Feels bursting anger during air travel? It is probably only because your flight has a first-class cabin and you have to walk past it before finding your own seat, a new study shows.

The study, published Monday in the Proceedings of the National Academy of Sciences of the United States of America, is co-authored by Katy DeCelles of the University of Toronto and Michael Norton of the Harvard Business School.

It reveals that class difference is a far more powerful factor triggering air rage incidents, compared with factors such as crowdedness, alcohol consumption and long flights.

Simply having a first-class compartment made an air rage incident nearly four times more likely, equivalent to the effect of a nine-hour flight delay, the study found. The bad behavior was higher not only for economy passengers, but those in first class too.

The findings came after the two researchers studied thousands of documented disruptive flight incidents over several years for a large international airline.

A suggestion for air travel operators would be to use a dual-gate boarding system, said DeCelles. "The more you can use those dual gates to board airplanes, separating the first-class cabin from the economy cabin, you're going to have less air rage in both cabins."