"The captain had a code to unlock the door, but the lock's code panel could be disabled from the cockpit controls...The captain then tried to break down the door, but like most cockpit doors made after the September 11 attacks, it had been reinforced to prevent intrusion."
> Robin said that when the captain left the cockpit, possibly to use the toilet, Lubitz locked the door, preventing anyone from entering. The captain had a code to unlock the door, but the lock's code panel could be disabled from the cockpit controls. The captain requested re-entry using the intercom; he knocked and then banged on the door, but received no response. The captain then tried to break down the door, but like most cockpit doors made after the September 11 attacks, it had been reinforced to prevent intrusion.
This seems like a pretty direct consequence to me. Similar to how an ultra isloated air-gapped environment with only one-way networking[0] would mean that the ops people couldn't easily stop e.g an ransomware attack in its tracks when detected. It's a cost/consequence of having the isolated network in the first place.
(If there was some magic code that always opened the cockpit door, then that could be coerced out of someone, yielding the system almost pointless)
EDIT post downvotes: what I mean is that even without a lock on the cockpit to prevent their copilot from entering, it seems difficult to prevent a determined pilot from crashing a plane.