TWA 800 story also had two combat experienced pilots witness the missile attack.
Yes, so I recalled. And a ton of other evidence as well, including the stuff the FBI was so anxious to prevent anyone from testing all over the seat covers. The most probable theories were a) that the plane was accidentally shot down in a Navy exercise going on in the area; and b) that it was shot down from a small boat by terrorists.
Frankly, I doubt a). It would seem to provide a more logical reason for covering it up, but I doubt that that many sailors could keep the secret this long. So, the only logical explanation is b).
What several observers said is that if it had been a fuel tank explosion, it would have been orange-red. But it was brilliant white, the color of an ordnance type explosion.
It's noticeable that Boeing was never sued, and nothing much was ever done to fix the combustibility of airplane fuel, which in fact was exceedingly unlikely to explode in the first place. Indeed, Boeing ceased protesting, probably under threat of losing contracts, but they never really admitted any fault.
No, the odds are about 95-5 that it was a terrorist missile (some witnesses say two missiles) that brought it down. There is also some talk that it may have been a Chinese made missile, since evidently China has given these SAMs extended range, but I won't get into that.