The underwater hunt for the missing Malaysia Airlines jet will be expanded to include a massive swath of ocean floor that may take up to eight months to thoroughly search, Australia's prime minister said Monday. The U.S. Navy's Bluefin 21 robotic submarine has spent weeks scouring the initial search area for Flight 370 in the remote Indian Ocean far off Australia's west coast, but has found no trace of the missing aircraft, Prime Minister Tony Abbott said. Officials are now looking to bring in new equipment that can search a larger patch of seabed for the plane, Abbott said.