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It also relied on a the pilot as a critical control - which is why there was no real automated backup or redundancy. Not unreasonable, doing stab trim cutout i

It also relied on a the pilot as a critical control - which is why there was no real automated backup or redundancy. Not unreasonable, doing stab trim cutout is a memory item for most operating manuals - pilots were already the circuit breaker for other stab trim issues. Automation working - great. Maintenance failures? Provide error messages (which occured here). Maintenance issues not resolved and automation misbehevior? Stab trim cutout memory item. Despite all the claims that the stab trim cutout did not work all real evidence is that it did. Other issues around pressure on flight surfaces not explored properly making recovery in overspeed and other conditions very hard. Badly designed system? Definitely. Brittle when facing poor maintenance? Clearly! Not taking into account broad pilot population. Of course. Definitely should be fixed, and frankly automation probably will be increased to decrease assumptions around pilot behavior which can be variable. This accident was the result not only of this bug but a chain of issues. That's why flying in the US is pretty safe, the chain from procurement to maintenance to pilot training is strong so compensates for poor elements. If you follow SAA technical for example there is evidence overseas that bogus parts are making it into plane repairs, with predictably bad results. We are not seeing that in the US (yet), though if inspections get soft I'm sure it would show up here too. Those bogus repairs will mean that some automation will break and the plane may not behave properly in ways that could have been designed around with better assumptions. My prediction? We are going to get iphone style authentication / serial number chips in key plane parts with electrical connections and the plane will eventually refuse to fly without the right parts - just like your coffee maker and iphone. Right now it is trust based.

largbae 7y ago
s/This accident/These accidents/ As you'll find in this article below, Boeing specifically removed the yoke-back function, which is the natural pilot input to nose up the plane. They also specifically for the MAX removed the separate switch for automatic stab trim assistance, so you have to turn off the motorized function entirely to turn off automated inputs including MCAS. The Lion Air crew could be heard on the radio saying that they did disable the stab trim, but in this situation the force required on the manual trim wheel was beyond the pilots' strength. The pilots turned the electronic stab trim back on in hopes of using the powered system to get back up, after which the undocumented and unstoppable MCAS nosed down the plane again, killing them and their passengers. https://www.seattletimes.com/business/boeing-aerospace/boeings-emergency-procedure-for-737-max-may-have-failed-on-ethiopian-flight/?amp=1 https://www.seattletimes.com/business/boeing-aerospace/boein... Your post reads like a sophisticated attempt to blame the victims, or at least the pilots and ground crews of the victims. These crashes were not caused by poor pilots, but rather secrets on top of secrets, all by Boeing, all for money. The MAX had new aerodynamic characteristics, but that needed to be a secret. So MCAS was added to the electronic trim assistance to hide the new characteristics, and the switch to disable it was removed to protect the secret. A faulty AOA sensor was now able to bring down the plane, but in order to keep the secret the single AOA option was still available and sold. Maintenance crews regardless of quality would not have been aware of the criticality of the AOA's secret role as a single point of failure for the whole plane. When the first one crashed, secrets covered it up. When the second one crashed, it still took all of those "ppor maintenance", "broad quality" non-US airlines and regulators to bring a stop to it. And apparently the secret-keepers are still trying to hide. Please don't blame dead pilots for this.
- salawat 7y ago
  One more thing, the flight computer was eventually found to be a single point of failure after being subjected to testing that should have been done in the first place. https://www.seattletimes.com/business/boeing-aerospace/newly-stringent-faa-tests-spur-a-fundamental-software-redesign-of-737-max-flight-controls/ https://www.seattletimes.com/business/boeing-aerospace/newly... Another regulatory no-no that wasn't brought up until the certified aircraft had been out in the wild long enough to kill people.
  - privateSFacct 7y ago
    Is this the five independent bit flips in worst possible order and combination from cosmic rays failure? First -> if this is your worst failure mode (ie, worse than pilot error, mechanical fatigue and failure, engine failures, fueling issues, crazy passengers etc) then you have a plane and overall safety system that is incredible. Second -> this wild set of events again does not crash the plane - though it would put the pilots in a bad spot similar to the existing MCAS issues.
    - salawat 7y ago
      >First -> if this is your worst failure mode (ie, worse than pilot error, mechanical fatigue and failure, engine failures, fueling issues, crazy passengers etc) then you have a plane and overall safety system that is incredible. Or would be, if it didn't violate design constraints that demand no single point of failure can have the capability to result in loss of the aircraft. I.e. components with failure profiles of catastrophic severity MUST have redundancy. You test the least likely events to ensure you have sufficient fault tolerance for that very reason. >Second -> this wild set of events again does not crash the plane - though it would put the pilots in a bad spot similar to the existing MCAS issues. Actually, one of the three test pilots did in fact lose the plane in the simulator. Hence the reclassification of the flight computer as a component with a catastrophic failure potential. Look, I'm about the last person you're going to get to buy into the awesome safety of an aircraft that can't even pass a textbook test case for computing in adverse environments. If the bloody thing was so safe and high quality, it wouldn't have been able to suffer that induced failure in the first place. It would have been designed out. The fact Boeing was caught off guard by that failure means they weren't looking very hard, and were banking that no one else would either. Which is generally a really bad assumption to make, because Murphy finds a way. Every time.
selimthegrim 7y ago
As Sullenberger said in his NYT reply to Langewiesche, blaming the pilots is out of line. I don't see anyone blaming that CHP officer who died in one of those unintentionally accelerated Toyotas because he in his panic didn't think to shut off the engine maybe for fear of losing power steering or most of the brake boost?

