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I'm not trying to excuse Boeing's shoddy implementation of MCAS, nor their hiding its existence from pilots - both of those are inexcusable in my opinion. But

I'm not trying to excuse Boeing's shoddy implementation of MCAS, nor their hiding its existence from pilots - both of those are inexcusable in my opinion. But my understanding is that when working properly, MCAS would not kick in except with angles of attack that should not be seen in normal flight conditions. It's quite likely that most pilots would never have experienced MACS in operation during their career. Having said that, the full flight envelope should be available to pilots should they need it, without it potentially biting them. Without MCAS, that's not the case with the Max.

m_mueller 8y ago
Main question for me is, why doesn't it use gyro meters for figuring out a rough approximation of AoA? So it would only kick in if gyro is above a certain boundaryb and the air speed sensor is below threshold. Then double up both the gyros and the air speed sensors, if anything disagrees give errors instead of activating. Even outside of aviation I find it incredible how naive the current design is.
acqq 8y ago
> my understanding is that when working properly, MCAS would not kick in except with angles of attack that should not be seen in normal flight conditions. Was the need for MCAS really so infrequent ("never during the pilot's career" -- are you aware how seldom it is?) the planes would simply have MCAS completely disabled and fly as we speak. That would be the full content of the Boeing's "software fix. It's obvious that MCAS has to be kept turned on as soon as no autopilot is activated. (I'd also like to know how non-redundant (i.e. max 2) faulty AoA sensors affect the autopilot, by the way -- having just read that the modern Airbuses have four of combined AoA-speed sensors). "But it's just because of the regulations" -- don't forget these regulations are there to minimize the number of crashes. And the regulations eventually in this case reduce to as simple as "the pilots have to be trained for the plane if the plane behaves differently." Which they weren't, and the latest Boeing claimed on that topic, after the two crashes was that the "one hour iPad training" will be enough(!?) And we now even know that Boeing was even allowed to do the certification process for themselves instead of FAA doing this.

m_mueller 8y ago

Main question for me is, why doesn't it use gyro meters for figuring out a rough approximation of AoA? So it would only kick in if gyro is above a certain boundaryb and the air speed sensor is below threshold. Then double up both the gyros and the air speed sensors, if anything disagrees give errors instead of activating. Even outside of aviation I find it incredible how naive the current design is.

acqq 8y ago

> my understanding is that when working properly, MCAS would not kick in except with angles of attack that should not be seen in normal flight conditions. Was the need for MCAS really so infrequent ("never during the pilot's career" -- are you aware how seldom it is?) the planes would simply have MCAS completely disabled and fly as we speak. That would be the full content of the Boeing's "software fix. It's obvious that MCAS has to be kept turned on as soon as no autopilot is activated. (I'd also like to know how non-redundant (i.e. max 2) faulty AoA sensors affect the autopilot, by the way -- having just read that the modern Airbuses have four of combined AoA-speed sensors). "But it's just because of the regulations" -- don't forget these regulations are there to minimize the number of crashes. And the regulations eventually in this case reduce to as simple as "the pilots have to be trained for the plane if the plane behaves differently." Which they weren't, and the latest Boeing claimed on that topic, after the two crashes was that the "one hour iPad training" will be enough(!?) And we now even know that Boeing was even allowed to do the certification process for themselves instead of FAA doing this.