Airworthiness Requirements and Means of Compliance for Flightdeck Installed Physical Secondary Barriers on Transport Category Airplanes

Flightdeck protection is of great significance for ensuring the flight safety of transport aircraft. In June 2023, the FAA issued Amendment 25–150 and Amendment 121–389, requiring that transport aircraft operated under Part 121 must be equipped with a second physical barrier to prevent unauthorized access to the flightdeck when the flightdeck door is open. Firstly, the airworthiness requirements and acceptable compliance methods for installing the second physical barrier in the flightdeck of transport aircraft were studied through the analysis of the amendments and Advisory Circular, secondly, the design requirements of the second physical barrier are summarized, and finally the impact of this amendment on China's relevant airworthiness regulations for transport category aircraft and the development of domes-tic passenger aircraft was analyzed, providing a reference for the design and certification of civ-il aircraft.