No biggie, but I prefer on.
I'f I'm stupid enough to hit a friendly, then I'd rather take the damage over him.
Although just last week I was in a 262 closing fast on an A-20, medium Gee, turning 6:00 approach. Just as I fired at 300, another 262 flew between us, perpendicular to our approach path. I saw a few hits on the A-20, then my windscreen was filled with part of a 262 profile... with hit sprites... then I was in the tower.
eskimo