[gnaffle]

> Air France 440 was also shrouded in mystery (but nowhere near this degree), and turned out to be very poor airmanship by one pilot.

It was poor airmanship by two pilots (and other factors, including the feedback mechanisms and the lack of training for this particular high altitude scenario).

[encoderer]

My understanding is that the pilot in the left chair didn't realize that the pilot in the right chair kept pulling his stick back. In boeing planes, the sticks move together, so that wouldn't be possible. And the pilot in the right chair clearly didn't understand that in the alternate law the fly by wire system was running in, his stick movements put the plane at risk.

[mikeash]

Yes, it was a completely incorrect reaction by a single pilot, combined with a catastrophically bad design for the controls, which caused that crash. It is completely insane to me that anyone would think that averaging inputs from two pilots and providing no feedback would be even remotely a good idea.

[radiowave]

The aircraft does provide feedback, it says, "DUAL INPUT, DUAL INPUT". IIRC this can be heard on the cockpit voice recorder of Air France 447.

[mikeash]

I mean physical feedback. In any rationally designed aircraft, the controls are physically linked, such that moving one moves the other (or at the very least this arrangement is faked with servos). When two pilots attempt to give contradictory inputs, they immediately know it because they can feel the other one fighting.

[engi_nerd]

Yes, in the Air France tragedy, the aural warning clearly wasn't enough. Through fear and panic, the pilots failed to understand what the plane was telling them. But the feeling of having a control yoke fight against you doesn't require much mental effort to process.

[mikeash]

Aural warnings are so easy to ignore. There are a ton of stories that go like, "What is that annoying buzzing sound? Well, no time to worry about it now, I'm landing. <CRUNCH> Oh, it was the gear warning." Happened to a friend of mine, even.

I think it ultimately comes down to engaging with the primary sense you're already using. If you're doing something visual, then a visual warning (on whatever you're looking at) can be effective, while an aural warning won't. If you're listening to something then interrupting it with an audio warning will work great. Hand flying is a tactile experience, so that's the sense you want to work with.

[gnaffle]

That's correct (even though he did mention "watch the height" and could have followed up on that). If I remember correctly, even the left chair pilot also applied nose-up inputs at some point in time.

[rogerbinns]

Well we could go into the whole 'swiss cheese' theory of accidents, and include a long list of causes. https://en.wikipedia.org/wiki/Swiss_cheese_model