WASHINGTON -- "Somebody came into our waters and shot down -- for the first time ever -- a flag carrier of the United States," an expert on the explosion of TWA Flight 800 said at a Washington briefing yesterday.

Commander Bill Donaldson, a retired Navy pilot and accident investigator who has spent 15 months examining the case, said that two missiles were fired in the vicinity of the airplane, and that one of them exploded close enough to bring the plane down. It's no wonder, he said, that investigators did not find evidence of a direct missile hit; the missile was of a type specifically designed to explode near (rather than in contact with) its target.

Flight 800, Donaldson said, "was intentionally destroyed by a powerful, proximity fused, airbursting, anti-aircraft weapon launched from a position approximately one nautical mile off shore and three nautical miles east of Moriches Inlet, Long Island, New York." In addition, the airplane was "engaged seconds later by a second missile fired from a closer position to the south of [the plane's] track."

There were 230 passengers and crew on board the Boeing 747 when it was destroyed, on the evening of July 17, 1996. The plane was bound for Paris and, at the time of the explosion, was eight miles off Long Island.

Government officials have suggested that the plane was brought down when a spark ignited fumes in a nearly empty fuel tank causing it to explode, but they haven't been able to explain the source for the spark.

Donaldson based his claims on an analysis of physical evidence and eyewitness accounts, which he has detailed in a 109-page report (available at http://members.aol.com/fl800/). Those appearing at the briefing to support Donaldson's theory included a helicopter pilot who saw the explosion, a man who saw it from the ground, and a now-retired TWA captain who had served as flight engineer on the same plane just a few hours before, on its flight from Athens.

Donaldson believes that a missile detonated on the plane's left side, about 20 feet from the hull and "probably slightly low," sending a shock wave that blew open the skin on the left wing. The airplane then moved violently to the right and rolled almost onto its back in an instant, some "144 degrees in one second." The stress created by the missile explosion caused the plane itself to explode in bright flash followed by a dull red-orange fireball that fell to the water amid a cloud of black smoke.

In preparing his report, Donaldson analyzed the composition and distribution of debris from the plane, interviewed witnesses who claimed to have seen a missile streaking toward the plane (and turning as if homing in on the plane's radio signals), and examined all the official documents released in the case. He said that he is apparently "the only trained accident investigator" who has interviewed most of the witnesses; the FBI allegedly blocked NTSB investigators from conducting their own interviews.

Among the eyewitnesses who saw what appeared to be a missile attack, Donaldson said, was an FBI agent. "He said he had seen a plane shot down."

Admiral Thomas Moorer, former chairman of the Joint Chiefs of Staff, attended the briefing in support of Donaldson. "This certainly appears to be an act of terrorism," Moorer said. He called the Donaldson report "very excellent" and said Congress should conduct its own investigation of the explosion.

Vernon Grose, a physicist and former member of the National Transportation Safety Board, attended the briefing as an observer. He said he was interviewed on CNN for six hours the night of the disaster and has been interviewed on the subject some 170 times. "I've spent two years defending the NTSB," he said, only to find that the facts don't seem to line up with the official story. He told WorldNetDaily that he felt "betrayed" by the NTSB.

The Donaldson briefing "disturbed" him, and he believes that government officials may have come to a conclusion first, then tried to make the facts fit their theory. "There ought to be an open, public hearing" to address the points made by Donaldson and others.

Grose said he's not a fan of conspiracy theories, and he believes there might be a reasonable explanation for the government's behavior in this case. "But if the truth contradicts what has been said, let it be heard," he said.

At the briefing, Captain Al Mundo, flight engineer on the same plane on its previous flight, said he finds the official theory "highly improbable."

After the earlier flight, he had performed a procedure that cleared the center fuel tank. "I question whether vapors were even in the tank," he said, due to physical processes that should have cleared any vapors that were present.

The helicopter pilot eyewitness -- Fred Meyer, a lawyer and Vietnam veteran Naval aviator -- said at the briefing that, "Based on two combat tours, it is my firm belief to this day that it was military ordnance." The government theory, he said, is "a government excuse for something -- totally mystifying. I know what I saw."

Richard Goss, a businessman who saw what appeared to be a missile, said that at first he thought it was part of a fireworks display. "Someone else at the Yacht Club [from which he saw the incident] even said, 'Look at the fireworks!,' and we waited for the display." His reaction to the government's version as seen in a CIA-produced computer simulation: "Personally, it was a joke to me. It was an insult. It was so different from what I saw."

Donaldson's report is full of tantalizing details.

On the day of the explosion, a Beirut newspaper received a fax, apparently from an Islamic terrorist group, stating that "Tomorrow morning we will strike the Americans in a way they do not expect and it will be very surprising to them." The Flight 800 disaster occurred at 8:31 p.m. EDT -- which, on the Arabian Peninsula, was the next morning.

On November 17, 1995, eight months before the Flight 800 disaster, two aircraft off Long Island reported seeing a bright, fast-moving object trailing smoke and not registering on FAA radar. The object passed within 2,000 to 3,000 feet of the two aircraft.

Radar detected an object, apparently a surface vessel, only 2.9 nautical miles from Flight 800 when it exploded. It was traveling at 30 knots and "avoided the visual range of all other surface contacts" until it got out of range of Islip radar. "This is a normal military tactic," Donaldson noted, not the action of someone who had just witnessed a plane crash.

Donaldson reported that some of the strongest evidence for a missile explosion -- the drastic change in apparent altitude, speed, and other factors noted by the flight data recorder (FDR) at 8:31:13 p.m. -- appeared to have been removed from the official version of the FDR's readout. "The first version of the digital readout of the flight data recorder the NTSB published on the Internet was correct. It showed [the] data record ending at the beginning of the 13 second line. The second version, handed to reporters at the Baltimore Hearings [conducted by NTSB], had the 12 second line penned out. The third version on the Internet, altered April 8, 1998, has now totally deleted the 12 second line."

NTSB officials claimed the numbers at the 13 second line are "garbage" akin to the "snow" that appears on a videotape between a newly-recorded segment and material that was previously recorded. But that doesn't make sense, Donaldson said, because the numbers are internally consistent (they relate logically to one another) and they are within the bounds of possibility (for example, degree measurements all fall between 0 and 360).

"You'll have a hard time finding an airline pilot, off the record," who believes the official story, Donaldson said. The NTSB, he said, "has been politicized."

"There is no organized cover-up" in the conspiratorial sense, he said. Rather, in typical bureaucratic fashion, top officials let the official version be known to the people under them. In turn, lower-level investigators -- each of whom possessed only partial knowledge of the facts in the case -- assumed that the higher-ups had a basis for their theory, and set about to find the facts that would back it up.

But who made the decision that the fuel-tank theory would become the official version? "You've got to go above the NTSB and above the Justice Department to get the answer," Donaldson suggested.