CNN Anderson Cooper 360 April 1, 2015 00:18:00
Airplane. just stay quiet. >> reporter: the 9/11 terror attack led to reinforced cockpit doors on all commercial airplanes. the doors so strong they can resist bullets, even sh raprapnel from a hand grenade. the ax isnt either but after flight 370 mysteriously disappeared in 2014 investigators wonder if the flight might have been doomed by a crew member. some took issue with those new cockpit doors. >> one either had to be incapacitated or locked out. thats one of the concerns we had after 9/11....
Source: archive.org