9 ms·

> That extra pilot, who was seated in the cockpit jumpseat, correctly diagnosed the problem and told the crew how to disable a malfunctioning flight-control sys

by gok 8y ago

> That extra pilot, who was seated in the cockpit jumpseat, correctly diagnosed the problem and told the crew how to disable a malfunctioning flight-control system and save the plane, according to two people familiar with Indonesia’s investigation. > The presence of a third pilot in the cockpit wasn’t contained in Indonesia’s National Transportation Safety Committee’s Nov. 28 report on the crash and hasn’t previously been reported. So the NTSC explicitly chose to exclude this and then two whistleblowers went to Bloomberg? That is fucking wild.

Someone1234 8y ago
It didn't need to be included in the preliminary report since it is contextual/background information. They did include in the report that on a previous flight the same sensor error occurred and the pilots resolved it by disabling auto-trim. The fact there was a third pilot there is definitely interesting, but they didn't make anyone less safe by not including it in the report. There's no bombshell here. Previous problems were well known/reported before today.
- zaphirplane 8y ago
  This is very important, as it shows the ratio of pilots aware of the mitigation is low, and/or the stress of fighting with the the computer makes you forget you training amendments Edited to add it’s a training amendment
  - arcticbull 8y ago
    It's a single data point / anecdote. These investigations are incredibly thorough, precise, and authoritative so it makes sense they'd seek to exclude that kind of information until they knew for sure.
    - hencq 8y ago
      I'm not sure that thorough and precise implies they would seek to leave out things. In fact, one would expect the opposite.
      - arcticbull 8y ago
        One data point may lead you to bad conclusions, like in this case "one third of pilots don't know how to disengage the MCAS" -- the fact is we don't know what ratio. It might be higher, it might be lower, but one data point isn't valuable or thorough. In the preliminary report they mentioned someone else disabled it. In their final, I'm sure we'll get the details.
    - tomnm 8y ago
      > It's a single data point / anecdote. A single data point is still a data point.
      - TomMarius 8y ago
        An irrelevant one in this case. This report needs to find out the technical/training/... reason, not why the other pilot needed a ride. I'm sure they'd have included it if they wanted to recommend having three pilots on every flight.
        deleted 8y ago
        [deleted]
      - yason 8y ago
        And a very relevant one, in this case: trim runaway with pilots not understanding it's a runaway. The visiting pilot does recognise the situation and restores expected flight dynamics. What went wrong, why did not two pilots realise something that is traditionally a known case and well understood? Because it didn't look like a traditional case.
  - cryptonector 8y ago
    It also shows that pilot awareness (and therefore training) should have been sufficient. The key deficiency here was Boeing's. The agency not disclosing this detail is a problem too.
    - cjbprime 8y ago
      That.. sounds like the literal opposite of what it shows, no?
      - cryptonector 8y ago
        I think you misunderstood. Had the pilots been trained, they could have dealt with it -- that the off-duty pilot was able to shows it was possible to respond correctly, while that the others weren't shows the lack of training is a real problem.
        cjbprime 8y ago
        Thanks, I see. I don't think it does much good to notice that a small percentage of pilots can be capable of figuring it out, if they have no other duties at the time. That doesn't tell us that it's reasonable to expect pilots in command under stress to always figure it out. And they have to figure it out 100% of the time to avoid statistically unacceptable crashes. So I don't agree that pilot training is an acceptable answer given what we know so far.
        cryptonector 8y ago
        Yes it does: it shows that there is a procedure that would have worked had the pilots recognized the issue and known about the procedure. The pilots were stressed in part because they didn't know -- they had plenty of time to recognize the issue and take action had they known, but they didn't, so no amount of time would have helped them. We don't know if one more thing to know about would too much, but I rather doubt that.
  - averros 8y ago
