July 15, 1997
Web posted at: 3:54 p.m. EDT (1954 GMT)
From Correspondent Christine Negroni
(CNN) -- It has been nearly a year since TWA Flight 800
crashed off the coast of New York, killing all 230 people on
board. Despite dramatic attempts to put together the puzzle
of the July 17 crash, investigators are still not sure
why it went down.
One theory is that volatile fumes in the plane's nearly
empty center fuel tank may have been heated to an explosive
point by air conditioner units while the plane sat on the
runway before takeoff. To test this theory, government
investigators sent a specially equipped Boeing 747 on the
first of a series of test flights this week.
The second flight, scheduled Tuesday, was designed to
replicate as closely as possible the amount of fuel in the
center fuel tank, and its temperature and pressure, said NTSB
spokeswoman Shelly Hazle.
The plane, a Boeing 747-100, is the same older model of the
747 as Flight 800 and is roughly the same age. Electronic
monitors mounted in the plane's center and wing fuel tanks
will record data during the flights.
Search for clues frustrating
The underwater search to retrieve the victims and the plane
was frustrating, and the search for the cause has been no
less so. While the safety board concentrated on what it
could learn from the plane's debris, hundreds of FBI agents
swarmed over Long Island, checking out eyewitness reports of
a light streaking toward the plane and acting on a collective
gut feeling that the crash was a terrorist act.
"It was a big event, a 747 inside the U.S. If it was an act
of terrorism, if it was state-sponsored, it was an act of
war," FBI Assistant Director Jim Kallstrom would later
Even NTSB Chairman Jim Hall admitted at a congressional
hearing that he initially thought the crash would prove to be
a deliberate attack, and that the
investigation would be taken over by the FBI. "Like many
Americans, I thought it might be a bomb," he said.
Science suggests non-criminal cause
As investigators reconstructed 90 feet of fuselage,
fired missiles at wreckage and set other test explosions,
sophisticated science steered the investigation away from a
criminal cause. Autopsies of the passengers showed no
evidence that a bomb or missile had gone off inside the
Instead, investigators found that the plane's air
conditioning units, located directly below the fuel tank, had
been running for three hours -- all the while, heating the
vapors inside the tank. By the time it was airborne, there
was an explosive brew in the belly of the plane.
Thirteen minutes after takeoff from New York's John F.
Kennedy International Airport, the jetliner exploded in a
fireball over the Atlantic Ocean.
"The plane essentially unzipped," Hall said, "creating a
downward force that broke the backbone, or the keelbeam, of
the plane, and the nose separated, and all that happened
quicker than I've been able to explain it."
Airplane safety depends on keeping ignition sources away from
the tank. Now, investigators hope to determine whether
flying with a volatile fuel mix is safe.