Yet another setback in the search for Flight 370: The first undersea mission to search for the Malaysia Airlines jet, scheduled to last 16 hours, was cut short after the Bluefin-21 underwater drone exceeded its 2.8-mile operating limit, authorities say. The drone collected around six hours of footage yesterday, which did not provide any clues, Reuters reports. Its sonar search is concentrating on a zone of around 230 square miles of Indian Ocean seabed, and authorities say it could take months to scan the entire area.