Originally Posted by ijgordon

Perhaps a brief example -- say a flight is F4 A0 P0 and departure is approaching. Yields on the flight aren't looking great, and they don't expect to sell many more full-F fare tickets, but they still want to try and make the flight profitable. Revenue management would possibly decide to open up A (and perhaps P) inventory, effectively lowering the first class price, in the hopes that supply-demand dynamics result in the sale of additional seats and the generation of additional revenue. By opening up A, however, they also put themselves at "risk" of losing that FC capacity to a mileage upgrader. Sure, they get a liability off their books, but on that particular flight they were really trying to get a higher level of cash flow. A bit of a quandry for AA.