"We think we may extend that area farther south; that's the thing we're currently considering," Mr Dolan said.
The new analysis data comes from two calls Malaysia Airlines staff tried to make to the flight's crew after MH370 was reported missing from radar screens.
Mr Dolan said the new analysis suggested the jet was already flying south when the first phone call was attempted, less than 20 minutes after the plane dropped off military radar.
"Previously, there was the possibility that it could have been quite a bit later, so we had to do our modelling based on a range of possibilities as to where the aircraft turned," Mr Dolan said.
In three weeks, the Dutch contractor Fugro Survey Pty Ltd will begin the operation with three vessels towing underwater vehicles equipped with side-scan sonar, multi-beam echo sounders and video equipment, Mr Truss said.
Malaysia, as the country where the Boeing 777 was flagged, has overall responsibility for the crash investigation. But Australia has search and rescue responsibility, and China - the country of origin for most of the passengers - said today that it too agreed the search will "not be interrupted or given up".