8 ms·

Boeing Knew the AOA Disagree Alert on the 737 Max Didn’t Work

93 points by samrohn 7y ago

basicplus2 7y ago
<The company said that a Boeing-convened safety review board affirmed in December that the absence of the AOA disagree alert from flight displays would not have presented a safety issue. The FAA confirmed the discussion and that it deemed the issue "low risk" at the time.> So the FAA is culpable as well as Boeing
- cottsak 7y ago
  That is true, but at some point it's hard to distinguish between parts of the FAA and parts of Boeing, owed to the simple fact that Boeing have so much influence over the FAA. Statements about how Boeing more or less "certified itself" speak to this. Just go and look at the LinkedIn history of the folks that move between Boeing/FAA. If you accept this, then the question might turn to how it was possible for the FAA to be weakened to such a degree that this corporate influence was possible. FAA are the regulator - at the end of the day, safety lies with them. Perhaps it's the responsibility of committee and congressional oversight to the aviation regulator? Perhaps the buck stops with the government representatives who have allowed this mess to be possible in the first place?
- briandear 7y ago
  How is the FAA culpable? No American planes crashed? The FAA doesn’t control regulations for Indonesia do they? Indonesian maintenance standards are atrocious. Look at Lion Air’s record. Is it a coincidence that one of the world’s worst airlines also happen to crash the 737 and yet Southwest Airlines that flew an order of magnitude more flights on the Max never had even a scratch? Lion Air knew they had a problem on the penultimate flight — but they ignored it. The FAA would never allow that level of negligence in the US: that plane would have been grounded. The FAA has a better safety record than anyone else — and that includes the Europeans.
  - frostburg 7y ago
    The FAA let Boeing do the certification of its own plane. The system is broken.
  - salawat 7y ago
    Doesn't matter. The design itself was unsafe. The reason the FAA has historically been so highly regarded is that it has fostered a design environment of generally implicit design safety. Ironically, however, Europe has called the FAA to task before on several models of Boeing aircraft that weren't implicitly design safe. See the D.P. Davies Interview w.r.t the Boeing 727 certification process. They cut corners, and did not inform pilots of the inherent risk that existed in a manner concomitant with the severity of the result. This originated in a desire to submit an aerodynamically deviant aircraft, yet attain type airworthyness certification with minimal friction. Lion Air may be last in safely operating aircraft, but the design standards were generally written in such a way where even the worst operators stood a good chance of going up, and getting back down free of harm. Obviously, that is no longer the case.
aaronbrethorst 7y ago
"Senior company leadership was not involved in the review and first became aware of this issue in the aftermath of the Lion Air accident." i.e. the buck stops somewhere else!
- pauljurczak 7y ago
  Scapegoating begins...
- raverbashing 7y ago
  And the damning thing was that they still thought it was ok to keep it absent There are a couple of reasons why "the existing functionality was acceptable" is a poor excuse: - It was present on early models (it was not an optional feature) - Its triggering indicate to the pilots that something is amiss. Especially after the 1st accident there should have been an association "AOA problems -> potential MCAS problems"
- seren 7y ago
  It is possible to not be in a review or aware and still be responsible if you instill a culture of fear and instruct your team that the plane should keep flying whatever the means. I don't have any information whatsoever to say it happened at Boeing, but saying you were not aware is sometimes not enough.
CamperBob2 7y ago
This is an interesting point. Some will argue that the AOA disagree indicator wouldn't have made any difference in either crash. But it seems like it would have caused Lion Air to take their aircraft out of service and fix the problem after it occurred on the penultimate flight. Of course, the fact that they kept the aircraft in service without bothering to diagnose the issue that almost got everyone killed on the previous flight is a counterargument in itself. There's more than enough gross negligence to go around in this case, unfortunately. Edit: actually, it appears that Lion didn't spring for the "optional" warning indicator feature in the first place.
- mormegil 7y ago
  > actually, it appears that Lion didn't spring for the "optional" warning indicator feature in the first place. AIUI, there was no "optional warning indicator feature" at all. The AOA disagree warning should have been a standard feature. Only the indicator of the current AOA was the optional feature.
- pergadad 7y ago
  Optional indicator that was previously - and should have been - standard issue. With the MAX being sold with the explicit promise that there is little/no additional pilot training need. Clear negligence on both sides, with Boeing being responsible at much grander scale.
jdsully 7y ago
It’s not clear the AOA disagree light would have saved the two flights, so waiting for the next release was reasonable. The critical jump pilots had to make was that this was a trim runaway event. AOA indicators were not connected to the trim system before.
- pauljurczak 7y ago
  > It’s not clear the AOA disagree light would have saved the two flights Unless you change it to "It’s certain the AOA disagree light would not have saved the two flights", you are basically arguing for presence of AOA disagree light.
  - jdsully 7y ago
    The FAA provides time to fix issues if its deemed to not be a critical issue - because if every problem results in grounding planes then people just won't report issues. The added stress of millions in losses could also result in subpar fixes that cause more problems. In this case I agree with the FAA's initial decision for this indicator. Its extremely unlikely having it working would have prevented the two crashes. The mere fact that it might have helped doesn't make the original decision incorrect.
- dagaci 7y ago
  It seems that the MCAS (Maneuvering Characteristics Augmentation System) system depended upon the AOA.
  - cottsak 7y ago
    Yes but not in an absolute way. I think we can only assume that MCAS uses this as one of it's many inputs in order to determine it's flight control logic.
frostburg 7y ago
Boeing should be fined enough that "shareholder value" would be roughly zero after all the assets are sold to pay the fine. That (besides any personal penalty that might be appropriate, of course) might realign the incentives for the next set of managers facing similar choices somewhere else, but it won't happen.
- dahdum 7y ago
