(USATODAY.com) - Search crews focused on a narrowed section of the Indian Ocean off Australia as they resumed the hunt for voice and data recorders and wreckage of the missing Malaysian jetliner.
Fourteen airplanes and 13 ships were scouring a search zone Thursday that has been reduced in size after Australian crews reported detecting electronic pings that could be from the dying batteries of the black boxes on board the plane when it was lost after leaving Kuala Lumpur for Beijing over a month ago.
Thursday's search zone was the smallest yet for Flight 370 —22,364 square miles of ocean — and comes a day after the Australian official in charge of the search expressed hope that crews were closing in on the "final resting place" of the vanished jet.
No further sounds had been picked up overnight, search officials said in Perth Thursday morning.
"Aircraft and ships reported spotting a large number of objects during yesterday's search, but only a small number were able to be recovered,'' search coordinators said in a statement. "None of the recovered items were believed to be associated with MH370.''
Angus Houston, who is leading the joint search, said Wednesday that equipment aboard the Australian ship Ocean Shield twice reacquired signals first detected last weekend that could be coming from the black box data and voice recorders on board the missing Malaysia Airlines Flight 370.
He said the ship has now heard the signal, which is "not of natural origin," a total of four times, most recently a seven-minute transmission Tuesday night.
The new data have allowed searchers to further reduce the size of the search area, Houston said Wednesday.
"I believe we are searching in the right area'' for the wreckage, he said. He hopes more transmissions will be detected and, "in a matter of days we will be able to find something on the bottom that might confirm that this was the last resting place of MH370."
Houston cautioned that nothing can be confirmed until wreckage from the plane is visually identified.
Searchers are in a race against time, trying to gain as much information from the underwater signals as they can before the batteries in the two boxes — already past their expected lifespan — expire and the data recorder pingers go silent.
It's been 33 days since the plane was lost March 8 on a flight from Kuala Lumpur, Malaysia, to Beijing, and Houston noted that the expected life of the batteries on the black box pingers is 30 days.
"It is important that we gather as much information .... while the pingers are still transmitting,'' he said.
"The last signal we got was a very weak signal,'' he said.
Before Wednesday's report by Houston, search crews had last heard the signals early Sunday.
A robot sub, the Bluefin 21, is loaded with equipment that can create a sonar map of an area to chart any debris on the sea floor. But it works slowly, so the search area must be sharply trimmed first by listening for the electronic pings.