FWIW...
The MANPADS Menace: Combating the Threat to Global Aviation from Man-Portable Air Defense Systems:
MANPADS can strike aircraft flying at altitudes up to approximately 15,000 feet (4572 meters) at a range of up to 3 miles (4.82 kilometers).
MANPAD Protection for Commercial Aircraft:
Scroll down to page 4 for a chart describing zone of susceptibility. (A box 25 miles long, 6 miles wide and 15,000' high)
If I read the altitudes right, 800 was higher than that. But NO ONE “saw” a trail zig-zagging from miles away-—according to the “reliable” eyewitnesses, it went straight up, meaning a boat right under the plane.