Hopes were both raised and lowered Friday by officials involved in the search for Malaysia Airlines Flight 370. The jet and the 239 people on board have now been missing for five weeks.

Australian Prime Minister Tony Abbott said he is "very confident" that pings detected by searchers this week in the south Indian Ocean are coming from one or both of the plane's two black boxes that record flight data and cockpit conversations. NPR's Anthony Kuhn reports that Abbott said it's his understanding the signals have significantly narrowed the focus of the search.

But Angus Houston, the retired Australian air defense chief who is leading the search effort, said Friday that "[based] on the information I have available to me, there has been no major breakthrough."

Houston also said it has been determined that the latest sound picked up by searchers, which was detected Thursday, "is unlikely to be related to the aircraft black boxes."

What's more, Houston said, it "could be some days" before it's decided whether the other sounds detected so far warrant sending an unmanned vehicle down to the seafloor. On Friday, the focus of the multinational searchers' operations was on three zones from 1,000 miles to about 1,500 miles northwest of Perth, Australia. The waters are about 3 miles deep.

"It is vital to glean as much information as possible" about the black boxes' possible locations "while the batteries on the underwater locator beacons may still be active," he said. Experts say those batteries likely began to fade after about 30 days in water. This is Day 35.

As we've written before:

The jet was about one hour into a flight from Kuala Lumpur to Beijing in the early morning hours of March 8 (local time) when it was last heard from. Flight 370 was headed north over the Gulf of Thailand as it approached Vietnamese airspace.

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