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morrisond
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Re: B737MAX Grounded Worldwide

Sat Mar 30, 2019 2:08 pm

Revelation wrote:
At the risk of being bitten as I throw red meat into the lion's cage, here is how Boeing explains itself ( ref: AvWeek ):

Commenting on criticism of the single-string-failure potential of the AOA input to the MCAS, a Boeing executive says the original design was based on a standard industry process of hazard classification, which defined the potential failure as one that could be mitigated “very quickly by a trained pilot using established procedures.”

“In this particular case, because we don’t know yet what the ultimate cause is, we can look at that one link in the chain and say we know ways to update the MCAS functionality to make it more robust, and that’s what we are doing,” the executive says. “While certification standards say a runaway stabilizer has a memory procedure associated with it—despite all of that, we are looking at it and saying, ‘We don’t want to intentionally provide the pilot with that scenario again.’ So in the design, we are using multiple inputs, even though in the original hazard classification, multiple inputs would not be required. We’ve seen two accidents, and we believe it’s appropriate to make that link in the chain more robust.”

While some here won't be sympathetic to this explanation, I personally think it's important we understand what the explanation is, right from a company executive.

My understanding of the context is that during this week's gathering in Seattle the media was allowed to attend and report on a question and answer session, as long as they did not report the names of the engineers and executives answering the questions, thus the reference to a "Boeing executive" as the source of the quote. This also shows that this is a very recent statement.

osiris30 wrote:
Or... maybe no one realized it was that bad/a big deal.. like leaded gas or paint.. or asbestos... or all the other stupid in hindsight mistakes man as made (I used three examples but there are literally ... at least millions that someone could cite)

My interpretation of the statement above is that even as of this week Boeing still feels their original design was sufficient and that if any problem with MCAS was encountered the pilots would recognize it as a runaway stabilizer problem and invoke the associated memory procedure to resolve the problem.

As I've written in another thread, the fact that they are issuing changes is a tacit admission that their MCAS design was found wanting. Above the Boeing exec is using the words "make it more robust" which is a very similar statement, but presumably out of legal necessity, admits no guilt.


Interesting - So if the plane has two sensors linked up and they both fail - it's still the planes fault if the pilot forgets the memory procedure?

Stuff fails. Pilots have to be trained to recognize issues (runaway trim) and be able to deal with it.
Boeing really screwed up on the design (as evidenced by the other changes they are making so that even if two sensors fail MCAS won't put the plane in a nose down position), however I hope that what happens as a result on these crashes is that flight training of commercial pilots is made a lot more robust.

A well trained crew should have been able to diagnose an electric trim issue and turned it off - even if they had never heard of MCAS.

For instance if it was the Speed Trim system (which I don't believe has had issues - but parts in it can fail leading to bizarre outcomes) had an issue causing the plane to do weird things and the pilots did not know how to turn off the electric trim - is that an inherent design problem or a failure in training?

Or if the Autopilot turns the plane the wrong direction 22 times (due to a part failure) and the pilots keep using it is that the planes fault or the pilot's for continuing to rely on it?
 
osiris30
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Re: B737MAX Grounded Worldwide

Sat Mar 30, 2019 2:50 pm

Revelation wrote:
At the risk of being bitten as I throw red meat into the lion's cage, here is how Boeing explains itself ( ref: AvWeek ):

Commenting on criticism of the single-string-failure potential of the AOA input to the MCAS, a Boeing executive says the original design was based on a standard industry process of hazard classification, which defined the potential failure as one that could be mitigated “very quickly by a trained pilot using established procedures.”

“In this particular case, because we don’t know yet what the ultimate cause is, we can look at that one link in the chain and say we know ways to update the MCAS functionality to make it more robust, and that’s what we are doing,” the executive says. “While certification standards say a runaway stabilizer has a memory procedure associated with it—despite all of that, we are looking at it and saying, ‘We don’t want to intentionally provide the pilot with that scenario again.’ So in the design, we are using multiple inputs, even though in the original hazard classification, multiple inputs would not be required. We’ve seen two accidents, and we believe it’s appropriate to make that link in the chain more robust.”

While some here won't be sympathetic to this explanation, I personally think it's important we understand what the explanation is, right from a company executive.

My understanding of the context is that during this week's gathering in Seattle the media was allowed to attend and report on a question and answer session, as long as they did not report the names of the engineers and executives answering the questions, thus the reference to a "Boeing executive" as the source of the quote. This also shows that this is a very recent statement.

osiris30 wrote:
Or... maybe no one realized it was that bad/a big deal.. like leaded gas or paint.. or asbestos... or all the other stupid in hindsight mistakes man as made (I used three examples but there are literally ... at least millions that someone could cite)

My interpretation of the statement above is that even as of this week Boeing still feels their original design was sufficient and that if any problem with MCAS was encountered the pilots would recognize it as a runaway stabilizer problem and invoke the associated memory procedure to resolve the problem.

As I've written in another thread, the fact that they are issuing changes is a tacit admission that their MCAS design was found wanting. Above the Boeing exec is using the words "make it more robust" which is a very similar statement, but presumably out of legal necessity, admits no guilt.



Maybe everyone should read this. FORMER engineers. Unnamed sources. Lots of cover for folks to hide behind and yet what is being said makes sense. Basically:. No one saw the issue till it happened. Then it became obvious.

Also read all of it. It is quite enlightening.

https://mobile.reuters.com/article/amp/idUSKCN1RA006

Sorry for mobile link
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scbriml
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Re: B737MAX Grounded Worldwide

Sat Mar 30, 2019 2:56 pm

Revelation wrote:
At the risk of being bitten as I throw red meat into the lion's cage, here is how Boeing explains itself ( ref: AvWeek ):

Commenting on criticism of the single-string-failure potential of the AOA input to the MCAS, a Boeing executive says the original design was based on a standard industry process of hazard classification, which defined the potential failure as one that could be mitigated “very quickly by a trained pilot using established procedures.”

“In this particular case, because we don’t know yet what the ultimate cause is, we can look at that one link in the chain and say we know ways to update the MCAS functionality to make it more robust, and that’s what we are doing,” the executive says. “While certification standards say a runaway stabilizer has a memory procedure associated with it—despite all of that, we are looking at it and saying, ‘We don’t want to intentionally provide the pilot with that scenario again.’ So in the design, we are using multiple inputs, even though in the original hazard classification, multiple inputs would not be required. We’ve seen two accidents, and we believe it’s appropriate to make that link in the chain more robust.”

While some here won't be sympathetic to this explanation, I personally think it's important we understand what the explanation is, right from a company executive.


Was the bolding and underlining yours or AvWeek's?

I'm not surprised you think some won't be sympathetic to the explanation because it's a little on the weasely side, isn't it? "we believe it's appropriate to make that link in the chain more robust". I understand that Boeing's lawyers must be working overtime to vet every executive utterance these days, but...

Revelation wrote:
As I've written in another thread, the fact that they are issuing changes is a tacit admission that their MCAS design was found wanting. Above the Boeing exec is using the words "make it more robust" which is a very similar statement, but presumably out of legal necessity, admits no guilt.


"Found wanting" is a pretty good euphemism as well.
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mjoelnir
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Re: B737MAX Grounded Worldwide

Sat Mar 30, 2019 2:58 pm

Revelation wrote:
My interpretation of the statement above is that even as of this week Boeing still feels their original design was sufficient and that if any problem with MCAS was encountered the pilots would recognize it as a runaway stabilizer problem and invoke the associated memory procedure to resolve the problem.

As I've written in another thread, the fact that they are issuing changes is a tacit admission that their MCAS design was found wanting. Above the Boeing exec is using the words "make it more robust" which is a very similar statement, but presumably out of legal necessity, admits no guilt.


I do not get it.

