UA algorithm for domestic complementary upgrade ranking
 

anyone knows this? sometimes my name shown up in the upgrade standby list several days before check-in (in my memory ,could be wrong), sometime only after I check-in.

On domestic flights it shows on the cleared list once you've cleared, so that could be up to T-96 (several days before check-in). If you don't clear before T-24 you won't show anywhere until you check-in and then, once checked-in, you'll show on the upgrade standby list.

Unless he clears after T-24 but before check-in, which is possible.

But if you have not cleared, you won't be on the list until check-in.

thanks, but what do you mean "clear" here?

upgraded

As an 1K you can get CPU cleared as earlier as 96 hours prior to departure
see Confirmation priority
and Upgrade confirmation priority for more

If cleared early, your name (for CPU flights) will appear as soon as upgraded, otherwise it will appear in the waitlist portion once you have checked in.

IME, you must clear & have a seat to show up on the list before check in. There are several instances where I get an email saying I have cleared, but don't have a seat assigned and to do this at the airport. At this point, I'll never show on the list. Then, invariably, I'll go online to select a seat, it will err out when I try, and then when re-loading the reservation, it will tell me I'm assigned to a seat that I couldn't have selected since it was shown as taken when trying to do seat selection. Then everything will be normal again - I can change my seat normally and will show up on the cleared list at that point.

A couple of times I've been upgraded before the 24 check in mark, and I received an email saying I was upgraded. Then when you check in you're automatically on the "upgraded" side of the list, not on standby.

In that case, you end up on the list even before you check in.

same thing happened to me before

Today, the opposite happened to me. I checked in at T-24: no upgrade, was pretty high on the list, and lots of seats available in F. About one hour later, got an email notification that I'd been upgraded. Went to see, and sure enough, my seat assignment had been changed, and I was up front.

Being Platinum, I'd have expected the automatic upgrades for my cohort to have been processed much earlier than T-23, and definitely not after T-24.

Don't get me wrong, it's nice to be upgraded no matter when it happens, so I'm not complaining (!!), just wondering why it apparently happened so late.

Because UA expected to possibly sell those seats.

Upgrades can happen earlier, or they can happen within T+24 if the seats haven't been sold or people no-show.

Are you joking? :D

The other day I was on a mid-week, mid-day flight on a 757-200. When I booked two weeks ago, only 5 of the 24 F seats were sold. I figured, out of all the CPUs I'm getting this year, this must be far and away the easiest. Well, I did get upgraded, but only after I was already sitting in my economy seat and the boarding door was about to close. So there you go.

IME, that's pretty normal on like an 8 or 16, or something like that, but 24 seems like A LOT!