[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.

[PhantomGremlin]

Aural warnings are so easy to ignore.

Yes. You give an example of someone ignoring a single aural warning. The case of AF447 was much worse.

There was a cacophony of different sounds and noises in the cockpit of AF447. All the various alarms are deliberately made to sound different. But when someone knows he's a minute from death, there's no way his reptilian brain can make sense of a plethora of simultaneous alarms. It will, instead, strive to tune them all out.

I remember a documentary where Duke Cunningham discussed his experiences as a fighter ace in Vietnam. In high stress situations he would switch his intercom to allow him to speak to his RIO, but not be able to hear his RIO. He didn't want the distraction. (Note: sadly, Cunningham disgraced himself in later life).

[engi_nerd]

I agree with you completely.

Also,

> Hand flying is a tactile experience, so that's the sense you want to work with.

is the primary reason why Boeing still uses yokes instead of sidesticks.

[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.