4 ms·

Yes! But even if you have 2 out of 3 vote you can still have two sensors that can fail, say due to a bird strike or something else and MCAS would have to be dis

Yes! But even if you have 2 out of 3 vote you can still have two sensors that can fail, say due to a bird strike or something else and MCAS would have to be disabled which means pilots need to learn to fly the plane w/o MCAS. The one part of the narrative that Boeing has tried to Jedi Mind Trick away is that even if the pilots knew to disable MCAS by pulling the fuse, they're still left with having to fly a plane which no longer flies as the previous generation that they were trained on -- which is what MCAS was designed to do. So you still have a safety issue.

ams6110 8y ago
In normal flight, MCAS is not active. The plane handles pretty much like any other 737. MCAS becomes active at high angles of attack, near the stall, to meet handling requirements for certification.
- salawat 8y ago
  Doesn't matter. The flight characteristics are still drastically different toward the extremes, and you never assume away the extremes. You now have to guarantee that every crew when faced with an MCAS disable situation that required piloting in a way that the MCAS would kick in can successfully mimic the action of the MCAS with only the manual trim wheels. I'm not saying that's impossible, but you'd want your aircrew to have sufficient training to be a stand in for the automation.
  - VBprogrammer 8y ago
    I think "drastically different" is probably overstating the truth. It certainly doesn't jibe with anything I've read. It's worth bearing in mind that, from what we know, neither of the two crashes had anything to do with handling difficulties in the new aircraft near the stall.
    - salawat 8y ago
      I say drastically different because no one pays the complexity tax of increased automation to deal with something that isn't important. In this case, to the certifiability of the airframe. I understand your caution against overstating things, but I'm not trying to be hyperbolic. If you think about the consequences of doing basic maneuvers in adverse conditions (weather/load/engine power conditions), you rapidly begin to get into areas where what seems minor would get into uncharted territory without a working MCAS. It is a different plane in terms of manual flying. The automation non-withstanding.
      - VBprogrammer 8y ago
        I get where you are coming from, and it's true that "the FARs are written in blood" but I'm not convinced that a non-linear stick force would have caused any real world issues. For a start, all of the critical phases of flight (takeoff, landing and go-around) usually involve some amount of flaps, for which MCAS is apparently unnecessary.
        salawat 8y ago
        I'd like to point you here, https://news.ycombinator.com/item?id=19527543 https://news.ycombinator.com/item?id=19527543 This is an interview with D.P. Davies, a test pilot of the Aviation Review Board of the UK. He faced many of the same arguments back in the 1950's with regards to the certifiability of the 707-300 I believe, but nevertheless rejected it for non compliance. In that case, even if the plane stalled itself, it would immediately pitch back down, making it a "benign" aberrant flight characteristic. However, as he successfully argued, certifying that plane as is would set a precedent Which would deteriorate the overall airworthyness of airframes over time as the goal posts were allowed to slip further and further away from what was required by law. We call this Normalization of Deviance, and it's an Engineering firms favorite way to get people killed in high profile ways. I am far from the best example of a person who doesn't exceed the boundaries of "rules" when they keep me from getting something done, but once you have the thing done in a non-compliant way, it is absolutely imperative to bring it back into compliance somehow or ensure every stakeholder (regulator/customer/user alike) is aware of the exceptionality of the non-compliant piece, and owning it in whatever capacity is required to get the job done safely. Creators, designers, manufacturers, etc are given a great deal of leeway when it comes to doing things; part of that is the expectation that you know the rules you are breaking, and you are making the best effort to either communicate or remedy the non-compliance. Don't know as it will change your mind, but I hope it makes where I'm coming from clearer.
  - ams6110 8y ago
    Fully agree that Boeing should have disclosed MCAS, why it's there, and details of its operation to the folks flying the planes. If I were a pilot I would certainly want to know about such a system, even if its behavior is not normally something I have to deal with. Sort of like a stick shaker. It's there for safety near the extremes, but it's not something a pilot ever encounters during line flying.

ams6110 8y ago

In normal flight, MCAS is not active. The plane handles pretty much like any other 737. MCAS becomes active at high angles of attack, near the stall, to meet handling requirements for certification.

salawat 8y ago
Doesn't matter. The flight characteristics are still drastically different toward the extremes, and you never assume away the extremes. You now have to guarantee that every crew when faced with an MCAS disable situation that required piloting in a way that the MCAS would kick in can successfully mimic the action of the MCAS with only the manual trim wheels. I'm not saying that's impossible, but you'd want your aircrew to have sufficient training to be a stand in for the automation.
- VBprogrammer 8y ago
  I think "drastically different" is probably overstating the truth. It certainly doesn't jibe with anything I've read. It's worth bearing in mind that, from what we know, neither of the two crashes had anything to do with handling difficulties in the new aircraft near the stall.
  - salawat 8y ago
    I say drastically different because no one pays the complexity tax of increased automation to deal with something that isn't important. In this case, to the certifiability of the airframe. I understand your caution against overstating things, but I'm not trying to be hyperbolic. If you think about the consequences of doing basic maneuvers in adverse conditions (weather/load/engine power conditions), you rapidly begin to get into areas where what seems minor would get into uncharted territory without a working MCAS. It is a different plane in terms of manual flying. The automation non-withstanding.
    - VBprogrammer 8y ago
      I get where you are coming from, and it's true that "the FARs are written in blood" but I'm not convinced that a non-linear stick force would have caused any real world issues. For a start, all of the critical phases of flight (takeoff, landing and go-around) usually involve some amount of flaps, for which MCAS is apparently unnecessary.
      - salawat 8y ago
        I'd like to point you here, https://news.ycombinator.com/item?id=19527543 https://news.ycombinator.com/item?id=19527543 This is an interview with D.P. Davies, a test pilot of the Aviation Review Board of the UK. He faced many of the same arguments back in the 1950's with regards to the certifiability of the 707-300 I believe, but nevertheless rejected it for non compliance. In that case, even if the plane stalled itself, it would immediately pitch back down, making it a "benign" aberrant flight characteristic. However, as he successfully argued, certifying that plane as is would set a precedent Which would deteriorate the overall airworthyness of airframes over time as the goal posts were allowed to slip further and further away from what was required by law. We call this Normalization of Deviance, and it's an Engineering firms favorite way to get people killed in high profile ways. I am far from the best example of a person who doesn't exceed the boundaries of "rules" when they keep me from getting something done, but once you have the thing done in a non-compliant way, it is absolutely imperative to bring it back into compliance somehow or ensure every stakeholder (regulator/customer/user alike) is aware of the exceptionality of the non-compliant piece, and owning it in whatever capacity is required to get the job done safely. Creators, designers, manufacturers, etc are given a great deal of leeway when it comes to doing things; part of that is the expectation that you know the rules you are breaking, and you are making the best effort to either communicate or remedy the non-compliance. Don't know as it will change your mind, but I hope it makes where I'm coming from clearer.
- ams6110 8y ago
  Fully agree that Boeing should have disclosed MCAS, why it's there, and details of its operation to the folks flying the planes. If I were a pilot I would certainly want to know about such a system, even if its behavior is not normally something I have to deal with. Sort of like a stick shaker. It's there for safety near the extremes, but it's not something a pilot ever encounters during line flying.