Minutes after its take off from New York’s Kennedy International Airport, a Boeing 747 headed for Paris exploded midair over the Atlantic Ocean off the coast of Long Island on July 17, 1996, leaving all 230 people aboard dead. The four-year investigation into what caused the crash of Trans World Airlines Flight 800 was the longest, and at $40 million, the priciest in the history of the National Transportation Safety Board.

The flight departed at 8:19 p.m. in muggy, but "fairly clear" weather, according to The New York Times, blowing apart in a fiery explosion 12 minutes later. Among the dead were 18 crew members and 212 passengers, including 16 students and five chaperones from Pennsylvania's Montoursville Area High School French Club.

Witnesses in the area of the crash reported seeing an explosion in the night sky, followed by a shower of flaming debris. Almost immediately there was speculation that the plane had been the target of a terrorist attack, with many claiming they’d spotted what appeared to be a missile heading toward the plane just before it exploded.

Although the source that led to the explosion was never discovered, the investigation concluded the crash’s cause was not a terrorist attack, but an electrical failure that ignited a nearly empty center wing fuel tank in the 25-year-old aircraft. The event remains one of the deadliest plane crashes in U.S. history.

“The investigation of the crash of T.W.A. Flight 800 is a seminal moment in aviation safety history,” the safety board’s managing director said in a 2021 statement. “From that investigation we issued safety recommendations that fundamentally changed the way aircraft are designed.”

The Investigation

Nearly all pieces of the 170-ton jet were recovered from the ocean floor and reconstructed as part of the ensuing investigation. Following the NTSB's ruling, the plane was used in training plane crash investigators and families of the victims were allowed to visit it, although it was never opened to the public. On July 7, 2021, 25 years following the crash, the NTSB will decommission the wreckage, which will be destroyed by the end of 2022. A 3-D scan of the reconstruction will be made for historical record.

John Purvis, head of the accident investigation unit for the Boeing Company at the time of the event, says airplane explosions are quite rare, in part due to security measures and equipment improvement.

“The explosion that occurred on TWA 800 was in the center wing fuel tank and was not from anything external,” he says. “The NTSB was never able to pin-point the precise cause, but it was clear that it was from within the tank.”

Purvis says while four years is a long time for an investigation, it’s not outside the accepted bounds.

“It was one of the two or three most complex accidents I was involved with during my 17 years doing that kind of work—in fact, it may have been the most complicated,” he says. “In the early days and weeks after the accident, the FBI was in charge because there was concern about it being a crime. That added some time to the investigation.”

According to commercial aviation historian Shea Oakley, NTSB investigations are almost never short-term affairs.

“When the rare fatal air accident occurs it usually involves a ‘causality chain,’ including a number of seemingly unconnected small anomalies that, together, create a sort of ‘perfect storm’ which causes a crash,” he says. “It takes a great deal of time and high-tech detective work to piece together the often seemingly disparate events in flight which, together lead up to a major accident.”

Oakley says the length of the Flight 800 investigation was due to a couple factors. First, the time it took to isolate the circumstances that caused a very rare event—the center fuel tank explosion, which, he adds, had never occurred with a 747. Plus, investigators applied extra diligence to accommodate a “huge amount of pressure applied from many quarters to make absolutely sure this was not the result of a terrorist operation, or an errant missile fired by our, or some other nation’s, military.”

New Safety Guidelines

According to Oakley, the 25 years following the tragic Flight 800 crash have included the safest years in U.S. commercial aviation history.

“Air travel safety, in general, has steadily improved since the beginning of the widespread use of jet aircraft in 1958,” he says. “Of the accidents that have occurred, spontaneous explosions in mid-air have always been responsible for a very small percentage of the total.”

He says fatal incidents tend to occur when an airplane is unintentionally flown into violent weather, usually a thunderstorm or, very rarely, some form of severe clear air turbulence (CAT).

“With today’s very sophisticated weather radar and stringent rules for avoiding potentially dangerous weather this virtually never occurs,” Oakley says. “So losing Flight 800 to an in-flight explosion of another kind was a very rare event indeed.”

Following its final report on the crash, the National Transportation Safety Board issued several safety recommendations including regular maintenance programs and design standards for fuel tanks.

“Many recommendations came out of the completed investigation, including everything from changes in daily operational procedures to modifications of the center fuel tanks on other 747s,” Oakley says. “It is fair to say that we will never see another accident of this kind involving this aircraft type. The elimination of the possibility of any reoccurrence of the same kind of incident is virtually always the fruit of an extensive accident investigation, and this one was certainly about as extensive as humanly possible.”

Conspiracy Theories Remain

Despite the safety board’s official findings, over the last two decades, conspiracy theorists, bolstered by eyewitness accounts reporting a missile strike, continue to charge that a terrorist attack, bombing or even friendly fire took down Flight 800.

According to Purvis, the safety board addressed the missile idea in its report.

“I made two visits to the mockup the NTSB assembled from the wreckage in a hangar on Long Island at the time,” he says. “I spent a fair amount of time examining the wreckage, looking for signs of missile/projectile entry. I saw none, and the real experts, who were much better at it than I, saw nothing either. However, I think the most compelling reason to say it was not shot down is that no one has ever claimed responsibility for any act against the plane. To me, it is impossible for secrets like this to be kept secret very long.”

Oakley notes that from the distant perspective of witnesses on the ground, the sequence of the explosion, a sudden shift of gravity and continuing forward momentum that caused a sharp temporary climb, and the plane’s vertical dive and fiery descent, the crash could have looked like the result of some sort of attack.

“What many thought was a missile was actually the death throes of an airplane that briefly went up before it, sadly and inevitably, went down,” Oakley says. “So the appearance of a missile was basically an optical illusion.”

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