French nuclear sub searches for plane's black boxes

10th June 2009, Comments 0 comments

Submarines will try to locate the homing beacons from the data and voice recorders of the Air France flight that crashed into the ocean.

Fernando De Noronha – A French nuclear submarine is to begin a painstaking undersea search Wednesday for the black box flight recorders that could hold the key to the mystery behind last week's loss of an Air France flight over the Atlantic with 228 on board.

"The Emeraude will begin its patrol this morning, in a first search zone measuring 20 nautical miles by 20, that is to say 36 kilometres by 36, which it should cover in a day," said military spokesman 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.

The vessels will be scouring a vast area 1,100 kilometres (700 miles) off Brazil's northeast coast in order to locate the homing beacons from the data and voice recorders of flight AF 447, which plunged into the ocean 1 June en route from Rio de Janeiro to Paris in the worst air disaster since 2001.

Brazil already has a large naval and air force contingent in the area, and it has recovered some debris and at least 41 bodies.

Preparations were also underway to equip two French tugboats with underwater pinger locations on loan from the US military that could pick up signals from the devices, believed to lie on the seabed as deep as 6,000 metres (20,000 feet) below the surface.

If the signal is located, the French scientific research vessel Pourquoi Pas will launch a mini-submarine – the same one that found the wreck of the Titanic – to retrieve the recorders.

It is hoped the 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 area.

No distress call was received from the pilots, but there was a series of 24 maintenance data alerts sent automatically by the twin-engine airliner in its final minutes.

Those messages 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, said aviation experts.

Airbus and Air France said older pitot probes have been problematic on other Airbus A330s and A340s, and the French airliner has stepped up a programme to install a newer type of pitot probe.

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 Tuesday at Fernando de Noronha. The other 25 were on their way to the islands off Brazil's northwest.

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.

AFP / Expatica

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