Originally Posted by
Hunter58
A better way, IMHO would be to have an override key in the cockpit that the person wanting to take a personal break takes with him/her and therefore can get into the cockpit any time.
That would be equally flawed.
The door has no way of knowing whether the key is being used by the crew member or by a terrorist who has gained possession of it by duress. And if it's the latter, you have taken away the ability of the cockpit occupant(s) to deny access.