In the check list for run away trim, you get to the point, I do not have the exact wording, does it react to the electrical trim switches on the column, if yes it is not a runaway trim.
So how do people here eat the Boeing statement that MCAS is a runaway trim. You stop MCAS in the same way as a runaway trim, but it is not a runaway trim. Runaway trim has a clear definition. Automatic running amok trim is something else. Again, you can switch of autopilot, why is there no switch switching off auto trim. Using the switches on the column to run the trim I would still call manual.

I think the Boeing executive is delusional. It may help in USA courtrooms to never have admitted guilt or any responsibility, but it will not help Boeing in the general perception. And Boeing may well save millions to loose billions. Boeing will get hammered in the courtrooms anyway. The Lion Air crash may have been unforeseeable, but than came the Ethiopian crash.

Statements like, we make a safe plane safer, comes over as arrogant and mocking the victims, when you say that after your frame crashed twice. And it may perhaps satisfy a corporate lawyer or a Boeing fan, but that is about it.

And yes, I have not flown any 737 or any jet. My experience comes from flying around in small single and old twin engine frames and I never had to fight an automatic.
 
XRAYretired
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Re: B737MAX Grounded Worldwide

Sat Mar 30, 2019 3:14 pm

morrisond wrote:
Revelation wrote:
At the risk of being bitten as I throw red meat into the lion's cage, here is how Boeing explains itself ( ref: AvWeek ):

Commenting on criticism of the single-string-failure potential of the AOA input to the MCAS, a Boeing executive says the original design was based on a standard industry process of hazard classification, which defined the potential failure as one that could be mitigated “very quickly by a trained pilot using established procedures.”

“In this particular case, because we don’t know yet what the ultimate cause is, we can look at that one link in the chain and say we know ways to update the MCAS functionality to make it more robust, and that’s what we are doing,” the executive says. “While certification standards say a runaway stabilizer has a memory procedure associated with it—despite all of that, we are looking at it and saying, ‘We don’t want to intentionally provide the pilot with that scenario again.’ So in the design, we are using multiple inputs, even though in the original hazard classification, multiple inputs would not be required. We’ve seen two accidents, and we believe it’s appropriate to make that link in the chain more robust.”

While some here won't be sympathetic to this explanation, I personally think it's important we understand what the explanation is, right from a company executive.

My understanding of the context is that during this week's gathering in Seattle the media was allowed to attend and report on a question and answer session, as long as they did not report the names of the engineers and executives answering the questions, thus the reference to a "Boeing executive" as the source of the quote. This also shows that this is a very recent statement.

osiris30 wrote:
Or... maybe no one realized it was that bad/a big deal.. like leaded gas or paint.. or asbestos... or all the other stupid in hindsight mistakes man as made (I used three examples but there are literally ... at least millions that someone could cite)

My interpretation of the statement above is that even as of this week Boeing still feels their original design was sufficient and that if any problem with MCAS was encountered the pilots would recognize it as a runaway stabilizer problem and invoke the associated memory procedure to resolve the problem.

As I've written in another thread, the fact that they are issuing changes is a tacit admission that their MCAS design was found wanting. Above the Boeing exec is using the words "make it more robust" which is a very similar statement, but presumably out of legal necessity, admits no guilt.


Interesting - So if the plane has two sensors linked up and they both fail - it's still the planes fault if the pilot forgets the memory procedure?

Stuff fails. Pilots have to be trained to recognize issues (runaway trim) and be able to deal with it.
Boeing really screwed up on the design (as evidenced by the other changes they are making so that even if two sensors fail MCAS won't put the plane in a nose down position), however I hope that what happens as a result on these crashes is that flight training of commercial pilots is made a lot more robust.

A well trained crew should have been able to diagnose an electric trim issue and turned it off - even if they had never heard of MCAS.

For instance if it was the Speed Trim system (which I don't believe has had issues - but parts in it can fail leading to bizarre outcomes) had an issue causing the plane to do weird things and the pilots did not know how to turn off the electric trim - is that an inherent design problem or a failure in training?

Or if the Autopilot turns the plane the wrong direction 22 times (due to a part failure) and the pilots keep using it is that the planes fault or the pilot's for continuing to rely on it?



I sincearly hope the design considerations were not as shallow as the 'Boeing Exec' has stated, especially since a little thought and a few dozen lines of code would have made the system tolerant and safe, otherwise we are in a lot more trouble than we think.

It should have been so easy.

Still, having a more tolerant and safe system would not be so much fun for the pilots would it?


Ray
 
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Revelation
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Re: B737MAX Grounded Worldwide

Sat Mar 30, 2019 3:59 pm

scbriml wrote:
Was the bolding and underlining yours or AvWeek's?

Mine, made because I felt I should emphasize what Boeing is saying about the original MCAS design and the changes it is making.

scbriml wrote:
I'm not surprised you think some won't be sympathetic to the explanation because it's a little on the weasely side, isn't it? "we believe it's appropriate to make that link in the chain more robust". I understand that Boeing's lawyers must be working overtime to vet every executive utterance these days, but...

I understand the lack of sympathy and the characterization of the statement as weasely. It is an exercise in understanding what they are willing to say after a strong scrub by the legal team.

scbriml wrote:
Revelation wrote:
As I've written in another thread, the fact that they are issuing changes is a tacit admission that their MCAS design was found wanting. Above the Boeing exec is using the words "make it more robust" which is a very similar statement, but presumably out of legal necessity, admits no guilt.

"Found wanting" is a pretty good euphemism as well.

An euphemism is "the substitution of a mild, indirect, or vague expression for one thought to be offensive, harsh, or blunt" -- not sure that's the right word.

Boeing's statement tells us they believe they released a design that worked, and if there were issues they felt the pilot's training would lead them to disable the trim circuit. Boeing says the "ultimate cause" is still unknown, but we have evidence that one set of JQ pilots did manage to disable the trim circuit, and another set of JQ pilots did not, nor presumably did a set of ET pilots.

My use of "found wanting" is Boeing's reliance on the pilots to detect the problem and apply the correct workaround in a workable amount of time. The "offensive, harsh, or blunt" part would be if Boeing is lying in this kind of statement like VW did in Dieselgate, where a VW executive signed a statement that he knew was untrue and has admitted so in legal documents. Some are comfortable reaching the conclusion that Boeing is doing something like that, but I for one don't think we know enough to reach that conclusion.
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kalvado
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Re: B737MAX Grounded Worldwide

Sat Mar 30, 2019 4:27 pm

Revelation wrote:
XRAYretired wrote:
I sincearly hope the design considerations were not as shallow as the 'Boeing Exec' has stated, especially since a little thought and a few dozen lines of code would have made the system tolerant and safe, otherwise we are in a lot more trouble than we think.

It should have been so easy.

That's easy to say with 100% hindsight.

Of course it is. That is why all those statements sound half-assed today, as Boeing doesn't recognize the problem even in hindsight.
Boeing statement should be - we classified problem as a hazard, but now we realize we screwed up that rating. We thought pilots would recognize the condition as something else - but apparently they didn't. We screwed up twice, and we screwed up over again when we didn't respond to first crash properly. That is three strikes against us.
We pray for forgiveness and ask for just another chance. No more cocky altitude, ever[*]
That would be the way to go. But now there is a recurrent attitude problem to edal with - on top of engineering psycology and aerodynamics design problems.


[*] at least until dust settles
 
shaner82
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Re: B737MAX Grounded Worldwide

Sat Mar 30, 2019 5:05 pm

One thing I haven't seen an explanation for yet, or much discussion on, is the few cases where Max planes suddenly dove while on autopilot. In all cases the pilots manually took control and flew the plane without further issue, but if AP was on, then it wouldn't be MCAS causing the nose to point down. It makes me wonder what caused that.
 
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scbriml
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Re: B737MAX Grounded Worldwide

Sat Mar 30, 2019 6:24 pm

Revelation wrote:
I understand the lack of sympathy and the characterization of the statement as weasely. It is an exercise in understanding what they are willing to say after a strong scrub by the legal team.


