PERTH, Australia – A robotic submarine completed its first successful scan of the seabed Thursday in the hunt for the missing Malaysian plane, and investigators were analyzing the sub's data while also trying to identify the origins of a nearby oil slick.
The Bluefin 21's first two missions were cut short by technical problems and deep water, but the unmanned sub finally managed to complete a full 16-hour scan of the silt-covered seabed far off Australia's west coast, the search coordination center said on Thursday. While data collected by the sub from its latest mission, which ended overnight, was still being analyzed, nothing of note had yet been discovered, the center said. The sub has now covered 90 square kilometers (35 square miles) of seafloor.
Meanwhile, officials in the western city of Perth were analyzing an oil sample that search crews collected earlier this week about 5.5 kilometers (3.4 miles) from an area where equipment picked up underwater sounds consistent with an aircraft black box. Angus Houston, who is heading up the search effort, has said the oil does not appear to be from ships in the region, but cautioned against jumping to conclusions about its source.
The analysis could provide further evidence that officials are looking in the right place for Flight 370, which vanished March 8 while en route from Kuala Lumpur, Malaysia, to Beijing. Searchers have yet to find any physical proof that the sounds that led them to the ocean floor where the Bluefin has been deployed were from the ill-fated jet.
Twelve planes and 11 ships were scouring a 40,300-square-kilometer (15,600-square-mile) patch of sea for any debris that may be floating on the ocean surface, about 2,200 kilometers (1,400 miles) northwest of Perth.
Despite weeks of searching, no debris related to the jet has been found and earlier this week, Houston said the surface search would be ending within days. But the search coordination center on Thursday said crews would continue searching the ocean surface into next week.
Malaysia's defense minister, Hishamuddin Hussein, confirmed that the search would continue through the Easter weekend, though acknowledged that officials would have to rethink their strategy at some point if nothing is found.
"There will come a time when we need to regroup and reconsider, but in any event, the search will always continue. It's just a matter of approach," he said at a news conference on Thursday.
Radar and satellite data show the Boeing 777 flew far off-course for an unknown reason and would have run out of fuel in a desolate patch of the Indian Ocean west of Australia.
A ship-towed device detected four underwater signals that are believed to have come from the plane's black boxes shortly before the batteries powering the devices' beacons likely died. The sounds helped narrow the search area to the waters where the Bluefin is now operating.
The U.S. Navy's unmanned sub cut short its first mission on Monday because it exceeded its maximum operating depth of 4,500 meters (15,000 feet). Searchers moved it away from the deepest waters before redeploying the sub to scan the seabed with sonar to map a potential debris field.
In addition to finding the plane itself, investigators want to recover the black boxes in hopes the cockpit voice and flight data recorders can explain why the plane lost communications and flew so far off-course before disappearing.
Associated Press writers Kristen Gelineau in Sydney and Rod McGuirk in Canberra, Australia, contributed to this report.
Follow Margie Mason on Twitter at twitter.com/MargieMasonAP