Originally Posted by
baliktad
A is always a subset of U, which in turn is always a subset of F.
If there are 3 F seats for sale, there can be 0, 1, 2, or 3 U seats available.
If there are 2 U seats available, there can be 0, 1, or 2 A seats available.
A space can open up at any time, but the closer you get to departure time, the more likely it is there is an AS or DL elite who has purchased a ticket and waitlisted for the U space.
It's not entirely clear who is first in line for an A seat when there are both premium award ticket-holders waitlisted for A as well as elites waitlisted for U.
Interesting. At first thought, I would believe they'd want to get the FF mileage liability off the books prior to a free upgrade. At second thought, I realize that someone might buy a fare with an instant upgrade to U, providing immediate cash revenue. As far as who
should be first in line with an award ticket v. an upgrade, it should be the award ticket, which already paid for the space with miles. Who actually is, who knows.