[gulikoza]

Because:

1. earlier 737 models didn't pitch up and Boeing wanted the plane to "feel" the same and not have to re-train the pilots

2. there is some certification requirement that the pitch has to be constant during climb (or something like this); if the plane doesn't have this, it is not certified to fly. It wouldn't pass FAA certification without MCAS.

[cmurf]

If MCAS is required for the plane to be airworthy, then it is not airworthy when the pilot disables it via stabilizer trim cutoff. And if the behavior of the plane is not subtly different in approach to stall, stall, or stall recovery, then the pilot might also not be type certified for the airplane with MCAS disabled.

I'm really suspicious, in a variety of ways, of cutoff switches effectively decertifying a plane in flight. And then how it's OK for pilots to not at least be made aware of that potential situation in advance?

An airplane suddenly rendered not airworthy, and pilot suddenly rendered without a proper type rating. It's absurd. I don't know how a software update gets them out of this predicament, if it's true.

Airbus fly-by-wire aircraft have numerous layers of safeguards (laws) in place. Each can be removed or degraded depending on the circumstances. But pilots are expected to know all of them, and know the consequences of each safeguard being removed, including the ensuing natural flight behavior of the airplane.

Anyway the story still isn't fully out yet.

[manfredo]

> there is some certification requirement that the pitch has to be constant during climb (or something like this); if the plane doesn't have this, it is not certified to fly. It wouldn't pass FAA certification without MCAS.

So what I gather is the issue was that the MAX didn't fit this requirement for steady pitch (hence the airframe problem referenced in the linked article), and MCAS was supposed to be the band-aid to fix this essentially by automatically pushing forward on the yoke during high angle of attack.

If that's the case then the following is especially concerning:

> Boeing offered the single angle-of-attack sensor as standard equipment, and charged extra for a second along with a “disagree” indicator that would allow 737 MAX pilots to “cross-check” a faulty sensor.

Seems pretty sketchy to ask airlines to cough up extra dough for redundancy on a safety critical system. Who knows what other systems are subject to the same cost/benefit tradeoffs.

[inferiorhuman]

Boeing offered the single angle-of-attack sensor as standard equipment, and charged extra for a second along with a “disagree” indicator that would allow 737 MAX pilots to “cross-check” a faulty sensor.

Yeah, that's factually incorrect. All 737 NG/MAX planes have two alpha vanes to detect the angle-of-attack. MCAS only ever uses one at a time.

Edit: You can see them both plainly in pictures:

https://www.planespotters.net/photo/806268/pk-lqg-lion-air-b...

https://www.jetphotos.com/photo/8686917