Click to play videoParis: The United States of America has also joined in the search operations for black boxes of Air France's AF 447 flight that crashed over the Atlantic Ocean on June 1.
French nuclear submarine Emeraude arrived in the area on Wednesday to begin search for sonar locator signals from the black boxes which were built into the tail of the aircraft.
But the search area is a huge 77,000 square miles and the submarine can only reliably cover about 400 square miles a day because the range of the black box signals which is limited to about 2,000 yards.
To help in the search, the US navy has flown in two pinger locators. The plan is to systematically cover the ocean floor with the two tugs and the sub hoping to pick up the the signals from the black boxes, if they survived the crash and are emitting signals.
The spokesman for the French military said he was not confident it will work,
but they had to try anyway despite the odds against finding them.
"We know the sea floor is rough and there are mountains and canyons and so anything could have happened to the black boxes. And the last thing, the black box is a small thing so its emission power is low, so its detection range is small. All these things are going against us but we will try," said Christophe Prazuck.
Prazuck said that if the data recorders can be pinpointed, the search operation will become one of recovery.
The French research vessel Pourquoi Pas, which translates as "why not", is on its way with a manned mini submarine which can be sent to depths as great as 18,000 feet, just shy of the deepest level in the area the plane went down.
The sub, best known for its dives to the wreck of the Titanic, would try to attach cables to bring the black boxes to the surface.
It is a complicated operation in the best of circumstances.
With so little information about what exactly caused flight 447 to go down, recovering the data recorders has become almost as important as recovering the bodies of those who died in the crash because the data recorders could provide the necessary information to prevent a similar crash and more deaths in the future.
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