By Jared Chausow
By Katie Toth
By Elizabeth Flock
By Albert Samaha
By Anna Merlan
By Jon Campbell
By Jon Campbell
By Albert Samaha
A spark is just one link in a chain. For an explosion to happen, a spark has to ignite all the fuel-air mixture in a very rapid burning reaction. But this cannot be counted on, especially in a large container like TWA 800's center tank, where there was so little fuel to begin with, and where temperatures varied widely. In such a situation, with some temperatures hovering down near 100oF, a small spark may simply have puffed and gone out, according to Kurt H. Strauss, a nationally recognized aviation fuel expert. Whether an explosion happened "would depend on total energy released when that ignition goes off," said Strauss.
Given that the tank exploded, the NTSB's rationale connecting the blast to the fuselage damage rests on surprisingly shaky ground. According to Jon Hjelm, a Federal Aviation Administration engineer and member of the Sequencing Group, who contributed pages of stress calculations as a kind of reality check on the deliberations of the group, an enormous force, equivalent to more than the thrust produced by one of the 747's jet engines, acted on the bottom of the tank to produce the cracking that sundered the fuselage in front of the tank. Hjelm said he came up with his figure for this force using assumptions he made about the distribution of the pressure from the explosion.
Hjelm said that in order for his calculations to confirm the breakup sequence, he made another assumption. The force had to remain, pushing down inside the tank, after the explosion had ruptured the front of the tank. For how long? "Maybe some number of seconds. Way more than one second," Hjelm said. What if the the pressure all dissipated in under one second? Hjelm said, "That's a question I feel uneasy to deal with." Yet according to the results of the NTSB's own explosive testing and scientists questioned by the Voice, not to mention the account of the breakup sequence given by Sequencing Group chairman Jim Wildey at the NTSB's Baltimore hearings in 1997, the initial explosion was certainly over within one second.
Wildey said in Baltimore that the Sequencing Group had relied upon Hjelm's calculations, which constitute apparently the only available engineering analysis of the breakup sequence. Boeing (according to its submission to the NTSB) did not complete a project to create a computer model of the breakup.
Dr. David Mayer, who holds a doctorate in applied experimental psychology, drew on studies by psychologists to suggest that influences acting on eyewitnesses in the aftermath of the crashthe chatter of friends, TV reports, even the leading questions of the FBI agents who interviewed themmight have led them to embellish their memories of the crash.
And when they reported seeing the initial explosion, which the NTSB says was contained "inside an intact airplane," and thus could not have been visible to witnesses miles away, that was understood by investigators not as a reason to reexamine their theory, but to assume the witnesses must have been mistaken. Thus the accounts even of seasoned airline pilots who reported to air traffic control (ATC) in the first moments that they saw the plane explode were essentially discounted.
In this regard, there is an unexplained apparent discrepancy between the account of the pilot who first reported an explosion and the official ATC transcript. According to the transcript, Captain David McClaine of Eastwind Airlines reported the explosion at 8:31 and 50 seconds, which is 38 seconds after the NTSB says the plane exploded, at 8:31 and 12 seconds. But McClaine states in a written account he gave the Witness Group that after the explosion he "immediately called Boston ATC and reported an inflight explosion out over the water."
When he was questioned by the group, he said in answer to a question from Mayer that roughly 10 seconds passed after the explosion before he made his first radio call to ATC. Ten seconds seems a reasonable pause between seeing something so dramatic and doing something about it. Thirty-eight seconds appears rather long to wait before making the call to air traffic control. But the apparent time lag could be used to support the notion, suggested by both the NTSB and the CIA, that McClaine, for example, saw only a later stage of the airplane's breakup, not the initial explosion.
As for those witnesses who saw a rising streak of light, Mayer said they probably saw the burning plane climb after the explosion. When the chairman asked him, if the plane did not climb, would that affect his analysis? Mayer said no, it wouldn't. "But we believe it climbed," he said. However, McClaine had been closely questioned about this very issue by the Witness Group, and repeatedly said the plane did not climb; he saw only falling debris after the explosion.
Investigators said, when they first examined the two "black boxes" a week after the crash, that neither device provided clues to explain what what happened. But there is indeed a marked sound signature, lasting less than two-tenths of a second, on the cockpit voice recorder (CVR) tape. That signature has never been explained, leading the Air Line Pilots Association in its submission to the NTSB to bemoan the lack of follow-up after a series of tests done in Bruntingthorpe, England, in 1997. The submission notes that research done at the University of Southampton shows that analysis of a sound signature can yield information about the type of explosion (whether a high explosive detonation or a lower-energy fuel-air explosion) and its location within the fuselage.