Originally Posted by
Capn Rex Havoc
Very hard for a pilot to deny entry to
his companion if the cabin crew is at the door and can open it in a second if the
sole pilot at the seat starts to get out of his seat.
And what happens if the cabin crew grabs the fire axe and kills the remaining pilot, then flies the plane into a nuclear plant's spent fuel pool?
The door itself is the cause of the problem - because it introduces a single point of failure in the pointy end of the plane. One rogue crew member is all it takes to commandeer a plane.
Even on 9/11, there was a chance to correct the situation - passengers could have fought the hijackers, and on UA93, they at least prevented deaths on the ground. In fact the only reason why it happened was that obeying hijackers was the standard practice back then.
With the new cockpit door, you have no such chance. And it is not impossible for a motivated terrorist to become a pilot or an FA - the 9/11 hijackers were not dumb either.