:

I don't see as much complexity in this as you and your sources are postulating. Every aircraft equipped with automatic stabilizer trim, from piston driven twins to the 380 has a cutout switch available to the flight crew to either disable the automatic trim or to remove power to the auto trim motor(s). The 737 max's elevator trim cutout switches are located adjacent to the first officer's left hand: in plain sight.

Once the cloud of "complexity" is stripped away, the question remains: why were the flight crew unable to determine that the nose down condition was a result of elevator trim or why didn't they activate the elevator trim cutout switches if they understood what was causing the nose down condition?

We need the CVR before we can answer those questions.

I really think that we ought to step back and ask why this plane not only flew this mission but continued on the previous one when the pilots encountered the same problem but were able to disable the auto trim. They should have returned to base and the plane should have been grounded. Barring that, this aircraft never should have taken off for the fatal flight when it was known to have a defect.

Again, the detection criteria for MCAS unintended activate due to AOA failure were not made available to flight crews before mishap. So procedure to handle MCAS failure does not exist. The point of issuing AD is to update procedure

LDRA wrote:

Again, the detection criteria for MCAS unintended activate due to AOA failure were not made available to flight crews before mishap. So procedure to handle MCAS failure does not exist. The point of issuing AD is to update procedure

Of what consequence is it knowing why the stabilizer trim has run away? The problem that is interfering with flight is the spurious stabilizer position. That is what everyone who flies any plane with automatic stabilizer trim is trained to recognize and act on whether it is incorrectly pitched up or down.

What if the erroneous command came from a faulty autopilot? Is it Ok to crash in that circumstance?

salttee wrote:

LDRA wrote:

Again, the detection criteria for MCAS unintended activate due to AOA failure were not made available to flight crews before mishap. So procedure to handle MCAS failure does not exist. The point of issuing AD is to update procedure

Of what consequence is it knowing why the stabilizer trim has run away? The problem that is interfering with flight is the spurious stabilizer position. That is what everyone who flies any plane with automatic stabilizer trim is trained to recognize and act on whether it is incorrectly pitched up or down.

What if the erroneous command came from a faulty autopilot? Is it Ok to crash in that circumstance?

Again, to REACT to an aircraft system problem, you first has to DETECT a problem exist, even if you can't IDENTIFY the root failure causing the condition. The DETECTION CRITERIA for abnormal aircraft system condition simply does not exist exist in the procedure before the mishap

LDRA wrote:

Again, to REACT to an aircraft system problem, you first has to DETECT a problem exist, even if you can't IDENTIFY the root failure causing the condition. The DETECTION CRITERIA for abnormal aircraft system condition simply does not exist exist in the procedure before the mishap

What you don't understand is that from a pilot's point of view, the problem was that the horizontal stabilizer was pitched up. How it got that way is academic to a pilot flying the plane; he can do the troubleshooting when he gets on the ground. His job is to understand how a plane flies and to be able to recognize that elevator trim has run away. It looks like he did get that far, he activated the trim cancel switch on the control column several times. But he and his first officer both failed to take the next step, which the pilot of any airplane with automatic trim is obligated to know about; they failed to activate the switches which were labeled and located in a prominent place of their control panel which were placed there to remove power to elevator trim. All planes with automatic trim have these switches located somewhere in the cockpit so that the pilot can operate them in an emergency. From a single engine piston plane to a 380, they all have the same arrangement.

Basic airmanship.

salttee wrote:

LDRA wrote:

Again, to REACT to an aircraft system problem, you first has to DETECT a problem exist, even if you can't IDENTIFY the root failure causing the condition. The DETECTION CRITERIA for abnormal aircraft system condition simply does not exist exist in the procedure before the mishap

What you don't understand is that from a pilot's point of view, the problem was that the horizontal stabilizer was pitched up. How it got that way is academic to a pilot flying the plane; he can do the troubleshooting when he gets on the ground. His job is to understand how a plane flies and to be able to recognize that elevator trim has run away. It looks like he did get that far, he activated the trim cancel switch on the control column several times. But he and his first officer both failed to take the next step, which the pilot of any airplane with automatic trim is obligated to know about; they failed to activate the switches which were labeled and located in a prominent place of their control panel which were placed there to remove power to elevator trim. All planes with automatic trim have these switches located somewhere in the cockpit so that the pilot can operate them in an emergency. From a single engine piston plane to a 380, they all have the same arrangement.

Basic airmanship.

