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This is in no way to detract from your analysis, but Air France wasn't instrument error, it was really pilot error. The instrument malfunctioned, but one pilot

This is in no way to detract from your analysis, but Air France wasn't instrument error, it was really pilot error. The instrument malfunctioned, but one pilot was pulling a lever up, while another pilot was pulling another lever down. This generated a stall. It could have been avoided if the cabin was more well lit, so that the pilot making the error could have been visually seen to be making the mistake.

xenadu02 8y ago
I maintain this is a flaw in the Airbus UX. When they get conflicting inputs they silently average them. Boeing uses force feedback so the two pilots are aware that something is counter-acting their input. I really don’t think the Airbus strategy is defensible - certainly not when the two inputs are far apart!
- renox 8y ago
  I agree: there should have been a warning that both pilots are doing (very) different commands. Airbus is responsible here. Boeing is responsible in the article too: adding such new feature without properly communicating with the pilots??
  - dotancohen 8y ago
    I have a hard time believing the statement from the fine article that the presence of the MCAS system was unknown to the pilots. I'm not a pilot, just an interested spaceflight and aircraft enthusiast, and I know about that system. There is no way that the pilots did not. Maybe the pilots did not receive proper sim time on a 737MAX, which I believe has different enough instrumentation and automation systems to require a separate sim from the standard 737. But they almost certainly knew which systems were on the plane, and how to operate them under normal conditions.
    - dunmalg 8y ago
      >Maybe the pilots did not receive proper sim time on a 737MAX, which I believe has different enough instrumentation and automation systems to require a separate sim from the standard 737 Isn't part of Boeing's marketing strategy that the 737MAX actually DOESN'T require additional training? The entire point of MCAS is to make the larger 737MAX react to control inputs just like a smaller 737, so flight crew can just fly them all "like a 737".
  - cryptonector 8y ago
    There were too many warnings already. That was the problem. More warning could not have helped. Instead, the fact that the pitot tube was inoperable should not have led to so many alarms, just one, and not an urgent one since the autopilot could have kept the throttle at its current setting. (Air speed is independent of land speed, and it's much more important to know the airspeed than the land speed, but wind speed is not going to fluctuate so much, so land speed can be used as a proxy for airspeed in that situation, and anyways there wasn't anything to be done about the lack of airspeed indication in that situation.)
- marksweston 8y ago
  This narrative is incorrect. The aircraft gave audio and visual warnings when there were multiple control inputs. And we can infer that the crew on AF447 noticed them because the 2 (IIRC) instances of dual input lasted less than a couple of seconds.
  - PuffinBlue 8y ago
    And the captain actually noticed it, told the pilot pulling back on the stick to push forward, who did momentarily and then he pulled back again. If you read the whole transcript and report it really does show just how wrong the pilot pulling back got it. And it speaks to the training and understanding that pilot had of how to fly the electronics vs how to fundamentally fly an aircraft.
    - anoncoward111 8y ago
      Agreed. Also, I can't imagine the feeling of the captain who was asleep in the crew area until the very end. He quite literally kicked down the door to the cockpit and asked "What the hell are you doing?" Moments later, the co-pilot at fault said "but I've had that stick down the whole time!"
      - sokoloff 8y ago
        Indeed; it was a stunning lack of basic airmanship; I would expect more from a 10-hour pre-solo student pilot...
        barrkel 8y ago
        I'd expect it from a student, because they're operating consciously. I'm not sure I'd expect it from someone who is in shock, who's experienced thousands of hours of uneventful operation and suddenly everything has changed. I don't know easily panicked mentality can be tested for. Training is one thing, but training is typically designed to instill automatic response to predetermined stimuli. Sometimes what you want is a reset back to first principles and activation of conscious reasoning. Which is exactly what you don't get in shock or panic, and is the reason for training automatic response.
- Animats 8y ago
  Not silently. There's a voice alert, "Priority Left" or "Priority Right", and a red light. But with other alarms active, it's likely to be missed. Airbus statement on sidesticks. [1] Boeing position on sidesticks.[2] This is a long-standing controversy. The F-16 fighter was the first aircraft produced with a sidestick. But that was so the pilot could control it during high-G maneuvers. Airbus's use of it has been controversial for years. For a good overview of the Airbus control system, read "Fly by Wire", by William Langewiesche. But that wasn't the problem with Lion Air. Airspeed. Attitude. Vertical speed. Altitude. If the pilot is operating on wrong information for any of those, they may lose control of the aircraft. All large aircraft have more than one of each of those. But when they disagree, or fail in a common mode, big trouble. Whether some other data source like GPS or inertial should be used to back up those is an open question. GPS can and is jammed. Inertial systems drift. Both are complicated. The classic instruments are so simple. But they rely on tubes to holes in the aircraft skin, which might become plugged for a number of reasons - ice, maintenance covers, insects, or dirt. [1] https://safetyfirst.airbus.com/app/themes/mh_newsdesk/documents/archives/dual-side-stick-inputs.pdf https://safetyfirst.airbus.com/app/themes/mh_newsdesk/docume... [2] http://archive.li/x0Pn8 http://archive.li/x0Pn8
dagoat 8y ago
OP says primary cause. Which it was. Pilot error happened after, and because of, instrument error. Being well lit is one part. But also, if the pilots had been in a Boeing that may have helped as well. Airbus joystick vs Boeing yoke. The latter would have provided feedback to the pilot not panicking and pulling up incessantly

xenadu02 8y ago

I maintain this is a flaw in the Airbus UX. When they get conflicting inputs they silently average them. Boeing uses force feedback so the two pilots are aware that something is counter-acting their input. I really don’t think the Airbus strategy is defensible - certainly not when the two inputs are far apart!

