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There are at least three inter-related issues here: 1) Was MCAS an issue in the Ethiopian Airlines crash? 2) Did Boeing err, prior to the Lion Air crash, in not

There are at least three inter-related issues here: 1) Was MCAS an issue in the Ethiopian Airlines crash? 2) Did Boeing err, prior to the Lion Air crash, in not informing pilots of the existence of MCAS, and the way it changes how a failure is experienced by the flight crew? 3) Does MCAS pose a risk that cannot be adequately addressed through appropriate awareness and training? IIRC, after the existence of MCAS was disclosed, the US pilots' unions were divided over this issue, with the union representing Southwest pilots castigating Boeing for its nondisclosure, while that representing United pilots did not consider it to be a big issue. Unfortunately, this article does not make it clear where pilots stand on issue 3, and the investigation of the Ethiopian Airlines crash might reveal additional issues. The forthcoming software upgrade for MCAS certainly implies that there were improvements to be made.

ddoolin 8y ago
I don't know the answer to 1 or 2, but regarding 3, if the issue in the reports via this article are the same issue, which it seems like they may be, then no I don't believe it poses a risk that can't be addressed through training. Through awareness these pilots and FOs filing reports seemed to know, at least through intuition if not outright knowledge of the new MCAS system, to disconnect the autopilot system when the nose goes down inappropriately. My question is, should the onus be on the pilots? Yes, they should know about it if they're going to be piloting an aircraft with it, but is this expected behavior? To me it seems more like a bug than expected behavior...why would you want to pitch downwards in a climb? I don't really understand defense of Boeing in any scenario. This seems like a mistake in any case, whether it's just lack of instruction or documentation in the relevant flight manuals, or an outright system failure.
- aaaaaaaaaaab 8y ago
  >why would you want to pitch downwards in a climb To avoid stalling?
  - deleted 8y ago
    [deleted]
- salawat 8y ago
  >why would you want to pitch downwards in a climb? Because due to the different shape and position of the nacelles, there are aerodynamic effects that cause the plane to want to pitch up at high AoA. If you are already close to a stall condition, and you were caught unawares, bad times would be had. The major issue though is pilots were left to 'just figure this out' instead of being informed of the change. I have a feeling Boeing felt justified doing this because they pitched it as a "reconfiguration" of an old airframe, not warranting any explanation. As with any task I've attempted that involves deadly failure modes, this should have struck someone as being a terrible idea.
  - kayfox 8y ago
    From what I have read, the NG series had the habit of pitching up under go-around conditions and this system exists because Boeing expected that issue to be more prevalent on the Max and also to try and solve it. So its not a new thing on the Max, its just expected to be more prominent.
blackflame7000 8y ago
Another issue is that the engines on the Max version are larger than the NG version and didn’t fit under the wing. So they had to raise the mounting point forward and up as well as extend the nose gear 18 inches. These changes caused the plane to have a different flight profile to the NG version. However it would have been disasterous if pilots already certified for the 737 couldn’t fly the 737 max. So boeing implemented the MCAS so make the max handle like the NG. That move is drawing a lot of skepticism because if the computer screws up then the pilots were never really trained to fly the Max https://theaircurrent.com/aviation-safety/what-is-the-boeing-737-max-maneuvering-characteristics-augmentation-system-mcas-jt610/ https://theaircurrent.com/aviation-safety/what-is-the-boeing...
- JKCalhoun 8y ago
  I'm ignorant of aviation, oversimplifying, but my summary: they fixed issues with the hardware in software. A little scary?
  - oliveshell 8y ago
    > A little scary? Perhaps, but it’s not unprecedented. The B2 stealth bomber, for example, famously lacks a vertical stabilizer (tail fin) and so is inherently unstable and relies on computerized control surfaces to maintain stable flight [1]. This seems to have worked fine, although the things definitely log way fewer flight hours than an airliner. I believe several other aircraft do this as well (fighter jets and such). Still, the idea of it would give me the willies if I were in charge of flying one. [1]: https://en.m.wikipedia.org/wiki/Northrop_Grumman_B-2_Spirit#Flight_controls https://en.m.wikipedia.org/wiki/Northrop_Grumman_B-2_Spirit#...
    - azernik 8y ago
      Fighters, in particular, are designed to be unstable to increase their control authority. That is, as an intended design feature they are easy to turn intentionally, which means they are also prone to turn unintentionally.
    - 8y ago
jahewson 8y ago
> 3) Does MCAS pose a risk that cannot be adequately addressed through appropriate awareness and training? If it fails this frequently, yes. Obviously pilots need to be informed about the failure modes of the planes they fly - but they also need to not be constantly subjected to them. Modern commercial aircraft are supposed to be waaay more reliable than this.
- mannykannot 8y ago
  How frequently it fails seems to depend on the answer to question 1 - unless you are aware of other incidents beyond the Lion Air crash?
deleted 8y ago
[deleted]
tuna-piano 8y ago
> The forthcoming software upgrade for MCAS certainly implies that there were improvements to be made. Not according to Boeing... "Boeing has been developing a flight control software enhancement for the 737 MAX, designed to make an already safe aircraft even safer."[1] To me an incredibly infuriating statement. The 737-MAX has a fatal crash rate of ~4 per million, when compared to .1 per million for the 737-NG models (40x). There is no currently flying major commercial aircraft which has a higher fatal crash rate than the 737-MAX [2] [3] Of course the MAX has a small sample size, but that's still not evidence of safety. What data is Boeing looking at to show that their aircraft is considered a safe aircraft? [1] https://boeing.mediaroom.com/news-releases-statements?item=130402 https://boeing.mediaroom.com/news-releases-statements?item=1... [2] https://finance.yahoo.com/news/boeing-737-crashes-liability-204033568.html https://finance.yahoo.com/news/boeing-737-crashes-liability-... [3] http://www.airsafe.com/events/models/rate_mod.htm http://www.airsafe.com/events/models/rate_mod.htm
- jussij 8y ago
  It really does not matter what spin Boeing comes up with regarding the cause of these crashes. The reality is in a very short space of time two 737-MAX have fallen out of the sky. You only have to look back at the McDonnell Douglas DC-10 to understand once a plane gets a bad reputation, it is doomed. For an example of how this can go bad so very quickly, here in Australia this issue has become so new worthy, it's now been revealed one our major carriers is planning to introduce the 737-MAX in November. I suspect just that little fact is going to become a major headache for that particular carrier.
  - rectang 8y ago
    The DC-10's infamous cargo door was a grievously poor design choice, violating well-understood safety principles for the sake of a little more cargo space. It's everything you fear about psychopath executives rolling the dice on safety because what do they care? The DC-10 deserved its ignominious reputation and the McDonnell-Douglas deserved every bit of the scorn they received and more.
    - 8y ago