  It might feel good to do that, but you’d be putting tens of thousands out of work, and handing the industry over to Airbus, which last I read, had an ever so slightly worse safety record (though both are quite good). That’s bad for cost and safety long term. By all means I support axing those responsible and criminal charges where/if appropriate, but a company death sentence does not serve the public interest.
  - MarkSweep 7y ago
    I think the argument for making it a corporate death sentence is that future companies and shareholders will know it is in their interest to make airplanes that don't kill people. More abstractly, if you value human life at a high enough dollar value and make corporations liable for loss thereof, they will expend effort to preserve human life. It appears that currently the externality of killing people is priced at a level where Boeing does not mind killing people. I don't know if lawsuit liability is the best way to police corporate behavior, but it is big part of the system we currently have in the USA.
    - briandear 7y ago
      They do make airplanes that don’t kill people. More people die per mile in cars than have ever died in airplanes. The train fatality rate in the United States is higher than that of airplanes — the majority of those airplanes being Boeing. More people died in cars yesterday than in all of 2018 for Boeing. And given fatalities per mile, air travel on Boeing airplanes is safer than any other form of transportation. Suggesting that Boeing makes planes that “kill people,” is about as ridiculous as saying that Specialized makes bikes that kill people. The safety record of American aviation is unmatched — and most of those planes are Boeing. Let’s tamp down on the hyperbole.
jandeboevrie 7y ago
First line: In 2017, Boeing learned that the angle-of-attack (AOA) disagree alert — a standard feature on all 737 MAX aircraft — didn't work on the majority of the planes. The company determined that the alert was not necessary for safe operation, so it did not inform operators or the FAA. So all those lives could have been saved and they knew it in 2017? And they let two crashes happen? Explain that to the ones who got left behind...
- ealexhudson 7y ago
  Previously, the thinking was that most airline pilots weren't using the AOA information anyway - they had included the feature because some airlines had ex-military staff who were used to having it, but most didn't. So the AOA being wrong wouldn't necessarily be that urgent a problem, if it was only the pilot we were talking about. Unfortunately, it wasn't only used by a small number of pilots, but also by MCAS. It seems that MCAS kicks in during scenarios that weren't originally intended - i.e. take-offs as well as stall scenarios - and they got two other things wrong: * MCAS was revised to be more aggressive toward the end of testing; * MCAS has a bug / design flaw that allowed the system to command an increasingly steep nose-down each time a pilot overrode it. There were lots of little signs all over the place that there was a problem. Unfortunately, they didn't seem to join the dots, and each seemingly-reasonable decision they made when taken together added up to a dangerous scenario.
  - cottsak 7y ago
    > "they didn't seem to join the dots" is what it will be made to look like. IMO, there would have been engineers and even some of the management chain who knew these risks, but for whatever reason, would have been pressured to make this go away. It seems like a conspiracist thing to say, but I've seen this in software engineering for years. There are heaps of perfectly legitimate pressures which will result in reduced quality and cutting of corners.. just in my work, lives are not at risk.
  - m_mueller 7y ago
    Or alternatively they didn't want to join the dots.
tus87 7y ago
Disagree with what? There was only one sensor!!
Deimorz 7y ago
This is blogspam from over a month ago. Here's the official release from Boeing that this is just reiterating (from May 5): https://boeing.mediaroom.com/news-releases-statements?item=130431 https://boeing.mediaroom.com/news-releases-statements?item=1... NYTimes article: https://www.nytimes.com/2019/05/05/business/boeing-737-max-warning-light.html https://www.nytimes.com/2019/05/05/business/boeing-737-max-w... HN discussion of that article: https://news.ycombinator.com/item?id=19835608 https://news.ycombinator.com/item?id=19835608
- acqq 7y ago
  More important than "the execs believed all planes have the feature" is that the claim after the Lion Air's crash was that at least these companies which did pay for the "extra" would be able to not fly the dangerous planes, as the technicians would discover that one of AoA vanes is not working while the plane is still on the ground. But that was also a lie (from the NYT article): "“We were told that if the A.O.A. vane, like on Lion Air, was in a massive difference, we would receive an alert on the ground and therefore not even take off,” said Dennis Tajer, a spokesman for the union representing American Airlines pilots. “That gave us additional confidence in continuing to fly that aircraft.” But in the last several weeks, Boeing has been saying something different. Mr. Tajer said the company recently told American pilots that the system would not alert pilots about any sensor disagreement until the aircraft is 400 feet above the ground."
afarrell 7y ago
Boeing has over 100,000 employees. What does it mean when a sentence says that "Boeing knew X"?
- Tempest1981 7y ago
  At least 1 of the engineering teams knew X, is my interpretation.
- maltalex 7y ago
  This was my question too. The real question isn't whether someone in the company knew. It's whether someone with decision power knew, and who was that person? And also, if people with decision power did not know - then why?
  - cottsak 7y ago
    I tend to agree. And if this can be traced to someone with influence, how was it possible for the company to be structured so that a single point of failure was possible - that speaks to a larger problem and then puts the senior exec on the chopping block too.
josefrichter 7y ago
I'd be curious to read more about those cases when MCAS was engaged, but the pilots were able to recover. There were a number of them.
- philjohn 7y ago
  IIRC there was one on the Lion Air plane that crashed, but because they had a 737 instructor aboard helping aleviate the pressures when things started going wrong they were able to land.
dfeojm-zlib 7y ago
Still wondering about why 737 NGs (-600,-700,-800,-900) are still deemed "airworthy" despite the 2010 investigative report on Boeing's intentional deception and cover-up of Ducommun's absurdly dangerous and substandard critical structural fuselage components. Several passengers have already died from fuselage breakups from hard landings and runway overruns when previous aircraft have survived similar situations intact; plus the possibility of aircraft catastrophically breaking up in heavy turbulence.

