Airliner "black boxes" record flight data and cockpit voice transmissions that could shed light on how a Malaysia Airlines Boeing 777 with 239 people on board seemingly vanished in Southeast Asia.
Rescue teams are in a race against time to locate the black boxes if indeed Malaysia Airlines Flight MH370 crashed. The black boxes emit signals or "pingers" that can be detected many miles away, but they can weaken in just days.
But the waters the flight is suspected to have crashed is shallow, according to ABC News consultant and former Deputy Assistant Secretary of State Col. Steve Ganyard.
"It's fairly shallow South China Sea water and so I think we do have a good chance of hearing those pingers - those under-water pingers that the black boxes have that will allow us to go out and find the wreckage somewhere between Vietnam and Malaysia," he said.
Air France Flight 447 disappeared over the Atlantic Ocean en route from Rio de Janeiro to Paris on June 1, 2009. Some wreckage and bodies were recovered over the next two weeks, but it took nearly two years for the main wreckage of the Airbus 330 and its black boxes to be located and recovered.