Agreed. I worked in the oil industry for 35 years, I've seen more than my fair share of legal dept approved releases. It's just frustrating.

Revelation wrote:
An euphemism is "the substitution of a mild, indirect, or vague expression for one thought to be offensive, harsh, or blunt" -- not sure that's the right word.


Exactly! In this case "found wanting" is a euphemism for "[expletive deleted] badly designed".
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zeke
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Re: B737MAX Grounded Worldwide

Sat Mar 30, 2019 8:35 pm

mjoelnir wrote:
So how do people here eat the Boeing statement that MCAS is a runaway trim. You stop MCAS in the same way as a runaway trim, but it is not a runaway trim. Runaway trim has a clear definition. Automatic running amok trim is something else. Again, you can switch of autopilot, why is there no switch switching off auto trim. Using the switches on the column to run the trim I would still call manual.


The runaway trim procedure does not turn off MCAS, MCAS would still be commanding the horizontal stabilizer nose down. The runaway trim procedure removes electrical power from the horizontal stabilizer actuator.

If for whatever reason the relay does not open on the stabilizer primary and backup switches, the actuator remains powered, MCAS will continue to trim nose down.

There is no way to turn MCAS off, nor does the aircraft tell the pilot when MCAS is active even after this so called fix. In my view it’s criminal to provide this autopilot function when manually flying an aircraft and give no notification to the crew it is active. Why cannot they provide a message on the PFD and HUD that MCAS is active ?

Revelation wrote:
Boeing's statement tells us they believe they released a design that worked, and if there were issues they felt the pilot's training would lead them to disable the trim circuit. Boeing says the "ultimate cause" is still unknown, but we have evidence that one set of JQ pilots did manage to disable the trim circuit, and another set of JQ pilots did not, nor presumably did a set of ET pilots.


JQ does not operate any 737 series aircraft, just A320 series and 787.
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mysfit
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Re: B737MAX Grounded Worldwide

Sat Mar 30, 2019 8:48 pm

Engineers made the classification based on TRAINED pilots.

But Boeing did NOT TRAIN pilots on the system. Because they would have lost a major selling point.
 
zakelwe
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Re: B737MAX Grounded Worldwide

Sat Mar 30, 2019 9:26 pm

The issue here is that that this is supposed to be an automated system to help pilots in a certain flight envelope, ie actually stalling, but here it seems it can be triggered when the plane is not actually stalling.

So it seems the testing didn't take into account enough parameters. If that is the case then we me see lots of litigation in the months ahead.
 
LDRA
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Re: B737MAX Grounded Worldwide

Sat Mar 30, 2019 9:34 pm

shaner82 wrote:
One thing I haven't seen an explanation for yet, or much discussion on, is the few cases where Max planes suddenly dove while on autopilot. In all cases the pilots manually took control and flew the plane without further issue, but if AP was on, then it wouldn't be MCAS causing the nose to point down. It makes me wonder what caused that.

AP disengages on airspeed disagree. Airspeed disagree due to AOA signal fault. So the same faulty AOA signal kicked airplane out of autopilot, then start driving nose down.

It will be interesting to see how Boeing does their failure analysis and how common mode failures are treated
 
Heinkel
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Re: B737MAX Grounded Worldwide

Sat Mar 30, 2019 9:43 pm

Revelation wrote:
At the risk of being bitten as I throw red meat into the lion's cage, here is how Boeing explains itself ( ref: AvWeek ):

Commenting on criticism of the single-string-failure potential of the AOA input to the MCAS, a Boeing executive says the original design was based on a standard industry process of hazard classification, which defined the potential failure as one that could be mitigated “very quickly by a trained pilot using established procedures.”

“In this particular case, because we don’t know yet what the ultimate cause is, we can look at that one link in the chain and say we know ways to update the MCAS functionality to make it more robust, and that’s what we are doing,” the executive says. “While certification standards say a runaway stabilizer has a memory procedure associated with it—despite all of that, we are looking at it and saying, ‘We don’t want to intentionally provide the pilot with that scenario again.’ So in the design, we are using multiple inputs, even though in the original hazard classification, multiple inputs would not be required. We’ve seen two accidents, and we believe it’s appropriate to make that link in the chain more robust.”


Very interesting. I'm shocked, that a Boeing exec still tells in an official press release, that MCAS relying on a single sensor was not a bad idea, because this was industry standard. So now they only make a safe plane safer (Now they call it ...more robust). So they did everything right. Nothing to see here.

The aviation experts all over the world are impressed.

Boeing simply lied or cheated with the hazard classification of the MCAS system. From "catastrophic" to a lower level. Looks like the lawyers from the legal department can't value these technical questions and so they gave permission to publish it.

To build an automatic system with the power and authority to override the pilot without telling him and the ability to trim "full down", which relies on single-circuit technology is bloodcurdling for anyone, who works in the field of technical hazard classification. Every cheap car today has a dual-circuit brake system, even a DACIA or a YUGO.

And now Boeing exec says, that they did it deliberately and still think it wasn't such a bad idea. Delusions of grandeur or loss of reality? (Or simply bad consultants / advisers?)
 
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NeBaNi
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Re: B737MAX Grounded Worldwide

Sat Mar 30, 2019 10:12 pm

Revelation wrote:
At the risk of being bitten as I throw red meat into the lion's cage, here is how Boeing explains itself ( ref: AvWeek ):

Commenting on criticism of the single-string-failure potential of the AOA input to the MCAS, a Boeing executive says the original design was based on a standard industry process of hazard classification, which defined the potential failure as one that could be mitigated “very quickly by a trained pilot using established procedures.”

“In this particular case, because we don’t know yet what the ultimate cause is, we can look at that one link in the chain and say we know ways to update the MCAS functionality to make it more robust, and that’s what we are doing,” the executive says. “While certification standards say a runaway stabilizer has a memory procedure associated with it—despite all of that, we are looking at it and saying, ‘We don’t want to intentionally provide the pilot with that scenario again.’ So in the design, we are using multiple inputs, even though in the original hazard classification, multiple inputs would not be required. We’ve seen two accidents, and we believe it’s appropriate to make that link in the chain more robust.”

While some here won't be sympathetic to this explanation, I personally think it's important we understand what the explanation is, right from a company executive.

My understanding of the context is that during this week's gathering in Seattle the media was allowed to attend and report on a question and answer session, as long as they did not report the names of the engineers and executives answering the questions, thus the reference to a "Boeing executive" as the source of the quote. This also shows that this is a very recent statement.

osiris30 wrote:
Or... maybe no one realized it was that bad/a big deal.. like leaded gas or paint.. or asbestos... or all the other stupid in hindsight mistakes man as made (I used three examples but there are literally ... at least millions that someone could cite)

My interpretation of the statement above is that even as of this week Boeing still feels their original design was sufficient and that if any problem with MCAS was encountered the pilots would recognize it as a runaway stabilizer problem and invoke the associated memory procedure to resolve the problem.

As I've written in another thread, the fact that they are issuing changes is a tacit admission that their MCAS design was found wanting. Above the Boeing exec is using the words "make it more robust" which is a very similar statement, but presumably out of legal necessity, admits no guilt.

This is not meant to be a personal attack, so I apologize in advance if it comes as such, but would you consider this quote as hearsay, since you posted on another thread that you attributed anonymous quotes in the media/news articles as hearsay? Or do you attach more weight to this quote vs. the others because it came from an anonymous Boeing executive?
 
markno
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Re: B737MAX Grounded Worldwide

Sat Mar 30, 2019 10:45 pm

osiris30 wrote:
Also read all of it. It is quite enlightening.

https://mobile.reuters.com/article/amp/idUSKCN1RA006


No call for simulators... wrote:
On Wednesday, Boeing said the MCAS system would now rely on two sensors.


