Beginning Dec. 1, American Airlines will charge $250 to customers who want to use miles for first-class upgrades on cheap overseas flights. The new fee applies to discounted coach-class tickets between North America and Europe, Japan and much of South America, including Brazil and Argentina. Full economy and business tickets will be exempt from the new charge.

Here’s the spin: “With fares so low, the disparity between discount and premium class fares is too great to be offset by miles alone,” American spokesman Tim Wagner told The Wall Street Journal. “Rather than limit upgrade awards to full-fare tickets only, it will allow AAdvantage members to upgrade even if they buy a deeply-discounted ticket.”

In American’s defense, it should be mentioned that Mr. Wagner is correct – most of the other Big Six programs do not allow upgrades from the super-cheap seats.

Not surprisingly, the move has met with some resistance among members. Many business travelers use miles exclusively for upgrades on paid tickets, and some have threatened to shift their mileage-spending to free tickets – essentially opting to pay for an upgrade, rather than the trip itself.

More optimistic members say there may be a silver lining: by essentially discouraging upgrades, business and first- class inventories may be freed up for those willing to pay the charge.

The move is not unprecedented. Continental charges an upgrade fee of up to $400 each way (that will jump to $450 next year).