No, they really don't. Stingers can't hit anything above 12,500 feet and they can't hit anything going anywhere near 500 mph. There's no way in hell that a Stinger -- or any MANPADS -- can come close to hitting a commercial airplane at speed and at altitude.
The Gremlin has a max range of 4500 meters, so that's not inconcievable
Yes, it is inconceivable. TWA 800 was at about 4500 meters when it exploded, so the Gremlin could have hit it... maybe... if it had been hovering like a helicopter and the person who was firing it was standing on dry land directly underneath. But at 500mph, there's no way it would have anything like the range needed to down the plane. Same goes for the SA-18. We're not talking about this being a little bit beyond the maximum capabilities of any of these missiles, this is far beyond their capabilities.
Moreover, all of them would have had to have been fired from boats 8 miles out into the ocean, not an easy task by any stretch. If you've ever tried to use a MANPADS, you'll understand what I'm talking about.
The SA-16 H Gimlet can hit a target moving over 800 mph. So you're full of crap on this one, too.
It took me all of 3 minutes to look that info up.
So you're simply wrong. Hit the links I provided and see it in black and white.
Hitting a commercial aircraft at 15K ft with a MANPADS wouldn't be all that difficult at all.
L
TWA800 was flying at 275 knots (316 mph), not 500 mph.