Originally Posted by
BlissWorld
I don't know if NWA is the same, but CO runs EUA 5, 3, and 1 day before departure and then again at 3 hours before departure. So, only during those windows will your upgrade clear.
Originally Posted by
GBadger
This is not necessarily true... Just because there are R seats available does not mean that EUA has run since those seats were made available. Therefore, there is a period of time during which upgrade space is available but automated upgrades have not yet been processed.
Got it, didn't realize that. On DL, it usually clears at booking or within 5 minutes after.