[the_af]

I actually thought something similar while typing my first reply. What if they gave pilots some sort of busywork to keep them engaged? But I guess it wouldn't work; as soon as you identify something as busywork, you stop giving it your full attention.

[eru]

In trains they have busywork to test your attention. (I rode a simulator once, it's like a flight simulator but for locomotives.)

There's a deadman pedal that you need to keep pressed to keep the train moving. Once every half a minute, you need to lift your feet of the pedal. If you fail, the train will soon break and come to a halt.