There are lots of ways to measure risk, says Frederic Lemieux, a criminologist and a professor at Georgetown University. He says researchers primarily quantify the risk of various transportation methods by looking at the number of deaths per passenger miles travelled. One passenger mile is the equivalent of one mile travelled by one passenger.
For every billion passenger miles travelled by car, approximately 7.2 people die, according to a 2013 study in the journal Research in Transportation Economics. While the number of deaths varies from year to year, approximately 3.17 people die on ferries per billion miles traveled, and fewer than 1 person dies on a train, urban rail, or bus. But the plane is even safer—at least by this one measurement. For every billion passenger miles travelled by commercial air, just 0.07 people die.
It’s a pretty good track record, but Lemieux has his concerns. While the number of deaths per mile traveled is an important statistic, he says risk models that prioritize this number over others are fundamentally incomplete. “Airlines, and international associations that are providing standards for risk assessment, have a very narrow approach at looking at risk and safety in the airline industry,” says Lemieux.
While deaths are rare, fliers often have other negative—and even dangerous—experiences during air travel that are worth reexamining. For example, experiments designed to track the efficacy of the TSA have shown the agency often fails to expose dangerous and illegal items in luggage. Economic woes mean pilots are often overworked and planes may be flown too long without inspection, which can result in disastrous events down the line.
And people may experience injuries from turbulence or other near misses, which are problematic even if they aren’t fatal, according to Lemieux. But time and again, planes have been shown to be a safer mode of transportation, at least in terms of getting you to your destination alive—if not exactly happy. In the aftermath of 9/11, for example, thousands of Americans cancelled their flights out of fear. Researchers were able to demonstrate that the uptick in people driving instead of flying in the months after the World Trade Center attack was associated with an increase in traffic deaths.