When we first heard this crash was due to a change in computer-controlled stabilizer behaviour, my question was "why on earth did Boeing do this?". Perhaps I didn't read deep enough, but the summary explanation that it was to improve handling was a poor answer.

I guess what really bugged me about it is how un-Boeing-like this behaviour was; a computer overriding a pilot (even if there is a way for a pilot to override it in turn). It's fundamentally an Airbus-esque design.

As I read this article though, everything fell into place. As you read it you start to see, with utter clarity, exactly how this happened organizationally.

It's well known that Airbus uses software flight envelope protection to enable them to reduce the safety margin applied to the airframe, reducing weight. In other words, fuel efficiency is improved by making airframes less airworthy and compensating for it in software. I don't actually disagree with this as such; it's been demonstrated to be a sound approach, but historically Airbus's domain.

Essentially, it seems like what happened here is that Boeing finally felt the need to adopt similar techniques to compete with Airbus on fuel efficiency (though regarding engine size issues, not airframe safety margins, but still making a plane's airworthiness more caveated and fixing it in software). Essentially, we're witnessing the point at which Boeing feels its traditional user interface philosophy (do what the pilot says) is conflicting with market pressures.

If this were a new plane with a new type rating, this wouldn't be unreasonable. Trying to tack this on to an existing plane, and not only that, but doing everything in your power to minimise the amount of transition training, is OTOH extraordinarily egregious.

The problem with this change isn't so much that Boeing's reasoning for not telling pilots about it isn't logical. If anything, the problem is that their reasoning is utterly logical: the checklist will solve the problem anyway, no matter the cause. You can see how this decision must have percolated through different teams at Boeing, through regulators, via this unimpeachable-seeming logic. The market pressures involved (fuel efficiency and retraining costs) would have made it particularly hard to contest. It's a completely logical line of reasoning... yet here we are with fatalities.

I'm very interested to note, though, this new revelation (to me at least) that the yoke behaviour re: extreme deflection mitigating stabilizer runaway was removed in the MAX. So what was Boeing's justification for this change? Was it even mentioned? If not, what on earth were the regulator's justifications for allowing it to go unmentioned? I want to hear those justifications, since it seems impossible to justify. I was under the impression that compatibility of type ratings fundamentally revolved around an absence of differences in how two planes handle, and how they respond to the yoke.

I should add, the reliance on a single sensor is also remarkable; makes me wonder if this entire subsystem was really rushed and not given proper design review, which would make sense given the circumstances (panicking to get a product to market).