Airlines generally strive to fill every seat in First Class, but they rarely do so with "free" upgrades for the average passenger. In 2026, most major carriers like Delta, United, and American use sophisticated algorithms to sell last-minute "paid upgrades" at a discount to those in Economy before giving seats away for free. If seats remain empty after the paid offers, the airline will then process the Standby Upgrade List for their elite frequent flyers (Medallion, MileagePlus Premier, etc.). However, it is a common industry practice to leave a First Class seat empty rather than upgrading a non-elite passenger for free; this maintains the "exclusivity" and perceived value of the premium cabin. On some international routes, particularly with airlines like Emirates or Singapore Airlines, they may fly with an entirely empty First Class cabin if no one has purchased the seats, as their high-end service standards are specifically catered to paying customers. On domestic "hub-to-hub" flights, however, the seats are almost always filled by elite members who have earned their way up the list through loyalty and high annual spending.