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Could the pings be from MH370?
02:07 - Source: CNN

Story highlights

Authorities scale back the size of the search area

Expert: "They've cut down the size of that haystack incredibly"

U.S. Navy official: "As hours pass, our optimism is fading away"

CNN  — 

Tuesday is Day 32 since Malaysia Airlines Flight 370 disappeared. One hundred and thirty-three search missions have been carried out so far but they have been fruitless.

Now, hope seems to rest on underwater pulses that an Australian navy ship has detected.

Investigators hope the signals could be locator beacons from the plane’s data recorders, but they’re not sure yet.

“This is the most positive lead and rest assured, we are pursuing it very vigorously,” Australian Defense Minister David Johnston told reporters Tuesday.

What happens after the Malaysian plane’s pingers die?

The signals were detected over the weekend. They have not been heard from since.

But buoyed by the hope that they’re closing in, they’re scouring the Indian Ocean and trying to hear the pings again.

“We have at least several days of intense actions ahead of us,” Johnston said. “We’re throwing everything at this difficult, complex task.”

It’s too soon to say whether the sounds were signals from the missing plane. But authorities appeared optimistic as they described the find on Monday.

“We’ve got a visual indication on a screen, and we’ve also got an audible signal. And the audible signal sounds to me just like an emergency locator beacon,” said retired Air Chief Marshal Angus Houston, the chief of the Australian agency coordinating the search. “We are encouraged that we are very close to where we need to be.”

But he cautioned reporters to “treat this information cautiously and responsibly until such time as we can provide an unequivocal determination.

“We haven’t found the aircraft yet,” he said. “We need further confirmation.”

Read: Four reasons to believe; six reasons to doubt

It could take days before officials determine whether the signals came from the plane, which fell off radar on March 8 on its way from Kuala Lumpur, Malaysia, to Beijing.

Search teams have been scanning vast swaths of the Indian Ocean in the search for the aircraft, with very little data to pinpoint its whereabouts.

Finding pings from the data recorders would be a major step in the investigation, helping searchers narrow the area where they’re looking. Authorities reduced the size of the search area on Tuesday, focusing on a smaller area about a third of the size of the previous search zone: 30,000 square miles (77,580 square kilometers) about 1,400 miles (2,270 kilometers) northwest of Perth.

For investigators trying to hear the signals, time is running out.

The batteries powering the beacons, which are designed to start sending signals when a plane crashes into water, last about 30 days after the devices are activated.

Experts have said it’s possible that the batteries could last several days longer if they were at their full strength.

That race against the clock is the “No. 1 challenge” searchers face, U.S. Navy Cmdr. William Marks told CNN on Monday.

The developments over the weekend were encouraging, he said, but it’s been almost a day and a half since then.

“This is a 24-hour operation. We haven’t quit since we initially heard these signals,” he said. “We’ve been going continuously around the clock and we haven’t been able to reacquire them.”

Searchers are still scouring the waters, but their optimism is “more cautious” now, he said.

“As hours pass,” he said, “our optimism is fading away, ever so slightly.”

Next steps in underwater search

Need to find signal again

Cheers erupted when the team aboard Australia’s Ocean Shield first reported a possible signal had been heard, according to Capt. Mark Matthews, the U.S. Navy’s salvage supervisor.