largbae 7y ago

s/This accident/These accidents/ As you'll find in this article below, Boeing specifically removed the yoke-back function, which is the natural pilot input to nose up the plane. They also specifically for the MAX removed the separate switch for automatic stab trim assistance, so you have to turn off the motorized function entirely to turn off automated inputs including MCAS. The Lion Air crew could be heard on the radio saying that they did disable the stab trim, but in this situation the force required on the manual trim wheel was beyond the pilots' strength. The pilots turned the electronic stab trim back on in hopes of using the powered system to get back up, after which the undocumented and unstoppable MCAS nosed down the plane again, killing them and their passengers. https://www.seattletimes.com/business/boeing-aerospace/boeings-emergency-procedure-for-737-max-may-have-failed-on-ethiopian-flight/?amp=1 https://www.seattletimes.com/business/boeing-aerospace/boein... Your post reads like a sophisticated attempt to blame the victims, or at least the pilots and ground crews of the victims. These crashes were not caused by poor pilots, but rather secrets on top of secrets, all by Boeing, all for money. The MAX had new aerodynamic characteristics, but that needed to be a secret. So MCAS was added to the electronic trim assistance to hide the new characteristics, and the switch to disable it was removed to protect the secret. A faulty AOA sensor was now able to bring down the plane, but in order to keep the secret the single AOA option was still available and sold. Maintenance crews regardless of quality would not have been aware of the criticality of the AOA's secret role as a single point of failure for the whole plane. When the first one crashed, secrets covered it up. When the second one crashed, it still took all of those "ppor maintenance", "broad quality" non-US airlines and regulators to bring a stop to it. And apparently the secret-keepers are still trying to hide. Please don't blame dead pilots for this.

salawat 7y ago
One more thing, the flight computer was eventually found to be a single point of failure after being subjected to testing that should have been done in the first place. https://www.seattletimes.com/business/boeing-aerospace/newly-stringent-faa-tests-spur-a-fundamental-software-redesign-of-737-max-flight-controls/ https://www.seattletimes.com/business/boeing-aerospace/newly... Another regulatory no-no that wasn't brought up until the certified aircraft had been out in the wild long enough to kill people.
- privateSFacct 7y ago
  Is this the five independent bit flips in worst possible order and combination from cosmic rays failure? First -> if this is your worst failure mode (ie, worse than pilot error, mechanical fatigue and failure, engine failures, fueling issues, crazy passengers etc) then you have a plane and overall safety system that is incredible. Second -> this wild set of events again does not crash the plane - though it would put the pilots in a bad spot similar to the existing MCAS issues.
  - salawat 7y ago
    >First -> if this is your worst failure mode (ie, worse than pilot error, mechanical fatigue and failure, engine failures, fueling issues, crazy passengers etc) then you have a plane and overall safety system that is incredible. Or would be, if it didn't violate design constraints that demand no single point of failure can have the capability to result in loss of the aircraft. I.e. components with failure profiles of catastrophic severity MUST have redundancy. You test the least likely events to ensure you have sufficient fault tolerance for that very reason. >Second -> this wild set of events again does not crash the plane - though it would put the pilots in a bad spot similar to the existing MCAS issues. Actually, one of the three test pilots did in fact lose the plane in the simulator. Hence the reclassification of the flight computer as a component with a catastrophic failure potential. Look, I'm about the last person you're going to get to buy into the awesome safety of an aircraft that can't even pass a textbook test case for computing in adverse environments. If the bloody thing was so safe and high quality, it wouldn't have been able to suffer that induced failure in the first place. It would have been designed out. The fact Boeing was caught off guard by that failure means they weren't looking very hard, and were banking that no one else would either. Which is generally a really bad assumption to make, because Murphy finds a way. Every time.

selimthegrim 7y ago

As Sullenberger said in his NYT reply to Langewiesche, blaming the pilots is out of line. I don't see anyone blaming that CHP officer who died in one of those unintentionally accelerated Toyotas because he in his panic didn't think to shut off the engine maybe for fear of losing power steering or most of the brake boost?