that, not to jump to that conclusion. sometimes pilots are fighting just amazing battles and hear about it. >> investigators in the u.s. as they have done in the past point out details to support their theorys. the latest is that the sharp turn to the west was preprogrammed into the plane's navigation, even before the co-pilot told control all right, good night. but that isn't evidence of foul play. the pilot could have done it protectively in the event of an emergency. theories based on hijacking have also fallen short. thus far, no one onboard flight 370 has been linked to any known terror group. background checks cleared all 153 of china's citizens. a malaysia officials have repeatedly stressed, in order to have the evidence, they must find the plane. >> the entire search area is now 2.24 million square nautical miles.