Investigators found more debris from the Air France jetliner that plunged into the Atlantic Ocean, but experts said the black box that holds the clues to the mysterious crash may never be recovered.
Rescue crews battling high seas and rough winds were headed toward the site to begin the grim recovery process while experts tried to figure out how the Paris-bound plane that took off from Rio de Janeiro carrying 228 people vanished over the open sea Sunday night.
New pieces of wreckage were found about 55 miles south of a three-mile trail of wreckage that included airplane seats, orange lifevests and a fuel slick had been spotted a day earlier.
Three Americans and an award-winning "Riverdance" performer were among the passengers on the ill-fated flight. A geologist from Louisiana and his wife of 16 years were feared dead in the crash. He was living in Rio and working for an Oklahoma-based energy company. A third American with dual nationality was also on board the plane.
Dancer Eithne Walls, 28, of Ireland spent more than a year performing on Broadway before taking up medicine. She was also a passenger.
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A man celebrating his birthday, a woman recovering from a brain injury and a group of 10 co-workers were among the 216 passengers and 32 nationalities on the flight, Reuters reported.
As four boats and a tanker ship sped toward the site, news surfaced that days before the crash of Flight 477 officials in Brazil delayed a flight from Buenos Aires to Paris because of a bomb threat -- but no explosives were ever recovered. There were no problems reported on board the Rio plane.
It's likely the plane went down so quickly the crew had no time to send a distress call -- the only communication was an automatic message reporting lost cabin pressure and electrical failure.
But without the black box -- two devices that include cockpit voice and instrument records -- the cause of the crash could remain unknown. The black box is designed to emit a sound for up to 30 days after it hits water from as deep as 14,000 feet. The ocean depth at the site believed to be the area of impact is 13,000.
But experts warned finding the black box could prove to be a Herculean task -- even more difficult than locating the wreckage of the Titanic.
"If you think how long it took to find the Titanic and that debris would be smaller, you are looking for a needle in a haystack," Derek Clarke, joint managing director of Aberdeen-based Divex, which designs and builds military and commercial diving equipment told Reuters.
The head of France's accident investigation agency, Paul-Louis Arslanian, also said he was "not optimistic" that rescuers will recover the devices, which are by now miles below the surface.