In late March 2015 many national aviation authorities and/or airlines made the cockpits of aircraft in flight mandatory " two-man " or " no-lone zones " as a result of the Germanwings Flight 9525 crash . Early on in the investigation of that crash , it was believed from the cockpit voice recorder audio , and later supported by flight data recorder information , that the co-pilot deliberately crashed the aircraft after locking the cockpit door when the captain left to use the toilet
Germanwings Flight 9525
Germanwings Flight 9525
Two-man rule