The Difficulties of Maritime Salvage

In 1990, Todd Robinson’s Tampa, Fla., maritime salvage firm found and recovered the cargo of an ancient Spanish galleon in 1,500 feet of water in the Caribbean Sea. But he is not that optimistic about the prospects of locating the debris from Trans World Airlines Flight 800.

“You have to remember they weren’t given an X on the map” to show them where the pieces are, Robinson said of the Texas company that is actually handling the Flight 800 job. “It’s a big ocean out there,” he said. “There are no giveaways on the surface.”

Other experts, both in the military and in the salvage industry, agreed. While the recovery crews have had their problems--an underwater camera on a police department inquiry failed to work on Sunday, for example--analysts asserted that the task is more daunting than it seems.

For one thing, experts cautioned, the sheer size of the area where the debris has scattered means that it probably will take search vessels a considerable time to locate all the missing pieces.

“You’ve got an expanded search area and you’re not going to cover more than a couple of square miles a day,” Robinson said. “You could even wind up with a ‘box’ of a couple of hundred square miles.”

For another, even after the aircraft sections are located, hauling them up is a delicate job, one that is bound to take time if the company is to avoid damaging key sections. And although the shallow depth may seem a blessing, it poses more problems with currents than deeper water.

The outlook is not entirely gloomy. Divers made important progress Monday, locating a “field” of assorted parts from the jumbo jet, which exploded and plunged into the waters off Long Island, N.Y., last week, killing 230 people.

The Grasp, a specially equipped Navy salvage ship that is able to raise heavy loads from the ocean floor and cut them apart if needed for closer examination, arrived in the New York area late Monday to help. Officials said that it would begin work early today.

Lee Brown, a spokeswoman for Oceaneering International, the Houston company that is carrying out the salvage operation, said that--despite Monday’s fortunate discovery--the firm itself is not expecting miracles.

“Some of the operations we have done have taken months,” she said. A few years ago, the company painstakingly raised a military helicopter virtually intact from 13,000 feet of water off the coast of Somalia--an operation conducted an inch at a time.

Moreover, off Long Island the salvage crew must follow priorities set by the National Transportation Safety Board, which is overseeing the investigation of the accident, and the Federal Bureau of Investigation, which is looking into the possibility of terrorist action.

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“The first two days, [the priority] was to recover floating debris and human remains,” Brown said. “Our second priority was to locate the black boxes. And our next priority was to pinpoint debris on the ocean floor, to map out and visually identify the target.”

The Pirouette, a commercial salvage ship that the Navy chartered during the initial phase of the operation, enabled investigators to deploy three pieces of equipment designed to help locate the fuselage and other parts:

* A pinger-locater system--a cylinder-shaped, 5-foot-long sonar set towed from the ship and designed to locate the emergency beacons that are automatically transmitted by electronic devices on key parts of the fallen aircraft, such as the flight-data recorder.

* An Orion search system, a special side-scan sonar that maps the ocean floor to a depth of 20,000 feet and then pinpoints--and photographs--both the location and the pattern of the aircraft’s debris.

* A mini-ROV--a miniature robot submarine that can search a particular stretch of water inch by inch, from the surface to a 1,000-foot depth, producing high-resolution television images of whatever it finds.

The search is being conducted methodically, by apportioning the stretch of ocean over a grid and then meticulously sweeping each section with sonar. Divers are sent down wherever authorities believe it is feasible.

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When investigators find a section of the fuselage and want to raise it to the surface, divers will attach salvage lines to haul it out. If the part appears to be fragile, they may use huge nets to help keep it intact.

Barrie Walden, a salvage expert at Woods Hole Oceanographic Institution in Massachusetts, said that such jobs are “considerably more difficult than people would anticipate”--particularly the current operation.

Not only was the Boeing 747 huge, it exploded at an altitude of about 13,000 feet, Walden notes, suggesting that it probably spewed debris over hundreds of square miles. And the jet is not the only thing on the ocean floor. There are wrecks of all sorts from the past.

Contrary to public perception, having the wreckage in shallow water is more a hindrance than a help. Currents are more difficult there than deeper out, while high-resolution video cameras--which produce clear images in deep water--do not work as well.

As a result, Walden said, searchers have to work with sonar, which is far less precise and requires more experienced personnel to operate. Almost every sounding is subject to a variety of interpretations.

Finally, there is the added requirement that the debris be brought up nearly intact, so that federal investigators can study it in detail.

Some analysts worry that key chemicals and other potential clues contained in the fragments already have been washed away by currents. “You need to make careful plans before you disturb anything,” Walden says.