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I feel like this is a strong argument for the airbus alpha protection. And I think Boeing agrees with that given the way the 777 fly by wire system is designed.

I feel like this is a strong argument for the airbus alpha protection. And I think Boeing agrees with that given the way the 777 fly by wire system is designed. There are plenty of people (on this site and on reddit) who jump on to criticize airbus for the way it puts the aircraft's computer systems ahead of the pilots and claim that the 737's flight controls are preferable to pilots because the pilots have full control. I don't want to spark any airbus vs boeing debate, but I want to point out these accidents seem to discredit that line of thinking.

snowwrestler 8y ago
Before we get excited about computer protections, let’s acknowledge that the MCAS system under debate on the 737 Max is itself a computerized system designed to protect pilots from themselves—in this case, from pitching too high and creating a stall. In the Lion Air accident, a malfunctioning sensor caused this system to react incorrectly, surprising the pilots. Let’s also remember that a malfunctioning sensor was a contributing factor in the crash of Air France 447... a problem which was exacerbated by human interface choices in Airbus’s fly by wire system. In particular, stick input is not physically synchronized and conflicting inputs were averaged; neither of which is true on a Boeing aircraft. Even on a 787 the yokes move together. Human factors matter a lot if the computers hand control back to the humans unexpectedly. That can happen even in fly by wire systems on Airbus. Edit: fixed 737 reference up top
- skybrian 8y ago
  Oops, did you mean 737?
  - snowwrestler 8y ago
    Thanks!
- Someone1234 8y ago
  Unclear why you're trying to conflate the MCAS issue with AF447. Or are even bringing up AF447 at all. On the Max 8 a bad sensor is causing an automated system to misbehave, and may have resulted in crashes. On AF447 ice blocking the pitot-static system caused automated systems to go offline (enter Alternative Law), and loss of situational awareness caused the pilots to crash their aircraft under manual control. If you read the final report[0] you'll see that pilot error and loss of basic airman-ship caused the accident. There's always improvements to the airframe to mitigate the human component, but acting like these two are somehow different sides of the same coin is disingenuous. I'm not actually sure why you brought it up. Comes across as "look they're both just as bad" while ignoring key details about AF447. [0] https://en.wikipedia.org/wiki/Air_France_Flight_447#Final_report https://en.wikipedia.org/wiki/Air_France_Flight_447#Final_re...
  - poof131 8y ago
    > the system rejected the data as invalid and temporarily stopped the stall warnings. However, "this led to a perverse reversal that lasted nearly to the impact: each time Bonin happened to lower the nose, rendering the angle of attack marginally less severe, the stall warning sounded again—a negative reinforcement that may have locked him into his pattern of pitching up", which increased the angle of attack and thus prevented the aircraft from getting out of its stall From your link. In my mind that is the critical piece. The pilot did the right thing, pushed the nose down, heard the stall warning again, and did the wrong thing, pulled the nose up, because that made the stall warning go away. Having been in a plane upside down at night pointed toward the ground I can imagine the stress on the crew. It’s easy to say dump the nose when the stall warning goes off, but what if they had been upside down, then he would have been doing the right thing by listening to the warning. The fact the stall warning cut off was the final critical link in the accident, not pilot error.
  - jbay808 8y ago
    For those of us non-experts, I am glad that it was brought up because that accident immediately came to mind for me as well, and I was curious about the differences between them. Thank you for the comparison!
  - snowwrestler 8y ago
    Did you read the comment I’m replying to? The common element between Lion Air and Air France crashes is bad sensor data: AOA and airspeed, respectively. A computerized system, no matter how sophisticated, cannot protect pilots from themselves in the absence of accurate sensor data.
    - lagolinguini 8y ago
      > The common element between Lion Air and Air France crashes is bad sensor data Agreed but the context is completely different. The airbus flight computers rely on data from three sensors and thus are triply redundant. AF447 happened in severe icing conditions with water ingressing into the pitot tubes on the ground. All three pitot tubes froze, causing all three sensors to report bad data. The aircraft identified the discrepancy and degraded from normal law to alternate law as expected so it would not make any decisions based on the faulty data. The crash ultimately was caused by the pilots being disoriented because of the very low visibility. The sidestick issue is a different discussion, but its not related to the 737MAX accidents. The MCAS system on the other hand is not triply redundant, and that's what people have issue with. Boeing itself has more redundant envelope protections on the newer models like the 777 and 787.
- lagolinguini 8y ago
  No, the MCAS is fundamentally different from the envelope protection on the airbus aircraft, and AFAIK the protections on the 777. The airbus aircraft sensors have triple redundancy, and if even one of the sensors disagrees with the others, the FBW system degrades from Normal law to Direct law. In the case of Airfrance 447, all three pitot tubes malfunctioned due to icing conditions well outside the the expected range required for type certification for that aircraft. The aircraft also did degrade down from normal law as was expected. Admittedly, the sidesticks on the airbus do not provide feedback but both pilots ignored the aural "dual input" warning, as well as the warning indication on the panel.
Pristina 8y ago
Just another case of humans being unable to accept the fact that computers are better than them.

