Jim Dawson and Devin Powell
Inside Science News Service

As search crews found debris fields Tuesday in the area where Air France flight 447 apparently crashed into the Atlantic Ocean, John Perry Fish was waiting for the phone to ring. Fish's company, American Underwater Search and Survey on Cape Cod, was involved recovering pieces of the 1996 TWA flight 800 crash in the Atlantic and the 2002 crash of China Airlines flight 611 over the Taiwan Strait. He described the difficulties and procedures needed to find the remains of Air France flight.

"The water is deep in that region," he said, “some 7000 meters deep in the deepest parts, but averaging about 4000 meters. It is near the mid-Atlantic ridge, [an undersea mountain range] which runs from Iceland to the south Atlantic."

FINDING THE SPOT

The first problem in finding the debris and black boxes from the plane, he said, is that the aircraft was not being tracked on radar when it disappeared, "so you don't know exactly where to start. If you have a radar track, you can plot an area of a couple miles out from that point and start searching."  Without the radar, he said, the task is to find the floating debris and do "hindcasting," which traces the path of debris backwards as it floats on the ocean currents.

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