93 points by samrohn 7y ago

<The company said that a Boeing-convened safety review board affirmed in December that the absence of the AOA disagree alert from flight displays would not have presented a safety issue. The FAA confirmed the discussion and that it deemed the issue "low risk" at the time.> So the FAA is culpable as well as Boeing

cottsak 7y ago
That is true, but at some point it's hard to distinguish between parts of the FAA and parts of Boeing, owed to the simple fact that Boeing have so much influence over the FAA. Statements about how Boeing more or less "certified itself" speak to this. Just go and look at the LinkedIn history of the folks that move between Boeing/FAA. If you accept this, then the question might turn to how it was possible for the FAA to be weakened to such a degree that this corporate influence was possible. FAA are the regulator - at the end of the day, safety lies with them. Perhaps it's the responsibility of committee and congressional oversight to the aviation regulator? Perhaps the buck stops with the government representatives who have allowed this mess to be possible in the first place?
briandear 7y ago
How is the FAA culpable? No American planes crashed? The FAA doesn’t control regulations for Indonesia do they? Indonesian maintenance standards are atrocious. Look at Lion Air’s record. Is it a coincidence that one of the world’s worst airlines also happen to crash the 737 and yet Southwest Airlines that flew an order of magnitude more flights on the Max never had even a scratch? Lion Air knew they had a problem on the penultimate flight — but they ignored it. The FAA would never allow that level of negligence in the US: that plane would have been grounded. The FAA has a better safety record than anyone else — and that includes the Europeans.
- frostburg 7y ago
  The FAA let Boeing do the certification of its own plane. The system is broken.
- salawat 7y ago
  Doesn't matter. The design itself was unsafe. The reason the FAA has historically been so highly regarded is that it has fostered a design environment of generally implicit design safety. Ironically, however, Europe has called the FAA to task before on several models of Boeing aircraft that weren't implicitly design safe. See the D.P. Davies Interview w.r.t the Boeing 727 certification process. They cut corners, and did not inform pilots of the inherent risk that existed in a manner concomitant with the severity of the result. This originated in a desire to submit an aerodynamically deviant aircraft, yet attain type airworthyness certification with minimal friction. Lion Air may be last in safely operating aircraft, but the design standards were generally written in such a way where even the worst operators stood a good chance of going up, and getting back down free of harm. Obviously, that is no longer the case.

