Up to 10 planes and nine ships from a half dozen countries are scouring a stretch of the Indian Ocean roughly the size of Britain, where the plane is believed to have crashed more than three weeks ago.Also read: UK submarine, Oscar-winning director Peter Jackson's jet join hunt for Malaysia Airlines Flight MH370
The search and rescue teams are in a race against time to locate the plane's black box recorder, which has an expected battery life of around 30 days and contains what could be the only clues about the plane's mysterious disappearance.
But retired Air Chief Marshal Angus Houston, the head of the Australian agency coordinating the operation, said that a lack of reliable flight telemetry and punishing conditions at sea were making the operation even more challenging.
"In other words, we don't have a precise aircraft location for six hours before the aircraft went into the water somewhere," he said in an interview with the Australian Broadcasting Corporation on Wednesday.
"The reality is it's the most complex and challenging search and rescue operation, or search and recovery operation now, that I've ever seen."
Broken clouds, sea fog and isolated thunderstorms were expected to further complicate operations on Wednesday, Australia's Joint Agency Coordination Centre said.
The search is now focused on an inhospitable 221,000 sq km (85,000 sq miles) swathe of the southern Indian Ocean some 1,500 km (932 miles) west of the Australian city of Perth. But despite the unprecedented effort, the international team has so far failed to spot any trace of the jetliner.
"Look, it's one of the great mysteries of our time," Australian Prime Minister Tony Abbott said in an interview with local Perth radio station Radio 6iX.
"We owe it to the world, we owe it to those families to do whatever we reasonably can do get to the bottom of this."
NAJIB TO PERTH
Malaysian Prime Minister Najib Razak is expected to arrive in Perth late Wednesday to inspect the search and rescue operations, which are being conducted out of RAAF Base Pearce north of the city.
He will arrive with Malaysia coming under fresh fire for its handling of the incident after authorities there changed their account of the plane's critical last communication from a more casual "All right, good night" to the standard "Good night Malaysian three seven zero."
Malaysia on Tuesday released the full transcript of communications between the Boeing 777 and local air traffic control before it dropped from civilian radar in the early hours of March 8 as it flew from Kuala Lumpur to Beijing. (for full transcript, click: http://r.reuters.com/kam28v)
Malaysian authorities have faced heavy criticism, particularly from China, for mismanaging the search, now in its fourth fruitless week, and holding back information. Most of the 239 people on board the flight were Chinese.
Minutes after the final radio transmission was received the plane's communications were cut off and it turned back across Peninsular Malaysia and headed towards the Indian Ocean, according to military radar and limited satellite data.
Malaysia says the plane was likely diverted deliberately, probably by a skilled aviator, leading to speculation of involvement by one or more of the pilots. Investigators, however, have determined no apparent motive or other red flags among the 227 passengers and 12 crew.
Najib is expected to meet Prime Minister Abbott on Thursday.
Among the vessels due to join the search in the coming days is an Australian defence force ship, the Ocean Shield, that has been fitted with a sophisticated U.S. black box locator and an underwater drone.
Time is running out because the signal transmitted by the missing aircraft's black box could die within days, leaving investigators with a vastly more difficult task.
Using faint, hourly satellite signals gathered by British firm Inmarsat PLC and radar data from early in its flight, investigators have only estimates of the speed the aircraft was travelling and no certainty of its altitude.
Still, Houston said the challenging search would continue based on the imperfect information with which they had to work.
"It's vitally important for the governments involved that we find this aeroplane," he said. "But I'm just pointing out that it won't be easy given the circumstances that surround this particular search and recovery operation."
A sign displays a message regarding the search for the missing Malaysian Airlines Flight MH370 outside the Uniting Church in New South Wales. (Reuters)