Plumbing the depths of disaster

Plumbing the depths of disaster
Date:1 August 2011 Tags:,

Air France flight 447 disappeared off the Brazilian coast in June 2009 with 228 people on board, leaving little but questions behind (“Anatomy of a Plane Crash,” January 2010). French aviation authorities needed to find the wreckage, especially the plane’s black boxes, to figure out what happened. Only problem: the impact site lay somewhere beneath a 150-kilometre-wide expanse of ocean.

The French called on their military and international oceanographic researchers to deploy submarines and an array of remotely operated vehicles. But the most powerful subsurface assets proved to be three Remus 6000 autonomous underwater vehicles, or AUVs. These torpedo-shaped robots can travel up to 22 hours at a stretch, systematically scanning the seabed with sonar that images a kilometre-wide swath with every pass. “The only way you’re going to be able to find an aircraft in deep water is by using this type of wide-area survey capability,” says Dominique Rissolo, executive director of the Waitt Institute, the nonprofit organisation that owns two of the AUVs used in the search. After two years of on-and-off searching, AF 447 remained lost. So the authorities revised simulations of ocean currents and looked in a new area. Just a week after reaching the new search zone, a Remus AUV launched from the vessel Alucia (below) found the wreckage, 4 000 metres down. – Jeff Wise

The searchers
Here are three submersibles that took part in the hunt for the doomed Airbus A330-203:

Emeraude
Type: French nuclear-powered attack submarine
Maximum rated depth: 500 metres
What it did: Listened for pinging of black box acoustic beacons
Sensors used: Hydrophones, sonar

Remora 6000
Type: Remotely operated vehicle
Maximum rated depth: 6 000 metres
What it did: Recovered black boxes
Sensors used: Scanning sonar, CCD camera

Remus 6000
Type: Autonomous underwater vehicle
Maximum rated depth: 6 000 metres
What it did: Searched and identified wreckage on the seafloor
Sensors used: Sidescan sonar, camera with strobe

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