TWA Flight 800's fuel tank exploded, causing the aircraft to break apart and crash shortly after departing John F. Kennedy International Airport on July 17, 1996 bound for Paris. All 230 souls on board were killed. Nine years later almost nothing has been done to prevent fuel tank explosions from occurring in the currently operating commercial fleet despite the FAA's development of a relatively simple system called fuel inerting, which makes fuel vapors less likely to ignite.

The FAA announced at a press conference in 2004 that the system, which consists mostly of a three-foot plastic tube, would be required to be installed in all airliners in service and new aircraft being built and designed. The device replaces oxygen inside the fuel tank with an inert gas, nitrogen. Although some progress has been made for new aircraft being built, including the 787 Dreamliner by Boeing, the FAA has yet to issue a formal requirement for the device to be retrofitted into aircraft already in service.

This issue remains on the NTSB's Most Wanted List. According to that list, the actions remaining are:

��To complete rulemaking efforts to preclude the operation of transport category airplanes with flammable fuel/air vapors in the fuel tank on all aircraft and

��To promote operational changes to reduce the generation of flammable fuel/air vapors in aircraft fuel tanks.

The Most Wanted List goes on to state that "the prototype inerting system that FAA developed required no moving parts, weighed less than 200 pounds, and could be retrofitted into existing airplanes at a fraction of the industry-estimated cost.�The system has been flight tested by the FAA, Boeing, and Airbus, and the results indicate that fuel tank inerting is practical and effective."

Actual installation of flammability reduction systems on current aircraft is several years away. In the interim, the FAA has indicated that it is not pursuing any further recommendations or rules to use operational means to reduce flammability. Concern remains that realizable reductions in fuel tank flammability are still several years away. Some estimates put the cost of installation of the inerting system at around $200,000 per aircraft. The FAA has said that approximately 3,800 aircraft need the modification.

The FAA maintains that although it has not implemented a formal requirement for inerting systems to be installed, it has worked to eliminate part of the fuel tank explosion problem by requiring the removal of ignition sources such as sparks and faulty wiring from the tank. But according to the Most Wanted List, the Board has urged the FAA to proceed as quickly as possible to require that these inerting systems be installed in new transport category aircraft, and that these systems be required in currently operating aircraft.

- By Joy Finnegan