You're assuming the missile flew where it was aimed. An error of a few feet could easily happened. What was then accuracy rate back then?
I would ask you to keep an open mind during this discussion. None of us here are experts in this niche area as far as I know.
In a missile like that, it'll go where the onboard guidance system takes it. The Stinger and other portable SAMs use infrared guidance that will aim for the hottest part of the target. In aircraft that part is the engine exhaust. Before launching the missile, the person firing it would have located the target, waited till the seeker locked on, and then fired. The missile would have guided itself from there.
I would ask you to keep an open mind during this discussion. None of us here are experts in this niche area as far as I know.
I am more than happy to keep an open mind. But if something doesn't make sense then I'm going to ask about it.