The National Transportation Safety Board, with the aid of the CIA and the FBI, determined the fatal crash was caused by a spark from faulty wiring. But the explanation never sat well with some and the account has been dogged by accusations of a coverup.
A new documentary premiering July 17, on the crash anniversary, claims to have new proof of a deliberate act of terrorism. "TWA Flight 800" says forensic evidence, along with eyewitness accounts, reveals a missile hit the plane's right wing, causing the explosion.
Six former investigators involved in the film are calling for the investigation to be reopened in light of what they say is new evidence and a "falsified probe," and filed a petition Wednesday with the NTSB.
"Early on in the investigation there was indication that the evidence was being tampered with," said Hank Hughes, a former senior accident investigator, who took part in the documentary.
Among the claims was that the FBI dismissed the claims of almost 800 eyewitnesses, who they say "recalled seeing something resembling a flare or firework ascend and culminate in an explosion."
"Had the crash been the result of state-sponsored terrorism, it would have been considered an act of war," a CIA report from 2008 said. After and eight-month investigation, the CIA "concluded with confidence and full substantiation that the eyewitnesses had not seen a missile."
Instead, the CIA determined the "eyewitness sightings of greatest concerns to us -- the ones originally interpreted to be a possible missile attack -- took place after the first of several explosions aboard the aircraft."
Jim Speer, an accident investigator for the Airline Pilots Association, said he found holes that would be explained by a high-energy explosion on the right wing. When the test came back positive, he said, he was "forcibly removed" from the room by CIA agents.
The film's co-producer Tom Stalcup said radar data offered "solid proof that there was an external detonation" that resulted in an "asymmetric explosion coming out of the plane -- something that didn't happen in the official theory."
But not everyone buys a coverup.
While investigators who took part in the documentary said they kept quiet at the time of the investigation out of fear they would lose their jobs, waiting until after they retired, the former Department of Transportation Inspector General Mary Schiavo was skeptical.
"If this really troubled them at the time and they had conclusive evidence, -- they said they kept quiet to keep their jobs -- well, there's a duty beyond that and there's ways to report this," Schiavo said. "I was the inspector general."
"We protect whistleblowers," she said. "So I'm very critical of them not coming forward before now if what they have really is new. I think the NTSB got it right."
And Pat Milton, a CBS reporter who wrote an account of the investigation called "In the Blink of An Eye" that came out of 11 months at the scene, said the conspiracy theories surrounding the crash have been discounted over time.
One of the oft-pinpointed reasons for doubt comes from the involvement of the FBI and CIA, and the FBI's initial report that terrorism could have been involved.
"At the time, bin Laden was just coming onto the radar of the FBI," she said, which is why the security agencies were involved at all. But the absence of "the tell-tale piece" of evidence eventually led the investigators to rule out terrorism.
The NTSB is required to respond to the petition requesting a reopened investigation, and said the Office of Aviation Safety would assign a team of people who were not involved in the original probe to determine if the documentary team indeed brought new information to the table.
Investigators "spent an enormous amount of time reviewing, documenting and analyzing facts and data, and held a five-day public hearing to gather additional facts before determining the probable cause of the accident," said NTSB spokeswoman Kelly Nantel.
"While the NTSB rarely re-investigates issues that have already been examined, our investigations are never closed, and we can review any new information not previously considered by the board," she said. Still, the Flight 800 probe "remains one of the NTSB's most extensive investigations."
The documentary will air July 17 on EPIX.