A decade after a Paris-bound jumbo jet exploded in the night sky and plummeted into waters off Long Island's south shore, killing all 230 aboard, the airline industry and federal officials still are strikingly at odds over measures that safety experts say would have prevented the accident.
Trans World Airlines Flight 800 crashed minutes after takeoff from New York's John F. Kennedy International Airport after a spark ignited vapors in a fuel tank in the center of the Boeing 747's wing. Officials never pinpointed the source of the spark but suspected a short circuit transferred excess voltage into the tank.
The July 17, 1996, accident prompted one of the most expensive and far-reaching investigations in aviation history and changed the way airplanes' fuel and wiring systems are designed, operated and maintained.
To rule out terrorism and determine the cause of the crash, officials recovered 98% of the plane from the ocean floor and painstakingly pieced it back together.
But 10 years later, safety experts are frustrated that the primary cause of the accident -- the flammability of fuel tanks -- has not been fixed.
The Federal Aviation Administration says the problem must be solved to save lives. The airline industry, and airplane manufacturer Airbus, disagree, arguing that dozens of retrofits since 1996 adequately limit the risk of future explosions.
The FAA concluded last year that if additional steps weren't taken to modify fuel tanks perched just a few feet beneath passengers on thousands of aircraft, nine jets would "likely be destroyed by a fuel tank explosion in the next 50 years."
In November, the agency proposed a system that would pump nitrogen into center fuel tanks to replace oxygen, which is flammable. The measure, which the FAA says would cost up to $225,000 per plane to install, would affect 3,800 aircraft with center fuel tanks -- about half of today's fleet.
The nation's airlines call the system redundant, saying they have spent $1 billion since 1996 to comply with new FAA rules seeking to limit hundreds of vapor ignition sources that might blow up fuel tanks. And system installation and maintenance would exceed the FAA's upper estimate, costing an average of $420,000 per plane, the airlines say.
The dispute underscores increasing tensions between cash-strapped carriers and safety regulators.
"Economics drives safety changes; it always has," said Michael L. Barr, director of the USC School of Engineering's Aviation Safety and Security Program. "I think the science is there, but is the money there to do the science?"
The FAA proposal to reduce fuel tank flammability is aimed at preventing a "rare occurrence," safety experts acknowledge, but they say the added protection is worth providing.
"We're dealing with extremely low levels of probability, but that's the nature of the safety business," said John J. Hickey, director of the FAA's aircraft certification service. "Fuel tanks are far safer than they were 10 years ago, there's no doubt about that, but we still feel we need this added level of protection."
Regulators blame center fuel tank explosions for the destruction of three other airplanes in recent years: In 2001 and 1990, explosions before scheduled takeoff killed nine people total; and about 100 died in a 1989 blast.
After Flight 800 went down, the FAA issued more than 100 directives ordering airlines to overhaul wiring and to assess fuel tank systems to ferret out equipment or processes that could spark an explosion.
Two hundred previously unknown ignition sources were discovered as a result.
The accident revolutionized the way experts approached fuel tank safety: They concluded they would never be able to predict every malfunction or maintenance error that might ignite a fuel tank, and that realization led regulators to search for ways to reduce the flammability of fuel tanks.
In 2004, the FAA unveiled a system it had invented for eliminating oxygen in fuel tanks. (Military jets had such technology in the 1990s, but it was too heavy and expensive for commercial airplanes.)
FAA experts say their new system could prevent five of the nine FAA-projected jet explosions originating in fuel tanks. Already-tightened maintenance controls for wiring and other equipment should prevent the other four accidents, Hickey said.
In response to the FAA's proposed mandate of its system on numerous Boeing and Airbus models, airlines said the agency's analysis was flawed and the system's costs outweighed its benefits.
"This doesn't seem to be a smart use of our valuable safety dollars," said Basil J. Barimo, vice president of operations and safety at the Air Transport Assn., a trade group that represents most U.S. carriers. "We're focusing on an issue that is not a risk that is out there today and is potentially a distraction from what the real risks are."
And manufacturer Airbus said there was no evidence that fuel tank systems on newer airplanes -- Airbus started designing planes in 1971 -- presented the same problems as older models. Flight 800's jet dated to 1971.
"This system does add a lot of weight and makes airplanes more expensive to operate," said Airbus spokesman Clay McConnell. "Ultimately, it makes air travel more expensive for passengers by solving a problem we don't believe exists."
The airlines and Airbus argue the FAA has overstated the risk of a catastrophic fuel tank explosion. The carriers also say the agency has understated the effectiveness of existing rules.
Replies the FAA's Hickey: "I categorically reject that. We have had several independent groups evaluate our analysis."
The FAA plans to review comments and hopes to issue its final ruling by September 2007.
Boeing says that its 787 Dreamliner will include a system to reduce fuel tank flammability and that other models are testing a system. Airbus says it will not install a nitrogen system on its mammoth A380 unless required to do so. Both the 787 and the A380 are still in production.
Safety experts and relatives of those who died on Flight 800 -- including 14 Los Angeles-area residents -- called on the FAA not to back down in the face of airline industry protests.
"The aviation industry has a history of being shortsighted," said Jim Hall, who was chairman of the National Transportation Safety Board when it investigated the TWA Flight 800 accident.
"I'm hoping in this case we won't have another tragedy occur as a result of their inability to understand common sense."
Reducing the flammability of fuel tanks is still on the board's priority list of safety improvements, and the board has urged the FAA to broaden its rule to apply to cargo airplanes and to all fuel tanks in aircraft wings. The FAA's proposed system could also help suppress fires in cargo holds and prevent explosions in fuel tanks if an aircraft is struck by a missile, the board says.
Some relatives of Flight 800 victims, and several retired airline pilots, still believe a missile or a bomb brought down the jumbo jet, which crashed in view of a couple of hundred witnesses -- many of whom told the FBI that they saw something approaching the airliner before it exploded. The FBI investigated for 16 months before determining a criminal act was not involved.
Today, family members will hold an annual service at a black granite memorial on a wind-whipped bluff on Long Island's south shore. Many have called on the FAA and the airlines to mend their differences and make additional modifications to fuel tank systems.
"Make the planes safer," said Jim Hurd, a vehicle mechanic whose 29-year-old son, Jamie, died in the crash and who spent years on FAA committees studying fuel tank safety. "They can eliminate this tragedy for the next group of people."