f9 wrote:
... There should be some rule which does not allow pilots to lock each other out (e.g. the door is open-able from outside when locked with a spare key). Otherwise there is no way to avoid suicides like this … (same would be helpful to avoid terrorist-pilots too)
Cockpit doors have three modes: (1) Unlocked; (2) Locked, but unlockable; and (3) 911 Lockdown.
That last mode is induced by a person in the cockpit to prevent terrorists from getting in. It is essentially the same as throwing a deadbolt or a bar across the door.
Once you compromise the 911 lockdown mode, you've made it possible for terrorists to enter the cockpit. Keys can be stolen. Cypher locks can be bypassed. Passwords can be forgotten.
We've made planes safer from terrorists posing as passengers and taking over. Now we have to make the
pilots safer, and prevent them from deviating from the flight plan.