MH370: BBC shown 'distinct search areas'
15 March 2014 Last updated at 10:04 GMT
The communications systems of missing Malaysia Airlines flight MH370 were deliberately disabled, Malaysia's Prime Minister Najib Razak has said.
According to satellite and radar evidence, he said, the plane then changed course and could have continued flying for a further seven hours.
The BBC's Jonah Fisher explains that there are specific search areas in which authorities are looking for the plane.