Originally Posted by
the810
They will use the entry code. The way I understand it - please correct me if I'm wrong - cockpit can be opened from outside using a code. Person inside the cockpit then has a few seconds to override the entry (i.e. lock themselves in; this is what Lubitz did), otherwise the door will open.
IIRC, after the code has been entered outside, someone in the cockpit has to “approve” it for the person to enter (so there is no few seconds to override the entry as this would be a big flaw in the system).