Re:Boeing Was ‘Go, Go, Go’ to Beat Airbus with the 737 Max
by cjbprime on Saturday March 23, 2019 @11:57PM
(#19474202)
It's more literally "just one sensor" than you say, I think. MCAS doesn't average or anything: it just picks one sensor at a time arbitrarily and uses it. (This will change in next month's software fix.)
(2) sounds like it could be airworthy, but I think Boeing might instead find that it has to add that third sensor. Airbus has three, and any rationale that Boeing only needs two because the disagreement consequences are not severe seems atop quicksand at this point.
Re:Boeing Was ‘Go, Go, Go’ to Beat Airbus with the 737 Max
by Animats on Saturday March 23, 2019 @11:06PM
(#19473954)
That's what really amazes me. Especially since AoA vanes are known to be troublesome.[1] In most aircraft they just trigger the stall warning horn and stick shaker; they don't directly affect aircraft control.
[1] https://mooneyspace.com/topic/19801-stall-warningaoa-failure...
Re:Boeing Was ‘Go, Go, Go’ to Beat Airbus with the 737 Max
by cjbprime on Saturday March 23, 2019 @11:58PM
(#19474204)
I think Airbus will disable the autopilot in case of AoA sensor failure, which is why it has three of them instead of two.
Re:Boeing Was ‘Go, Go, Go’ to Beat Airbus with the 737 Max
by D_Alex on Sunday March 24, 2019 @12:40AM
(#19474357)
Option (4): input from other sensors (altitude, climb rate, gyroscope/artificial horizon, pilot actions etc) for a sense check...?
Re:Boeing Was ‘Go, Go, Go’ to Beat Airbus with the 737 Max
by arcticbull on Sunday March 24, 2019 @01:21AM
(#19474514)
My gut tells me aerospace errs on the side of simplicity and reproducibility. It could work, though ideally system errors wouldn’t interfere with other systems.
Re:Boeing Was ‘Go, Go, Go’ to Beat Airbus with the 737 Max
by 7952 on Sunday March 24, 2019 @07:12AM
(#19475670)
And the engine stats should be a good source of data.
Re:Boeing Was ‘Go, Go, Go’ to Beat Airbus with the 737 Max
by 7952 on Sunday March 24, 2019 @07:09AM
(#19475659)
It is worth pointing out that an AOA sensor should not be critical for normal flight. If a sensor is faulty then why not simply stop using angle of attack as a data point. It should still be perfectly possible to fly safely and using a configuration that will avoid a stall. Pilots should be able to fly on a minimum set of instruments.
(1) 3 sensors plus majority voter.
(2) A mandatory AoA disagree indication plus some training on how to react to it.
They chose option (3): Neither. Frankly when I heard there were just two sensors and no disagree indication, my first thought was well that’s just as good as one sensor and hoping for the best, isn’t it? The “challenger moment” would have been after the meeting they decided on this.