[randita]

Question. When a pilot leaves the cockpit, does the door automatically lock behind him/her or does it require an action from inside to lock it?

[halo66]

I believe that they lock it from within the cockpit.

[WeatherGuy]

Bigger question: Why would one pilot leave the cockpit 40 minutes into the flight?

[Leaning Right]

Question. When a pilot leaves the cockpit, does the door automatically lock behind him/her or does it require an action from inside to lock it?

I wonder if that even matters. If a terrorist were sitting near the very front of the plane, he'd be able to shove his way through that open door regardless.