mad8 writes:

does anybody know where the regulation is? i can't find it in the FAR
but then again, i'm not anywhere near an expert

There isn't any. It's the _absence_ of a specific prohibition that
makes it legal. There has to be a licensed pilot in command on board
the aircraft, who takes responsibility for operation of that aircraft,
but nothing in the regulations requires him or her to actually be at
the controls ... which means that it is legal for anyone to control
the plane.

I believe it is indeed inherited from maritime law, wherein the
captain of a vessel is master and commander of that vessel with very
broad authority.

Note that refusing to obey the commands of the pilot in command would
be mutiny. So if the PIC tells a passenger to give up the controls
and the latter refuses to do so, it's a felony.

--
Transpose mxsmanic and gmail to reach me by e-mail.