It may not be the lack of elbow room or the expensive food.

By Melissa Locker
May 05, 2016
Peter Dazeley

There are many reasons passengers could use to justify bad behavior on airplanes, from stressful security lines to lack of overhead bin space to a spike in flight delays.

New research reveals that it’s not shrinking seats that is the biggest cause of air rage, though. As reported by New York Magazine, a new study shows that air rage may be linked plane design and class inequality.

In the new study published in Proceedings of the National Academies of Sciences, researchers from the University of Toronto’s Rotman School of Management found that air rage cases are more frequent on flights when passengers are forced to walk through the first-class cabin on their way to the more cramped digs in economy class.

The researchers, who looked at data spanning some 1 to 5 million flights over several years, also found that the mere existence of a first class cabin on a plane—even if passengers don’t have to walk through it—can lead to a spike in bad behavior in economy class and, perhaps more surprising, in first class, as well.

According to the study, when a plane has a first class cabin, the chances of a coach passenger erupting in air rage are nearly four (3.84) times higher, which the researchers say is equivalent to the effects of a nine-hour flight delay.

The study’s lead researcher Katherine DeCelles explained to Gizmodo, that airplanes are a microcosm of class-based society. “It’s a small world of the greater society that we live in, though one that’s greatly concentrated,” she said. According to DeCelles, seeing how the other half flies with free champagne, comfortable seats, and leg room often serves as “the straw that breaks the camel’s back.”

As the price of tickets continues to rise and the amenities continue to disappear (at least in coach) the mere sight of someone enjoying air travel seems patently unfair. According to New York Magazine, “Flying alongside first class highlights the indignities of economy travel—just a few yards away are a bunch of people enjoying much more humane conditions—and, for many, no amount of cost savings makes this seem fair.”