Assuming the hijackers weren't already in the cockpit. It seems to me that the most likely people taking control of the plane in the situation stipulated were the people already in control of the plane when it left the ground.
The majority of hijackings have the original pilot at the controls under duress. In 9/11, it was unusual that the hijackers had done flight training and piloted the planes. That was because the pilots wouldn't have done what those hijackers wanted.