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Comment by 3JPLW | Hacker News Reader

I completely agree.

Here's the deal, though: this wasn't just one crash. It was two. The failure mode of the second was indeed different than the first: it was a failure of Boeing and the aviation authorities to appropriately respond to the first disaster.

To propose that pilots should have willy-nilly flipped MCAS on and off based on your reading of the news is just staggering. What if there was another bug where turning on MCAS when there was an AoA disagree led to an instant plunge, regardless of etrim inputs? I'd bet you'd be critiquing those dead pilots for not following the checklist — and keeping MCAS off — in such a case.

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Turning it back on is indeed what the EA pilots did after being unable to use the manual trim, if I read the account correctly, the MCAS re-engaged and caused the final plunge. That wasn't on the checklist. But if they'd also engaged the manual trim switches, it would have corrected the nose down.

It's not willy-nilly nor staggering. The EAD (referenced in another post here) indeed talks about using the electric trim to fix the nose down problem, and then cutting off power to the system.

Yes, indeed. It doesn't talk about turning STAB TRIM back on, though, nor does it talk about turning STAB TRIM on with etrim inputs already applied — that's what I was calling your homegrown protocol.

My point is that it's easy to armchair quarterback the pilots whether they followed the checklist or went off checklist to do something better or worse. The problem started long before they got in the cockpit, though, and had been made evident once before at the cost of 189 lives. To continue to focus on pilots' actions at this point is missing the elephant for the flea.

> It doesn't talk about turning STAB TRIM back on, though, nor does it talk about turning STAB TRIM on with etrim inputs already applied — that's what I was calling your homegrown protocol.

The EA pilots already had gone off the checklist when they turned the stab trim back on.

I think one piece of information you’re missing is that they also had cockpit warnings that the sensors were malfunctioning, and the pilot side controls were stuck on stick-shake the whole ride.

So add in the part where you can’t actually trust what your instruments are telling you, and the plane is flying like a demon has possessed it.

In the moment you are wondering, is the plane stalling? Is my airspeed actually what is being displayed? Why is trim not responding? My heart is beating 200bpm. Is that whooshing the blood in my ears or the wind?

The answers to these questions is obvious in hindsight. In that moment the flight had entered mortal peril. The question is not why didn’t the pilots recover from mortal peril with perfect hindsight. The question is how did this flight get into mortal peril in the first place?

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