<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by willflyforfun:
From checking the UA posts, I'm kinda of confused. Can you guys determine UA's C upgrade availability, buy a H fare, use miles and confirm the upgrade at the time you buy the ticket? Or do you always have to wait until 72 - 24 hours until your flight to know if your upgrade cleared? If your upgrade didn't clear anyway to refund the H fare?</font>
Welcome to FlyerTalk,
willflyforfun!
On UA, an international ticket can be upgraded in advance is space is available. Here's a
link with instructions on viewing upgrade inventory. This is not limited to Premier members. If your upgrade is waitlisted and it does not clear, you will be stuck with the H ticket. No refunds, unfortunately.
The 100/72/48 hour upgrade clearances are for domestic/North America upgrades, sometimes referred to as Region 1.