To solve one of the most vexing mysteries in aviation history, the search for missing Malaysia Airlines Flight 370 will now focus on what may lie underwater – in an area nearly as big as West Virginia.
On Wednesday, the U.S. Navy's Bluefin 21 completed its last underwater mission near where acoustic signals, believed to possibly be emitting from the missing jet's data recorders, were picked up in April, according to the Australian-based Joint Agency Coordination Center.
"The Australian Transport Safety Bureau (ATSB) has advised that the search in the vicinity of the acoustic detections can now be considered complete,'' the JACC said in a statement, "and in its professional judgment, the area can now be discounted as the final resting place of MH370.''
Now, experts will work on determining an underwater search area of up to 21,600 square miles along the arc in the southern Indian Ocean, and an underwater survey of the ocean floor will map the terrain.
"Knowing the seafloor terrain is crucial to enabling the subsequent underwater search,'' the JACC said.
Still, it will be roughly another three months before that more intensified search can even begin, as experts first survey the ocean floor. And then it could be another year before the underwater search ends, and answers finally emerge.
"The search will be a major undertaking," Martin Dolan, chief commissioner of the Australian Transport Safety Bureau, which has been assisting the Malaysian government, said in a statement posted Monday. "The complexities and challenges involved are immense, but not impossible. The best minds from around the world have been reviewing, refining and (localizing) the most likely area where the aircraft entered the water, which is why we remain confident of finding the aircraft.''
Flight 370 disappeared March 8 as it headed from Kuala Lumpur to Beijing with 227 passengers and 12 crewmembers on board.
Investigators from various countries joined together to launch one of the most extensive searches ever by air and by sea. The focus in recent weeks has been on the southern Indian Ocean. But so far, not a trace of the vanished plane has been found.
The upcoming survey of the ocean floor, which will take about three months, has already begun. A Chinese survey ship began the mapping. It will be joined by another vessel in June.
Once the survey is complete, the underwater search is expected to begin in August. Commercial side-scan sonar operators will scour the ocean for the missing Boeing 777 and any debris. That search will likely last up to a year.
Robert Mann, an aviation analyst at R.W. Mann & Co. in Port Washington, N.Y., says he feels that the plane will one day be found, but perhaps not by those who are so vigorously trying to discover it.
"I think it'll be found, there's no question about that ,'' he says. "It's just a matter of time. Ultimately, it may not be found by the people who are looking for it. It may be found as a byproduct of some other activity going on. That's the unfortunate part. I think the directed search, given the best efforts of those involved, is no more or less likely to find it than it was the other day.''
U.S. Navy spokesman Chris Johnson has dismissed comments made to CNN by ocean engineering expert Michael Dean that the acoustic "pings" heard in the area in April did not come from the missing airliner's black boxes. Dean said those sounds came from another source not connected to the plane.
"Mike Dean's comments today were speculative and premature," Johnson said in a statement.
Contributing: The Associated Press