Are helicopters safer than cars?

Answers to your questions about the news.
June 3 2011 3:57 PM

Are Helicopters Safer Than Cars?

Chris Christie seems to think so.

New Jersey Governor Chris Christie. Click image to expand.
New Jersey Gov. Chris Christie

New Jersey Gov. Chris Christie has reimbursed the state for personal and fund-raising helicopter trips, even though he insists the expenses were legitimate. The governor also argued that it's safer to take a chopper than to speed around in a police escort, a practice that caused a near-fatal accident for his predecessor, Jon Corzine. What's the safer form of transit: the car or the helicopter?

It's unclear. Comparing the crash and fatality rates for automobiles and helicopters is an exceedingly complicated task, because the methods for data analysis are completely different. The National Transportation Safety Board measures automobile accidents per miles traveled, number of registered vehicles, number of licensed drivers, and total population. Helicopter crash statistics, by contrast, are denominated in hours of flight time. None of the experts the Explainer tracked down thought there was a meaningful conversion factor between the two, leaving us without a definitive answer.

Still, it's possible to do a little speculation with the data that are available. Between 2005 and 2009, there was an annual average of 1.44 fatalities (PDF) per 100,000 flying hours in nonmilitary helicopters. Over the same period, there were 13.2 traffic fatalities per 100,000 population in the United States annually. Since the average American spends around 780 hours per year (PDF) in the car, that means the fatality rate per 100,000 hours of driving time is just 0.017. Based on hours alone, helicopters are 85 times more dangerous than driving.

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Helicopters cover a lot more ground in an hour than a driver on the New Jersey Turnpike, so it might be better to come at the question from another angle. There are approximately 0.8 deaths on the interstate highway system for every 100 million miles traveled. There have been a fair number of studies on the average speed on the interstate system with varying results, but the average is probably somewhere around 68 miles per hour, give or take a few mph. That means it took drivers approximately 1.47 million hours to travel those 100 million miles, yielding a fatality rate of 0.054 per 100,000 hours in the car. By this measure, helicopter flying is just 27 times more dangerous than driving.

To be fair to Gov. Christie, there are a lot of variables that can't be easily integrated into these back-of-the-envelope calculations. The governor has a professional pilot, which makes him far safer. Personal helicopters, often operated by inexperienced pilots, crash 18 times as often (PDF) as commercial helicopter taxis. (Of course, the governor also travels the roads with a professional driver.) The governor also has the benefit of a high quality, well maintained aircraft. Low-end helicopters crash at least five times as often as the top-of-the-line models.

Crash statistics are also influenced by conditions. Many fatal commercial helicopter crashes occur during urgent flights and in risky weather, which wouldn't apply to Gov. Christie's trip to his son's baseball game. Fatalities in emergency medical transport crashes, for example, are higher than for other helicopters. According to some analyses of the 10-year period ending in 2007, working as crew on an emergency medical helicopter was the most dangerous job in America (PDF).

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Brian Palmer is Slate's chief explainer. He also writes How and Why and Ecologic for the Washington Post. Email him at explainerbrian@gmail.com. Follow him on Twitter.