As the focus narrows, more questions emerge in search for Malaysia 370

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    What you need to know about a black box

What you need to know about a black box 01:51

Story highlights

  • "We believe these are the boxes," says beacon maker director
  • He predicts they'll hold a charge for 35 days -- til Friday
  • The search zone is nearly 3 miles deep
  • "As they say in Australia, make hay while the sun shines," says Houston

Injected with fresh hope and urgency after the discovery Tuesday of more signals that appear to be from Malaysia Airlines Flight 370's so-called black boxes, investigators began looking Wednesday toward what new challenges may await if that proves true.

A raft of new questions awaits:

How sure are experts that the detected signals are, in fact, from the pingers?

Pretty darned sure, but not certain.

One of two signals detected on Tuesday was at 33.331 kHz and was pulsed at a 1.106-second interval, according to retired Air Chief Marshal Angus Houston, who cited a data analysis carried out by experts at the Australian Joint Acoustic Analysis Centre.

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That's near the standard 37.5 kHz frequency used by the recorders; the difference is not surprising, given the vagaries of how sound travels under water. "They believe the signals to be consistent with the specification and description of a flight data recorder," he said.

Adding to experts' confidence is the fact that the signals were detected along the missing plane's estimated flight path, which was calculated based on its direction and fuel capacity.

    Two other signals were detected nearby on Saturday.

    Here's how various experts characterized their confidence in the pings:

    -- "What we're picking up is a great lead," Houston said. "I'm now optimistic that we will find the aircraft, or what is left of the aircraft, in the not-too-distant future." But, he added, "We need to visually identify aircraft wreckage before we can confirm with certainty that this is the final resting place of MH370."

    -- "I think their optimism is justified," Mary Schiavo, a former inspector general for the U.S. Department of Transportation, told CNN. "Now, it's just a matter of time and work and narrowing it down."

    -- "We believe these are the boxes," said Chris Portale, director of Dukane Seacom, the beacon maker.

    From how far away can the pingers be detected?

    Their range of 2 nautical miles (2.3 miles) is less than the depth of the waters they are believed to be in, which makes the discovery of the signals all the more impressive.

    How long will they keep emitting signals?

    They are certified to keep working for 30 days, though "our testing has indicated that it should get 35 days," Portale said.

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    Angus, though, noted Wednesday that the signals detected appeared to be weakening.

    What happens once the pingers are located?

    Investigators would use an underwater autonomous vehicle to travel to the ocean floor to reach them, Houston told reporters in Perth on Wednesday, 33 days after the plane disappeared while flying from Kuala Lumpur, Malaysia, to Beijing.

    How deep is that stretch of ocean?

    It's 2.8 miles (4.5 kilometers) to the bottom in the remote section of the Indian Ocean 1,400 miles (2,260 kilometers) northwest of Perth, where pieces of the aircraft are presumed to lay, Houston said.

    What other complications could lurk there?

    Silt. Lots of silt. "Sometimes silt can be tens of meters thick," Houston said, referring to the search area. "It's a very difficult environment."

    And there may be more complications. "It's quite possible that there are currents down there, which could have disturbed the debris," said Commodore Peter Leavy, who is coordinating military contributions to the search. "It has been said we know more about the surface of the moon than our own seabed of our ocean floor. I think that's probably right."

    Why don't they bring in more equipment to speed this thing up?

    Because needless noise would complicate the search for the audio signals. Even the Ocean Shield is minimizing all its systems, using only the equipment they can't do without, according to Houston. ""Everything else is turned off."

    What about the Chinese ship Haixun 01 that reported Saturday having detected a pulse more than 300 miles to the south?

    Since then, there have been no further detections in the area, Houston said. Still, he added, "We're continuing to look where Haixun 01 is."

    What next?

    The Ocean Shield and its towed pinger locator plans to continue searching as long as there is a possibility that the batteries are still powering the devices. "We need to, as we say in Australia, make hay while the sun shines," Houston said. "By getting more data, we will be able to compress this area into a much smaller area where we do the very difficult and very challenging search with the autonomous underwater vehicle.

    And when they're pretty surely dead?

    Searchers would send out a Bluefin-21 autonomous underwater vehicle with a more accurate sonar and possibly a camera for mapping the ocean floor, said Leavy.

    OK, let's say they get a good fix on the pingers. Then how long before they're brought up?

    The device(s) would be transferred to fresh water, then dried before the data they contain would be pulled out, Schiavo said. "Then they'll discover on the FDR what they're dealing with and how much of the wreckage they really have to bring up to solve the mystery."

    But don't hold your breath. Houston noted that, when Air France Flight 447 plunged into the South Atlantic Ocean in 2009, killing all 228 people aboard, it took investigators nearly two years to determine the location of the wreckage.

    And the tough slogging wasn't over. "They thought they had a good fix, and it took the underwater vehicles 20 days to get to the wreckage," Houston said.

    But the efforts paid off. Once that happened, submersible vehicles retrieved the plane's voice and flight data recorders, which led investigators to conclude that a series of pilot errors and their failure to react effectively to technical problems had caused the crash.

    What happens after the pingers die?

    In search for Malaysia Airlines Flight 370, two new signals buoy hope

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