Originally Posted by
maunder
What I dont understand is whether UA have an equation that says "at x days from departure, if there are y empty seats then we will upgrade z seats from the top priority wait list." Further, how does UA determine who gets to be top of the WL?
I try to pick flights that are lightly loaded as best as I can (as determined from the seat assignment map) but at the moment I dont know any other tehcniques.
Revenue management manages the buckets and releases seats for upgrades as they see fit -- based on bookings, historical loads, etc. Pretty much a series of formulas like you describe.
The waitlist is sorted by status and fare class, and time of when you were added.
Finally, as for finding flights, look for NC space. If you have route or date flexibility, sometimes shifting a trip a bit will allow upgrades to clear right after requesting them.