The assumption is that if a crew member (pilot) wishes to suicide and take passengers lives as well, that placing a cabin crew member with the remaining pilot will solve the problem.
What seems to have been overlooked is that the cabin crew member is even more probable to have the same suicidal/homicidal intent. They have been subject to less screening and observation in all respects. You are now placing them behind the remaining pilot and within reach of controls in a locked room.
The problem has merely been moved sideways.
Furthermore, with cabin crew outnumbering pilots by up to 10 to 1 on some aircraft, the probability of a terrorist 'plant' within the cabin crew possibly increases the overall odds that the alone pilot is a safer option.
Last edited by RifRaf3; 30th Mar 2015 at 23:09.