A fifth acoustic signal was detected on Thursday by an Australian AP-3C Orion aircraft searching the Indian Ocean for Malayasia Airlines Flight 370, but Air Chief Marshal Angus Houston, the official coordinating the search, said it is "unlikely to be related to the aircraft black boxes." Houston, who sounded more optimistic earlier this week, added, "On the information I have available to me, there has been no major breakthrough in the search for MH370." Australian Prime Minister Tony Abbott was far more upbeat, declaring, "We have very much narrowed down the search area and we are very confident that the signals that we are detecting are from the black box on MH370."
This week, the Australian ship Ocean Shield detected four underwater pings consistent with a plane's black box, but Abbott noted that they're "starting to fade." On Friday, the Ocean Shield will continue scanning the underwater search zone, which is currently about the size of Los Angeles, with its towed pinger locator. Searchers hope to obtain as much information as possible before the signals die completely, and will then launch the Bluefin 21 submersible to seek out debris. The submarine is much slower than the towed locator, and pinger manufacturer Dukane Seacom says sounds from the submarine would probably drown out the pulses.
"We are confident that we know the position of the black box flight recorder to within some kilometers," Abbott said, adding, "But confidence in the approximate position of the black box is not the same as recovering wreckage from almost 4 ½ kilometers beneath the sea or finally determining all that happened on that flight."