Large Salvage Effort Fails To Detect Cause Of Air Crash Divers Plan To Search The Last Wreckage Area Today

Scuba divers began to wind down their three-month search for the shattered wreckage from Trans World Airlines Flight 800 Saturday, and, sometime today, the Navy will conclude one of the largest deep-sea salvage missions in United States history.

Despite more than 3,200 dives in an operation that retrieved 95 percent of the shattered jumbo jet and the remains of 214 of the 230 victims, investigators still do not know whether a malfunction or a criminal act caused the July 17 crash, which has evolved into a modern-day mystery.

Divers plan to explore the last wreckage area detected by side-scan sonar sometime today, Commander Gordon Hume, a Navy spokesman, said Saturday. Then, in a last-ditch effort to try to retrieve some important unrecovered fragments, a “scalloping” trawler will begin later this week to churn the ocean bottom for pieces of the jet that may be buried beneath silt and sand.

For the family and friends of the 16 victims whose remains have not been recovered, news of the approaching end of the salvage effort was disheartening, but they clung to hopes that the scalloping might turn up more bodies. The last victim recovered was found two weeks ago by a commercial fisherman trawling the ocean floor.

Since July 17, when the Boeing 747 exploded and crashed shortly after leaving Kennedy International Airport, the salvage operation off the southeastern shore of Long Island has recovered nearly all of the shattered Boeing, which amounts to the largest amount of wreckage ever retrieved at sea.

But federal investigators still have not determined whether a malfunction, a bomb or a missile caused the center fuel tank to explode.

The hunt for answers will now shift to a cavernous hangar in Calverton, N.Y., where investigators plan to continue reassembling thousands of pieces from the 92-foot-long midsection of the aircraft, the equivalent of a gigantic, three-dimensional jigsaw puzzle.

Described by investigators as an “airplane autopsy,” the reconstruction could take months to complete and is critical to any determination of the explosion’s source. Investigators say they hope the mock-up will make the cause emerge before their eyes.

Already, the close inspection of 200 tons of mangled wreckage has ruled out various scenarios, including a bomb planted in the baggage compartment or cockpit. But there are significant pieces of the plane still missing, including the sides of the center fuel tank. Several investigators last week talked more openly about their concern that some pieces would never be found.

But like the victims’ families, even the investigators are holding out hope that a few more important clues will still surface during the trawling operation in the coming weeks.

“As far as I know, we still have a lot of pieces that we have not found that we will still desperately need,” James K. Kallstrom, the assistant director of the FBI, said Saturday. “I think a lot of pieces have been buried by the hurricanes that came through. So I have some confidence that the dredging could turn up more of what we need.”

Kallstrom said that investigators had not found any clear physical indicators of a bomb on recovered pieces of metal.

Safety board investigators say that the lack of evidence of sabotage has convinced them that the buildup of jet fuel vapors in the center fuel tank was ignited by a spark, either from a defective auxiliary fuel pump or a fuel probe inside the nearly empty tank.

But although all the divers had been shown photographs of the auxiliary fuel pump, a beer-can-sized unit called a scavenge pump, the part has not been recovered.

In the face of one of the worst airline disasters in recent U.S. history, the Navy quickly embarked on one of its most ambitious salvage and recovery efforts, which ranks in scope with the recovery of the Challenger space shuttle in 1986, the clearing of the Suez Canal in 1974 and the cleanup following the bombing of Pearl Harbor in 1941.

Two aptly named salvage ships, the Grapple and the Grasp, were used to haul the larger chunks of wreckage out of the Atlantic.

In the first weeks after the crash, the 250-diver contingent - led by the Navy, with assistance from divers from the Suffolk County police and fire departments, the New York Police Department and the New York state police divers - focused on their first priority: the recovery of human remains. When no more remains were visible, divers then worked full-time on collecting pieces of the plane by hand and piling them into metal baskets.