Sorry if this has been discussed before, and just in case that the second sensor for MCAS has been mounted on the planes from day one:

What's the reason to not write a software version 1 that uses two sensors, when they are mounted in the plane? The software is probably no "crippleware" that "takes away" a function just so that it can be "bought back" like common software is monetized. So I assume the reason is some difficulty that is not easy to handle. But I wonder what reason. Like, maybe, it was unclear what signal processing filter to use? Or maintainance issues?
 
shaner82
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Re: B737MAX Grounded Worldwide

Sat Mar 30, 2019 11:31 pm

LDRA wrote:
shaner82 wrote:
One thing I haven't seen an explanation for yet, or much discussion on, is the few cases where Max planes suddenly dove while on autopilot. In all cases the pilots manually took control and flew the plane without further issue, but if AP was on, then it wouldn't be MCAS causing the nose to point down. It makes me wonder what caused that.

AP disengages on airspeed disagree. Airspeed disagree due to AOA signal fault. So the same faulty AOA signal kicked airplane out of autopilot, then start driving nose down.

It will be interesting to see how Boeing does their failure analysis and how common mode failures are treated


Good to know.
So in the cases described in the following article, do you believe that's what is the likely explanation?

https://globalnews.ca/news/5049364/boei ... t-problem/
 
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keesje
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Re: B737MAX Grounded Worldwide

Sat Mar 30, 2019 11:57 pm

Maybe MCAS/ trimming based on 1 AOA sensor was allowed under grandfathered certification requirements, instead of today requirements. Lets not forget MCAS, as originally presented to the FAA was't as powerfull as implemented later on.
"Never mistake motion for action." Ernest Hemingway
 
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Finn350
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 12:10 am

markno wrote:
osiris30 wrote:
Also read all of it. It is quite enlightening.

https://mobile.reuters.com/article/amp/idUSKCN1RA006


No call for simulators... wrote:
On Wednesday, Boeing said the MCAS system would now rely on two sensors.


Sorry if this has been discussed before, and just in case that the second sensor for MCAS has been mounted on the planes from day one:

What's the reason to not write a software version 1 that uses two sensors, when they are mounted in the plane? The software is probably no "crippleware" that "takes away" a function just so that it can be "bought back" like common software is monetized. So I assume the reason is some difficulty that is not easy to handle. But I wonder what reason. Like, maybe, it was unclear what signal processing filter to use? Or maintainance issues?


As I understand it, the single AoA reading is used for a trim stabilization (STS) in the 737NG series. Trim stabilization is not flight critical, and if it fails there are no flight safety considerations. MCAS in the 737 MAX is similar to the STS in the 737 NG except MCAS is flight critical. I suppose they didn’t properly account single sensor failure modes when designing MCAS.
 
smartplane
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 12:59 am

Finn350 wrote:
markno wrote:
osiris30 wrote:
Also read all of it. It is quite enlightening.

https://mobile.reuters.com/article/amp/idUSKCN1RA006


No call for simulators... wrote:
On Wednesday, Boeing said the MCAS system would now rely on two sensors.


Sorry if this has been discussed before, and just in case that the second sensor for MCAS has been mounted on the planes from day one:

What's the reason to not write a software version 1 that uses two sensors, when they are mounted in the plane? The software is probably no "crippleware" that "takes away" a function just so that it can be "bought back" like common software is monetized. So I assume the reason is some difficulty that is not easy to handle. But I wonder what reason. Like, maybe, it was unclear what signal processing filter to use? Or maintainance issues?


As I understand it, the single AoA reading is used for a trim stabilization (STS) in the 737NG series. Trim stabilization is not flight critical, and if it fails there are no flight safety considerations. MCAS in the 737 MAX is similar to the STS in the 737 NG except MCAS is flight critical. I suppose they didn’t properly account single sensor failure modes when designing MCAS.

And presumably described to FAA, EASA and customers, as STS re-named and better (for certification and type approval).
 
mzlin
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 7:15 am

FAA defended the categorization of MCAS as a supplement to STS which is what allowed it to use a single sensor. Nobody apparently thought of the possible consequences of failure, or had too much faith in the ability of pilots to figure it out:
https://www.mro-network.com/airlines/fa ... t-handover
"Boeing, relying on the flight standardization board (FSB) feedback and the concept that MCAS was an expansion of the 737NG speed-trim system (STS) and not a standalone addition to the design, did not include MCAS-related training in the 737 MAX documentation."

For the technically curious, here is a nice detailed description of how MCAS was designed (it includes some assumptions by the author but everything in it is consistent with what has been reported) and also a set of deductions about possible failure modes. The author is a former 767 engineer and FAA employee:
https://www.satcom.guru/2018/11/737-mca ... ption.html
 
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seahawk
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 8:26 am

Revelation wrote:
At the risk of being bitten as I throw red meat into the lion's cage, here is how Boeing explains itself ( ref: AvWeek ):

Commenting on criticism of the single-string-failure potential of the AOA input to the MCAS, a Boeing executive says the original design was based on a standard industry process of hazard classification, which defined the potential failure as one that could be mitigated “very quickly by a trained pilot using established procedures.”

“In this particular case, because we don’t know yet what the ultimate cause is, we can look at that one link in the chain and say we know ways to update the MCAS functionality to make it more robust, and that’s what we are doing,” the executive says. “While certification standards say a runaway stabilizer has a memory procedure associated with it—despite all of that, we are looking at it and saying, ‘We don’t want to intentionally provide the pilot with that scenario again.’ So in the design, we are using multiple inputs, even though in the original hazard classification, multiple inputs would not be required. We’ve seen two accidents, and we believe it’s appropriate to make that link in the chain more robust.”

While some here won't be sympathetic to this explanation, I personally think it's important we understand what the explanation is, right from a company executive.

My understanding of the context is that during this week's gathering in Seattle the media was allowed to attend and report on a question and answer session, as long as they did not report the names of the engineers and executives answering the questions, thus the reference to a "Boeing executive" as the source of the quote. This also shows that this is a very recent statement.

osiris30 wrote:
Or... maybe no one realized it was that bad/a big deal.. like leaded gas or paint.. or asbestos... or all the other stupid in hindsight mistakes man as made (I used three examples but there are literally ... at least millions that someone could cite)

My interpretation of the statement above is that even as of this week Boeing still feels their original design was sufficient and that if any problem with MCAS was encountered the pilots would recognize it as a runaway stabilizer problem and invoke the associated memory procedure to resolve the problem.

As I've written in another thread, the fact that they are issuing changes is a tacit admission that their MCAS design was found wanting. Above the Boeing exec is using the words "make it more robust" which is a very similar statement, but presumably out of legal necessity, admits no guilt.


The problem with this reasoning is that MCAS was not documented in the pilot manuals, nor in the type training papers nor could it be simulated in the early simulator version.

That is the checklist: https://aviation.stackexchange.com/ques ... ax-9/61482

So if you follow it to the letter, you disengage the AP you trim with your control at the stick and in case of a MCAS failure the runaway trim will stop for the moment and trim control will work as expected. End of checklist. Nothing says that in case of an MCAS failure the trimming will restart in a few seconds.
 
uta999
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 8:33 am

Both Boeing and the FAA now need to change their take on the MAX. They have created a PR disaster, by continuing “the aircraft is safe, we’re just making it safer”

Everyone now knows both crashes were caused by MCAS and were identical in all respects. They cannot continue saying they are not admitting MCAS was to blame. It was.

The FAA also needs to admit they are too close to Boeing. In future, they must seek certification of all new types and sub-types jointly with authorities in the UK, EU, Canada and Australia. This should include their pilots actually flying the plane, not just a simulator.

Everyone involved in the process should be looking for these ‘hidden new features’ and traps.
Your computer just got better
 
WIederling
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 9:06 am

shaner82 wrote:
One thing I haven't seen an explanation for yet, or much discussion on, is the few cases where Max planes suddenly dove while on autopilot. In all cases the pilots manually took control and flew the plane without further issue, but if AP was on, then it wouldn't be MCAS causing the nose to point down. It makes me wonder what caused that.


