The mini-sub searching for Malaysia Airlines flight MH370 had reached depths well beyond its normal operating limits, officials said yesterday, as it made its fifth dive to the seabed.
Searchers have extended the hunt beyond the normal 4,500-metre depth range of Bluefin-21, the US Navy's Autonomous Underwater Vehicle (AUV).
"The AUV reached a record depth of 4,695 metres during mission four," the US Navy said. "This is the first time the Bluefin-21 has descended to this depth. [It] does carry with it some residual risk to the equipment and this is being carefully monitored."
With no results to show since the Boeing 777 carrying 239 people disappeared on March 8, Australian Prime Minister Tony Abbott has stepped up the timetable to locate the plane, which is believed to have crashed in the Indian Ocean west of Perth.
The unmanned Bluefin-21, which maps the seafloor by sonar, has searched 110 square kilometres so far. But the data retrieved has not yet revealed anything of value.
Abbott was quoted on Wednesday as saying that "we believe [the underwater] search will be completed within a week or so. If we don't find wreckage, we stop, we regroup, we reconsider".
Asked to clarify Abbott's comments, his office said he was only suggesting that authorities may change the area being searched by the Bluefin-21, not that the search would be called off.
Malaysia's acting transport minister, Hishammuddin Hussein, promised that the search would continue even if there was a pause to re-evaluate the mission, including the best area to scour.
Suggestions have emerged that more sophisticated - and very expensive - deep-diving equipment may be needed for the search.
"We have to look at contractors, and the cost of that will be huge," he said, though he indicated that such concerns were not yet testing the resolve of multinational search partners.
Analysts have said they expect the search will be the most expensive in aviation history, with Ravikumar Madavaram, an aviation expert at Frost & Sullivan Asia Pacific, estimating the bill at US$100 million so far.
"This is definitely the biggest operation ever," he said. "In terms of costs, this would be the highest."
Malaysian media, meanwhile, reported that Canberra and Kuala Lumpur would sign a deal specifying who handles any wreckage that may be recovered, including the crucial "black box" flight data recorders.
Malaysia was drafting the agreement "to safeguard both nations from any legal pitfalls that may surface during that [recovery] phase,"
New Straits Times reported.
"The memorandum of understanding spells out exactly who does what and the areas of responsibility," civil aviation chief Azharuddin Abdul Rahman was quoted as saying.
The New Straits Times quoted a source with "intimate knowledge" of the deal saying that it also specified where any passenger remains would be taken to and who would be responsible for autopsies.
Agence France-Presse, Reuters, Bloomberg