Again, elevator trim never run away in the mishap. The repeated elevator trim down was discontinuous, flight crew was able to stop the nose down trim using control column switch

How is the flight crew supposed to recognize something that did not occur? The symptons of MCAS failures are listed in FAA AD that came out, only then flight crews are aware and can IDENTIFY that specific failure

PixelFlight wrote:

salttee wrote:

I don't see as much complexity in this as you and your sources are postulating. Every aircraft equipped with automatic stabilizer trim, from piston driven twins to the 380 has a cutout switch available to the flight crew to either disable the automatic trim or to remove power to the auto trim motor(s).

It look like it's a bit more sophisticated on some Airbus in order to reduce crew load and increase redundancy: viewtopic.php?t=765147#p11043627 post #12 by zeke
Some others posts on the same thread are very interesting. I only chose one that summarize the best my point of view: the 737-8/-9 design is dangerous precisely because he it too simple for the critical MCAS stab trim function. Airbus, especially since the A330, (and certainly the B787, but to be verified) use a lot of redundancy in the sensors, the ADIRU, the FCC, the actuators and take a system width approach of the design. The 737 (and in part the A320) are stuck in the past in comparison. There is no reason why this very common category of aircraft is still allowed to have a underrated grade of security. Both brands are perfectly capable to upgrade there design with the most advanced ADFX avionic, more sensors and more actuators.

A 30 year old design competing against a heavily warmed-over 51-year-old design doesn't get you that far.

salttee wrote:

LDRA wrote:

Again, to REACT to an aircraft system problem, you first has to DETECT a problem exist, even if you can't IDENTIFY the root failure causing the condition. The DETECTION CRITERIA for abnormal aircraft system condition simply does not exist exist in the procedure before the mishap

What you don't understand is that from a pilot's point of view, the problem was that the horizontal stabilizer was pitched up. How it got that way is academic to a pilot flying the plane; he can do the troubleshooting when he gets on the ground. His job is to understand how a plane flies and to be able to recognize that elevator trim has run away. It looks like he did get that far, he activated the trim cancel switch on the control column several times. But he and his first officer both failed to take the next step, which the pilot of any airplane with automatic trim is obligated to know about; they failed to activate the switches which were labeled and located in a prominent place of their control panel which were placed there to remove power to elevator trim. All planes with automatic trim have these switches located somewhere in the cockpit so that the pilot can operate them in an emergency. From a single engine piston plane to a 380, they all have the same arrangement.

Basic airmanship.

Pages and pages ago these same points were made and some people refuse to accept them.

But what’s true is true: the pilots did not use the trim cutouts. Why? We can only speculate.

Confusion? Okay, but while the names have changed, the game remains the same. The switches are in basically the same place they have always been. Why the trim wasn’t reacting as the pilots expected is more trivia than import. The procedure to stop it (not trouble shoot it into the sea) is to cutout the power to the whole shebang.

Well, it’s easy for us to say, not being there. Except the previous pilots did just that, and the final pilots didn’t do the same. So the real question becomes: where was the failure at Lion...

Letting the plane fly af all?
Not turning back the day before?
Not repairing things correctly?
Not briefing the pilots on what happened the flight before?
Not training the pilots well enough on dealing with runaway trim on the 737max? The 737 in general? Any aircraft?

Boeing’s bad system design presented the pilots with a problem. But the problem was not insurmountable. It’s something they train for. The exact cause of the problem isn’t the primary concern of the pilots. “Can we make it stop?” Is the first step. The previous pilots knew how. The final pilots did not know or didn’t decide to act. Why?

Edit: In that regard it’s similar to the AF crash. The Airbus presented a problem that caused confusion. Lack of flight data caused the system to go wonky. The pilots reacted badly, stalling the plane. Then a poor design choice added to the confusion (the audible stall warning turning off when you are still in a stall, then turning on when you attempt to correct). But it wasn’t the cause of the accident. Poor piloting was the reason for the crash.

salttee wrote:

Just looking at the trim wheel should provide evidence that elevator trim is the cause and from there the remedy is the same whether he is flying a Max or a Learjet: disable automatic trim and apply manual counter-trim.

They did apply manual counter trim. Dozens of times. And every time the wheel not only stopped, but even followed their command. So the symptoms of a stabilizer runaway were not there. By repetition the pilots learned, they could control the trim. What they did not know, was that this system would wake up as long as they flew with clean configuration, 6 times per minute, trying to push the nose down, and that failing to interupt just two full trim down cycles would bring them into a not recoverable flight state. After 26 cycles it ended like that.