MCAS is one path to hell and the design characteristics give it a large lever.
But
IT IS obvious from early on that there is some error producer in the signal path. ( "entry gate" to that path to hell )
The majority of pro Boeing posters try to keep it invisible,
Boeing itself is completely mum. Discussion here: https://www.satcom.guru/
Same for the "obvious" checklist fall through.

I see parallels to the Batteries issue on the 787. The Boom Box was marched up and down the catwalk
with much fanfare while in the background charging and discharging management ( the actual cause ) was fixed silently.
Murphy is an optimist
 
WIederling
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 9:08 am

uta999 wrote:
Everyone involved in the process should be looking for these ‘hidden new features’ and traps.


Did Boeing just mangle this single design detail or are there gobs of Easter Eggs hidden in the NG to MAX change list?
Murphy is an optimist
 
mjoelnir
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 9:49 am

WIederling wrote:
shaner82 wrote:
One thing I haven't seen an explanation for yet, or much discussion on, is the few cases where Max planes suddenly dove while on autopilot. In all cases the pilots manually took control and flew the plane without further issue, but if AP was on, then it wouldn't be MCAS causing the nose to point down. It makes me wonder what caused that.


MCAS is one path to hell and the design characteristics give it a large lever.
But
IT IS obvious from early on that there is some error producer in the signal path. ( "entry gate" to that path to hell )
The majority of pro Boeing posters try to keep it invisible,
Boeing itself is completely mum. Discussion here: https://www.satcom.guru/
Same for the "obvious" checklist fall through.

I see parallels to the Batteries issue on the 787. The Boom Box was marched up and down the catwalk
with much fanfare while in the background charging and discharging management ( the actual cause ) was fixed silently.


There are clear differences to the battery issue.

The box was an acceptable solution, practical a bomb.container, taking completely out the danger of an explosion in the electrical cabinet.
I still do not understand how thick people were. A lithium ion battery is based on a hydrocarbon solvent. When heated you get hydrocarbon gas in an electrical cabinet, where spark plugs abound aka relays producing sparks when switching.
The rest, charging and discharging management, was getting rid of nuisance and cost factor, simply how often you have to exchange the battery.

Here Boeing still refuses to look at the underlying danger, in a bid not to disturb the training regime and therefore cost with moving pilots from the NG to the MAX. Still on the track of cost trumping safety considerations.

that is the regulation.

REGULATIONS - ADVISORY CIRCULARS
14 CFR § 25.672 - STABILITY AUGMENTATION AND AUTOMATIC AND POWER-OPERATED SYSTEMS
If the functioning of stability augmentation or other automatic or power-operated systems is necessary to show compliance with the flight characteristics requirements of this part, such systems must comply with § 25.671 and the following:

(a) A warning which is clearly distinguishable to the pilot under expected flight conditions without requiring his attention must be provided for any failure in the stability augmentation system or in any other automatic or power-operated system which could result in an unsafe condition if the pilot were not aware of the failure.

To fulfill the above a MACAS active warning sign is necessary.

I still not understand, as far as automatic trimming is gripping in regarding the pilots authority, that an automatic trim off switch is not required.
Last edited by mjoelnir on Sun Mar 31, 2019 9:57 am, edited 1 time in total.
 
RickNRoll
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 9:56 am

osiris30 wrote:
StTim wrote:
Revelation wrote:
... and the MAX is still grounded, so maybe we should discuss this in the ET thread instead?


To be fair with so many threads I wasn't sure of the best one to use. I thought it was relevant to both the ET thread and this one as we have had claims on this thread that it was not known if the ET crash had anything to do with the MCAS system.


And we still don't. MCAS activated... doesn't mean it caused the crash. Given the flight profile we HAVE seen from ADS-B data, it's entirely possible MCAS was trying to the right thing in this instance. Please note the wording in the article. It doesn't say MCAS caused the issue. It says it activated. It goes on to state it was involved in the Lion Air crash. It then goes on to say the cause of either crash is not known yet (as the final reports haven't been released). MCAS likely contributed to Lion Air (that is ABUNDANTLY clear). We do not know if it contributed at all to this crash or maybe was doing its job and helped prevent/delay a crash. If the pilots got into a stall condition MCAS would be EXPECTED to activate. That is what it does. Without more data it is impossible to know if it contributed or delayed the eventual crash and the leak provides insufficient data (as published) to make that call.
Give us a break. Boeing and the FAA and everyone else knows what happened except you. There was no stall.
 
trauha
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 10:27 am

A shift in philosophies that lead to a decline of more than just safety.

- companies that move the business accent on making bankable money, not flyable planes.
- less government, less oversight.
- the diminished government that is left is held close to the interests that make money

This short termism is leading to the decline of a once great Seattle industry.
The lessons of the auto industry not learned.
Competitors elsewhere on the globe with another balance of priorities given opportunities by these philosophical weaknesses.

The good engineers at Seattle deserve thoughts and prayers as their futures are eroded by corporate wants.
DC3, CONVAIR CV440, Sud Aviation Caravelle, BOAC VC10,Convair Coronado,BAE 1-11,Vickers Viscount. Pan Am 707 747, Saab 340 2000,TWA Lockheed TriStar, DC-8,9,10, MD11. 727,757,767.SHORT 330, CRJ200, ERJ145, E190. F27, A340-600. Atr42 72.
 
packsonflight
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 10:36 am

Grandfathered design is the name og the game here.
Grandfathered technology and safety standards are one thing, but is it really so that Boeing is grandfathering in the risk assessment aswell.
Can it be that they are carrying out risk assessment according to 50 years old standards?
 
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PW100
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 1:28 pm

packsonflight wrote:
Grandfathered design is the name og the game here.
Grandfathered technology and safety standards are one thing, but is it really so that Boeing is grandfathering in the risk assessment aswell.
Can it be that they are carrying out risk assessment according to 50 years old standards?

Is this true?

It is my understanding that the specific FAR that requires MCAS, did not exist with the initial 737 received its Type Certificate. If that is so, how does grandfathering come into play in this respect?
Immigration officer: "What's the purpose of your visit to the USA?" Spotter: "Shooting airliners with my Canon!"
 
mjoelnir
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 1:59 pm

PW100 wrote:
packsonflight wrote:
Grandfathered design is the name og the game here.
Grandfathered technology and safety standards are one thing, but is it really so that Boeing is grandfathering in the risk assessment aswell.
Can it be that they are carrying out risk assessment according to 50 years old standards?

Is this true?

It is my understanding that the specific FAR that requires MCAS, did not exist with the initial 737 received its Type Certificate. If that is so, how does grandfathering come into play in this respect?


It seems that the FAA locked at MCAS as an extension of STS and not as something new.
 
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Revelation
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 2:07 pm

NeBaNi wrote:
This is not meant to be a personal attack, so I apologize in advance if it comes as such, but would you consider this quote as hearsay, since you posted on another thread that you attributed anonymous quotes in the media/news articles as hearsay? Or do you attach more weight to this quote vs. the others because it came from an anonymous Boeing executive?

I anticipated the question so my post included the following:

My understanding of the context is that during this week's gathering in Seattle the media was allowed to attend and report on a question and answer session, as long as they did not report the names of the engineers and executives answering the questions, thus the reference to a "Boeing executive" as the source of the quote. This also shows that this is a very recent statement.

Google defines heresay as "information received from other people that one cannot adequately substantiate". So, without additional corroboration I think it would be hearsay, which presumably is why Boeing insisted that the media use no names for things said in the Q&A session as opposed to Mike Sinnett's opening comments. This stipulation allows Boeing to get their side of the story out with a high level of credibility, but without exposing themselves legally.

