Today, an armada of ships is converging on an area about 400 miles northeast of the Brazilian island of Fernando de Noronha. Some are carrying submersibles that can work miles underwater, all to start piecing together the disaster of Air France Flight 447, which disappeared over the Atlantic Ocean.
One expert said it could be the hardest recovery since the search to find the Titanic, which took decades. Underwater recovery expert John Perry Fish spoke to John Roberts on CNN’s “American Morning” Wednesday.
John Roberts: What will searchers be looking for at this point in their operation? And what kind of topography of the ocean floor are they going to be searching in?
John Perry Fish: The searchers are going to be looking for a very important piece of equipment called a digital flight data recorder… These record many, many parameters of the flight, the aircraft, its attitude, even the amount of force that one of the pilots might put on a pedal. And it’s very important to find these in order to find out what happened to the flight. Attached to each of these data recorders is what we call a “pinger.”
It puts out an acoustic pulse once a second for 30 days as soon as it's submerged in the water and these contacts are joined by electrical forces. So it's important to find these. And they'll be looking for these in an area that's fairly deep, as deep as a couple of miles and also part of the Mid-Atlantic Ridge, which is a mountainous area that runs all the way from Iceland down into the South Atlantic.
Roberts: Some people described it as trying to find a flight data recorder in the Rocky Mountains or the Grand Canyon.
Fish: That would be right. These are very small instruments and sonar used to image the topography may not be able to see that. But the “pinger” that is attached to it might be the key to finding it.
Roberts: How will they look for the “pinger?” The Navy is flying one of the Orion P-3 surveilance planes over the area. They’ve got some submersibles in the water. Will they all have their ears tuned to the frequency of this transponder?
Fish: The aircraft won't, but anything that’s submerged underwater that could sense the acoustic pulse, they will have receivers that are tuned to the frequency of this “pinger.”
Roberts: You're an expert in side-scan sonar… That's the way they located John F. Kennedy's plane off of the coast of Martha's Vineyard and the wreckage of TWA Flight 800 was found off of the coast of Long Island. In the type of ocean bottom you're talking about, you're an expert in this particular field, is side-scan sonar very effective?
Fish: Well, it's difficult if there's a lot of geology in the area. But side-scan is probably the best tool to try to locate the debris field of a downed aircraft.
Roberts: We talked a second ago about John F. Kennedy's plane, TWA 800, Egypt Air 900, they were all found in relatively shallow waters. The wreckage of the "Challenger" space shuttle was found in about a 1,000 feet of water. But we’re talking about a couple of miles of water here. 12,000 to 15,000 feet. Is it possible to find anything at that depth and with those crushing pressures too, which by some estimation would be 7,000 pounds per square inch?
Fish: That's correct. The pressure is high. But instruments are produced and designed and developed and we currently use them that work at those depths. One of the problems is getting the instrumentation down that deep requires long tote cables and it's very time consuming. So the fact that it’s deep water may increase the time it takes to locate the debris.
Roberts: The French authorities are pessimistic about finding anything. In 1987, the cockpit voice recorder from a South African Airways plane that went down off of the coast of Mauritius was found in 16,000 feet of water. If you were a betting man and based on your expertise, do you think they would find anything from the aircraft?
Fish: I do. I think it’s possible to find it. It's just going to take a little longer and require a greater effort working in this deep water. The South African Airways debris was located and Air India back in the '70s, I believe, was located in very deep water in the North Atlantic. So, I believe it can be found, it just will take a little longer.