A French nuclear sub launched a high-tech undersea sweep on Wednesday to track down the black boxes missing after an Air France flight plunged into the Atlantic.
The Emeraude, a nuclear hunter-killer submarine, will use its sensitive sonar to probe the ocean depths off Brazil in a desperate race to find the flight data recorders before their locator beacons run out of power.
If the boxes are not recovered within three weeks they might be never be found, complicating the investigation into to the loss of Air France Flight 447 from Rio to Paris, which crashed on June 1 with the loss of 228 people.
”The Emeraude will begin its patrol this morning, in a first search zone measuring 20 nautical miles by 20, that is to say 36km by 36, which it should cover in a day,” said military spokesperson Captain Christophe Prazuck.
”It will change zone each day and no time limit has been set,” he said, adding that the Emeraude would be joined in the area by the Mistral, a naval command and control vessel equipped with helicopters.
Brazil already has a large naval and air force contingent in the crash zone, which has recovered some plane debris and at least 41 bodies, and the Pentagon has sent sonar gear to help in the search.
French officials acknowledge the search will not be easy.
The black boxes are thought to be in waters as deep as 6&nsp;100m and 1 150km from the Brazilian coast.
”We’ll need a major strike of luck, since we don’t know exactly where the flight went down, but it’s worth a try,” a military official said last week.
If the Emeraude does locate the signal, the French scientific research vessel Pourquoi Pas will launch a mini-submarine — one which was used to survey the wreck of the Titanic — to retrieve the recorders.
”The Emeraude will operate a bit like an airship hovering over a mountain chain and searching with binoculars,” Captain Jerome Erulin, spokesperson for the French navy, said in Paris.
In this case the role of the ”binoculars” will be played by the Emeraude‘s passive sonar, sensitive underwater microphones designed to hear enemy nuclear missile subs patrolling almost silently through deep waters.
Preparations were also under way to equip two tugboats with underwater pinger locations on loan from the US military that could pick up locator signals.
It is hoped the black boxes — in reality bright orange, and designed to emit a locator signal for at least a month after a crash — hold clues as to what brought down the Airbus A330 as it flew through a storm.
No distress call was received from the pilots, but a series of 24 electronic warnings were sent automatically by the twin-engine airliner in its final four minutes as its flight systems shut down one by one.
These showed the cockpit was getting faulty airspeed readings and that the autopilot was suddenly disengaged. Navigation and power systems also failed.
The messages have focused suspicions on the plane’s exterior airspeed sensors, known as pitot probes.
There is speculation the tubes may have iced up during a storm at high altitude, leaving the Air France pilots to guess how fast they were going as they flew into a fierce and disorienting Atlantic storm.
If the pilots were flying too slow the airliner could have stalled, or if they pushed the Airbus too fast it could have ripped the airframe apart, aviation experts say.
Airbus and Air France say older pitot probes have been problematic on other Airbus A330s and A340s, and the French airline has stepped up a programme to install a newer type after pilots’ unions threatened to refuse to fly.
The European air safety agency said Tuesday that Airbus models were ”safe to operate,” but added that a bulletin had gone out to remind airlines of what to do ”in the event of loss of, or unreliable, speed indication.”
The first 16 of the 41 bodies so far recovered arrived on Tuesday at Fernando de Noronha. The other 25 were on their way to the islands.
Once photographed and inspected for distinguishing features such as tattoos, piercings or unique physical characteristics, the remains were to be flown to the mainland city of Recife for formal identification.
That process was to involve DNA samples from relatives. Interpol is assisting because of the 32 nationalities on the flight. — Sapa-AFP