Originally Posted by
alanR
Member of the Flight Deck Officer Program takes his gun, shoots their fellow pilot after take off, declares and emergency and in the confusion flies plane into building - even if the rest of the crew know what's happening they can't do anything about it as the door is locked
That would involve only a single plane. I highly doubt that you would get several pilots to participate in such an event. Even in that case a gun is not needed. The CP goes to the bathroom every once in while, nothing to stop the pilot from locking them out and flying the plane in to the ground. Life involves risk.