I'll never forget the time I first got into RC planes and built a glider to fly at the local park. I'd let my puppy run around off leash before there were "leash rules" while I flew my glider for hours on end. My eyes were fixed on the plane looking up in the sky but I would always call my dog over to me before a landing to ensure a safe landing zone. Needless to say there was an irresponsible parent who decided to let their toddler run across the field toward my plane as it was coming in for a landing. Not even a single word of caution was mentioned as my plane was effectively targeting a direct head shot into the child (as he continued to run into the plane) when the kid came into focus of my peripheral vision and I instantly jerked the elevator back, nearly missing the kid's forehead by inches! No doubt the plane would've killed the kid and the parent was clueless to the level of danger of what just happened. I was really shook up over it and never flew at that park ever again.
I immediately joined the AMA and started flying at a sanctioned club with restricted space to never risk that experience again.
Not saying that RC cars are nearly as dangerous as planes, but somebody can get seriously hurt and this can be avoidable, I only race my cars at RC Car Clubs to avoid the following scenarios: