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> Investigators believe both accidents were triggered by the failure of a single sensor. Reminder that the 737 was far, far, far more than a "software failure"

• mtgx 6y ago
  Didn't they actually blame the pilots initially?
  • dataflow 6y ago
    Yeah. But at least initially maybe things were still unclear to some folks. Why are they still ignoring the root cause now?
  • Gibbon1 6y ago
    The criticism of the pilots on HN was hella racist.
    • Majestic121 6y ago
      Can you substantiate this statement ?
      • Gibbon1 6y ago
        Sure go back an read the threads after the first and second crashes and half the people were blaming the pilots being incompetent because they were Indian and Indonesian. And then same for the second crash. Specifically saying that the planes were safe in the hands of American and European pilots. It was very disgusting all around.
        • _ph_ 6y ago
          Blanket statements are certainly inappropriate, but as it happens, some months later it came to the public, that over half of the pilots in Pakistan had not passed the proper tests for their license. The Airbus crash in Karachi was entirely due to incompetent flying, like way to high approach speed and not checking whether the wheels were down.
          • selimthegrim 6y ago
            While the approach controllers share some blame too, it turns out that Pakistan CAA had recently changed the test scheme and a lot of pilots fully qualified under the old regime hadn’t taken the new set of exams which used to be optional
    • JasonFruit 6y ago
      I remember the criticism of flight training in Asian airlines occasionally verging on racism, but the basic criticism is valid: Asian airlines are faced with market pressures that do not allow them to train pilots adequately, and many don't know how to fly an airplane apart from a checklist; their understanding of piloting is in marginal cases frighteningly superficial.
  • alwayseasy 6y ago
    To be honest that's their default position in every crash.
  • _ph_ 6y ago
    A quick correct pilot action would have prevented both accidents. The whole reason that MCAS, even in its previous certainly faulty version, was approved was the fact, that there is always the possibility for the pilot to stop a runaway stabilizer by using the cut-off switches. Which was done only just before the second crash, but to late and they were flying too fast, so they struggled to manually correct the trim. While the accidents were certainly caused by MCAS activating in error, there was at least a chance of preventing them.
• adamjb 6y ago
  edit: I was labouring under an illusion. Comment left up as a monument to my hubris *** >The airframe with the engines mounted differently did not have adequately stable handling at high AoA to be certifiable. Boeing decided to create the MCAS system to electronically correct for the aircraft's handling deficiencies. While accurate, it omits that part of the certification Boeing were chasing was a common type rating with previous 737s on the basis of it having similar handling characteristics. MCAS did not exist because the 737 Max was unsafe, just different. The reason they were chasing fleet commonality is because it would massively reduce adoption costs for airlines by making expensive training for existing 737 pilots unnecessary.
  • dataflow 6y ago
    > MCAS did not exist because the 737 Max was unsafe, just different. You're saying the plane is "safe, just different" without MCAS? But Wikipedia says: "The MCAS flight control law was implemented on the 737 MAX to mitigate the aircraft's tendency to pitch up [...]" I'm a layman but it sure doesn't sound like safe or normal behavior for a passenger airplane to be fundamentally designed so that it "tends to pitch up"... is it? Are there other airliners that do such a thing?
    • l33tman 6y ago
      The placements of the engines affected tendencies at some pretty extreme parts of the flight envelope as far as I understood, and MCAS helped make these tendencies similar to the previous 737. I guess an analogy could be that depending on the weight distribution and drive train in your car, it will have tendencies to oversteer or understeer when you go too fast into a turn in bad weather, or something. All cars have different behaviours and tendencies in these extreme circumstances. So the 737Max would not "pitch up" in most normal flying, this is under high AoA situations, like a tight overspeed banking turn I think.
    • deleted 6y ago
      [deleted]
    • roelschroeven 6y ago
      All jet airliners have a tendency to pitch up under thrust, because of the low position of the engines. The 737 Max has a whole other issue separate from that, caused by the aerodynamic effects of the engines placed far forward of the wings. Airplanes are not allowed to pitch up more unless the pilot applies progressively more and more backward stick force. The 737 Max has a tendency in certain conditions (high angle of attack) to pitch up even when the pilot keeps applying a constant force. Some people argue that that behavior, without measures to prevent it, would disqualify the plane from certification completely. Others say that those measures are only needed to keep the Max under the same type rating as previous 737 generations. I'm inclined to the former, but I'm no expert so that's certainly not definitive.
