The National Transportation Safety Board has asked the Federal Aviation Administration to describe any short-term actions it is contemplating in response to an urgent NTSB safety recommendation aimed at avoiding airliner fuel tank explosions similar to the one that downed TWA flight 800, which crashed nine years ago last Sunday. The Board sent a letter to FAA Administrator Marion Blakey last week.
In announcing the Board’s action, Acting Chairman Mark Rosenker noted that the FAA had achieved significant success in eliminating potential ignition sources in a number of aircraft models. “However, it is disappointing nine years after the tragedy of flight 800 that fuel tanks are as flammable today as they were in 1996, and particularly disheartening that the FAA has done almost nothing on this urgent recommendation.”
On July 17, 1996, TWA flight 800, a Boeing 747, crashed minutes after takeoff from New York’s John F. Kennedy Airport on a flight to Paris. All 230 persons aboard the plane died in the accident. The Board determined that the accident was caused by an explosion of the center wing fuel tank (CWT), resulting from ignition of the flammable fuel/air mixture in the tank.
Five months after the crash, in December 1996, the NTSB issued two safety recommendations aimed at reducing flammable fuel/air mixtures on airliners. One recommended short-term actions in airplane operations that could immediately reduce the levels of these flammable mixtures, while the other called for design changes that would understandably take years to implement. Both recommendations were placed on the Board’s Most Wanted list of Safety Improvements the following year.
Five years after the TWA crash, the NTSB participated in the investigation of another center wing tank explosion, this time of a Thai Airways 737-400 in Bangkok, Thailand in March 2001. The airplane, which was sitting on the ground at the time, was completely destroyed, and a flight attendant was fatally injured. Again, the presence of flammable fuel/air mixtures in the center wing tank was responsible for the accident.
There has reportedly been little action by the FAA in response to the Board’s short-term recommendation. In 2000, the FAA concluded that operational changes that used ground-conditioned air instead of running the airplane’s on-board air conditioning system while on the ground could reduce flammable fuel/air mixtures in center wing tanks, and requested its inspectors to encourage airlines to follow this procedure. However, the FAA did not require airlines to comply with this procedure.
At the Safety Board’s request, FAA staff surveyed airlines last year to determine whether the use of ground conditioned air had changed within the previous 5 to 7 years. The FAA found that only one airline had changed procedures to use ground conditioned air on all of its flights. It further found that 94 percent of daily airline flights do not exclusively use ground-conditioned air.
“Fuel tank explosions are rare events,” Rosenker said, “but as we learned in Thailand, TWA800 was not an isolated case. I urge the FAA to act quickly on our urgent recommendation to implement airline operational actions, including requiring ground conditioned air.
“Furthermore, I would remind everyone that we are still awaiting issuance by the FAA of a proposed rule announced 17 months ago that would require inerting of airliner fuel tanks. It is time for the FAA and its parent agency, the Department of Transportation, to issue this proposal as soon as possible.
“I hope the Safety Board won’t be asking these same questions as we approach the 10th anniversary of this tragedy.”
The Board will use the information submitted by the FAA when it reviews and evaluates the FAA’s activities associated with these and other recommendations on its Most Wanted List at a meeting later this year.
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