aaronbrethorst 7y ago

"Senior company leadership was not involved in the review and first became aware of this issue in the aftermath of the Lion Air accident." i.e. the buck stops somewhere else!

pauljurczak 7y ago
Scapegoating begins...
raverbashing 7y ago
And the damning thing was that they still thought it was ok to keep it absent There are a couple of reasons why "the existing functionality was acceptable" is a poor excuse: - It was present on early models (it was not an optional feature) - Its triggering indicate to the pilots that something is amiss. Especially after the 1st accident there should have been an association "AOA problems -> potential MCAS problems"
seren 7y ago
It is possible to not be in a review or aware and still be responsible if you instill a culture of fear and instruct your team that the plane should keep flying whatever the means. I don't have any information whatsoever to say it happened at Boeing, but saying you were not aware is sometimes not enough.

CamperBob2 7y ago

This is an interesting point. Some will argue that the AOA disagree indicator wouldn't have made any difference in either crash. But it seems like it would have caused Lion Air to take their aircraft out of service and fix the problem after it occurred on the penultimate flight. Of course, the fact that they kept the aircraft in service without bothering to diagnose the issue that almost got everyone killed on the previous flight is a counterargument in itself. There's more than enough gross negligence to go around in this case, unfortunately. Edit: actually, it appears that Lion didn't spring for the "optional" warning indicator feature in the first place.

mormegil 7y ago
> actually, it appears that Lion didn't spring for the "optional" warning indicator feature in the first place. AIUI, there was no "optional warning indicator feature" at all. The AOA disagree warning should have been a standard feature. Only the indicator of the current AOA was the optional feature.
pergadad 7y ago
Optional indicator that was previously - and should have been - standard issue. With the MAX being sold with the explicit promise that there is little/no additional pilot training need. Clear negligence on both sides, with Boeing being responsible at much grander scale.

jdsully 7y ago

It’s not clear the AOA disagree light would have saved the two flights, so waiting for the next release was reasonable. The critical jump pilots had to make was that this was a trim runaway event. AOA indicators were not connected to the trim system before.

pauljurczak 7y ago
> It’s not clear the AOA disagree light would have saved the two flights Unless you change it to "It’s certain the AOA disagree light would not have saved the two flights", you are basically arguing for presence of AOA disagree light.
- jdsully 7y ago
  The FAA provides time to fix issues if its deemed to not be a critical issue - because if every problem results in grounding planes then people just won't report issues. The added stress of millions in losses could also result in subpar fixes that cause more problems. In this case I agree with the FAA's initial decision for this indicator. Its extremely unlikely having it working would have prevented the two crashes. The mere fact that it might have helped doesn't make the original decision incorrect.
dagaci 7y ago
It seems that the MCAS (Maneuvering Characteristics Augmentation System) system depended upon the AOA.
- cottsak 7y ago
  Yes but not in an absolute way. I think we can only assume that MCAS uses this as one of it's many inputs in order to determine it's flight control logic.

frostburg 7y ago

Boeing should be fined enough that "shareholder value" would be roughly zero after all the assets are sold to pay the fine. That (besides any personal penalty that might be appropriate, of course) might realign the incentives for the next set of managers facing similar choices somewhere else, but it won't happen.

dahdum 7y ago
It might feel good to do that, but you’d be putting tens of thousands out of work, and handing the industry over to Airbus, which last I read, had an ever so slightly worse safety record (though both are quite good). That’s bad for cost and safety long term. By all means I support axing those responsible and criminal charges where/if appropriate, but a company death sentence does not serve the public interest.
- MarkSweep 7y ago
  I think the argument for making it a corporate death sentence is that future companies and shareholders will know it is in their interest to make airplanes that don't kill people. More abstractly, if you value human life at a high enough dollar value and make corporations liable for loss thereof, they will expend effort to preserve human life. It appears that currently the externality of killing people is priced at a level where Boeing does not mind killing people. I don't know if lawsuit liability is the best way to police corporate behavior, but it is big part of the system we currently have in the USA.
  - briandear 7y ago
    They do make airplanes that don’t kill people. More people die per mile in cars than have ever died in airplanes. The train fatality rate in the United States is higher than that of airplanes — the majority of those airplanes being Boeing. More people died in cars yesterday than in all of 2018 for Boeing. And given fatalities per mile, air travel on Boeing airplanes is safer than any other form of transportation. Suggesting that Boeing makes planes that “kill people,” is about as ridiculous as saying that Specialized makes bikes that kill people. The safety record of American aviation is unmatched — and most of those planes are Boeing. Let’s tamp down on the hyperbole.