And I have no problem with use of hearsay when it's not presented as fact, and some basis to weigh the credence of the statement is given.

For instance in this thread we just read:

Lets not forget MCAS, as originally presented to the FAA was't as powerfull as implemented later on.

I would prefer it had been stated as:

Lets not forget an unnamed FAA employee told the media that MCAS, as originally presented to the FAA was't as powerfull as implemented later on.

I'm not saying the media report is wrong, I'm saying we can't know if it is right because there's no way to question the unnamed source.

The unqualified statement could imply FAA has stated such, but AFAIK that is not the case.
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art
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 2:42 pm

mzlin wrote:
FAA defended the categorization of MCAS as a supplement to STS which is what allowed it to use a single sensor. Nobody apparently thought of the possible consequences of failure (emphasis added by this poster), or had too much faith in the ability of pilots to figure it out:


How could FAA have certified without looking into the consequences of failure? That's not regulation to me.

LDRA wrote:
AP disengages on airspeed disagree. Airspeed disagree due to AOA signal fault. So the same faulty AOA signal kicked airplane out of autopilot, then start driving nose down.


Sounds like a potentially murderous combination to me.
Last edited by art on Sun Mar 31, 2019 2:50 pm, edited 1 time in total.
 
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spinotter
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 2:46 pm

NeBaNi wrote:
Revelation wrote:
At the risk of being bitten as I throw red meat into the lion's cage, here is how Boeing explains itself ( ref: AvWeek ):

Commenting on criticism of the single-string-failure potential of the AOA input to the MCAS, a Boeing executive says the original design was based on a standard industry process of hazard classification, which defined the potential failure as one that could be mitigated “very quickly by a trained pilot using established procedures.”

“In this particular case, because we don’t know yet what the ultimate cause is, we can look at that one link in the chain and say we know ways to update the MCAS functionality to make it more robust, and that’s what we are doing,” the executive says. “While certification standards say a runaway stabilizer has a memory procedure associated with it—despite all of that, we are looking at it and saying, ‘We don’t want to intentionally provide the pilot with that scenario again.’ So in the design, we are using multiple inputs, even though in the original hazard classification, multiple inputs would not be required. We’ve seen two accidents, and we believe it’s appropriate to make that link in the chain more robust.”

While some here won't be sympathetic to this explanation, I personally think it's important we understand what the explanation is, right from a company executive.

My understanding of the context is that during this week's gathering in Seattle the media was allowed to attend and report on a question and answer session, as long as they did not report the names of the engineers and executives answering the questions, thus the reference to a "Boeing executive" as the source of the quote. This also shows that this is a very recent statement.

osiris30 wrote:
Or... maybe no one realized it was that bad/a big deal.. like leaded gas or paint.. or asbestos... or all the other stupid in hindsight mistakes man as made (I used three examples but there are literally ... at least millions that someone could cite)

My interpretation of the statement above is that even as of this week Boeing still feels their original design was sufficient and that if any problem with MCAS was encountered the pilots would recognize it as a runaway stabilizer problem and invoke the associated memory procedure to resolve the problem.

As I've written in another thread, the fact that they are issuing changes is a tacit admission that their MCAS design was found wanting. Above the Boeing exec is using the words "make it more robust" which is a very similar statement, but presumably out of legal necessity, admits no guilt.

This is not meant to be a personal attack, so I apologize in advance if it comes as such, but would you consider this quote as hearsay, since you posted on another thread that you attributed anonymous quotes in the media/news articles as hearsay? Or do you attach more weight to this quote vs. the others because it came from an anonymous Boeing executive?


What is the relevance of your question? Throwing dust in people's eyes? Work for Boeing?
 
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keesje
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 2:48 pm

Revelation wrote:
NeBaNi wrote:
This is not meant to be a personal attack, so I apologize in advance if it comes as such, but would you consider this quote as hearsay, since you posted on another thread that you attributed anonymous quotes in the media/news articles as hearsay? Or do you attach more weight to this quote vs. the others because it came from an anonymous Boeing executive?

I anticipated the question so my post included the following:

My understanding of the context is that during this week's gathering in Seattle the media was allowed to attend and report on a question and answer session, as long as they did not report the names of the engineers and executives answering the questions, thus the reference to a "Boeing executive" as the source of the quote. This also shows that this is a very recent statement.

Google defines heresay as "information received from other people that one cannot adequately substantiate". So, without additional corroboration I think it would be hearsay, which presumably is why Boeing insisted that the media use no names for things said in the Q&A session as opposed to Mike Sinnett's opening comments. This stipulation allows Boeing to get their side of the story out with a high level of credibility, but without exposing themselves legally.

And I have no problem with use of hearsay when it's not presented as fact, and some basis to weigh the credence of the statement is given.

For instance in this thread we just read:

Lets not forget MCAS, as originally presented to the FAA was't as powerfull as implemented later on.

I would prefer it had been stated as:

Lets not forget an unnamed FAA employee told the media that MCAS, as originally presented to the FAA was't as powerfull as implemented later on.

I'm not saying the media report is wrong, I'm saying we can't know if it is right because there's no way to question the unnamed source.

The unqualified statement could imply FAA has stated such, but AFAIK that is not the case.


To support your case, lets include the source:

The safety analysis:

Understated the power of the new flight control system, which was designed to swivel the horizontal tail to push the nose of the plane down to avert a stall. When the planes later entered service, MCAS was capable of moving the tail more than four times farther than was stated in the initial safety analysis document.
Failed to account for how the system could reset itself each time a pilot responded, thereby missing the potential impact of the system repeatedly pushing the airplane’s nose downward.
Assessed a failure of the system as one level below “catastrophic.” But even that “hazardous” danger level should have precluded activation of the system based on input from a single sensor — and yet that’s how it was designed.
The people who spoke to The Seattle Times and shared details of the safety analysis all spoke on condition of anonymity to protect their jobs at the FAA and other aviation organizations.

Both Boeing and the FAA were informed of the specifics of this story and were asked for responses 11 days ago, before the second crash of a 737 MAX on March 10
.

https://www.google.com/amp/s/www.seattl ... h/%3famp=1

We don't want to divert attention or try to disqualify research by questioning sources. We want to get behind what really happened. Even if the final report is not out and not all facts are known. That approach could have caused a third crash.
"Never mistake motion for action." Ernest Hemingway
 
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PW100
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 3:00 pm

art wrote:
mzlin wrote:
FAA defended the categorization of MCAS as a supplement to STS which is what allowed it to use a single sensor. Nobody apparently thought of the possible consequences of failure (emphasis added by this poster), or had too much faith in the ability of pilots to figure it out:


How could FAA have certified without looking into the consequences of failure? That's not regulation to me.


According to earlier posts, and reporting by some journalists (I believe Seattle Times), FAA did perform a risk/failure analysis, and found that MCAS as originally defined (like STS), would not be categorized in the extreme category. Therefore a single sensor approach (and redundancy provided by pilot 1 and pilot 2) was deemed acceptable.

Only when during flight testing MCAS parameters and authority were changed, the risk/failure assessment was no longer valid. But the changes were not fed back into the certifying group and thus risk/failure assessment was not adjusted.

Point I'm trying to being forward, is that there are indications that consequences of failure were assessed and taken into account.
Million dollar question is how the flight test changes were not fed back into the certification system, and how oversight missed that as well.
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RickNRoll
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 3:05 pm

Revelation wrote:
scbriml wrote:
Was the bolding and underlining yours or AvWeek's?

Mine, made because I felt I should emphasize what Boeing is saying about the original MCAS design and the changes it is making.

scbriml wrote:
I'm not surprised you think some won't be sympathetic to the explanation because it's a little on the weasely side, isn't it? "we believe it's appropriate to make that link in the chain more robust". I understand that Boeing's lawyers must be working overtime to vet every executive utterance these days, but...