We have the evidence, that if this failure mode occurs, only one of two crews without the training will bring the plane back (survivability was 50%). A design that results in a survivability of 50% in aviation is bloody awful.

Note: even if maintenance would have done their job, the AoA sensing system could fall into this failure mode by just e.g. a bird strike. So any 737 MAX which is currently flying world wide, even if perfectly maintained, could end up in this condition before you finish reading this sentence.

trav777 wrote:

I really think that we ought to step back and ask why this plane not only flew this mission but continued on the previous one when the pilots encountered the same problem but were able to disable the auto trim.

One crew was lucky, the other failed to handle the situation. How is a survivability of 50% satisfying you?

rheinwaldner wrote:

They did apply manual counter trim. Dozens of times. And every time the wheel not only stopped, but even followed their command. So the symptoms of a stabilizer runaway were not there. By repetition the pilots learned, they could control the trim. What they did not know, was that this system would wake up as long as they flew with clean configuration, 6 times per minute, trying to push the nose down, and that failing to interupt just two full trim down cycles would bring them into a not recoverable flight state. After 26 cycles it ended like that.

Twenty six times the pilot had to stop the (runaway) trim and you don't call that "runaway? That struck me as cognitive bias until I remembered another post of yours:
In a recent post discussing an engine failure over water, you took the position:

If "following" would end after an engine relit, it would have to be mentioned. Following means at least until landing without explicit termination condition. The wording makes the "land asap" phase indefinitely long after it has been triggered by the starting event "engine failure" imho.

Earlier, in the case of a flameout, you saw a relight as not ending the event, the event continues until wheels touch ground, but in the case of stab trim runaway, you see twenty six occurrences in an eight minute span as being twenty six separate events.

Get real guy, that was stab trim runaway.

More:

We have the evidence, that if this failure mode occurs, only one of two crews without the training will bring the plane back (survivability was 50%). A design that results in a survivability of 50% in aviation is bloody awful.

Statistical analysis on two data points? I hope you don't do statistical analysis for a living. Again, that sounds less like a statistical analysis and more like an A vs B thing.
Methinks you should limit yourself to posting in the A vs B forum.

And the earlier event has been described as failure of IAS and altitude information, not pitch down, so it appears to be a different failure or a different manifestation of the same failure, there is an unknown at play in this.

ikramerica wrote:

Poor piloting was the reason for the crash.

There is no single cause for this or most crashes. Why do so many want to make it so.

1989worstyear wrote:

PixelFlight wrote:

salttee wrote:

I don't see as much complexity in this as you and your sources are postulating. Every aircraft equipped with automatic stabilizer trim, from piston driven twins to the 380 has a cutout switch available to the flight crew to either disable the automatic trim or to remove power to the auto trim motor(s).

It look like it's a bit more sophisticated on some Airbus in order to reduce crew load and increase redundancy: viewtopic.php?t=765147#p11043627 post #12 by zeke
Some others posts on the same thread are very interesting. I only chose one that summarize the best my point of view: the 737-8/-9 design is dangerous precisely because he it too simple for the critical MCAS stab trim function. Airbus, especially since the A330, (and certainly the B787, but to be verified) use a lot of redundancy in the sensors, the ADIRU, the FCC, the actuators and take a system width approach of the design. The 737 (and in part the A320) are stuck in the past in comparison. There is no reason why this very common category of aircraft is still allowed to have a underrated grade of security. Both brands are perfectly capable to upgrade there design with the most advanced ADFX avionic, more sensors and more actuators.

A 30 year old design competing against a heavily warmed-over 51-year-old design doesn't get you that far.

AFAIK the current general upper design of redundancy (system level approach of multiple sensors, multiple ADIRU, multiple FC, multiple actuators) was first matured on the A330. Many details was improved since, but I think that the general upper design is the same. The implementation design of the communications is now ADFX network since the A380 (and B787), introduced about ~10 years ago , vastly improving the availability of all data to system width algorithms. Those algorithms can now evolve too, to integrate flight dynamic predictors, allowing more cleaver sensors filtering than the current compare/vote/select algorithm.

salttee wrote:

rheinwaldner wrote:

They did apply manual counter trim. Dozens of times. And every time the wheel not only stopped, but even followed their command. So the symptoms of a stabilizer runaway were not there. By repetition the pilots learned, they could control the trim. What they did not know, was that this system would wake up as long as they flew with clean configuration, 6 times per minute, trying to push the nose down, and that failing to interupt just two full trim down cycles would bring them into a not recoverable flight state. After 26 cycles it ended like that.

