This question already has an answer here:
Is there anything a copilot in a commercial aircraft can do to stop a pilot from doing anything while flying?
As I see it, there are two scenarios:
- The pilot is going to do something malicious, in which case the copilot could physically try to restrain or disable the pilot.
- It's not malicious, but just something that is a bad idea (say could get the pilot fired or in legal trouble). In my imagination, this could be something like a dangerous like a fly-by.
This question is a different from this one, since the scenario in that question is when the pilots are cooperating but have some misunderstanding on when command is transferred to one from the other, or if one doesn't accept to receive command of the aircraft.