In reply to jezb1:
> Don't forget it could just as likely be the belayer getting injured, falling coin or iphone from climbers pocket, broken hold. I've seen each of those happen. They'd make quite an impression on little Johnny's head if they hit him.
> Unlikely maybe, but possible.
But worth considering.
Some kids and student groups have members that seem to have a fairly thin 'field of awareness', its rare but sometimes they lower their partner onto somebody elses head! I'm wary around student climbing club groups for this reason, so often it seems like the belayer is only focused on his/her climber, then they lower off at speed or without looking around and warning people and almost nail the belayer next to them.
To be fair in all cases its not entirely the student pairs fault, everyone should really have one eye looking up when they are wandering though any part of a wall anyone is climbing in.
One thing i see VERY often is the proper young 'uns getting out of control for a moment and then wandering into the fallpath of a climber while totally oblivious to whats above them. Having personally had to throw a 6 year old like a rugby ball out of the path of a falling boulderer I'd personally say sticking a lid on the little kids is worth it, even if its just for the rare occasion Tarquin takes a rockshoe in the head.
Main thing with helmets, they are there to prevent a rare accident possibly having worse consequences. Not to prevent that accident happening in the first place. Important to remember that.