    Actual instrument-rated pilot here. What people (including pilots) do under stress is resort to simple actions drilled in by training. That's why emergency procedure training is a major part of pilot training curriculum. What goes away first under stress is capability for complex reasoning, which is what one would need to figure out what the heck is going on and take appropriate action. In this case an a/c doing uncommanded dive can be a result of three things: elevator controls malfuncion (unlikely in modern jets, the mechanisms for transmitting control forces from the yoke to the elevator are multiply redundant and well-understood to be critical), structural breakdown (empennage falling off would do that), or run-away elevator or stabilizer trim. In most a/c the runaway trim can be only caused by malfunctioning auto-pilot (that's why APs have multiple redundant ways to disable them), so the pilots faced this situation react by trying to disable AP in all available ways and then immediately jumping to conclusion that there's something catastrophically wrong with elevator system or even airframe integrity. The thought that there could be yet another system which can do major trim adjustment doesn't even enter their consciousness. Training (and/or being in a position where there's no immediate stress of wrangling misbehaving a/c) would help to get to the correct solution (disabling trim motor by pulling the circuit breaker). That said, flying an a/c seriously out of trim is hard, and can cause an accident on its own (the fine pitch control is gone, and you can even be so far out of trim that you cannot do landing flare no matter how hard you pull up, which in heavy jets would result in structural breakdown when the plane slams into runway).
    - StavrosK 8y ago
      My question is why doesn't the "omg something is seriously fucked up give me manual control NOW" button disable the MCAS as well? That seems like a UX failure.
      - dpe82 8y ago
        That's an excellent question, and will likely be one of the conclusions of the accident investigations.
      - varjag 8y ago
        Could be related to the issue that MAX is unstable in flight with that system off. Unlike previous 737s.
- gok 8y ago
  It suggests that no LionAir crews knew how to handle this.
  - Someone1234 8y ago
    US pilots say they didn't either. The training wasn't out there.
    - js2 8y ago
      The runaway stabilizer trim procedure is how it was expected to be handled: https://www.flightglobal.com/news/articles/faa-order-tells-how-737-pilots-should-arrest-runawa-453443/ https://www.flightglobal.com/news/articles/faa-order-tells-h... https://www.youtube.com/watch?v=3pPRuFHR1co https://www.youtube.com/watch?v=3pPRuFHR1co The specifics of MCAS weren't out there because Boeing expected the pre-existing procedure to have been sufficient. That procedure wasn't sufficient, or the Lion and Ethiopian Air pilots were somehow not aware of it, or they forgot their training in a stressful situation. To be clear: the planes should not have put these pilots into the situation they were in, but unless the recovery procedure doesn't work, these planes should not have crashed. [One thing I've been wondering: somehow the pilots were able to bring the nose back up... it was only (apparently) after multiple nose downs that they eventually failed to recover the plane. What was going on there? It's as if they understood how to correct the stabilizer trim, but weren't aware of the cut-off switches.]
      - Someone1234 8y ago
        Runaway stabilizer feels nothing like MCAS. They likely didn't associate the training they received with the problem at hand.
        js2 8y ago
        Can you explain how they are different? Both cause the stabilizer to tilt. Both cause the stabilizer wheels next to the pilot/co-pilot to turn. If the plane is pitching down, and you pull back the yoke and that still doesn't recover, don't you at some point check the stabilizer angle? If it's wrong, you use the stabilizer trim switch on the yoke under your thumb to correct it. Won't you see the stabilizer wheel turn when you do that? If you let go and the wheel immediately starts turning again the wrong way (pitching the plane down), doesn't that look like runaway stabilizer? Also, how did the off-duty pilot figure it out if they are nothing alike? BTW, when you write "runaway stabilizer feels nothing like MCAS" are you speaking from personal experience?
petee 8y ago
> So the NTSC explicitly chose to exclude this [...] Jeez, what a PAL...
- Crosseye_Jack 8y ago
  That pun just hertz.