Twenty six times the pilot had to stop the (runaway) trim and you don't call that "runaway? .

no
it wasnt

there is a clear definition of a runaway trim in the training manual
the original has been postet a few pages up from here

a runaway trim is per definition a electrical failure
the crew @ a runaway trim cannot stop the trim and it cannot reverse the trim

but
they could stop it
they could reverse it
it even stopped and reveres by itself

so per definition this was nothing near a runaway trim


at this point nobody can be shure that the cockpit crew does NOT follow the procedures and the checklists

maybe they didnt

maybe they should not and could have brought that ship back home in one piece if they would have acted againgst the checklists

we will not know if we do not find the CVR

but that whole „it was a simple runaway trim“ moaning is simply embrassing

salttee wrote:

Twenty six times the pilot had to stop the (runaway) trim and you don't call that "runaway"?

Dear colleague, would it not be common sense, that something, that can be stopped and reversed easily is not a "runaway"? How can you call that runaway? Doing a proper error analysis the symptoms did not point to a stab runaway. The behavior could not be recognized as trim runaway.

Regarding the engine shutdown there were not many professional pilots in the other thread (if any), who would have agreed with the opposite position to mine. And how you can compare shutting down an engine, with trimming the nose upwards for a few seconds (because that's what the pilots initially did and it solved the problem), is beyond me.

salttee wrote:

We have the evidence, that if this failure mode occurs, only one of two crews without the training will bring the plane back (survivability was 50%). A design that results in a survivability of 50% in aviation is bloody awful.

Statistical analysis on two data points?

We dont have more data points. Of course one of two is not a precise statistics. But even if only successful recoveries would have been recorded in the coming years, resulting in a survivability of 10% or so, that would still be bloody awful. Note: as the MAX pilots today know MCAS better than many other systems, I dont expect there to be new data points at all in the future. The two occurrences, are all we'll ever observe.

salttee wrote:

Get real guy, that was stab trim runaway.

Forced to agree on the wording "Runaway Stabilizer" as even Boeing use it his AD 2018-23-51. But this very AD 2018-23-51 was precisely issued to urgently add this information into the Operating Procedures:

"The 737-8/-9 uses a Flight Control Computer command of pitch
trim to improve longitudinal handling characteristics. In the event of
erroneous Angle of Attack (AOA) input, the pitch trim system can trim
the stabilizer nose down in increments lasting up to 10 seconds.

In the event an uncommanded nose down stabilizer trim is experienced
on the 737-8/-9, in conjunction with one or more of the indications or
effects listed below, do the existing AFM Runaway Stabilizer
procedure above, ensuring that the STAB TRIM CUTOUT switches
are set to CUTOUT and stay in the CUTOUT position for the
remainder of the flight.

An erroneous AOA input can cause some or all of the following
indications and effects:
• Continuous or intermittent stick shaker on the affected side only.
• Minimum speed bar (red and black) on the affected side only.
• Increasing nose down control forces.
• IAS DISAGREE alert.
• ALT DISAGREE alert.
• AOA DISAGREE alert (if the option is installed).
• FEEL DIFF PRESS light.
• Autopilot may disengage.
• Inability to engage autopilot."

You can't deny that those information was unknown to the JT610 crew. Please respect that there wanted to survive. Human limitation in a unknown situation is very hard to study especially in high stress situation. This is not the first accident that a simple action could have avoided. The tragic fact is that this destroy lives and this must be addressed. So what can be done ? Blaming the pilot is not a constructive action addressing the identified unsafe condition.

So what can be done?
Boeing is working on a software fix for MCAS. Could be as simple as AoA = Disagree, then MCAS = OFF?
Boeing can clarify the term "Runaway" and change the NNC(s) accordingly. Uncommanded perhaps?
According to the KNKT Report the JT43 crew ran three NNC's: Airspeed Disagree, Alt Disagree and Runaway Trim.
If you need a checklist to solve the issue that faced this crew, I am at a loss for words.
Turn the dang thing off and fly Pitch and Power IMO.
It's scary to think we've reached such a low point in AVIATION and some seem to have forgotten how to AVIATE.

