Hi,

I would like to know whether there is a known formula for the UA auto upgrade process from economy/coach to business on international flights?

Here's my circumstances. I am 1K. I always book B class & use miles or SWU's to u/g to business. My travel is usually SYD/SFO or LAX & return.

If I am lucky when I book, I get a confirmed u/g immediately. Other times I am placed on a WL. Almost always, I clear from the WL by some mysterious automated process at a time that I cant predict.

So my question is, "is there a formula behind this?".

I understand that a higher paid fare (ie B) will clear before a lower paid fare (eg M). I also understand that 1K will clear before Premier Exec.

What I dont understand is whether UA have an equation that says "at x days from departure, if there are y empty seats then we will upgrade z seats from the top priority wait list." Further, how does UA determine who gets to be top of the WL?

I try to pick flights that are lightly loaded as best as I can (as determined from the seat assignment map) but at the moment I dont know any other tehcniques.

Does anyone have insight/clues into this?

Thanks,

John