BEIJING – After six days of silence, with no signals detected that might be from the missing Malaysian airliner, "it is time to go underwater," and end the air and surface search, said the Australian official in charge of the search Monday.
A U.S.-made underwater search vehicle, Bluefin-21, will be deployed Monday night local time in the southern Indian Ocean to map the ocean floor, said Angus Houston, who leads the Joint Agency Coordination Centre that is responsible for the search and recovery effort.
Malaysia Airlines flight MH370 from Kuala Lumpur to Beijing, with 239 people on board, disappeared soon after take-off on March 8, sparking a massive, multi-national search effort including planes and vessels from the USA and China.
Australia's Ocean Shield ship will stop searching for acoustic signals, given the strong likelihood that the batteries of the black box recorders have now expired and will no longer transmit signals. The air and surface search for debris will also be completed in the next two to three days, said Houston, as chances of finding wreckage "have greatly diminished."
One possible new lead is an oil slick found Sunday in the same vicinity where four strong underwater signals were detected last week, he said. A two-liter sample was collected and is being analyzed, said Houston.
That oil slick, and the four earlier transmissions, are "the only leads" authorities currently have, said Houston, who said an earlier signal detected by a Chinese vessel has been discounted as a credible transmission.
The four signals detected by the towed pinger locator on the Ocean Shield represent "the most promising lead in the entire search," said Houston, who spoke in Perth, Australia, at JACC's first news conference in five days. "We (will) start where we think the best location is, then go out from there," he said. "If we don't find anything, we go further out and look a bit further afield."
The search area for the first mission will cover 15.4 square miles of the ocean floor, said Houston.The Bluefin-21 will operate on a continuous cycle of 24 hour-long missions, said Houston.
It takes 2 hours to descend to 4,500 meters, the very limits of its operating ability, spends 16 hours on mission, takes 2 hours to resurface and 4 hours to download the data. Analysts will get no indication of its progress until that daily download, he said.
Houston, a former Air Chief Marshal of Australia, cautioned against raising hopes.
"Don't be over optimistic, be realistic," he said. The ocean floor that will be mapped by side-scan sonar is "new to man," and the search may be complicated by heavy silt that could be "quite layered and quite deep," he said.
The majority of passengers aboard MH370 were from China, where many relatives still await evidence before they will accept Malaysian authorities' earlier conclusion that the plane ended up in the ocean, thousands of miles from its planned flight path.
To meet the strong interest in China, Houston held a separate press conference Monday for Chinese media, with Mandarin translation.
Many relatives remain in Beijing at the Lido Hotel, where Malaysia Airlines has provided rooms for families of MH370 passengers. The families gather in daily meetings, sometimes with representatives from the airline and Malaysian or Chinese governments, and occasional prayer sessions.
For better co-ordination, the relatives recently set up a voting structure, with one voting member per passenger. The group will decide on media releases, legal and other matters.
"The new structure is working," said Ma Tong, 29, a Beijing actuary whose mother Ma Wenzhi, 57, was on the plane. "The relatives are too numerous and loosely-organized, and we want to be more efficient, so we established this smaller group with 154 people," he said.
After agonizing weeks of waiting and many false leads, "we are more calm now, we don't care so much about the latest updates," said Ma. "Even if they find the black boxes later, if no bodies of our relatives are found, most of us won't go to Australia," he said. "We doubt the plane is there, our relatives could be in another place. We don't believe any news now."