snowwrestler 8y ago

Before we get excited about computer protections, let’s acknowledge that the MCAS system under debate on the 737 Max is itself a computerized system designed to protect pilots from themselves—in this case, from pitching too high and creating a stall. In the Lion Air accident, a malfunctioning sensor caused this system to react incorrectly, surprising the pilots. Let’s also remember that a malfunctioning sensor was a contributing factor in the crash of Air France 447... a problem which was exacerbated by human interface choices in Airbus’s fly by wire system. In particular, stick input is not physically synchronized and conflicting inputs were averaged; neither of which is true on a Boeing aircraft. Even on a 787 the yokes move together. Human factors matter a lot if the computers hand control back to the humans unexpectedly. That can happen even in fly by wire systems on Airbus. Edit: fixed 737 reference up top

skybrian 8y ago
Oops, did you mean 737?
- snowwrestler 8y ago
  Thanks!
Someone1234 8y ago
Unclear why you're trying to conflate the MCAS issue with AF447. Or are even bringing up AF447 at all. On the Max 8 a bad sensor is causing an automated system to misbehave, and may have resulted in crashes. On AF447 ice blocking the pitot-static system caused automated systems to go offline (enter Alternative Law), and loss of situational awareness caused the pilots to crash their aircraft under manual control. If you read the final report[0] you'll see that pilot error and loss of basic airman-ship caused the accident. There's always improvements to the airframe to mitigate the human component, but acting like these two are somehow different sides of the same coin is disingenuous. I'm not actually sure why you brought it up. Comes across as "look they're both just as bad" while ignoring key details about AF447. [0] https://en.wikipedia.org/wiki/Air_France_Flight_447#Final_report https://en.wikipedia.org/wiki/Air_France_Flight_447#Final_re...
- poof131 8y ago
  > the system rejected the data as invalid and temporarily stopped the stall warnings. However, "this led to a perverse reversal that lasted nearly to the impact: each time Bonin happened to lower the nose, rendering the angle of attack marginally less severe, the stall warning sounded again—a negative reinforcement that may have locked him into his pattern of pitching up", which increased the angle of attack and thus prevented the aircraft from getting out of its stall From your link. In my mind that is the critical piece. The pilot did the right thing, pushed the nose down, heard the stall warning again, and did the wrong thing, pulled the nose up, because that made the stall warning go away. Having been in a plane upside down at night pointed toward the ground I can imagine the stress on the crew. It’s easy to say dump the nose when the stall warning goes off, but what if they had been upside down, then he would have been doing the right thing by listening to the warning. The fact the stall warning cut off was the final critical link in the accident, not pilot error.
- jbay808 8y ago
  For those of us non-experts, I am glad that it was brought up because that accident immediately came to mind for me as well, and I was curious about the differences between them. Thank you for the comparison!
- snowwrestler 8y ago
  Did you read the comment I’m replying to? The common element between Lion Air and Air France crashes is bad sensor data: AOA and airspeed, respectively. A computerized system, no matter how sophisticated, cannot protect pilots from themselves in the absence of accurate sensor data.
  - lagolinguini 8y ago
    > The common element between Lion Air and Air France crashes is bad sensor data Agreed but the context is completely different. The airbus flight computers rely on data from three sensors and thus are triply redundant. AF447 happened in severe icing conditions with water ingressing into the pitot tubes on the ground. All three pitot tubes froze, causing all three sensors to report bad data. The aircraft identified the discrepancy and degraded from normal law to alternate law as expected so it would not make any decisions based on the faulty data. The crash ultimately was caused by the pilots being disoriented because of the very low visibility. The sidestick issue is a different discussion, but its not related to the 737MAX accidents. The MCAS system on the other hand is not triply redundant, and that's what people have issue with. Boeing itself has more redundant envelope protections on the newer models like the 777 and 787.
lagolinguini 8y ago
No, the MCAS is fundamentally different from the envelope protection on the airbus aircraft, and AFAIK the protections on the 777. The airbus aircraft sensors have triple redundancy, and if even one of the sensors disagrees with the others, the FBW system degrades from Normal law to Direct law. In the case of Airfrance 447, all three pitot tubes malfunctioned due to icing conditions well outside the the expected range required for type certification for that aircraft. The aircraft also did degrade down from normal law as was expected. Admittedly, the sidesticks on the airbus do not provide feedback but both pilots ignored the aural "dual input" warning, as well as the warning indication on the panel.

Pristina 8y ago

Just another case of humans being unable to accept the fact that computers are better than them.