SomebodyInTLS wrote:

SomebodyInTLS wrote:

Strangely, a search only shows replies to mandala499 - not his original posts - so maybe he has removed them due to being involved now...

Never mind. I did a test - the search function is rubbish and doesn't find user names unless these are quoted in someone's text...

The "Gear Icon" to the right of the search bar will open an "Advanced Search" option where you can search by Author.

rheinwaldner wrote:

We have the evidence, that if this failure mode occurs, only one of two crews without the training will bring the plane back (survivability was 50%). A design that results in a survivability of 50% in aviation is bloody awful.

Note: even if maintenance would have done their job, the AoA sensing system could fall into this failure mode by just e.g. a bird strike. So any 737 MAX which is currently flying world wide, even if perfectly maintained, could end up in this condition before you finish reading this sentence.

trav777 wrote:

I really think that we ought to step back and ask why this plane not only flew this mission but continued on the previous one when the pilots encountered the same problem but were able to disable the auto trim.

One crew was lucky, the other failed to handle the situation. How is a survivability of 50% satisfying you?

Dude, what's even worse is I have a coin that I tossed and it came up heads THREE TIMES IN A ROW, therefore this coin SUCKS and gives 100% odds of heads!

Sorry but if you actually believe a sample size of n=2 is large enough to base a statistical probability estimate off of, then you're....uninformed. And I'm being polite here.

These were Lion Air "pilots". "Flying" a jet that should have returned to base on the previous leg. This plane should not have been in the air at all. Nothing is wrong with MCAS, the lack of redundancy in the AoA sensor chain is the defect here.

But, reading the reports of pilot activity...I'm sorry. I've flown. If the plane is going haywire and you do something and it goes straight and level, YOU DON'T TOUCH A THING AFTER THAT and you return to the runway. I cannot even fathom a professional pilot in a jet that is trying to push you into the ground and you go flaps 1 and it levels out and you....disengage flaps!??!? Then it tries to kill you again and you go flaps1 and it stops and you....AGAIN disengage flaps? This is insane. If I am in the right seat in that jet and you are the captain at that point I threaten to physically kill you if you disengage those flaps again.

Both flight legs show that Lion Air pilots appear to be trained to attempt to continue to destination on a plane that is trying to kill them. We have, using your math, a 100% sample on that.

Let me ask you- would YOU want to be on an airline on ANY jet where the pilots do stuff like this? Where unbeknownst to you the plane is trying to kill everyone onboard and the pilots are up there trying to find a way to get you to point B instead of back on the ground to safety?

FlyXLsa wrote:

SomebodyInTLS wrote:

SomebodyInTLS wrote:

Strangely, a search only shows replies to mandala499 - not his original posts - so maybe he has removed them due to being involved now...

Never mind. I did a test - the search function is rubbish and doesn't find user names unless these are quoted in someone's text...

The "Gear Icon" to the right of the search bar will open an "Advanced Search" option where you can search by Author.

Thanks - I did find that option, but only after the first search had made me post (incorrectly) that mandala499's posts had been removed.

PixelFlight wrote:

banghead wrote:

A 30 year old design competing against a heavily warmed-over 51-year-old design doesn't get you that far.

AFAIK the current general upper design of redundancy (system level approach of multiple sensors, multiple ADIRU, multiple FC, multiple actuators) was first matured on the A330. Many details was improved since, but I think that the general upper design is the same. The implementation design of the communications is now ADFX network since the A380 (and B787), introduced about ~10 years ago , vastly improving the availability of all data to system width algorithms. Those algorithms can now evolve too, to integrate flight dynamic predictors, allowing more cleaver sensors filtering than the current compare/vote/select algorithm.

But how does the moon cycle or wind direction factor into any of this?

salttee wrote:

rheinwaldner wrote:

They did apply manual counter trim. Dozens of times. And every time the wheel not only stopped, but even followed their command. So the symptoms of a stabilizer runaway were not there. By repetition the pilots learned, they could control the trim. What they did not know, was that this system would wake up as long as they flew with clean configuration, 6 times per minute, trying to push the nose down, and that failing to interupt just two full trim down cycles would bring them into a not recoverable flight state. After 26 cycles it ended like that.

Twenty six times the pilot had to stop the (runaway) trim and you don't call that "runaway?

Albert Einstein once made a statement that pretty well describes this situation:

Insanity: doing the same thing over and over again and expecting different results

Suddenly, KRI Spica has company...


