4 ms·

My plan is to not fly on these for 6 - 12 month; see if any more crash. On the one hand, I would be terrified because, obviously! But on the other, they must no

My plan is to not fly on these for 6 - 12 month; see if any more crash. On the one hand, I would be terrified because, obviously! But on the other, they must now be extremely safe, with all the scrutiny, right?

donkeyd 6y ago
Not flying at all for the next 6-12 months seems reasonable too, in light of the ongoing pandemic.
DennisP 6y ago
They crashed because they made an unstable airframe and tried to make up for it with sensors and software. They've presumably improved the sensors and software, along with training, but the airframe is the same. I'd much rather ride some boring old design that's been flying safely for decades without needing fancy software to keep it in the air.
- mumblemumble 6y ago
  My understanding is that the airframe wasn't unstable in a way that's particularly unusual for commercial aircraft, and these sorts of things are regularly handled just fine with pilot training. The problem was that it was unstable in a way that wasn't exactly like previous 737 models. Except actually that probably wasn't a problem so much as an annoyance. The problem was that, since retraining pilots for the MAX's quirks would have been unpalatable for customers, they decided to try and use software to sweep it under the carpet. Except perhaps the even more fundamental problem was that the FAA was so deeply asleep on their post that this glaring snow job apparently flew past them without notice.
- tzs 6y ago
  It is not an unstable airframe. See this prior thread for more detail: https://news.ycombinator.com/item?id=21245975 https://news.ycombinator.com/item?id=21245975
  - VBprogrammer 6y ago
    I've gotten fed up of trying to explain this to people. The tldr is that the most reasonable interpretation of events is that the 737 Max without MCAS is not certifiable without MCAS (or at least a better thought out modification to the control feel system). There is no particular requirement for aircraft on the same type certificate to "handle" the same way. For an extreme example look at the Cessna 500 series. The CJ4 has a note in its pilot operations hand book that it is high performance and is basically at the limit of what a single pilot can handle.
    - hindsightbias 6y ago
      It might have been certifiable without MCAS but not without some significant retraining requirement.
      - VBprogrammer 6y ago
        That's precisely contrary to my point. The available evidence is that the 737 Max did not meet the certification requirements for force vs pitch. As such no amount of extra training would have sufficed to make it a certifiable aircraft. I appreciate that Boeing themselves have made this difficult by their PR line that MCAS makes it fly like other 737s. If you have ever been involved in something like this being managed in the public perception you'll understand this is pretty typical of how technical issues are dumbed down for public consumption. In this case it also happens to be technically correct, in that other 737s have certifiable behaviour in this flight regime, so MCAS makes it fly more like them.
      - kayfox 6y ago
        The control forces have to to always increase linearly into a stall, theres no amount of training that will allow for anything otherwise. The aircraft is not certifiable without MCAS.
- rob74 6y ago
  No. The MAX is basically a boring old design that's been flying safely for decades, and it is perfectly stable. The only problem was a small handling issue that appeared at very steep climbs because of the new engines. And because they wanted to keep the same type certificate, the MAX had to handle exactly the same as the "old" 737, so they introduces MCAS to adjust the "maneuvering characteristics" automatically. Which was so badly designed that it led to the crashes. So the problem is not with the basic 737 design, the problem is that the new MCAS was much worse than the problem it was supposed to fix.
  - capableweb 6y ago
    > and it is perfectly stable Was thought to be perfectly stable. Turns out it wasn't, in their new edition. > problem is that the new MCAS was much worse It's common in airplane industry to never blame users nor the instruments, but the process. Things should be able to fail, and pilots should be able to recover. Now both Boeing and the FAA failed catastrophically in their certification process, leading to missing vital information about the MCAS. Overall the core problem wasn't the MCAS but the process (or lack of process) that didn't find out the edge-cases where it didn't work.
    - rob74 6y ago
      As with most aviation accidents, you always have a chain of things that have to fail. If memory serves, any one of the following would probably have prevented the accidents: - if Boeing would have designed MCAS better - if anyone inside Boeing or the FAA would have flagged the bad design before the accidents - if Boeing would have enabled the "Angle of attack sensor disagree alert" by default on all MAX airplanes (https://aviation.stackexchange.com/questions/64020/is-the-737-maxs-aoa-disagreement-warning-light-an-actual-light https://aviation.stackexchange.com/questions/64020/is-the-73...) - if the issues with the AOA sensors on the crashed planes would have been fixed before the accidents

donkeyd 6y ago

Not flying at all for the next 6-12 months seems reasonable too, in light of the ongoing pandemic.

