<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by Beef or Chicken?:
No, date of ticket purchase is now trumped by fare basis. The EUA/yield management algorithm is taking into account both historical fare-basis bookings as well as current fare-basis bookings (i.e., for an upcoming flight on a given day/time). As would be expected, the release of seats into the F bucket from A/D is done on the basis of this historical booking data and current reservations. But now, wih greater stringency, EUA is releasing *only enough* inventory into F at each upgrade window (5/3/1 days prior to departure) into which only the higher fare-basis reservations will be upgraded, e.g., 6 plats on day 5, 3 of whom on K fare, 2 on Q, 1 on T. Yield management/EUA spots this, so only three seats open up in F. The three on K get the EUA; the 3 on T/Q are skipped. Day 3: Same thing, but for Gold - and the lower fare basis Plats from before (in addition to the lower fare Golds) are nixed out of the running. And so on. Of course, this is the general paradigm, so specific routes and days of the week will throw in different variables. Still, overall, the machination of EUA is different from before.
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Your analysis isn't consistent with my experience at all. EUA has been broken for me, regardless of fare class purchased.
Additionally, what would be the motivation to hold out seats on the day of departure? I've seen A9F0 at 1am on a 6am departure. If the system is as sophisticated as you've indicated, it would certainly be capable of giving away a few seats to Platinum and Gold T/Qs to save them from having to get to the airport early to fight the silvers for seats.
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What's more, as has been mentioned previously and in other threads, the at-airport upgrade standby list doesn't work reliably anymore. I was "number one on the standby list" for upgrades on the day of travel the other day on a 5-segment itinerary, none of which were EUA'd (one segment was on a junglejet). Watched AOW classavailability (BTW, it's so much easier than ITN I find), saw the F bucket go live, went over to the P-Club desk to get my upgraded boarding pass, and you know what? The F inventory was still sitting there, my original reservation un-upgraded, and *several* club agents hoarded around to observe this new twist, chattering about how I should have been automatically upgraded[/b]</font>
Once you're checked in, you will not be automatically upgraded by EUA or anything anymore. Either you will need to have someone manually grab a seat from F for you or wait until the GA clears the F upgrade standby list before push-back.
This has been a long-time bug that is part of the airport "free for all." This would generally be fixed by the 3h EUA system.