And yes in this case I think the risk was greater than I would have thought prudent.

I´d say risk equals chance times consequence. With consequences of getting hit being that big (death), I´d say being in the path of any low flying aircraft carries a great risk, no matter how small the chance of getting hit.

PS, spoke to the guy standing next to the photographer that lost his life in the glider accident referred to above, some years later. Traumatic would be an understatement for what bystanders witnessed. Some of these witnesses are visitors to this forum.