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Untangling a mystery: How do ocean recoveries work?

By Dana Ford, CNN
updated 10:01 AM EDT, Tue March 25, 2014
  • NEW: The United States sends specialized equipment to Australia
  • Search crews can use manned and unmanned vehicles to hunt for plane
  • Autonomous vehicles can search for long periods and works with sonar
  • Remotely operated vehicles are tethered, have claws to pick up debris

(CNN) -- The fate of Malaysia Airlines Flight 370 may no longer be a mystery: The Malaysian Prime Minister said Monday the flight went down somewhere in the southern Indian Ocean.

But for search crews, the announcement is just the beginning.

Their work now begins in earnest as teams step up their hunt for the plane and for clues about what exactly went wrong.

Ian MacDonald, a professor of oceanography at Florida State University, spoke to CNN's "The Lead With Jake Tapper" about how such a search would work.

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"The first task is to look from the surface, to use listening devices as we heard, and then sonar and swath mapping techniques to try to locate anomalous debris fields, anomalous objects on the bottom and try to zero in based on that," he said.

"But, ultimately, you have to go to the bottom of the ocean and search ... in a nested way, starting in a big area and honing in as the evidence begins to indicate where the debris might be."

Crews could use manned and unmanned vehicles in that next stage of the search.

One example of a manned craft is the Jiaolong -- one of the deepest diving research submersibles in the world. The Chinese took it to a depth of more four miles in 2012, MacDonald said, indicating that country's capabilities for deep ocean operations.

China has a particularly large stake in the search for Malaysia Airlines Flight 370: Its citizens made up about two-thirds of the passengers on the missing Boeing 777.

"I would not be at all surprised to see the Chinese take a very active role in trying to locate this aircraft, MacDonald said.

He also considered two types of unmanned vehicles -- autonomous underwater vehicles and remotely operated vehicles.

"Operators program a search pattern and then the vehicle is deployed," he said of the autonomous technology. "It dives to the bottom, usually operates about 100 feet or more off the bottom, and looks with sonar and other listening devices and tries to find the debris.

A policewoman watches a couple whose son was on board the missing Malaysia Airlines Flight 370 cry outside the airline's office building in Beijing after officials refused to meet with them on Wednesday, June 11. The jet has been missing since March 8. A policewoman watches a couple whose son was on board the missing Malaysia Airlines Flight 370 cry outside the airline's office building in Beijing after officials refused to meet with them on Wednesday, June 11. The jet has been missing since March 8.
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"So, it goes back and forth -- mowing the lawn -- and it can operate autonomously for periods of up to 24 hours, and then it's recovered and the operators download its data and try to see if they've located something," MacDonald said.

Pentagon spokesman Rear Adm. John Kirby said Monday that U.S. Navy equipment is en route to Australia to be used in case a debris field is found.

The Navy's Towed Pinger Locator 25 is able to locate flight recorders on downed aircraft to a maximum depth of 20,000 feet. The Bluefin-21 autonomous underwater vehicle has side-scanning sonar, which is useful in a debris field if there are underwater objects that need to be researched, Kirby said. It can operate at a depth of up to 14,700 feet.

Similar technology was used successfully in the hunt for Air France Flight 447, which disappeared in June 2009.

It took four searches over the course of nearly two years to locate the bulk of that wreckage and the majority of the 228 bodies in a mountain range deep in the Atlantic Ocean.

Once the wreckage has been located, MacDonald said crews could turn to using remotely operated vehicles.

They have an umbilical cord, which runs from the vehicle to the surface.

"The pilots can see what the ROV is seeing in real-time. They have mechanical arms, with claws and lifters that can untangle debris," he said. "The ROV technology would be crucial for manipulating the wreckage and untangling this mystery."

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