The next phase of the underwater search for the missing Malaysian airliner will focus on an area of the Indian Ocean hundreds of kilometres south of the first suspected crash site.
Martin Dolan, chief commissioner of the Australian Transport Safety Bureau, said yesterday an announcement would be made next week on exactly where a 60,000 square kilometre search of the ocean floor for wreckage using powerful sonar equipment would be focused.
Dolan said he expected the probable crash site would be hundreds of kilometres south of where a remote-controlled underwater drone scoured 850 square kilometres of seabed in the first fruitless search that ended last month.
That search area was defined by acoustic signals suspected to have come from the missing plane's black boxes, which promised to be the best clue to finding Malaysia Airlines flight 370.
But those acoustic signals are now widely believed to have originated from some other source.
The new search area will not be based on new data, but on refined analysis of existing satellite information from the doomed Boeing 777 after it veered off course during a flight from Kuala Lumpur to Beijing on March 8.
"All the trends of this analysis will move the search area south of where it was," Dolan said. "Just how much south is something that we're still working on."
Private contractors are expected to start the new search far off the west Australian coast in August, using powerful side-scan sonar equipment capable of probing ocean depths of seven kilometres. The job is expected to take up to 12 months to complete. Australia, which is leading the hunt given the plane is likely to have crashed in its search-and-rescue zone, said the vessel Fugro Equator, which it contracted, had begun its work mapping the ocean floor.
It will be joined by PLA navy ship Zhu Kezhen in conducting the bathymetric survey crucial to carrying out the search.
The Zhu Kezhen surveyed 4,088 square kilometres of the ocean floor before it was forced back to port for repairs.
The search area is in the vast expanse of ocean that was thoroughly swept for floating debris by search aircraft in the weeks after the plane disappeared with 239 passengers and crew aboard. Dolan said the new search area would not be as far southwest of Perth as the initial air search had been, near the limit of planes' range and in storm-prone seas.