Highway Terror

Reader AS looked up the Bureau of Transportation statistics data and did a calculation for me:

In the US, 583 billion passenger-miles were flown in 2008, the most recent year available (I think I can mix numbers from ’08 and ’09 without loss of generality). So if all that travel was done by car instead (obviously not feasible) with a fatality rate of 11.35 deaths per billion miles, we’d expect an increase of 6,617 deaths. In other words, terrorists would have to blow up 16 full 747’s a year (about one every three weeks) to make air travel as dangerous as car travel. I think that number gets at the point you were trying to make about the exaggerated scale of the threat of aviation terrorism.

I don’t think this is necessarily a point about how we should care less about aviation terrorism. But it is a call to try to think more rigorously and systematically about transportation security. I’m of the view that we under-emphasize the importance of reducing automobile-related fatalities in the United States. But it’s also true that driving a car, while quite dangerous, is also very useful. So faced with a proposal to make driving safer we do try to trade it off against both direct financial costs and reduced convenience. A well-enforced nationwide speed limit of 50 miles per hour would save a lot of lives but it would also have a lot of downsides.

Air travel should be regarded similarly. We obviously have an interest in making it safe to fly in airplanes. But we also have an interest in making it fast and convenient to fly in airplanes. Currently flying in airplanes is dramatically safer than driving a car. Under the circumstances, only measures with a very high ratio of increased safety to increased hassle really make sense.


Now obviously part of the issue here is that people are more upset about deaths caused by bad guys than deaths caused by “accidents.” So fair enough. But plenty of automative deaths are caused by bad guys who are driving under the influence. And more broadly I would say that if we want to invest more money and energy in terrorism investigations in general that seems a lot more rational to me than specifically working on the problem of aviation safety. Hire more FBI agents. Do more language training. Whatever.