 Two seconds later, they were about 625 feet apart vertically, but the Delta flight had started a right turn away from American 5511 and potential disaster. When the two planes reached the same altitude about 16 seconds later, possibly the moment seen in this video, they were actually a mile apart. That's not a good situation. Airplanes should be spaced a certain interval apart. They lost it. Former NTSB Chair Robert Sumwalt.