I understand the lack of sympathy and the characterization of the statement as weasely. It is an exercise in understanding what they are willing to say after a strong scrub by the legal team.

scbriml wrote:
Revelation wrote:
As I've written in another thread, the fact that they are issuing changes is a tacit admission that their MCAS design was found wanting. Above the Boeing exec is using the words "make it more robust" which is a very similar statement, but presumably out of legal necessity, admits no guilt.

"Found wanting" is a pretty good euphemism as well.

An euphemism is "the substitution of a mild, indirect, or vague expression for one thought to be offensive, harsh, or blunt" -- not sure that's the right word.

Boeing's statement tells us they believe they released a design that worked, and if there were issues they felt the pilot's training would lead them to disable the trim circuit. Boeing says the "ultimate cause" is still unknown, but we have evidence that one set of JQ pilots did manage to disable the trim circuit, and another set of JQ pilots did not, nor presumably did a set of ET pilots.

My use of "found wanting" is Boeing's reliance on the pilots to detect the problem and apply the correct workaround in a workable amount of time. The "offensive, harsh, or blunt" part would be if Boeing is lying in this kind of statement like VW did in Dieselgate, where a VW executive signed a statement that he knew was untrue and has admitted so in legal documents. Some are comfortable reaching the conclusion that Boeing is doing something like that, but I for one don't think we know enough to reach that conclusion.


I would love to know. Did Boeings testing evaluate the stat of a failed AoA sensor? Did they also know that this would raise other serious alerts before MCAS kicked in that would disctract pilots from any MCAS issues?
 
RickNRoll
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 3:10 pm

In contrast the Asiana 777 crash in San Francisco would not have been something Boeing would reasonably have expected to happen.
However, with automated testing and simulation, would it be possible to test all combinations of all failurs to see what unexpected failure modes can occur.
 
olle
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 3:14 pm

As I understand, pilots will not be able to mpve from NG to MAX without expensive in the future.

Second there seems like Boeing will need to chsnge the functionality of the system. Will this decrease the performance of MAX?

So when Boeing in the future propose Max against Neo the obstacle to change to Neo will be less while both requires costly education.

If measures is done that decreases Max performance what will the effect against ghe Neo?

As i understands it Neo already have more efficient engines compared to Max.
 
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Revelation
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 3:23 pm

keesje wrote:
To support your case, lets include the source:

....
The people who spoke to The Seattle Times and shared details of the safety analysis all spoke on condition of anonymity to protect their jobs at the FAA and other aviation organizations.

Both Boeing and the FAA were informed of the specifics of this story and were asked for responses 11 days ago, before the second crash of a 737 MAX on March 10
.
https://www.google.com/amp/s/www.seattl ... h/%3famp=1

My point is we should understand which statements are official, actionable facts and what things are unactionable hearsay.

I didn't say to ignore hearsay, but I did say to understand that it may or may not be true, and to label it as such.

keesje wrote:
We don't want to divert attention or try to disqualify research by questioning sources. We want to get behind what really happened. Even if the final report is not out and not all facts are known.

How can you know what really happened if you accept sources without understanding their credibility?

How can you know what really happened if you proceed on a subset of the facts?

IMHO you can only do that if you've decided "what really happened" in advance and are selecting information sources that fit your pre-ordained outcome.

Otherwise you do have to wait till you have all the information and you can evaluate its credibility.

keesje wrote:
That approach could have caused a third crash.

We're well past that point now.
Wake up to find out that you are the eyes of the world
The heart has its beaches, its homeland and thoughts of its own
Wake now, discover that you are the song that the morning brings
The heart has its seasons, its evenings and songs of its own
 
Amiga500
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 3:39 pm

Boeing wrote:
Commenting on criticism of the single-string-failure potential of the AOA input to the MCAS, a Boeing executive says the original design was based on a standard industry process of hazard classification, which defined the potential failure as one that could be mitigated “very quickly by a trained pilot using established procedures.”

“In this particular case, because we don’t know yet what the ultimate cause is, we can look at that one link in the chain and say we know ways to update the MCAS functionality to make it more robust, and that’s what we are doing,” the executive says. “While certification standards say a runaway stabilizer has a memory procedure associated with it—despite all of that, we are looking at it and saying, ‘We don’t want to intentionally provide the pilot with that scenario again.’ So in the design, we are using multiple inputs, even though in the original hazard classification, multiple inputs would not be required. We’ve seen two accidents, and we believe it’s appropriate to make that link in the chain more robust.”


BULLSH.

It is absolutely not "industry standard practice" for any competent safety engineer to offload the problem from the machine to the pilot.

Some useless MBA qualified c**t up the food chain in Boeing "mitigated" the need to spend the time & money doing the job right as they made a crap judgement call (which probably netted them a nice performance related bonus) that pilots could "figure it out" on the hoof without any documentation referencing any system that would show a failure mechanism like it.

Hopefully there is an email trail leading to the gormless idiot so they can spend a bit of time to reflect on the risks of a continuous nose down pitch when picking up some soap.




Revelation: This problems with MCAS are so far off the beaten track in terms of acceptable mistakes* that multiple serious failures in decisions, processes and oversight within Boeing and the FAA have got us to where we are now. This is deeply concerning precisely because it could also be present elsewhere on the aircraft and we have yet to find out.

*i.e.
1. safety analysis is wrong
2. stability & control is wrong
3. high level system architecture is wrong
4. high level software design is wrong
5. low level system design is wrong
6. low level software coding is wrong
7. oversight failed to pick up any of the above.
[may keep adding to this as I realise more areas that would be required for this development]

That is 7 stages of work that have seen this disaster pass through review gates. Was time pressure in Boeing so much that safety went out the window? Whatever it was - safety definitely was not top priority regardless of what weasel words Dennis says now.
Last edited by Amiga500 on Sun Mar 31, 2019 3:48 pm, edited 2 times in total.
 
WIederling
Posts: 9291
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 3:43 pm

Revelation wrote:
Google defines heresay as "information received from other people that one cannot adequately substantiate". So, without additional corroboration I think it would be hearsay, which presumably is why Boeing insisted that the media use no names for things said in the Q&A session as opposed to Mike Sinnett's opening comments.

That is splitting hairs imho.

Here you have authoritative information jointly provided by representatives of the company and the institution involved in the issue.
Even if you may not name the persons talking you still have it from the horses mouth.

Hearsay would be information provided but you can't tack it down to source ( like potentially some Airbus representative was present too ) like something passed on in the elevator and you didn't know it was the Boeing boss :-).
Murphy is an optimist
 
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Lingon
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 3:48 pm

PW100 wrote:
art wrote:
mzlin wrote:
FAA defended the categorization of MCAS as a supplement to STS which is what allowed it to use a single sensor. Nobody apparently thought of the possible consequences of failure (emphasis added by this poster), or had too much faith in the ability of pilots to figure it out:


How could FAA have certified without looking into the consequences of failure? That's not regulation to me.


According to earlier posts, and reporting by some journalists (I believe Seattle Times), FAA did perform a risk/failure analysis, and found that MCAS as originally defined (like STS), would not be categorized in the extreme category. Therefore a single sensor approach (and redundancy provided by pilot 1 and pilot 2) was deemed acceptable.

Only when during flight testing MCAS parameters and authority were changed, the risk/failure assessment was no longer valid. But the changes were not fed back into the certifying group and thus risk/failure assessment was not adjusted.

Point I'm trying to being forward, is that there are indications that consequences of failure were assessed and taken into account.
Million dollar question is how the flight test changes were not fed back into the certification system, and how oversight missed that as well.


Thank you. I have tried to post this at least ten times, refrained to click the post button because I failed to phrase it clearly enough. But you did.
 
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Revelation
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 3:52 pm

WIederling wrote:
Revelation wrote:
Google defines heresay as "information received from other people that one cannot adequately substantiate". So, without additional corroboration I think it would be hearsay, which presumably is why Boeing insisted that the media use no names for things said in the Q&A session as opposed to Mike Sinnett's opening comments.

