Canberra - An Australian vessel searching for the missing Malaysia Airlines plane has detected signals consistent with those from "black box" flight recorders. Defence vessel Ocean Shield acquired the signal twice, once for more than two hours, said Air Chief Marshal Angus Houston, who is leading the search. He called it the "most promising lead" so far. But he said more information was needed: "We haven't found the aircraft yet and we need further confirmation." The plane, carrying 239 people, was flying from Kuala Lumpur to Beijing on 8 March when it disappeared. Malaysian officials say they believe it crashed in the southern Indian Ocean. ACM Houston said the signals were detected using the towed pinger locator deployed on the Ocean Shield. Two separate detections occurred, he said. The first was held for two hours and 20 minutes before being lost. The ship then turned around and on the return leg detected the signal again for 13 minutes. "On this occasion two distinct pinger returns were audible. Significantly this would be consistent with transmissions from both the flight data recorder and the cockpit voice recorder," ACM Houston said. "I'm much more optimistic than I was a week ago," he said. "We are now in a very well defined search area, which hopefully will eventually yield the information that we need to say that [Malaysia Airlines flight] MH370 might have entered the water just here." The Ocean Shield was still in the area but had not been able to reacquire the signals since, he said. (FA)