In 1956, when there were few rules for flying, there was a mid-air collision of two passenger planes: a Lockheed Super Constellation on flight TWA 2 and a Douglas DC-7 on flight United Airlines 718. Both started in Los Angeles, but never reached a certain checkpoint, the Painted Desert. After colliding, the planes plummeted into the Grand Canyon. Unfortunately, nobody survived the crash. Although most parts have been already removed, there is still some debris in the area. It is forbidden to access crash site.