by gok 8y ago

Someone1234 8y ago

It didn't need to be included in the preliminary report since it is contextual/background information. They did include in the report that on a previous flight the same sensor error occurred and the pilots resolved it by disabling auto-trim. The fact there was a third pilot there is definitely interesting, but they didn't make anyone less safe by not including it in the report. There's no bombshell here. Previous problems were well known/reported before today.

zaphirplane 8y ago
This is very important, as it shows the ratio of pilots aware of the mitigation is low, and/or the stress of fighting with the the computer makes you forget you training amendments Edited to add it’s a training amendment
- arcticbull 8y ago
  It's a single data point / anecdote. These investigations are incredibly thorough, precise, and authoritative so it makes sense they'd seek to exclude that kind of information until they knew for sure.
  - hencq 8y ago
    I'm not sure that thorough and precise implies they would seek to leave out things. In fact, one would expect the opposite.
    - arcticbull 8y ago
      One data point may lead you to bad conclusions, like in this case "one third of pilots don't know how to disengage the MCAS" -- the fact is we don't know what ratio. It might be higher, it might be lower, but one data point isn't valuable or thorough. In the preliminary report they mentioned someone else disabled it. In their final, I'm sure we'll get the details.
  - tomnm 8y ago
    > It's a single data point / anecdote. A single data point is still a data point.
    - TomMarius 8y ago
      An irrelevant one in this case. This report needs to find out the technical/training/... reason, not why the other pilot needed a ride. I'm sure they'd have included it if they wanted to recommend having three pilots on every flight.
      - deleted 8y ago
        [deleted]
    - yason 8y ago
      And a very relevant one, in this case: trim runaway with pilots not understanding it's a runaway. The visiting pilot does recognise the situation and restores expected flight dynamics. What went wrong, why did not two pilots realise something that is traditionally a known case and well understood? Because it didn't look like a traditional case.
- cryptonector 8y ago
  It also shows that pilot awareness (and therefore training) should have been sufficient. The key deficiency here was Boeing's. The agency not disclosing this detail is a problem too.
  - cjbprime 8y ago
    That.. sounds like the literal opposite of what it shows, no?
    - cryptonector 8y ago
      I think you misunderstood. Had the pilots been trained, they could have dealt with it -- that the off-duty pilot was able to shows it was possible to respond correctly, while that the others weren't shows the lack of training is a real problem.
      - cjbprime 8y ago
        Thanks, I see. I don't think it does much good to notice that a small percentage of pilots can be capable of figuring it out, if they have no other duties at the time. That doesn't tell us that it's reasonable to expect pilots in command under stress to always figure it out. And they have to figure it out 100% of the time to avoid statistically unacceptable crashes. So I don't agree that pilot training is an acceptable answer given what we know so far.
        cryptonector 8y ago
        Yes it does: it shows that there is a procedure that would have worked had the pilots recognized the issue and known about the procedure. The pilots were stressed in part because they didn't know -- they had plenty of time to recognize the issue and take action had they known, but they didn't, so no amount of time would have helped them. We don't know if one more thing to know about would too much, but I rather doubt that.
- averros 8y ago
  Actual instrument-rated pilot here. What people (including pilots) do under stress is resort to simple actions drilled in by training. That's why emergency procedure training is a major part of pilot training curriculum. What goes away first under stress is capability for complex reasoning, which is what one would need to figure out what the heck is going on and take appropriate action. In this case an a/c doing uncommanded dive can be a result of three things: elevator controls malfuncion (unlikely in modern jets, the mechanisms for transmitting control forces from the yoke to the elevator are multiply redundant and well-understood to be critical), structural breakdown (empennage falling off would do that), or run-away elevator or stabilizer trim. In most a/c the runaway trim can be only caused by malfunctioning auto-pilot (that's why APs have multiple redundant ways to disable them), so the pilots faced this situation react by trying to disable AP in all available ways and then immediately jumping to conclusion that there's something catastrophically wrong with elevator system or even airframe integrity. The thought that there could be yet another system which can do major trim adjustment doesn't even enter their consciousness. Training (and/or being in a position where there's no immediate stress of wrangling misbehaving a/c) would help to get to the correct solution (disabling trim motor by pulling the circuit breaker). That said, flying an a/c seriously out of trim is hard, and can cause an accident on its own (the fine pitch control is gone, and you can even be so far out of trim that you cannot do landing flare no matter how hard you pull up, which in heavy jets would result in structural breakdown when the plane slams into runway).
  - StavrosK 8y ago
    My question is why doesn't the "omg something is seriously fucked up give me manual control NOW" button disable the MCAS as well? That seems like a UX failure.
    - dpe82 8y ago
      That's an excellent question, and will likely be one of the conclusions of the accident investigations.
    - varjag 8y ago
      Could be related to the issue that MAX is unstable in flight with that system off. Unlike previous 737s.
gok 8y ago
It suggests that no LionAir crews knew how to handle this.
- Someone1234 8y ago
  US pilots say they didn't either. The training wasn't out there.
  - js2 8y ago
    The runaway stabilizer trim procedure is how it was expected to be handled: https://www.flightglobal.com/news/articles/faa-order-tells-how-737-pilots-should-arrest-runawa-453443/ https://www.flightglobal.com/news/articles/faa-order-tells-h... https://www.youtube.com/watch?v=3pPRuFHR1co https://www.youtube.com/watch?v=3pPRuFHR1co The specifics of MCAS weren't out there because Boeing expected the pre-existing procedure to have been sufficient. That procedure wasn't sufficient, or the Lion and Ethiopian Air pilots were somehow not aware of it, or they forgot their training in a stressful situation. To be clear: the planes should not have put these pilots into the situation they were in, but unless the recovery procedure doesn't work, these planes should not have crashed. [One thing I've been wondering: somehow the pilots were able to bring the nose back up... it was only (apparently) after multiple nose downs that they eventually failed to recover the plane. What was going on there? It's as if they understood how to correct the stabilizer trim, but weren't aware of the cut-off switches.]
    - Someone1234 8y ago
      Runaway stabilizer feels nothing like MCAS. They likely didn't associate the training they received with the problem at hand.
      - js2 8y ago
        Can you explain how they are different? Both cause the stabilizer to tilt. Both cause the stabilizer wheels next to the pilot/co-pilot to turn. If the plane is pitching down, and you pull back the yoke and that still doesn't recover, don't you at some point check the stabilizer angle? If it's wrong, you use the stabilizer trim switch on the yoke under your thumb to correct it. Won't you see the stabilizer wheel turn when you do that? If you let go and the wheel immediately starts turning again the wrong way (pitching the plane down), doesn't that look like runaway stabilizer? Also, how did the off-duty pilot figure it out if they are nothing alike? BTW, when you write "runaway stabilizer feels nothing like MCAS" are you speaking from personal experience?

petee 8y ago

> So the NTSC explicitly chose to exclude this [...] Jeez, what a PAL...

Crosseye_Jack 8y ago
That pun just hertz.