American Airlines is testing the idea of letting customers bid for upgrades to first class.
Passengers can submit a bid -- along with a credit card number -- up to six days before the flight.
"Make us an offer ... and we will email you before check-in to let you know whether your offer was accepted," the airline says on its website.
The airline says that winning bidders will also get priority check-in, boarding and baggage, and complimentary food and beverage. However, passengers will earn frequent-flier miles based on the class of service that they bought with the ticket, not the upgraded class.
American began the test quietly this week. It wouldn't disclose the number or location of routes being tested or how much a winning bid might cost.
"We'll evaluate the results in the coming weeks to determine if this is something our customers value," a spokesman for the airline, Matt Miller, said on Wednesday.
However, the Fort Worth-based airline told NBC DFW that Dallas-Fort Worth is a test market and that bidding is being tested now on domestic routes.
On the website, American says upgrade requests by elite-status members of its AAdvantage frequent-flier program will continue to get priority and won't be affected by the test. It says the new "Plusgrade" upgrades are for passengers who aren't AAdvantage members or bought tickets that normally aren't eligible for upgrades.
In the fine print, American says it doesn't promise that any of the bidders will get upgrades even if seats are available, and it won't guarantee specific seat assignments.
The airline also won't promise that successful bidders will get a first-class meal. The promised complimentary food could be snack items or meals that are available for purchase in the main cabin, Miller said.
NBC DFW's Omar Villafranca contributed to this report.