My understanding of the process is a bit hazy, but it seems like this is how it works:
- Based on your level, you may be upgraded before check in (by getting an email with a link to upgrade). I haven't had this happen to me yet.
- When you check in, if there is an upgrade available, you will be presented with a button to click to upgrade to first. If an upgrade is not available, there is a link to add yourself to the upgrade standby list.
- At the gate, the agents will go through the standby list if there are upgrades available and call you to the podium for a new boarding pass. The standby list is prioritized first by your status (CP, plat, gold, silver), then mileage flown YTD, then check in time. I'm not 100% sure of this order.
I've never asked a gate agent to upgrade me, but I've asked where I fall on the standby list. I've heard of people calling for upgrades when they don't get the automated emails, I've never done this.