At least in the air one's highly polished skills, judgment, experience and equipment are less likely to be rendered nugatory by some git in a rusty Fiesta pulling out without looking. I don't know how valid the motorbiking claim really is, but it feels about right to me. Flying is, I would say, definitely safer than horse riding and probably safer than skiing, but the other oft-repeated claim, that flying is as safe as or safer than driving, appears to me to be misleading. You can debate forever the statistics in terms of fatalities per operating hour, but the fact remains that aviation is a risk sport. The thing is to manage the risk.