Based on the latest news relating to the Germanwings crash, it appears one of the pilots was locked out of the cockpit. http://www.bbc.co.uk/news/world-europe-32062278 Whether it was deliberate by the pilot who remained in the cockpit, or that pilot suffered some sort of problem which prevented them opening the door again to let the other pilot back in, it's clear that procedures will have to change. Currently when a pilot leaves the cockpit, the remaining pilot locks the door. When the pilot returns, the pilot inside unlocks the door. There is no way the pilot locked out can gain access otherwise. In this case the pilot who was locked out was unable to break in after almost eight minutes of trying. This was a disaster always waiting to happen since the rules were changed after the terrorist attacks in the US.