The French navy has located the black box flight recorders from the jet which plunged into the Atlantic killing 228 people last summer, including Co Down doctor Eithne Walls.
However officials said there was still no guarantee the recorders, which could explain the cause of the crash, would ever be brought to the surface.
Flight AF447 went down off the coast of Brazil on June 1 last year. Among the victims was Ms Walls, a 28-year-old doctor from Ballygowan.
Ms Walls, who had performed in Riverdance on Broadway and was pursuing her ambition to become an eye-surgeon at the Royal Victoria Eye and Ear hospital in Dublin, was en route from Rio De Janeiro to Paris when the plane crashed into the Atlantic.
She was travelling with two friends, Aisling Butler (26) from County Tipperary and Jane Deasy (27) from Dublin, both of whom were also doctors.
A search last year found several chunks of wreckage and 50 bodies, but the reasons behind the crash have never been fully explained.
The black boxes have now been located with a ‘margin of error' of three nautical miles, more than 700 miles off Brazil's north-eastern coast.
They are fitted with locater beacons, known as pingers, which transmit an electronic pulse every second, but only for around 30 days before their battery runs out.
France's deputy defence ministry spokesman General Christian Baptiste said: “It is in no way certain we are going to retrieve the black boxes because they are not giving off a signal any more and the zone where they are is very rugged terrain.”
There were also doubts over whether vital information on the boxes has been preserved after almost 12 months underwater, the defence ministry said.