We begin with new hope and caution in the search for the missing passenger jet flight 370. Had the black positions finally sent a message? Tonight investigators zeroing in and pushing harder to find... See More
We begin with new hope and caution in the search for the missing passenger jet flight 370. Had the black positions finally sent a message? Tonight investigators zeroing in and pushing harder to find the boxes before they go silent. ABC's David Kerley has the latest on what they're hearing tonight. Reporter: This U.S. Navy listening device heard this. Today the man leading the search said he believes that is the distinctiontive sound of the pinger. Clearly this is the most promising lead and probably in the search so far it's probably the best information that we have had. Reporter: The pinger locater heard the sing nal for more than two hours. The ship turned around and heard it again for another 13 minutes. Two distinct pinger returns were audible. Significantly this would be consistent with transmissions from both the flight data recorder and the cockpit voice recorder. Reporter: The ship is now Chris crossing a three square mile section listening again. Searchers will then send this robot down to the bottom using sonar and mapping the ocean floor looking for wreckage. But the depths in the area are nearly 15,000 feet, right at the limit of the robot's capabilities. If you're picking up one or two sources, then we have more than likely found them. Reporter: Those black boxes will tell us so much. Was the voice a hijacker? Were all those course changes on purpose? Did the cabin depressurize on purpose killing the passengers and when were those systems intentionally shut down. As we learned, $1,51500 feet under water these boxes survived. But they have got to get the boxes first. The battery in this pinger ran out for its guaranteed 30 days yesterday. Making it another three or four days. They haven't heard it in a day and a half. Inside here is an indestructible container that holds that board with the memory chips that will tell us what this plane was doing. So if it's intact, it's in there somewhere? So it's almost indestructible. They can handle the water. Thank you, David, monitoring it. Back here at home millions
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