The NTSB’s finding, in a letter to the FAA, did not definitively rule out the lingering possibility of a bomb or missile attack. But the agency said its reconstruction of the downed plane strongly suggested that the first explosion occurred inside the 747’s center fuel tank, rather than in the cabin or baggage hold. That fact alone almost eliminated the possibility of a bomb on board, since it would be very difficult for terrorists to place a bomb inside the tank itself. Further, the NTSB said, exhaustive examination of the rest of the recovered wreckage showed “no evidence of bomb or missile damage.”
The billion-dollar question is what exactly caused the explosion–and NTSB investigators offered a three-step technical guess. One element was fact: the center tank contained less than 100 gallons of jet fuel on the night the plane, a Boeing 747-100, took off from New York’s Kennedy airport. That meant the fuel had plenty of room to vaporize in the nearly empty tank. The second element, also fact, is that the center fuel tank on a 747 is directly above the plane’s air conditioner. All air conditioners emit heat, which could have warmed the fuel vapor to potentially explosive temperatures. The third element was a hunch–that a random electrical spark then touched off the massive explosion. The NTSB wasn’t sure where such a spark came from, although its technical experts said that the fuel itself, by sloshing through a pipe in the center tank, could have built up enough static electricity to ignite the vapors. The problem with the static-electricity theory is that the NTSB has no evidence to back it up. So the case for an accidental explosion is by no means proven.
Still, the NTSB’s findings are dynamite–a potential financial disaster for Boeing Aircraft Corp., which could wind up with hundreds of millions in civil-liability claims from the families of Flight 800’s 230 victims, and a massive burden for the FAA and the airlines that fly 747s. Essentially, the NTSB urged the FAA, which alone has authority to order safety improvements, to consider a massive retrofit. One goal would be to prevent jet fuel from being overheated by the air-conditioning equipment–a complex task that could cost millions. As an interim precaution, NTSB also urgently recommended that 747 fuel tanks be kept filled with cool fuel and that pilots be advised to monitor fuel-tank temperatures. “To me, it was a recommendation only,” a Boeing official said. “They still have no proof of anything.” An FAA spokesman, Drucella Anderson, said agency officials were “already on it” but did not yet know what action would be taken or how many airplanes would be affected. But after the ValuJet controversy, the FAA may feel forced to take a hard line.
Worse yet, the NTSB also indicated that 747s may not be the only commercial jets that have air conditioners next to a fuel tank: in a footnote, its letter mentioned the Airbus A-320, built by a European consortium, as having the same design. All this can only make white-knuckle fliers more fearful. If TWA 800 was an accident–even a million-to-one freak accident–it could theoretically happen again.
Last week the NTSB posed a new theory about what caused the midair explosion of TWA Flight 800 in July. The culprit: static electricity. A look at their hypothesis:
Small amount of fuel, 50 gallons, mixes with air–highly flammable
Units resting under tank heat the already volatile fuel mix to the flash point
Circulating fuel creates static-electricity spark, igniting tank
Sources: The Boeing Co.
Research by Dante Chinni–Newsweek
