Here’s Why American Airlines Has Passengers Ticked Off

Update: This story has been revised to reflect comment from American Airlines.

American Airlines is altering its loyalty program to reward frequent flyers based on the price they pay for a ticket instead of the amount of miles flown, and that has sparked passengers’ ire.

Beginning in the second half of 2016, American will be awarding AAdvantage members a minimum of five miles per U.S. dollar spent on the base fare plus carrier fees, excluding taxes. Gold members will receive seven miles per dollar spent, while upper tiers will get eight miles and 11 miles per dollar spent respectively.

A number of AAdvantage members have taken to Twitter to voice their complaints:

American has been trying to respond to a number of the Twitter complaints :

Update: American Airlines spokesperson Laura Nedbal replied back to our query for a response to ongoing customer feedback: “We wanted to reward customers relative to the fares they’ve purchased,” she said. “If you spend more money with us, we just want to reward that.”

American is the latest major carrier to embrace the revenue-based model for its rewards program after similar moves made by United Airlines and Delta Air Lines last year. JetBlue revamped its TrueBlue program in 2009 away from a miles-based system, and Southwest Airlines followed suit in 2011.

Arguably, the change benefits those who pay for higher-tier seats on a plane, which usually means first or business class passengers. A study conducted by flight research site Hopper last year on United and Delta’s program shows that fare-based rewards will result in fewer reward miles earned for flyers. Hopper’s study found that United MileagePlus members would earn on average 11% fewer rewards miles on the most popular routes, while Delta’s passengers would be granted 22% less reward-miles.

This article originally appeared on Fortune.com