Somebody somewhere knows the logistics of the upgrade system. It seems that the ones who actually know say they don't, and the ones that don't know say they do. I guess the hard and fast rule is that the system is dynamic, and there is criteria other than the final 'EUA running at ~3 hrs prior to flight'. So many posts here are very helpful, along with different experiences we are constantly learning more and more about the system. A situation that I am partial to: EWR-LAS rt on 11/18-11/21. Both flights have been F0 since purchasing tix in mid-Sept. Now this morning I find that the returning flight on 11/21 has an F1...Both flights have 12 seats avail in F ( hoping for last minute revenue?). My ques is: Why would *one* F seat be released now? It seems like it goes against their standard proc.

Someone may have been "holding" that seat with a mileage upgrade, and they changed their travel plans, decided not to use the upgrade, etc.

It may not have been necessarily "released by continental", if you get what I'm saying.

With the assumption that there *is* a reason I would guess that it was an F seat that was returned to inventory from a passenger who changed their plans.

Others may suggest better "reasons"

Good luck.

Keith