Experts will re-examine all data gathered in the hunt for the missing Malaysia jet to ensure search crews are looking in the right place.
Senior officials from Malaysia, Australia and China met to work out the details of the next steps in the search for Malaysia Airlines Flight 370.
They will target an expanded patch of seabed in a remote area of the Indian Ocean off Western Australia.
The area became the focus of the hunt after a team of analysts calculated the plane's likeliest flight path based on satellite and radar data.
Starting on Wednesday, that data will be re-analysed and combined with all information gathered so far in the search, which has not turned up a single piece of debris despite crews scouring more than 1.8 million square miles of ocean.
"We've got to this stage of the process where it's very sensible to go back and have a look at all of the data that has been gathered, all of the analysis that has been done and make sure there's no flaws in it, the assumptions are right, the analysis is right and the deductions and conclusions are right," Angus Houston, head of the search operation, said.
Investigators have been frustrated by a lack of hard data since the plane vanished on March 8 during a flight from Kuala Lumpur to Beijing.
A weeks-long search for surface debris was called off last week after officials decided any wreckage that may have been floating has probably sunk.
"Unfortunately, all of that effort has found nothing," Australian transport minister Warren Truss said.
"We've been confident on the basis of the information provided that the search area was the right one, but in practice, that confidence has not been converted into us discovering any trace of the aircraft."
Mr Houston has warned the underwater search is likely to drag on for up to a year.
Mr Houston and Mr Truss met Malaysian defence Minister Hishammuddin Hussein and Chinese transport minister Yang Chuantang in the Australian capital Canberra today to map out the next steps of the underwater search, which will focus on a 23,000 square mile patch of seabed.
Officials are contacting governments and private contractors to find out whether they have specialised equipment that can dive deeper than the Bluefin 21, an unmanned sub that has spent weeks scouring the seabed in an area where sounds consistent with a plane's black box were detected in early April.
The Bluefin has been limited by the fact that it can dive only to depths of 2.8 miles - and parts of the search zone are probably deeper than that.
Adding to the difficulties is the fact no one really knows exactly how deep the water in the search area is.
"I don't know that anyone knows for sure, because it's never been mapped," Mr Truss said, adding that detailed mapping of the seabed will be a key focus of the next phase of the search.
In addition to deeper diving capabilities, the new equipment will be able to send information back to crews in real time. The Bluefin's data can be downloaded only once it returns to the surface after each of its 16-hour dives.
It will probably take another two months before any new equipment is in the water, Mr Truss said.
The Bluefin will continue to be used in the meantime, though its search is currently on hold while the Ocean Shield, which has the sub on board, is taking on supplies at a base in Western Australia.