ddoolin 8y ago

I don't know the answer to 1 or 2, but regarding 3, if the issue in the reports via this article are the same issue, which it seems like they may be, then no I don't believe it poses a risk that can't be addressed through training. Through awareness these pilots and FOs filing reports seemed to know, at least through intuition if not outright knowledge of the new MCAS system, to disconnect the autopilot system when the nose goes down inappropriately. My question is, should the onus be on the pilots? Yes, they should know about it if they're going to be piloting an aircraft with it, but is this expected behavior? To me it seems more like a bug than expected behavior...why would you want to pitch downwards in a climb? I don't really understand defense of Boeing in any scenario. This seems like a mistake in any case, whether it's just lack of instruction or documentation in the relevant flight manuals, or an outright system failure.

aaaaaaaaaaab 8y ago
>why would you want to pitch downwards in a climb To avoid stalling?
- deleted 8y ago
  [deleted]
salawat 8y ago
>why would you want to pitch downwards in a climb? Because due to the different shape and position of the nacelles, there are aerodynamic effects that cause the plane to want to pitch up at high AoA. If you are already close to a stall condition, and you were caught unawares, bad times would be had. The major issue though is pilots were left to 'just figure this out' instead of being informed of the change. I have a feeling Boeing felt justified doing this because they pitched it as a "reconfiguration" of an old airframe, not warranting any explanation. As with any task I've attempted that involves deadly failure modes, this should have struck someone as being a terrible idea.
- kayfox 8y ago
  From what I have read, the NG series had the habit of pitching up under go-around conditions and this system exists because Boeing expected that issue to be more prevalent on the Max and also to try and solve it. So its not a new thing on the Max, its just expected to be more prominent.

