Tests Fail to Find Cause of TWA Crash Yet

Careful analysis of sounds from the TWA Flight 800 cockpit-voice recorder and tests on wreckage have failed to provide definitive clues about the crash, investigators said Monday, as hopes dimmed about finding the cause of the explosion soon.

Robert Francis, vice chairman of the National Transportation Safety Board, said a painstaking study of sounds heard by a microphone designed to pick up all the sounds in the cockpit “found no acoustic evidence regarding the source of the catastrophic event.”

“It is doubtful,” he added, “that the cockpit-voice recorder alone will be definitive in determining the cause of this catastrophe.”

Joe Cantamessa, the agent in charge of special operations for the FBI field office in New York, said various pieces of wreckage have been reviewed by federal law enforcement experts in Washington, and “nothing’s come back conclusive.” Those experts are looking for chemical and other indicators of an explosive device.

“That information is sent down to the lab in Washington where some serious equipment is used to perform an analysis, and none of the serious analysis that has been performed so far has come back with anything that can confirm the presence of some particular item that everybody has been looking for,” Cantamessa said.

Preliminary field tests had indicated “a positive chemical presence,” he said. But those tests “are not done in ideal conditions.”

There is general agreement that the Boeing 747 jetliner was torn apart by a violent explosion that was followed 24 to 36 seconds later by a giant fireball. The July 17 tragedy killed all 230 people on board.

Two other possibilities of what might have caused the blast--some sort of mechanical failure or a missile fired at the plane--have been largely discounted.

As of Monday evening, 161 bodies had been recovered, and Francis said divers have seen more bodies but could not immediately retrieve them because they are entangled in underwater wreckage. He was optimistic that these and other bodies would be recovered soon.

Some family members of still-unrecovered victims expressed new frustrations Monday, saying they believe officials are concentrating more on retrieving wreckage than on recovering bodies.

To allay those concerns, Francis met with family members again Monday and told them that recovery of victims is still the operation’s No. 1 mission.

“All of the divers continue to prioritize their work on victim recovery,” he said.

Although Cantamessa said the bodies of some victims who had been seated in the front of the plane showed very severe injuries, he added that it was premature to suggest that those injuries were worse than the ones suffered by people in the rear of the plane.

Investigators said the type and severity of the injuries could provide a clue as to where a bomb might have gone off.

The plane is thought to have broken in two moments after the explosion, possibly near where the first- and business-class sections are divided from the coach section. In the bombing of Pan Am Flight 103 over Lockerbie, Scotland, a small explosive device had been placed in a cargo hold underneath the front of the plane.

Francis had said earlier that the cockpit-voice recorder had picked up a “loud sound” just before it went dead. It had been hoped that analysis would show that sound was a bomb, perhaps even revealing what type of bomb and where it was located on the plane.

But the NTSB official said Monday that the one microphone reading studied thus far had not been definitive. It was not known whether readings from the recorder’s other microphones would be more revealing.

Cantamessa said some promising leads already have dried up for investigators. For instance, he said, pit marks on the some of the bodies, which at first were thought to be from bomb fragments, were later determined to be caused by seawater and oxidation.

And he said a prediction by his boss, FBI Assistant Director James K. Kallstrom, that an explanation for the tragedy could come as early as today is diminishing. Even as debris is brought to the surface, Cantamessa said, it now is “more than likely” that it will then take days of analysis both here and in Washington before any conclusive results are reached.

He said investigators continue to be frustrated that they have not gotten critical parts of the debris, most specifically ones from where it is believed the plane split apart.

“That’s the particular area we’re interested in,” Cantamessa said.