The Navy "tug-type" vessel: KRI Leuser

It appears another navy vessel KRI Leuser is now in the vicinity of KRI Spica. Is it a good sign??





The initial plan was to have KRI Spica search for the CVR for 10 days. After which, the search operation will be re-assessed for either continuance or termination.



- https://www.marinetraffic.com/en/ais/ho ... .9/zoom:11

rheinwaldner wrote:

Note: even if maintenance would have done their job, the AoA sensing system could fall into this failure mode by just e.g. a bird strike.

Many have been stating here for awhile this (MCAS) was a non-redundant design that could fail with one bad AOA sensor. How did we come to that conclusion? Maybe the design was intended to incorporate redundancy (there are at least two AOA sensors on the 737 Max), but something malfunctioned within MCAS subsystem, or wasn't tested thoroughly enough to find all the bugs. This would explain why Boeing hasn't come out strong on this being a runaway trim situation and pilots, including Lion Air pilots, should already know how to deal with. Ie, that MCAS is _supposed_ to be redundant, but somehow ignored the good sensor (and Boeing is waiting for the CVR to be found that shows pilots confused and incompetent, before they put their own foot in their mouth).

And Boeing has the FDR data for two months now. That's enough time to recreate the inputs fed to MCAS and determine if a bug exists but somehow wasn't caught in the software verification phase of certification.

I mean, one of the most essential systems on the plane is designed to look at only the pilot side's AOA sensor seems ludicrous to me.

It's good to see the Indonesian Navy trying to find the CVR with some specialist vessels. Brave venture I hope they find it.

sgrow787 wrote:

rheinwaldner wrote:

Note: even if maintenance would have done their job, the AoA sensing system could fall into this failure mode by just e.g. a bird strike.

Many have been stating here for awhile this (MCAS) was a non-redundant design that could fail with one bad AOA sensor. How did we come to that conclusion?

Seriously? We didn't "come to that conclusion", the emergency AD and various diagrams posted early in this thread show unequivocally that that is how the system is designed.

I mean, one of the most essential systems on the plane is designed to look at only the pilot side's AOA sensor seems ludicrous to me.

Well, that's why this is kind of a big deal (and why some deflect blame away from Boeing all the time).

BTW, I'm not in this to kick Boeing, but we need to know how such an odd design choice was made and approved. I understand that the MCAS behaviour was deliberately not communicated in training etc. since the whole point was for it to make MAX behave like previous models, but it's hard to understand why they didn't seem to consider redundancy complications and why the regulator didn't take issue with it either.

trav777 wrote:

If the plane is going haywire and you do something and it goes straight and level, YOU DON'T TOUCH A THING AFTER THAT and you return to the runway. I cannot even fathom a professional pilot in a jet that is trying to push you into the ground and you go flaps 1 and it levels out and you....disengage flaps!??!?

The nerves that you are demonstrating do not convince me, that you would have noticed the unknown causality between the flaps position and the trim movements. You are aware that several system from time to time do move these trim wheels, perfectly legitimate and meaningful? A spinning trim wheel is not an indication of a trim runaway. There is no obvious evidence available, whether any particular trim wheel movement was triggered by a disturbed or a working system.

Again, in a situation overwhelmed by a flood of different error messages they flew manually, a lot of things happened at the same time, trimming manually they had dozens of time trimmed away the somewhat built up forces on the control column (maybe not even by conscious actions, so the fact that the applied trim was always upwards and always repeated in steady cycles maybe went unnoticed). As speculated here earlier, they could have attempted to make a turn, and during turns you dont trim. And, bang, the two cycles the disturbed MCAS needed to become a deadly monster passed unopposed...

Considering that, IMO any pilot who now steps up and claims, that he would have survived like the first crew, shows nothing than arrogance.

salttee wrote:

PixelFlight wrote:

banghead wrote:

A 30 year old design competing against a heavily warmed-over 51-year-old design doesn't get you that far.

AFAIK the current general upper design of redundancy (system level approach of multiple sensors, multiple ADIRU, multiple FC, multiple actuators) was first matured on the A330. Many details was improved since, but I think that the general upper design is the same. The implementation design of the communications is now ADFX network since the A380 (and B787), introduced about ~10 years ago , vastly improving the availability of all data to system width algorithms. Those algorithms can now evolve too, to integrate flight dynamic predictors, allowing more cleaver sensors filtering than the current compare/vote/select algorithm.

But how does the moon cycle or wind direction factor into any of this?

Exactly as it should.