New underwater pings could soon lead to plane

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Search for Flight 370: New underwater pings could soon lead to plane

Houston has expressed optimism about the sounds detected earlier in the week, saying on Wednesday that he was hopeful crews would find the aircraft - or

what's left of it - in the "not-too-distant future."

Separately, a Malaysian government official told The Associated Press Thursday evening that investigators have concluded the pilot spoke the last words to

air traffic control, "Good night, Malaysian three-seven-zero," and that his voice had no signs of duress. A re-examination of the last communication from the

cockpit was initiated after authorities last week reversed their initial statement that the co-pilot was speaking different words.

The senior government official spoke on condition of anonymity because he wasn't authorized to speak to the media. The conclusion was first reported by CNN.

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Why haven't airlines installed deployable black boxes?

Investigators suspect the plane went down in the southern Indian Ocean based on a flight path calculated from its contacts with a satellite and analysis of

its speed and fuel capacity, but the content of the flight data and cockpit voice recorders is essential to solving the mysteries of why the plane was lost.

An Australian government briefing document circulated among international agencies involved in the search on Thursday said the acoustic pingers likely would

continue to transmit at decreasing strength for up to 10 more days, depending on conditions.

Once there is no hope left of the Ocean Shield hearing more sounds, the Bluefin sub will be deployed.