Don't Drive, if Ya Want to Stay Alive...

If you're traveleing more than about 12 miles, fly.

That's not the actual conclusion of a study published in the January-February issue of American Scientist; but it can be extrapolated from their data, and they say so.

What's wrong with the study:

Any study such as this is necessarily limited, given that commercial flying and driving are different, in most-basic ways. Drivers are usually alone, and control their vehicles; and they make the go/no-go decisions. None of that obtains in commercial air travel.

The most-important obvious difference seen when comparing these radically-different data, is that fatalities are most-common in different modes: in flying, the takeoff/landing modes account for 95% of fatalities; in driving, the distance per leg is the determinant -- the longer the leg, the greater the chance of the driver's being involved in a fatal accident.

The study included 2001 data; thus, it included September 11's terrorist attacks, and the 18% drop in airline RPMs that followed. The driving data were pulled from 2000, the latest year from which such statistics were available.

The study looked at just the ten largest airlines. On the "car" side, it considered deaths to drivers only; passenger deaths were not included. (Car passenger survival wasn't included, either; but the great majority of car trips are taken solo.) Of course, when a major airline flight goes successfully, a LOT of passenger-miles are added to the total. (Vehicle-mile safety data were not compared.)

Partially offsetting the use of major airline data, was the use, for car drivers, of interstate traffic figures only. Commuter airlines have historically-higher death rates than majors (due to number of passengers carried, airports used, an numbers of takeoffs/landings); and most auto fatalities occur on non-limited-access roadways.

Those two groups' being studied, therefore, are roughly analogous. (Hey -- it's close enough to give an idea; since the two modes are so different, what's your method of comparison?)

Buses, motorcycles, and semis were excluded from the highway death tolls.

So, given the limitations of the study, what did they find out?

With airlines, the best chance of your getting killed is when the plane is taking off or landing. Therefore, you are better-off flying direct, whenever possible. In your car, the death rate increases, as the length of the drive increases. Therefore, you're better-off making frequent stops.

As the journal summarized, "Just how much safer is flying than driving? For an average-length nonstop flight (which works out to 1,157 kilometers), the risk of flying is just the 78.6 X 10–9 value derived above. The risk of driving those same 1,157 kilometers is 1,157 X 4.4 X 10–9, or 5,091 X 10–9. Dividing 5,091 by 78.6, we estimate that driving the length of a typical nonstop segment is approximately 65 times as risky as flying. Driving farther than 1,157 kilometers would be more than 65 times as risky; driving shorter than 1,157 kilometers, but longer than the 18-kilometer indifference distance, would be between 1 and 65 times as risky as nonstop flying (neglecting the drive to the airport and the travel on local roads on the way to the interstate)."

[The extra time involved in short-hop airline flights (travel, two-hour recommended "security hassle" time, rental car snafys at the destination) was not considered; but it would surely affect mortality rate, as it adds so much to one's blood pressure, while it literally shortens one's useful life, by wasting time. That's another reason to drive the shorter distances, although it's not really related to the question at hand --ed.]

FMI: www.americanscientist.org/Issues/Macroscope/macroscope03-01.html