"A locked cockpit door, installed to keep out terrorists, kept...

"A locked cockpit door, installed to keep out terrorists, kept out the second pilot. "

The guys at PPRune say a locked out pilot can gain entry UNLESS the pilot in the cockpit resists his entry.....

However there is a precedent on a Delta airlines flight where the door malfunctioned and the Co-pilot had to make an emergency landing without the Captain in the cockpit....

GZ