Originally Posted by
SchmutzigMSP
Well, just to be concise, EUA doesn't typically run 6 days out, but it's not at all uncommon for it to do so. If you start traveling Plat-heavy flights, you'll notice your EUAs coming closer and closer to departure date, and perhaps not at all (battlefield upgrade time). It's really fluid depending on the loads of the specific flight. A lot of the "off-peak" and leisure-travel routes will EUA earlier than the stated 5-day window.
Very well explained and my experience also. E.g. if you are traveling next Friday you can start looking for your upgrade status early Saturday morning.
NW does "sweeps" X times a day, matching whatever criteria are used (status, fare, projected sales, etc.) against seat availability.
Not to hold out false hopes but I have noticed that if the flight is really full you actually have a better chance than you might think of being upgraded the night before or a battlefield upgrade because they may have oversold and need coach seats.