Abstract: The present invention is directed to increasing ight deck security in support of, and in conjunction with, the new FAA mandated bullet-proof cockpit door. This is accomplished by the Crupax Flight Deck Security System (FDSS), which provides a lightweight, flexible, mechanically strong isolation curtain which is mounted in the aircraft cabin at a predetermined distance from the cockpit door to act as a physical barrier that cannot be penetrated by unauthorized persons while the cockpit door is unlocked. The curtain forms a secure zone at the cockpit door whereby a person wanting to gain entry to the flight deck will stand so that the pilot can positively identify the person as bona fide aircrew member or as a person known to him/her. The pilot will also determine that the person is alone in the secure zone. The pilots have full control of the system, and must approve each entry or exit operation.