Kazakhstan national carrier Air Astana has introduced an online-auction model for business class upgrades on select routes,

the carrier announced Tuesday. With the MyUpgrade tool on Air Astana’s website, passengers booked in economy can bid a price range they'd pay for an upgrade. Bidding ends 72 hours before departure, and 48 hours before departure, Air Astana awards upgrades to the high bidders who bid above a certain minimum. Routes on which the tool is offered will “change from time to time depending on expected demand,” according to the carrier.