KUALA LUMPUR, Malaysia — Australia and Malaysia led an intensified multinational search on Monday for the remains of Malaysia Airlines Flight 370 in the southern Indian Ocean and prepared to deploy a submersible device to detect any pings from the aircraft’s black boxes, only days before their batteries are expected to die.
But in contending with a revised search area the size of Poland, there was no immediate indication the searchers were any closer to finding traces of the aircraft or its 239 passengers and crew. The plane has now been missing for more than three weeks.
Although frustrations and costs have escalated, Malaysian and Australian officials asserted that they would keep searching indefinitely.
Malaysia has been under increasing pressure, particularly from relatives of Chinese passengers on the March 8 flight from Kuala Lumpur to Beijing, to produce evidence of the plane’s fate. Most of the passengers were Chinese.
“We understand that it has been a difficult time for all the families and we appreciate that many families want to see physical evidence before they will accept that MH370 ended in the south Indian Ocean,” Hishammuddin Hussein, Malaysia’s defense minister, said at a news conference here, using the flight’s call sign.
“We will continue with all our efforts to find MH370,” he said. “This is a promise that Malaysia intends to keep.”
Earlier in the day, Prime Minister Tony Abbott of Australia, whose country has been coordinating the search in the Indian Ocean, said he was not considering ending Australian participation.“We can keep searching for quite some time to come,” he said.
Ten planes and 11 ships were ordered to scour the latest search area, about 1,100 miles west of Perth. The Australian defense minister, David Johnston, said about 100 air personnel and 1,000 sailors were in the zone.
Additional ships were en route, expected to arrive within days, including an Australian naval vessel, the Ocean Shield, equipped to detect the pings of the plane’s data and cockpit voice recorders, or black boxes, according to the Australian Maritime Safety Authority, the government agency coordinating the search.
Captain Mark Matthews, a supervisor of a team from the US Navy that is involved in the search, said the effectiveness of the detection equipment would depend on “how effective we are at reducing that search area.”
Matthews said the so-called pinger locator, towed behind the ship, was a batwing-shaped device with a microphone that could pick up signals from Flight 370’s black boxes.
The submersible can be deployed to map a debris field on the ocean floor using sonar and then to use a camera to provide what Matthews called “a full mosaic” of the debris field.
But the ping detector’s utility, in the absence of more specific information about the location of the wreckage, is doubtful. The device will be towed at an average speed of about 3 miles per hour, Matthews said, and the submersible moves at about 3.5 miles per hour.
“Nothing is fast in underwater search,” Matthews said.
Searchers say there is no time to waste: The pinger locator will be ineffective once the batteries powering the black boxes die, which is expected to happen next week.
Hishammuddin said the Malaysian prime minister, Najib Razak, would travel to Pearce Air Force Base in Australia on Wednesday to thank the multinational force participating in the search and to view the efforts.
Since Friday, when the search zone was shifted from an area about 700 miles south, aircraft have made daily sightings of floating objects. On closer inspection by crews on the ships, none of the items has been linked to the missing plane, a Boeing 777-200.