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0 pointslosvedir7y ago0 comments

> MCAS will trim in increments of 10s. So it will trim, pause, trim some more, pause.

No, not quite. By itself MCAS will only trim once, I believe.

But if it's interrupted by a pilot manually trimming, then it will stop, wait 5 seconds, and then try to do its 10 second trim again.

The characteristic up-down pattern from the Lion Air flight I think was from the latter scenario of MCAS starting to trim, the pilot manually trimming back (disabling MCAS for 5 seconds) and then it activating again.

> Yes. MAX 8 has two AOA sensors.

But I think the MCAS system only gets its input from one! (And it switches each flight.) If true, that's just appallingly bad.

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linuxftw7y ago

> No, not quite. By itself MCAS will only trim once, I believe.

Unfortunately, we don't know this is actually true. Certainly, it's what Boeing wants us to believe, that their software is perfect in this regard. Might be completely broken. Where's the independent verification. And, allegedly, it's only supposed to trim just a little bit at each increment. If you look at the accounts, there are roller coaster-like drops. Seems to me it started nosing down really hard.

outworlder7y ago

> No, not quite. By itself MCAS will only trim once, I believe.

Under normal operation, that seems to be the case. But note that we are operating with the assumption that the AoA sensor is faulty. So it may still think the plane is in a bad attitude.

> But I think the MCAS system only gets its input from one! (And it switches each flight.) If true, that's just appallingly bad.

As far as public information goes, that's correct.

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