The first example is taken from Evans, Frick & Schwing (1989). It is often stated that the most dangerous part of a trip by plane is the trip to the airport. Evans, Frick & Schwing show this not to be the case. When comparing air travel with road travel, the risks look very much worse for road travel. Death rates per billion miles travelled are 0.6 by air, compared to 24 by road. But, there are three reasons why such a comparison is inappropriate. First, the airline rate is 'passenger fatalities per passenger mile', whereas the road rate is 'all fatalities (including occupants, pedestrians, motorcyclists,
etc.) per vehicle mile'. Second, road travel that competes with air travel is mostly done on rural freeways, which are among the safest part of the road network. Third, driver and vehicle characteristics vary over a wide range of risks. In their study, Evans, Frick & Schwing make a number of assumptions and show that a 40-year-old, belted, alcohol-free driver of a car which is 700 pounds heavier than average is slightly less likely to be killed in a 600-mile-trip on the rural interstate freeway system than in a regularly scheduled airline trip of the same length. For 300 mile trips, the driving risk
is about half that of flying.