DennisP 6y ago

They crashed because they made an unstable airframe and tried to make up for it with sensors and software. They've presumably improved the sensors and software, along with training, but the airframe is the same. I'd much rather ride some boring old design that's been flying safely for decades without needing fancy software to keep it in the air.

mumblemumble 6y ago
My understanding is that the airframe wasn't unstable in a way that's particularly unusual for commercial aircraft, and these sorts of things are regularly handled just fine with pilot training. The problem was that it was unstable in a way that wasn't exactly like previous 737 models. Except actually that probably wasn't a problem so much as an annoyance. The problem was that, since retraining pilots for the MAX's quirks would have been unpalatable for customers, they decided to try and use software to sweep it under the carpet. Except perhaps the even more fundamental problem was that the FAA was so deeply asleep on their post that this glaring snow job apparently flew past them without notice.
tzs 6y ago
It is not an unstable airframe. See this prior thread for more detail: https://news.ycombinator.com/item?id=21245975 https://news.ycombinator.com/item?id=21245975
- VBprogrammer 6y ago
  I've gotten fed up of trying to explain this to people. The tldr is that the most reasonable interpretation of events is that the 737 Max without MCAS is not certifiable without MCAS (or at least a better thought out modification to the control feel system). There is no particular requirement for aircraft on the same type certificate to "handle" the same way. For an extreme example look at the Cessna 500 series. The CJ4 has a note in its pilot operations hand book that it is high performance and is basically at the limit of what a single pilot can handle.
  - hindsightbias 6y ago
    It might have been certifiable without MCAS but not without some significant retraining requirement.
    - VBprogrammer 6y ago
      That's precisely contrary to my point. The available evidence is that the 737 Max did not meet the certification requirements for force vs pitch. As such no amount of extra training would have sufficed to make it a certifiable aircraft. I appreciate that Boeing themselves have made this difficult by their PR line that MCAS makes it fly like other 737s. If you have ever been involved in something like this being managed in the public perception you'll understand this is pretty typical of how technical issues are dumbed down for public consumption. In this case it also happens to be technically correct, in that other 737s have certifiable behaviour in this flight regime, so MCAS makes it fly more like them.
    - kayfox 6y ago
      The control forces have to to always increase linearly into a stall, theres no amount of training that will allow for anything otherwise. The aircraft is not certifiable without MCAS.
rob74 6y ago
No. The MAX is basically a boring old design that's been flying safely for decades, and it is perfectly stable. The only problem was a small handling issue that appeared at very steep climbs because of the new engines. And because they wanted to keep the same type certificate, the MAX had to handle exactly the same as the "old" 737, so they introduces MCAS to adjust the "maneuvering characteristics" automatically. Which was so badly designed that it led to the crashes. So the problem is not with the basic 737 design, the problem is that the new MCAS was much worse than the problem it was supposed to fix.
- capableweb 6y ago
  > and it is perfectly stable Was thought to be perfectly stable. Turns out it wasn't, in their new edition. > problem is that the new MCAS was much worse It's common in airplane industry to never blame users nor the instruments, but the process. Things should be able to fail, and pilots should be able to recover. Now both Boeing and the FAA failed catastrophically in their certification process, leading to missing vital information about the MCAS. Overall the core problem wasn't the MCAS but the process (or lack of process) that didn't find out the edge-cases where it didn't work.
  - rob74 6y ago
    As with most aviation accidents, you always have a chain of things that have to fail. If memory serves, any one of the following would probably have prevented the accidents: - if Boeing would have designed MCAS better - if anyone inside Boeing or the FAA would have flagged the bad design before the accidents - if Boeing would have enabled the "Angle of attack sensor disagree alert" by default on all MAX airplanes (https://aviation.stackexchange.com/questions/64020/is-the-737-maxs-aoa-disagreement-warning-light-an-actual-light https://aviation.stackexchange.com/questions/64020/is-the-73...) - if the issues with the AOA sensors on the crashed planes would have been fixed before the accidents