Originally Posted by Cathay Boy

I was told CX system doesn't process upgrades on its own, but rather will highlight for the station mangers what's going on (over-sold cabins, special occasions like birthdays, milestones, etc.), and it's up to the station managers to actually act on them. (this was informed to me by the JFK station manager 4 years ago, should still apply today)

Of course there are other avenues of upgrades: CX Reservations intervene and change your ticket, etc.