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>First, we know that any decision that forces passengers from flying to driving will likely lose more lives, just due to the inherit risk in flying vs driving.

>First, we know that any decision that forces passengers from flying to driving will likely lose more lives, just due to the inherit risk in flying vs driving. So it's possible that grounding the plane will cause cancellations and force some passengers into driving, especially in the US. Well air travel is safer than driving in aggregate, over decades, across hundreds of models of cars and dozens of models of planes. Even though Ford cars on the whole are quite safe, the Pinto was a death trap. Likewise although Boeing planes are safe on the whole (the regular 737 is very safe) this model could be a death trap. I disagree with your claim here. Two crashes in under 6 months is an abysmal safety record.

js2 8y ago
Right, that's an example of Simpson's paradox (I think). I agree two crashes in six months seems abysmal, but it could also be an awful coincidence with different factors at play. If it's so obvious that Boeing should ground this plane and they aren't, might it be due to something we don't know? Yes, this could be another Challenger-type situation of executives overriding engineers, but the incentives don't make sense to me for that to be the case. Anyway, I've played devil's advocate enough here. I'm just trying to understand the situation too.
- bdamm 8y ago
  Another possibility is that the 737 MAX 8 is, just like the rest of the 737 fleet, an outstanding performer with one flawed subsystem, the AoA sensor. The FAA and the aviation industry in general has been very excited to deploy these AoA sensors; they've reduced regulatory hurdles across the board to get AoA sensors of all different types installed and retrofitted into airplanes of all sizes and shapes. The reworked part 23 rules were first put to work on AoA sensors, and the expansion of AoA deployment was part of the drive to do the part 23 rework (which has ripple effects across the entire industry, for the better.) But when you push new technology, inevitably there will be unexpected failure scenarios. This may be one of those, with a particularly catastrophic series of events. It is a simple fix, and Boeing is already rolling out software updates to manage this failure scenario. If it does turn out to be the MCAS/AoA fault, it would in fact be the best scenario, because it's already fixed.
  - js2 8y ago
    Thanks for the info. I guess the question for me is: even with a bad AoA sensor and the current MCAS behavior, can it be safer flying a 737 Max than whatever equipment I'd end up on if the 737 Max were grounded until the s/w update is deployed. I seem to recall after the MCAS came to light as being involved in the Lion crash, some folks here were arguing that there was no way that exact crash would happen again because all pilots would now be aware of that failure scenario. And yet here we are. Unless the Ethiopian plane crashed for another reason entirely.
    - bdamm 8y ago
      Well yes, although it's possible the Ethiopian Air pilots haven't seen that memo. If I recall correctly, a fast remediation suggestion was to switch off all avionics power. As a pilot myself, I would be deeply reluctant to do such a drastic move, especially in an emergency. With the airplane in an overpowering dive, removing all instrumentation in one kill switch move just doesn't seem like the right thing to do. While I don't know the 737 MAX 8 electrical layout, in small planes that would also kill the radios, transponder, and navigation systems, possibly also flap controls, lighting, and some direct instrumentation. Such direction would have to be very strongly communicated if it were a viable escape from the MCAS/AoA failure.

js2 8y ago

Right, that's an example of Simpson's paradox (I think). I agree two crashes in six months seems abysmal, but it could also be an awful coincidence with different factors at play. If it's so obvious that Boeing should ground this plane and they aren't, might it be due to something we don't know? Yes, this could be another Challenger-type situation of executives overriding engineers, but the incentives don't make sense to me for that to be the case. Anyway, I've played devil's advocate enough here. I'm just trying to understand the situation too.

bdamm 8y ago
Another possibility is that the 737 MAX 8 is, just like the rest of the 737 fleet, an outstanding performer with one flawed subsystem, the AoA sensor. The FAA and the aviation industry in general has been very excited to deploy these AoA sensors; they've reduced regulatory hurdles across the board to get AoA sensors of all different types installed and retrofitted into airplanes of all sizes and shapes. The reworked part 23 rules were first put to work on AoA sensors, and the expansion of AoA deployment was part of the drive to do the part 23 rework (which has ripple effects across the entire industry, for the better.) But when you push new technology, inevitably there will be unexpected failure scenarios. This may be one of those, with a particularly catastrophic series of events. It is a simple fix, and Boeing is already rolling out software updates to manage this failure scenario. If it does turn out to be the MCAS/AoA fault, it would in fact be the best scenario, because it's already fixed.
- js2 8y ago
  Thanks for the info. I guess the question for me is: even with a bad AoA sensor and the current MCAS behavior, can it be safer flying a 737 Max than whatever equipment I'd end up on if the 737 Max were grounded until the s/w update is deployed. I seem to recall after the MCAS came to light as being involved in the Lion crash, some folks here were arguing that there was no way that exact crash would happen again because all pilots would now be aware of that failure scenario. And yet here we are. Unless the Ethiopian plane crashed for another reason entirely.
  - bdamm 8y ago
    Well yes, although it's possible the Ethiopian Air pilots haven't seen that memo. If I recall correctly, a fast remediation suggestion was to switch off all avionics power. As a pilot myself, I would be deeply reluctant to do such a drastic move, especially in an emergency. With the airplane in an overpowering dive, removing all instrumentation in one kill switch move just doesn't seem like the right thing to do. While I don't know the 737 MAX 8 electrical layout, in small planes that would also kill the radios, transponder, and navigation systems, possibly also flap controls, lighting, and some direct instrumentation. Such direction would have to be very strongly communicated if it were a viable escape from the MCAS/AoA failure.