By Melanie Lieberman
December 13, 2013

How much would you pay to upgrade on your next flight? That’s what American Airlines is finding out, now that they’ve launched their trial Plusgrade program.

“It’s simple,” their website promises. Six days before a flight, travelers can check to see if an upgrade is available (currently, the test is only being conducted in 13 undisclosed markets). If there’s a seat open in the next-highest class, flyers are encouraged to name their price.

If accepted, the upgrade will include priority check-in, boarding, and baggage, and complimentary food and beverage service.

When you put your fare on the auction block, you must also submit your credit card information. American will automatically charge cards if the bid is accepted.

American has assured elite members that their upgrade requests, submitted via the frequent-flier program, will still be prioritized.

The fine print? Even if seats are available, bids to upgrade may not be accepted.

“The plan is to run this program until early January,” a representative told us. At that time, they will determine whether or not to gamble the program on a bigger market.

Melanie Lieberman is an editorial intern at Travel + Leisure.