• varispeed 6y ago
  > Investigators believe both accidents were triggered by the failure of a single sensor. It is kind of like saying that a person was raped because of wearing revealing clothes. So disgusting.
  • dang 6y ago
    "Eschew flamebait. Don't introduce flamewar topics unless you have something genuinely new to say. Avoid unrelated controversies and generic tangents." "Please don't fulminate." https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html
• jiri 6y ago
  Yeah. Problem is that it is pretty hard to fix such system problem: - Plane was bad, so they band-aided it in factory, but band-aid keeps falling off sometimes. So planes stay grounded. - Sure, they can make better band-aid but everyone knows planes are bad designed so it won't help much (even if super safe band-aid) - Correct way is to rebuild the plane to make it good, but this is/was out of the table - it was already way too expensive in the first place. And here we are.
  • frombody 6y ago
    The plane was designed with dual AoA sensors from the beginning. Boeing management made a decision to sell dual sensors as an option package, cutting the base model down to one single AoA sensor per MCAS. (there are two MCAS systems to provide redundancy) It was already built adequately, the decision to cut corners on safety to try and leverage a small profit was the problem. Dual AoA sensors as part of the standard option package and providing adequate training to pilots would have prevented all of this.
    • FabHK 6y ago
      Source? My understanding is that all MAX have dual AoA, and all MAX used only one of them for MCAS.
      • frombody 6y ago
        That's correct. One sensor per MCAS means that only one sensor is used at a time, so if it is installed incorrectly or is faulty. The faulty data is fed into the MCAS. This is what caused the crashes. The more expensive option packages included dual-AoA sensors. Two AoA sensors per MCAS, and then an AoA disagree alarm that would alert the pilot that the AoA sensors are not in agreement.
        • labawi 6y ago
          AFAIU, there are only two AoA sensor total in both cases. But you only get an AoA disagree alert, if purchase an AoA indicator. https://boeing.mediaroom.com/news-releases-statements?item=130431 https://boeing.mediaroom.com/news-releases-statements?item=1...
• tim333 6y ago
  It never was aerodynamically unstable. It was just at some point if you raised the nose further the force needed on the stick got less rather than more.
• whalesalad 6y ago
  Is there a term for this phenomenon? When a collective group is obsessed over a “problem” (mcas) which is actually just a symptom of a much larger issue (bad airframe design). I feel like this is happening more and more in our collective society. People are unable to see the forest through the trees at almost all levels: engineering, politics, etc...
  • dataflow 6y ago
    Depends on if you think it's deliberate or not. If you think it's deliberate, then scapegoating? If not, then I think it's either what you mentioned (not seeing the forest through the trees) or mass delusion...
  • craftinator 6y ago
    Mass delusional groupthink perhaps?
• FabHK 6y ago
  I think several issues are frequently conflated here. 1. Could the 737 MAX be certified without MCAS? 1b. Could the 737 MAX be certified within the existing 737 family without MCAS? 2. Could the 737 MAX be flown safely under normal circumstances without MCAS? 3. Could the 737 MAX be flown safely under exceptional circumstances by a competent pilot without MCAS? 3b. Could the 737 MAX be flown safely under exceptional circumstances by an average pilot without MCAS? (Note: By competent, I mean a hypothetical "no human errors" pilot. I don't mean to imply that the real pilots were bad or are to be blamed for the crashes; and I am fully aware that systems must be built taking into account that minor operator error will invariably happen.) As far as I can tell: 1. No, the MAX would not be certifiable without MCAS, due to the requirement that AoA not increase without stick forces increase in certain flight regimes. 1b. No, if the MAX can't be certified, it can't be grandfathered into the existing certificate. 2. Yeah, the MAX would fly perfectly fine in almost all flight regimes without MCAS. 3a. Yeah, even in exceptional flight regimes, a competent pilot could fly the MAX perfectly fine. He'd have to recognise an uncommanded AoA increase and push the stick forward. 3b. Maybe. A mediocre pilot might struggle with the MAX in certain flight regimes, due to its pitch-up tendencies. Interestingly, a competent pilot could also deal with the erroneously deployed MCAS (recognise the ran away stab trim condition, pull the circuit breaker), as Boeing explicitly assumed. > mask the reality that the plane needed a recertification due to its inadequate aerodynamics That's not accurate, I'd say. There was no "masking" going on. I think the aerodynamics are fine, largely, and MCAS was added to fulfil a certification requirement.