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Comment by nradov | Hacker News Reader

Mechanically joined flight controls typically have a linkage designed to break when sufficient force is applied. This can cause equally disastrous results when the two pilots are putting in different control inputs.

https://www.aopa.org/news-and-media/all-news/2000/february/p...

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My dad taught instrument flying in fighter jets. He'd ride in the back seat, with the student in the front. The controls were linked together.

Against regulations, he carried with him a length of steel pipe. The problem was sometimes a student would freeze and hang onto the controls with all his might. The pipe was so my dad could beat him on the head until he let go, and save both their lives.

Fortunately, he was never forced to do this. But he said "I'll be damned if I let any student kill me!"

P.S. the thing about instrument flying is your senses lie to you, and you need to rely on the instruments. A green student is at risk of panicking and believing the lies his inner ear is telling him (spacial disorientation). When JFK jr crashed in the mist at sunset, my dad passed by the TV when they reported it, and said "spacial disorientation". It's killed a lot of pilots.

A major part of learning to fly instrument is to learn to ignore your body screaming at you that you're flying upside down.

And the reason they have this, is so that pilots can overcome a jam by breaking that linkage. Only half the plane will then be responding to the controls, but that's much better than none.

The rationale for this (I did some work on this system at Boeing) was that the pilots would not be fighting each other for control, they would be fighting a jam.

Flight controls at the time were not designed for dealing with a crazy or malicious pilot.

A stick to the head is the classic solution for a pilot going crazy on controls for whatever reasons. Sometimes the stick is not metaphorical.

Interestingly, when this happens on the 777 (and I guess the 787), the inputs are averaged, like on an Airbus.

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