Here's what Chilli Monster found:
GA flying covers small training aircraft capable of cruising at 100mph, and business jets capable of cruising at several hundred miles per hour, so choosing an average cruise speed is difficult, but for the sake of argument, we'll choose 150mph. This gives us a comparison of:
GA: 7.46 fatal accidents and 13.1 fatalities per 100M miles
driving: 1.32 fatal accidents and 1.47 fatalities per 100M miles
So when compared on a mile to mile basis, flying has 5.6 times as many fatal accidents, and 8.9 times as many fatalities (these number would be even worse for flying if we took out motorcyle and pedestrian fatalities).
How about if we compare on an "hour to hour" basis? That requires an assumption of an average speed for autos. We'll choose 40mph. This leads to the following numbers:
GA: 11.2 fatal accidents and 19.7 fatalities per million hours
driving: .528 fatal accidents and .588 fatalities per million hours
On this basis, flying has 21 times the number of fatal accidents and 33.5 times the number of fatalities per hour of operation.
(With thanks to the orginators of the information).
These stats are not by any means precise, though they're about as good a stab as you'll find. I'm comfy with them as an accurate representation...
I hesitate to say this, but the numbers for some sorts of GA (gyroplanes, for example), are horrifyingly worse.