blackflame7000 8y ago

Another issue is that the engines on the Max version are larger than the NG version and didn’t fit under the wing. So they had to raise the mounting point forward and up as well as extend the nose gear 18 inches. These changes caused the plane to have a different flight profile to the NG version. However it would have been disasterous if pilots already certified for the 737 couldn’t fly the 737 max. So boeing implemented the MCAS so make the max handle like the NG. That move is drawing a lot of skepticism because if the computer screws up then the pilots were never really trained to fly the Max https://theaircurrent.com/aviation-safety/what-is-the-boeing-737-max-maneuvering-characteristics-augmentation-system-mcas-jt610/ https://theaircurrent.com/aviation-safety/what-is-the-boeing...

JKCalhoun 8y ago
I'm ignorant of aviation, oversimplifying, but my summary: they fixed issues with the hardware in software. A little scary?
- oliveshell 8y ago
  > A little scary? Perhaps, but it’s not unprecedented. The B2 stealth bomber, for example, famously lacks a vertical stabilizer (tail fin) and so is inherently unstable and relies on computerized control surfaces to maintain stable flight [1]. This seems to have worked fine, although the things definitely log way fewer flight hours than an airliner. I believe several other aircraft do this as well (fighter jets and such). Still, the idea of it would give me the willies if I were in charge of flying one. [1]: https://en.m.wikipedia.org/wiki/Northrop_Grumman_B-2_Spirit#Flight_controls https://en.m.wikipedia.org/wiki/Northrop_Grumman_B-2_Spirit#...
  - azernik 8y ago
    Fighters, in particular, are designed to be unstable to increase their control authority. That is, as an intended design feature they are easy to turn intentionally, which means they are also prone to turn unintentionally.
  - 8y ago

jahewson 8y ago

> 3) Does MCAS pose a risk that cannot be adequately addressed through appropriate awareness and training? If it fails this frequently, yes. Obviously pilots need to be informed about the failure modes of the planes they fly - but they also need to not be constantly subjected to them. Modern commercial aircraft are supposed to be waaay more reliable than this.

mannykannot 8y ago
How frequently it fails seems to depend on the answer to question 1 - unless you are aware of other incidents beyond the Lion Air crash?

deleted 8y ago

[deleted]

tuna-piano 8y ago

> The forthcoming software upgrade for MCAS certainly implies that there were improvements to be made. Not according to Boeing... "Boeing has been developing a flight control software enhancement for the 737 MAX, designed to make an already safe aircraft even safer."[1] To me an incredibly infuriating statement. The 737-MAX has a fatal crash rate of ~4 per million, when compared to .1 per million for the 737-NG models (40x). There is no currently flying major commercial aircraft which has a higher fatal crash rate than the 737-MAX [2] [3] Of course the MAX has a small sample size, but that's still not evidence of safety. What data is Boeing looking at to show that their aircraft is considered a safe aircraft? [1] https://boeing.mediaroom.com/news-releases-statements?item=130402 https://boeing.mediaroom.com/news-releases-statements?item=1... [2] https://finance.yahoo.com/news/boeing-737-crashes-liability-204033568.html https://finance.yahoo.com/news/boeing-737-crashes-liability-... [3] http://www.airsafe.com/events/models/rate_mod.htm http://www.airsafe.com/events/models/rate_mod.htm

jussij 8y ago
It really does not matter what spin Boeing comes up with regarding the cause of these crashes. The reality is in a very short space of time two 737-MAX have fallen out of the sky. You only have to look back at the McDonnell Douglas DC-10 to understand once a plane gets a bad reputation, it is doomed. For an example of how this can go bad so very quickly, here in Australia this issue has become so new worthy, it's now been revealed one our major carriers is planning to introduce the 737-MAX in November. I suspect just that little fact is going to become a major headache for that particular carrier.
- rectang 8y ago
  The DC-10's infamous cargo door was a grievously poor design choice, violating well-understood safety principles for the sake of a little more cargo space. It's everything you fear about psychopath executives rolling the dice on safety because what do they care? The DC-10 deserved its ignominious reputation and the McDonnell-Douglas deserved every bit of the scorn they received and more.
  - 8y ago