Department of Transportation officials have begun meeting with airlines as part of an inquiry into the airlines' loyalty programs.
"We plan to carefully review complaints regarding loyalty programs and exercise our authority to investigate airlines for unfair and deceptive practices that hurt travelers," the DOT said in an email.
The investigation was first reported Thursday by Reuters. Anonymous sources told the news agency that the DOT is looking into transparency practices for award bookings, devaluation of frequent flyer miles, transferability of miles and whether airlines provide adequate notice before making changes.
Airline trade group Airlines for America (A4A) declined to comment. A4A represents the U.S. carriers with the largest loyalty programs -- American, Delta, United, Southwest, Alaska and JetBlue.
Loyalty programs and their related co-branded credit cards, which provide airlines with much higher profit margins than flight operations, have grown quickly since the pandemic. Delta, for example, expects to bring in close to $7 billion in revenue from its American Express co-branded credit cards this year. The carrier's third-quarter revenue from co-branded cards was up 20% year-over-year.
American, meanwhile, says membership in the AAdvantage loyalty program is up 50% since 2019.
The Biden administration has focused on aviation consumer protection more than recent administrations. Most recently, the department levied a $140 million fine on Southwest for the carrier's operational collapse during the 2022 holidays.
The department has also proposed new consumer-protection regulations, including mandatory airline refunds for lengthy flight delays and new upfront disclosure requirements for ancillary fees.