Common sense and courtesy go a long way. I always tend to ask first if possible. But there are some fields I fly at where I have never asked permission. One is a locally owned park. The township building is just behind the park and they always see me when I fly. They haven't asked me to stop. The thing I look out for is if others are around, especially kids, I as a rule don't fly. Kids are unpredictable and may try to "catch" my heli! Heck, my oldest borther tried that once! [X(]

Jim