That is splitting hairs imho.

Here you have authoritative information jointly provided by representatives of the company and the institution involved in the issue.
Even if you may not name the persons talking you still have it from the horses mouth.

Hearsay would be information provided but you can't tack it down to source ( like potentially some Airbus representative was present too ) like something passed on in the elevator and you didn't know it was the Boeing boss :-).

Yes, the key part is "adequately substantiate", and there's no one standard.

Some want to apply courthouse standards, some are OK with going with unverifiable sources and subsets of information.

Since we won't get agreement on what standard to apply, I think it is helpful to keep track of what the source of the information is.

That way the reader can decide how meaningful or unmeaningful the information is.

As above, I'm not saying the media reports are false, I am saying we can't really tell how true they are.
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NeBaNi
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 3:52 pm

spinotter wrote:
NeBaNi wrote:
Revelation wrote:
At the risk of being bitten as I throw red meat into the lion's cage, here is how Boeing explains itself ( ref: AvWeek ):


While some here won't be sympathetic to this explanation, I personally think it's important we understand what the explanation is, right from a company executive.

My understanding of the context is that during this week's gathering in Seattle the media was allowed to attend and report on a question and answer session, as long as they did not report the names of the engineers and executives answering the questions, thus the reference to a "Boeing executive" as the source of the quote. This also shows that this is a very recent statement.


My interpretation of the statement above is that even as of this week Boeing still feels their original design was sufficient and that if any problem with MCAS was encountered the pilots would recognize it as a runaway stabilizer problem and invoke the associated memory procedure to resolve the problem.

As I've written in another thread, the fact that they are issuing changes is a tacit admission that their MCAS design was found wanting. Above the Boeing exec is using the words "make it more robust" which is a very similar statement, but presumably out of legal necessity, admits no guilt.

This is not meant to be a personal attack, so I apologize in advance if it comes as such, but would you consider this quote as hearsay, since you posted on another thread that you attributed anonymous quotes in the media/news articles as hearsay? Or do you attach more weight to this quote vs. the others because it came from an anonymous Boeing executive?


What is the relevance of your question? Throwing dust in people's eyes? Work for Boeing?

Neither. I am interested in the human/people side of the story as well, not just the technical, and I've followed and participated with great interest in Revelation's previous thread on the changes in Airbus top management. That's where the question was coming from, wasn't throwing dust in people's eyes at all. I don't work for Boeing, and if I did, I probably wouldn't be posting here.
 
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speedbored
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 3:53 pm

Revelation wrote:
Otherwise you do have to wait till you have all the information and you can evaluate its credibility.

Perhaps. But, especially when information is presented in a reputable media publication, we should be able to trust the journalists to have done that source evaluation on our behalf.

There's a big difference between a genuinely anonymous source, and a source who asks a journalist not to publish their name.
 
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Revelation
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 4:00 pm

Amiga500 wrote:
Hopefully there is an email trail leading to the gormless idiot so they can spend a bit of time to reflect on the risks of a continuous nose down pitch when picking up some soap.

Thanks for the strong post.

Personally, I have a lot of confidence in the FBI's investigative skills and if there is a email trail to be found I think they will find it.

Also, as we now know, pretty much every worldwide aviation regulator with the skill and resources to do so are going to go through all the certification paperwork with a fine toothed comb.

Something as obvious as being suggested by you and by the media's anonymous sources should be pretty easy to identify, no?
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zeke
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 4:15 pm

Certification paperwork shows the compliance with various regulations, it does not go into the decision making process or trade offs that were made during development.

MCAS itself is not a FAR 25 required feature, it a tool that was used to meet a stability requirement. It is very likely the fine details of the actual inner workings of the system were never presented to the FAA.

Manufacturers do this to give themselves some room to make improvements with in service data.
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Revelation
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 4:19 pm

NeBaNi wrote:
spinotter wrote:
NeBaNi wrote:
This is not meant to be a personal attack, so I apologize in advance if it comes as such, but would you consider this quote as hearsay, since you posted on another thread that you attributed anonymous quotes in the media/news articles as hearsay? Or do you attach more weight to this quote vs. the others because it came from an anonymous Boeing executive?

What is the relevance of your question? Throwing dust in people's eyes? Work for Boeing?

Neither. I am interested in the human/people side of the story as well, not just the technical, and I've followed and participated with great interest in Revelation's previous thread on the changes in Airbus top management. That's where the question was coming from, wasn't throwing dust in people's eyes at all. I don't work for Boeing, and if I did, I probably wouldn't be posting here.

For the record, I think the question was a thoughtful and perceptive one. I think we're all having issues figuring out how we should or should not consume information these days. As much as we hear the world now operates on millennial time, we also have to understand that there still are ramifications based on what a company says to the public, and there are good reasons why the whole concept of due process exists, along with some less good ones too. I also am interested in the human/people side of the story as well as the business/ethics side of the story too.
Wake up to find out that you are the eyes of the world
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Wake now, discover that you are the song that the morning brings
The heart has its seasons, its evenings and songs of its own
 
planecane
Posts: 1559
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Re: B737MAX Grounded Worldwide

Sun Mar 31, 2019 4:51 pm

Amiga500 wrote:
Boeing wrote:
Commenting on criticism of the single-string-failure potential of the AOA input to the MCAS, a Boeing executive says the original design was based on a standard industry process of hazard classification, which defined the potential failure as one that could be mitigated “very quickly by a trained pilot using established procedures.”

“In this particular case, because we don’t know yet what the ultimate cause is, we can look at that one link in the chain and say we know ways to update the MCAS functionality to make it more robust, and that’s what we are doing,” the executive says. “While certification standards say a runaway stabilizer has a memory procedure associated with it—despite all of that, we are looking at it and saying, ‘We don’t want to intentionally provide the pilot with that scenario again.’ So in the design, we are using multiple inputs, even though in the original hazard classification, multiple inputs would not be required. We’ve seen two accidents, and we believe it’s appropriate to make that link in the chain more robust.”


BULLSH.

It is absolutely not "industry standard practice" for any competent safety engineer to offload the problem from the machine to the pilot.

Some useless MBA qualified c**t up the food chain in Boeing "mitigated" the need to spend the time & money doing the job right as they made a crap judgement call (which probably netted them a nice performance related bonus) that pilots could "figure it out" on the hoof without any documentation referencing any system that would show a failure mechanism like it.

Hopefully there is an email trail leading to the gormless idiot so they can spend a bit of time to reflect on the risks of a continuous nose down pitch when picking up some soap.




Revelation: This problems with MCAS are so far off the beaten track in terms of acceptable mistakes* that multiple serious failures in decisions, processes and oversight within Boeing and the FAA have got us to where we are now. This is deeply concerning precisely because it could also be present elsewhere on the aircraft and we have yet to find out.

*i.e.
1. safety analysis is wrong
2. stability & control is wrong
3. high level system architecture is wrong
4. high level software design is wrong
5. low level system design is wrong
6. low level software coding is wrong
7. oversight failed to pick up any of the above.
[may keep adding to this as I realise more areas that would be required for this development]

That is 7 stages of work that have seen this disaster pass through review gates. Was time pressure in Boeing so much that safety went out the window? Whatever it was - safety definitely was not top priority regardless of what weasel words Dennis says now.


While you make some very good points about the design/oversight, bad engineering and management decisions are not criminal acts. Unless there are emails that show someone being told that a sensor failure could cause a situation where pilots won't know what to do and the plane will crash, nobody will be in jail. Boeing will certainly be held liable for damages in civil court.

My guess would be that any emails about the reaction of MCAS to an AoA sensor failure will show an expectation that the pilots would recognize it as runaway trim, hit the cutoff switches and land safely. Bad assumption? Absolutely. Criminal? Not if that is what happened.

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