SYDNEY - Improving weather conditions should help the search for missing Malaysia Airlines flight MH370 on Friday, forecasters said, as Australian Prime Minister Tony Abbott vowed everything "humanly possible" was being done to find the aircraft.
Grainy satellite imagery taken on Sunday detected a pair of floating objects in the southern Indian Ocean. Malaysia and Australia called the images a "credible" lead in the drawn-out hunt for the jet that vanished on March 8 with 239 passengers and crew on board.
But four planes from Australia, New Zealand and the United States that flew over a 23,000-square kilometre (8,800-square mile) area of ocean some 2,500 kilometres southwest of Perth on Thursday saw nothing of significance, with the search hampered by low cloud.
"The weather conditions were such that we were unable to see for very much of the flight," Royal Australian Air Force Flight Lieutenant Chris Birrer told reporters of his crew's sortie.
But conditions are improving, Australia's Bureau of Meteorology told AFP.
"Showers associated with the passage of a cold front on Thursday, which saw low cloud and drizzle affect visibility, are easing," the bureau said.
"Winds are currently 15-20 knots, with swell 2 to 2.5 metres, and also easing. Overall conditions are expected to slowly improve today for the search operations in the area."
The Australian Maritime Safety Authority (AMSA), which Malaysia tasked with heading the southern Indian Ocean search, said the five planes would scour the ocean Friday to try and find the two objects, one as large as 24 metres (79 feet) in size.
Military jets dispatched
"Five aircraft will be involved in today's search for Malaysia Airlines flight MH370," it said, adding that they would focus on a 23,000-kilometre area, about 2,500 kilometres south-west of Perth.
"Due to the distance to and from the search area, the aircraft involved have an endurance of approximately two hours of search time."
As well as the four planes that were involved Thursday, AMSA said a civil Gulfstream jet was also being used. The first plane, an Australian Orion, was due over the area around 0215 GMT.
A Norwegian merchant ship is currently in the search area and AMSA said another merchant ship was expected Friday evening, but Australia's HMAS Success, which is capable of retrieving any wreckage, was still some days away.
New Zealand Air Commodore Mike Yardley, commenting to TV3 on the sortie flown by the New Zealand P3 Orion on Thursday, warned that "there's a lot of debris out there in the ocean".
"Our crews picked up debris out there that was not part of the aircraft," he said.
"Our radar will pick up containers that have fallen off container vessels as well, and last night our radar system was picking up marine life - whales and dolphins."
Abbott, who first announced the potential breakthrough to parliament on Thursday, again cautioned that they were looking in "a remarkably isolated location in very deep and inaccessible ocean".
"Nevertheless, we are throwing all the resources we can at it," he said late Thursday after arriving in Papua New Guinea for a visit.
"We will do everything we humanly can to try to get to the bottom of this.
"We don't know what that satellite saw until we can get a much better, much closer, look at it. But this is the first tangible breakthrough in what up until now has been an utterly baffling mystery."