Last month, an American Airlines passenger jet and an Army helicopter collided as the plane prepared to land at Washington D

The National Transportation Safety Board provided an update on Friday into the investigation of the deadly Army Black Hawk helicopter and American Airlines flight collision.

LIVE: Watch the NTSB press conference in the video player above. The collision was the deadliest plane crash in the U.S. since 2001, when a jet slammed into a New York City neighborhood just after takeoff,