SYDNEY/PERTH, Australia (Reuters) - An Australian ship which picked up possible "pings" from the black box recorders of a missing Malaysia Airlines jetliner has been unable to detect any further signals and time is running out to narrow the massive search, officials said on Tuesday. Up to 11 military planes, three civilian planes and 14 ships planned to take part in the search on Tuesday, with good weather in the search area. BLUEFIN ON HOLD 
 
 An autonomous underwater vehicle (AUV) named Bluefin-21 is onboard the Ocean Shield and could be sent to look for wreckage on the sea floor, but narrowing the search zone first was critical, Houston said. "It is a large area for a small submersible that has a very narrow field of search, and of course, it is literally crawling along the bottom of the ocean," he said. A U.S. Navy "towed pinger locator" onboard Australia's Ocean Shield picked up two signals consistent with black box locator beacons over the weekend - the first for more than two hours and the second for about 13 minutes. It is designed to detect signals at a range of 1.12 miles, meaning it would need to be almost on top of the recorders to detect them if they were on the ocean floor, which is about 2.8 miles deep. One-hundred-thirty-three missions have been completed so far in the hunt from the air for debris that could be from Flight 370, but no debris from the plane has been found.
– When an Australian ship heard pings possibly from Malaysia Airlines Flight 370, officials saw a big lead open up in the search—but since then, investigators haven't been able to recapture the signal, Reuters reports. That's particularly worrying since the batteries on the jet's black boxes have likely just about run out. But "we need to continue (searching) for several days right up to the point at which there's absolutely no doubt that the batteries will have expired," says Angus Houston, the Australian official leading the search, per CBS News. "If we don't get any further transmissions, we have a reasonably large search area of the bottom of the ocean to prosecute and that will take a long, long time," Houston says. The ship is carrying an autonomous underwater vehicle that can search the depths for the plane, "literally crawling along the bottom of the ocean," Houston notes. Trouble is, findings so far point to "a large area for a small submersible that has a very narrow field of search." Once the vehicle, called Bluefin-21, does head downward, it will conduct 20-hour sonar missions to try to find the plane.