WASHINGTON -- As divers recover the final bits of wreckage from TWA Flight 800 on the ocean floor, the leading investigators in the case briefed senior government officials yesterday on their options for the investigation's next stage, including scanning the bottom with sand-penetrating sonar and then scouring it with clam rakes or giant vacuum cleaners.
In a 3 1/2 -hour session, investigators from the National Transportation Safety Board told officials from the White House, FBI, Federal Aviation Administration and other agencies that they still have found no firm evidence of a bomb, though they have not finished analyzing the twisted, torn parts already in hand in a hangar in Calverton, N.Y.
With about 95 percent of the wreckage recovered, they also have a clearer idea of what they still lack, including parts of the center fuel tank and two areas of the plane's belly between the wings, one on each side.
James E. Hall, NTSB chairman, said he hoped the investigators would be able to retrieve everything they needed by conventional means. But with the end of the salvage operation expected in seven to 10 days, the Navy told the group yesterday that it was time to lay out other options.
After the briefing, James K. Kallstrom, the head of the FBI's New York office, who flew to Washington for the session, said the 11-week salvage effort has still not recovered "the Eureka piece" -- the piece that he and others have hoped to find that would show what destroyed the plane.
Nonetheless, he said, "We are still optimistic that we will find the clue to what happened here."
In a windowless conference room at the safety board's headquarters, board investigators showed diagrams and charts. They also showed a picture of a missing fuel pump from the center tank under the label, "Wanted," as if it were a bank robbery suspect.
The investigators also stressed that they have one of the fuel gauges from the main tank but would like to find the other six, or identify them from parts already in the hangar. Any of these objects could, in theory, have set off an explosion in the center fuel tank, though so far no one has found any evidence of that.
FBI Director Louis J. Freeh attended the meeting, as did Elaine C. Kamarck, who is a senior adviser to Vice President Al Gore and the staff official in charge of the White House commission on aviation safety and security.
Also attending were Kathryn Higgins, the secretary of the Cabinet; Linda Hall Daschle, the deputy administrator of the FAA; and Adm. Robert E. Kramek, the commandant of the Coast Guard.
Searchers are planning to try a new tool on the ocean floor: sonar that can see through an inch or two of sand and silt for parts that have been buried or heavily dusted with sand stirred by recent storms.
"The tides and storms uncovered and covered things," said one crash investigator, who asked not to be named. "Very light parts moved around as well," he said. "They're finding targets where there weren't targets before."
Law enforcement officials say telltale traces of a bomb or missile could be limited to a metal piece smaller than a legal pad, making the search for small parts more urgent. And the remaining parts of the center fuel tank are also mostly small. Investigators want that tank because it remains possible that the tank alone was responsible for the crash on July 17, which killed all 230 people aboard the Paris-bound Boeing 747.
Thus far, the searchers have used high-frequency sonar, which can find objects as small as a clam, but only if they are on the surface. The new equipment, which is low frequency, gives a fuzzier picture but penetrates the sand.
Pub Date: 10/03/96