Thinking about your last flight, did it feel as if everyone in the world was on the airplane with you? The “load factor” for airlines worldwide—the amount of seats filled with fare-paying passengers—is currently running at about 80 percent, and the industry keeps breaking records for the number of people flying each year. The International Civil Aviation Organization reports that 3.5 billion passengers buckled up for takeoff in 2015, and the International Air Transport Association expects that number to jump to 3.8 billion next year.
Those of you inclined to do the math will realize that 3.5 billion is nearly half the world’s population. Does this mean that one out of two people on Earth flew sometime last year? Not at all.
“One person can be multiple passengers on a given day” explains John Heimlich, chief economist for Airlines for America, a trade association representing U.S. carriers. In other words, if your most recent journey involved a change of planes, you counted as two of the 3.5 billion passengers, or four if you flew round-trip.
No worldwide database keeps track of the number of discrete individual travelers taking to the air each year. Airlines may have that information for their own passengers, but they don’t share. So determining with any precision how many individual global citizens flew in a year, let alone what percentage of the world’s population has ever flown in an airplane, may be impossible.
Just because the number is unknowable does not mean it is un-guessable. One way to approach the question is to look at surveys, but the data are spotty at best, sometimes conflicting, and often out of date. In 2003, the U.S. Bureau of Transportation Statistics estimated, based on its Omnibus Household Survey, that one-third of U.S. adults had flown in the previous 12 months. And—the closest thing we’ve seen to the number we’re after—18 percent of Americans said they had never flown in their life, meaning that 82 percent had.
By 2009, the amount of people who flew a commercial airliner in the previous year had risen to 39.85 percent in the Omnibus Household Survey. Gallup polls give numbers that are a little higher. In 2012, 52 percent of respondents said they had flown at least once in the past year, the highest number in a decade.
Of course, these are only U.S. flyers, and for many parts of the world, information is even scarcer. A consumer survey conducted by Credit Suisse First Boston in 2004 found that 47 percent of respondents in eight large Chinese cities had ever flown in an airplane. Air travel is on the rise in China, as well as in other parts of Asia and Latin America. “As gross domestic product increases the number of trips per capita increases,” Heimlich says, citing numbers produced by airplane manufacturers. “What they show is, to a point, air travel increases exponentially. Places with large populations like China and India are of great interest.”
A country’s level of development may not always track with the number of air passengers. Some underdeveloped nations have a large number of flyers because of the inaccessibility of ground transport. Indonesia comes to mind.
According to Boeing’s market outlook for the next 20 years, “China and the Middle East once again led all regions [in 2014] with double-digit traffic growth. Europe traffic grew at five percent in 2014, far outpacing economic growth, while North America traffic grew more than two percent.”
What’s not clear from these statistics is whether more people were flying, or the same people were flying more often, or both. It seems likely that the percentage of global citizens who have ever flown is growing, and will continue to grow. We just don’t have the data to back it up.
Tom Farrier, an air safety specialist who contributes to the crowd-sourced information site, Quora, took a shot at answering the question a couple of years ago. He assumed most people fly round-trip, and that a number of flights are not point-to-point but involve a stop along the way. He then calculated that the majority of air tickets are purchased by people who travel for business. His final guess: Maybe six percent of the world’s population flew in a single year.
If you can be more precise than that, we’d love to hear from you.