>> what does this prove? >> reporter: it shows prior intent. was it a mechanical problem or they be attempt to take the airport? 30 minutes on the way to beijing it took a turn by punching a code in the auto pilot. 12 minutes before that, the copilot told the tower all right, good night. if there was a mechanical issue on board why didn't he tell air traffic control and request a new landing spot? >> we know within the first 26 minutes, they had reprogrammed the plan and were turning west far before they signed off with air traffic control. >> reporter: so bill, the last thing that is odd about that, and you can probably figure this