More and more airlines have been adopting upgrade auctions for otherwise-unsold premium economy, business, and first class seats.” For airlines, Keyes says the rationale is simple: upgrade auctions generate significantly more revenue for airlines than handing out upgrades for free.

When first-class or business-class seats remain unsold as the departure time approaches, airlines utilize a tiered strategy to maximize revenue and reward loyalty. First, they offer paid upgrades via their mobile apps or at check-in kiosks, often at a significantly reduced rate compared to the original ticket price. Second, they fulfill mileage upgrades for frequent flyers who have requested to use their points to move up. If seats still remain, airlines grant complimentary upgrades to their top-tier elite status members based on a strict priority list. In 2026, many carriers have also integrated "bidding" systems, where passengers can submit a blind offer for an empty seat. As a last resort, if the economy cabin is oversold, the airline will perform an "operational upgrade," moving passengers to the premium cabin for free to make room in the back. Interestingly, some ultra-premium carriers prefer to fly with empty seats rather than "diluting the product," ensuring that the high price paid by full-fare first-class passengers continues to guarantee a sense of exclusivity and superior service.