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> MCAS was put in place to allow the MAX to be type certified w/ other 737's But the expected behavior which MCAS was to provide was not something invented onl

• lmm 7y ago
  > But the expected behavior which MCAS was to provide was not something invented only for "other 737's." Whichever plane would behave as the MAX behaves without MCAS turned on would also be rejected from certification. No, it would have been a perfectly certifiable plane with a particular set of handling characteristics (including 777-like pitch-up). It just wouldn't be a 737, and would require its own type certificate. No-one's suggesting that large turbofan aircraft with pitch-up behaviour are inherently unsafe when flown by pilots appropriately trained and certified for them - otherwise the 777 would be grounded.
  • acqq 7y ago
    > No-one's suggesting that large turbofan aircraft with pitch-up behaviour are inherently unsafe It is as long it keeps 737 MAX body and engines and doesn’t have something like MCAS I.e. Inherently unsafe under conditions under which MCAS was supposed to turn on when properly functioning. The certification requirements are the result of the clear safety goals not something invented “just so.”
    • salawat 7y ago
      MCAS was a type certificate hack. The poster you're responding to is right; there isn't anything wrong with the behavior given the right training. It's just that the investment in that training, and extra certification hoops to jump through would have made WhateveroModelNumberus MAX a non-starter. It had to be a 737 to work at all.
      • acqq 7y ago
        > there isn't anything wrong with the behavior given the right training. The behaviour without MCAS on 737 MAX is that minimal movements of pilot’s controls effectively activate what would be considered “amplification” of nose up movement, resulting in an uncontrollable plane and sure crash. It’s definitely not something that pilots or passengers should be exposed to: being punished for approaching more dangerous position by plane forcing a deadly outcome. Training pilots to not to move even minimally the controls in the “wrong” direction is maybe technically possible but in practice still totally wrong: It’s comparable to what Boeing told everybody before Ethiopian crash, and their attempts to blame the pilots. In reality, the pilots had almost no chance to rescue themselves and the plane. In engineering the “positive feedback loops” (amplification of control inputs) are bad the “negative feedback loops” (correction of the input) are good. The functioning MCAS provides a correction. The plane without MCAS amplification. Badly functioning MCAS also amplification and crash. That's why the wrong behavior was regulated, and that's why it had to be fulfilled for the certification. It’s that easy. To convince me that 737 MAX without the "properly functioning MCAS" isn't inherently dangerous under higher angles of attack you'd have to provide some explicit proofs.
        • caconym_ 7y ago
          > To convince me that 737 MAX without the "properly functioning MCAS" isn't inherently dangerous under higher angles of attack you'd have to provide some explicit proofs. I am legitimately curious, do you have any explicit proofs of the converse, that (as you say) "the behaviour without MCAS on 737 MAX is that minimal movements of pilot’s controls effectively activate what would be considered “amplification” of nose up movement, resulting in an uncontrollable plane and sure crash"? The standard should be that a an unimpaired pilot properly trained in flying the aircraft will normally (practically) be in no danger of a "sure crash".
          • acqq 7y ago
            > The standard should be that a an unimpaired pilot properly trained in flying the aircraft will normally (practically) be in no danger of a "sure crash". Exactly. And under that assumptions 737 MAX with no MCAS was never certified. Boeing didn't even want to admit that MCAS even exists to avoid even showing the flight characteristic of the plane "without MCAS." It's on Boeing to prove "737 MAX without MCAS" is safe, and up to now they did all they could to avoid that, and I expect they'll do more of that unless there is a pressure outside of both Boeing and FAA.