Normal Lock News Today

Door screaming, for gods sake let me back in. here is kyung lah. >> reporter: the switch is surprisingly simple and exists in the cockpit of every single commercial plane thats flying around the world. he cannot imagine why a pilot would do this. but he knows how. a commercial retired pilot forsythe has flown thousands of hours. >> normal lock and unlock. >> reporter: he like all pilots has used the switch hundreds of time. >> to unlock you have to pull up and hold it and a light comes on saying...

Prosecutors reprogrammed the planes autopilot to crash. he changed the cruising altitude from 38,000 feet to just 100 feet. the cockpit voice recorder indicates the co-pilot locked the captain out. he then ignored screaming and pounding of the cockpit door putting the plane that steady descent and crashing it into a mountain. how was this pilot able to pull off this horrific act? >> reporter: he cannot imagine why a pilot would do this. bugs forscythe knows how. a retired military commercial pil...