Originally Posted by
morphogencc
A simple reading of Alaska's own page on how upgrades work suggest that starting at T - 5 days, all open F seats will start being assigned to elite members in descending order of the waitlist (as described in the first post). In reality, not all open seats go to complimentary upgrades at T - 5, T - 3, or T - 2, so what I'm asking is how /availability/ is determined, not upgrade order.
The web page talks about upgrades "being available". That's not every first class seat! They don't publish their methods for deciding when to make U space available, but it probably has something to do with the probability that the seat will be sold if it's left available (if they upgrade you, and then someone comes to buy it later and it's not there, that upgrade costs them a lot of money, and they don't want that).
They seem to have been making changes to how they do this, but lately they seem to be (usually) holding the last 1-3 F seats up until boarding, and upgrading people then. It probably varies a lot by route though.