(CNN) -- Accident investigators said Wednesday they would not re-open the probe of the mid-air explosion that brought down TWA 800 nearly 18 years ago, killing all aboard.
The decision by the National Transportation Safety Board dashed the hopes of a documentary film team claiming to have uncovered "solid proof" that investigators erred in concluding it was an accident.
The safety board said a team that was not involved in the original investigation took a look at the new evidence and found it "flawed," and said the board would stand by its determination.
The documentary team, which included a former safety board investigator, filed a petition a year ago asking the NTSB to revisit the matter.
All 230 people aboard the Boeing 747 died when the plane headed for Paris blew up and crashed into the Atlantic Ocean shortly after takeoff from John F. Kennedy International Airport in New York in July 1996.
The NTSB found four years later that the explosion was caused by an electrical short that detonated vapors in the center-fuel tank.
From the start, there were suspicions — including from law enforcement authorities — that it may not have been accidental.
One reason: scores of witnesses observed a streak of light and a fireball, raising suspicions that terrorists hit it with a rocket.
Tom Stalcup, who led the TWA 800 Project and co-produced the documentary, claims the group has radar data showing an "asymmetric explosion." The group claims evidence suggests one or more missiles destroyed the plane.
But investigators concluded the light streak likely was burning fuel streaming from the plane's wing.
An FBI investigation failed to find any criminal or terrorist connection to the catastrophe. But a veritable cottage industry of skeptics and critics has flourished on the internet.
"None of the physical evidence supports the theory that the streak flight observed by some witnesses was a missile," the NTSB said in a statement on Wednesday.
It said two specific issues raised by the filmmakers that fall under the NTSB jurisdiction were unfounded.
"The original investigation looked for evidence of fragments from a missile warhead and found none," the NTSB statement said. "Further, the damage patterns within the airplane were consistent with a center wing fuel tank explosion."
"Ultimately, the petitioners did not show that the NTSB's conclusion or determination of probable cause were wrong," the statement said.
On Monday, the filmmakers submitted a "letter of protest" to the safety board after it declined to allow them to make an oral presentation to members.