Airlines crack down on cheap bookings from pricing glitches

But two major airlines are now taking steps to make sure these so-called "mistake fares" won’t appear on their websites anymore.

According to Brian Sumers, a columnist for Aviation Week magazine, United Airlines is working to establish a digital operations center to help identify pricing mistakes and deceptive booking practices.

And American Airlines is taking a different approach — not allowing passengers to earn promotional bonus rewards points if they book a "mistake fare."

So why are these airlines taking a stand now?

Well, back in March, American offered business-class tickets from Washington, D.C., to Beijing for just $442 each way.

And because of a currency conversion error on its website, United sold first-class tickets from London to Honolulu for $193 and Newcastle to Newark for $51 in February. And those are just two recent examples.

American Airlines honored that mistake fare. United, however, did not — because to get those prices, customers had to book through the airline's Danish website and set their home country as Denmark. A judge decided United was off the hook since customers had "misrepresented their billing address."

Though mistake fares aren't new, they're becoming a greater problem for airlines as travelers use online forums to spread the word before the airlines can fix them.

This video includes images from Getty Images.