renox 8y ago
I agree: there should have been a warning that both pilots are doing (very) different commands. Airbus is responsible here. Boeing is responsible in the article too: adding such new feature without properly communicating with the pilots??
- dotancohen 8y ago
  I have a hard time believing the statement from the fine article that the presence of the MCAS system was unknown to the pilots. I'm not a pilot, just an interested spaceflight and aircraft enthusiast, and I know about that system. There is no way that the pilots did not. Maybe the pilots did not receive proper sim time on a 737MAX, which I believe has different enough instrumentation and automation systems to require a separate sim from the standard 737. But they almost certainly knew which systems were on the plane, and how to operate them under normal conditions.
  - dunmalg 8y ago
    >Maybe the pilots did not receive proper sim time on a 737MAX, which I believe has different enough instrumentation and automation systems to require a separate sim from the standard 737 Isn't part of Boeing's marketing strategy that the 737MAX actually DOESN'T require additional training? The entire point of MCAS is to make the larger 737MAX react to control inputs just like a smaller 737, so flight crew can just fly them all "like a 737".
- cryptonector 8y ago
  There were too many warnings already. That was the problem. More warning could not have helped. Instead, the fact that the pitot tube was inoperable should not have led to so many alarms, just one, and not an urgent one since the autopilot could have kept the throttle at its current setting. (Air speed is independent of land speed, and it's much more important to know the airspeed than the land speed, but wind speed is not going to fluctuate so much, so land speed can be used as a proxy for airspeed in that situation, and anyways there wasn't anything to be done about the lack of airspeed indication in that situation.)
marksweston 8y ago
This narrative is incorrect. The aircraft gave audio and visual warnings when there were multiple control inputs. And we can infer that the crew on AF447 noticed them because the 2 (IIRC) instances of dual input lasted less than a couple of seconds.
- PuffinBlue 8y ago
  And the captain actually noticed it, told the pilot pulling back on the stick to push forward, who did momentarily and then he pulled back again. If you read the whole transcript and report it really does show just how wrong the pilot pulling back got it. And it speaks to the training and understanding that pilot had of how to fly the electronics vs how to fundamentally fly an aircraft.
  - anoncoward111 8y ago
    Agreed. Also, I can't imagine the feeling of the captain who was asleep in the crew area until the very end. He quite literally kicked down the door to the cockpit and asked "What the hell are you doing?" Moments later, the co-pilot at fault said "but I've had that stick down the whole time!"
    - sokoloff 8y ago
      Indeed; it was a stunning lack of basic airmanship; I would expect more from a 10-hour pre-solo student pilot...
      - barrkel 8y ago
        I'd expect it from a student, because they're operating consciously. I'm not sure I'd expect it from someone who is in shock, who's experienced thousands of hours of uneventful operation and suddenly everything has changed. I don't know easily panicked mentality can be tested for. Training is one thing, but training is typically designed to instill automatic response to predetermined stimuli. Sometimes what you want is a reset back to first principles and activation of conscious reasoning. Which is exactly what you don't get in shock or panic, and is the reason for training automatic response.
Animats 8y ago
Not silently. There's a voice alert, "Priority Left" or "Priority Right", and a red light. But with other alarms active, it's likely to be missed. Airbus statement on sidesticks. [1] Boeing position on sidesticks.[2] This is a long-standing controversy. The F-16 fighter was the first aircraft produced with a sidestick. But that was so the pilot could control it during high-G maneuvers. Airbus's use of it has been controversial for years. For a good overview of the Airbus control system, read "Fly by Wire", by William Langewiesche. But that wasn't the problem with Lion Air. Airspeed. Attitude. Vertical speed. Altitude. If the pilot is operating on wrong information for any of those, they may lose control of the aircraft. All large aircraft have more than one of each of those. But when they disagree, or fail in a common mode, big trouble. Whether some other data source like GPS or inertial should be used to back up those is an open question. GPS can and is jammed. Inertial systems drift. Both are complicated. The classic instruments are so simple. But they rely on tubes to holes in the aircraft skin, which might become plugged for a number of reasons - ice, maintenance covers, insects, or dirt. [1] https://safetyfirst.airbus.com/app/themes/mh_newsdesk/documents/archives/dual-side-stick-inputs.pdf https://safetyfirst.airbus.com/app/themes/mh_newsdesk/docume... [2] http://archive.li/x0Pn8 http://archive.li/x0Pn8

dagoat 8y ago

OP says primary cause. Which it was. Pilot error happened after, and because of, instrument error. Being well lit is one part. But also, if the pilots had been in a Boeing that may have helped as well. Airbus joystick vs Boeing yoke. The latter would have provided feedback to the pilot not panicking and pulling up incessantly