FLAPHappy, the issue is not what altitude, it is all tied to "see and avoid" . Flying in a park, hospital, school and at an AMA club field if you cannot "see and avoid" then IMHO you are flying recklessly. Flying anything above 400' without a spotter is taking an unnecessary chance. i don't think that you can both concentrate on controling yout aircraft and also be aware of possible full scale conflicts.