Kinda “shoots a hole” in the “big sky, small bullet” theory. When I was in the Army, they taught us to fire a point in the sky though which you thought the plane would fly, rather than try to continuously lead it. I knew a guy who “duelled” an ME-109 with a 0.50 cal and was totally fustrated by the his lack of success. The 109 took big lazy looping turns and he couldn’t but a round on it.
I was in the 82nd’s air defense battalion. We give classes at the ranges in shooting at aircraft. We had radio controlled styrofoam airplanes that would fly back and forth in front of a hundred guys with M-16’s, M-60’ MG’s. They’d hardly ever get hit. Five, or more passes.
I doubt the gunner hit the jet. He said he only had one gun working and he was untrained.
My recollection was that we were trained not to bother firing on aircraft. The chances of success were so low that it was considered a waste of ammo. I can certainly see firing at a helicopter, though some helicopters are so well armed it might just draw fire.