PERTH, Australia -- Three Australian planes took off at dawn today for a third day of scouring the desolate southern Indian Ocean for possible parts of missing Malaysia Airlines Flight 370, now lost for two full weeks.
Australia promised its best efforts to resolve "an extraordinary riddle," but two days of searching the seas about 2,500 kilometres southwest of Perth have not produced any evidence.
A satellite spotted two large objects in the area earlier this week, raising hopes of finding the Boeing 777 that disappeared March 8 with 239 people on board.
"It's about the most inaccessible spot that you could imagine on the face of the Earth, but if there is anything down there, we will find it," Prime Minister Tony Abbott said at a news conference in Papua New Guinea.
"We owe it to the families and the friends and the loved ones of the almost 240 people on Flight MH370 to do everything we can to try to resolve what is as yet an extraordinary riddle," he added.
A total of six aircraft were searching the region today: two ultra long-range commercial jets and four P3 Orions, the Australian Maritime Safety Authority said.
Because of the distance to the area, the Orions will have enough fuel to search for two hours, while the commercial jets can stay for five hours before heading back to the base.
Two merchant ships were in the area, and the HMAS Success, a navy supply ship, was due to arrive late Saturday afternoon. Weather in the search zone was expected to be relatively good, with some cloud cover.
Two Chinese aircraft are expected to arrive in Perth today to join the search, and two Japanese planes will arrive Sunday. A small flotilla of ships from China is still several days away. The plane passengers included 154 Chinese citizens.
AMSA officials also were checking to see if there was any new satellite imagery that could provide more information. The satellite images were taken March 16, but the search in the area did not start until Thursday because it took time to analyze them.
In Kuala Lumpur, where the plane took off for Beijing, Malaysian Defence Minister Hishammuddin Hussein called the process "a long haul" as he thanked the more than two dozen countries involved in a search that stretches from Kazakhstan in Central Asia to the southern Indian Ocean.
Searchers on Friday relied mostly on trained spotters aboard the planes rather than radar, which found nothing Thursday, Australian officials said. The search will focus more on visual sightings because civilian aircraft are being brought in. The military planes will continue to use both radar and spotters.
"Noting that we got no radar detections yesterday, we have replanned the search to be visual. So aircraft flying relatively low, very highly skilled and trained observers looking out of the aircraft windows and looking to see objects," said John Young, manager of the maritime safety authority's emergency response division.
Malaysia asked the U.S. for undersea surveillance equipment to help in the search, said Rear Adm. John Kirby, a Pentagon spokesman. Defence Secretary Chuck Hagel promised to assess the availability of the technology and its usefulness in the search, Kirby said.
The Pentagon says it has spent $2.5 million to operate ships and aircraft in the search and has budgeted another $1.5 million for the efforts.
-- The Associated Press