Originally Posted by
abmj-jr
Please correct my misapprehension on this. I thought you had to purchase US 500s to upgrade. Are you saying that you can use UA e500s on US on day of travel - space available?
No, the OP asked about a flight on UA metal, but with a US code. In that case, UA e-500s can be used, but only on day of travel (no advance waitlist).