jandeboevrie 7y ago

First line: In 2017, Boeing learned that the angle-of-attack (AOA) disagree alert — a standard feature on all 737 MAX aircraft — didn't work on the majority of the planes. The company determined that the alert was not necessary for safe operation, so it did not inform operators or the FAA. So all those lives could have been saved and they knew it in 2017? And they let two crashes happen? Explain that to the ones who got left behind...

ealexhudson 7y ago
Previously, the thinking was that most airline pilots weren't using the AOA information anyway - they had included the feature because some airlines had ex-military staff who were used to having it, but most didn't. So the AOA being wrong wouldn't necessarily be that urgent a problem, if it was only the pilot we were talking about. Unfortunately, it wasn't only used by a small number of pilots, but also by MCAS. It seems that MCAS kicks in during scenarios that weren't originally intended - i.e. take-offs as well as stall scenarios - and they got two other things wrong: * MCAS was revised to be more aggressive toward the end of testing; * MCAS has a bug / design flaw that allowed the system to command an increasingly steep nose-down each time a pilot overrode it. There were lots of little signs all over the place that there was a problem. Unfortunately, they didn't seem to join the dots, and each seemingly-reasonable decision they made when taken together added up to a dangerous scenario.
- cottsak 7y ago
  > "they didn't seem to join the dots" is what it will be made to look like. IMO, there would have been engineers and even some of the management chain who knew these risks, but for whatever reason, would have been pressured to make this go away. It seems like a conspiracist thing to say, but I've seen this in software engineering for years. There are heaps of perfectly legitimate pressures which will result in reduced quality and cutting of corners.. just in my work, lives are not at risk.
- m_mueller 7y ago
  Or alternatively they didn't want to join the dots.

tus87 7y ago

Disagree with what? There was only one sensor!!

Deimorz 7y ago

This is blogspam from over a month ago. Here's the official release from Boeing that this is just reiterating (from May 5): https://boeing.mediaroom.com/news-releases-statements?item=130431 https://boeing.mediaroom.com/news-releases-statements?item=1... NYTimes article: https://www.nytimes.com/2019/05/05/business/boeing-737-max-warning-light.html https://www.nytimes.com/2019/05/05/business/boeing-737-max-w... HN discussion of that article: https://news.ycombinator.com/item?id=19835608 https://news.ycombinator.com/item?id=19835608

acqq 7y ago
More important than "the execs believed all planes have the feature" is that the claim after the Lion Air's crash was that at least these companies which did pay for the "extra" would be able to not fly the dangerous planes, as the technicians would discover that one of AoA vanes is not working while the plane is still on the ground. But that was also a lie (from the NYT article): "“We were told that if the A.O.A. vane, like on Lion Air, was in a massive difference, we would receive an alert on the ground and therefore not even take off,” said Dennis Tajer, a spokesman for the union representing American Airlines pilots. “That gave us additional confidence in continuing to fly that aircraft.” But in the last several weeks, Boeing has been saying something different. Mr. Tajer said the company recently told American pilots that the system would not alert pilots about any sensor disagreement until the aircraft is 400 feet above the ground."

afarrell 7y ago

Boeing has over 100,000 employees. What does it mean when a sentence says that "Boeing knew X"?

Tempest1981 7y ago
At least 1 of the engineering teams knew X, is my interpretation.
maltalex 7y ago
This was my question too. The real question isn't whether someone in the company knew. It's whether someone with decision power knew, and who was that person? And also, if people with decision power did not know - then why?
- cottsak 7y ago
  I tend to agree. And if this can be traced to someone with influence, how was it possible for the company to be structured so that a single point of failure was possible - that speaks to a larger problem and then puts the senior exec on the chopping block too.

josefrichter 7y ago

I'd be curious to read more about those cases when MCAS was engaged, but the pilots were able to recover. There were a number of them.

philjohn 7y ago
IIRC there was one on the Lion Air plane that crashed, but because they had a 737 instructor aboard helping aleviate the pressures when things started going wrong they were able to land.

dfeojm-zlib 7y ago

Still wondering about why 737 NGs (-600,-700,-800,-900) are still deemed "airworthy" despite the 2010 investigative report on Boeing's intentional deception and cover-up of Ducommun's absurdly dangerous and substandard critical structural fuselage components. Several passengers have already died from fuselage breakups from hard landings and runway overruns when previous aircraft have survived similar situations intact; plus the possibility of aircraft catastrophically breaking up in heavy turbulence.