Originally Posted by
fliesdelta
UA and AR are two different alliances (Star and Skyteam), is it common to get a single ticket like that?
Yes. Interline, joint fares/ticketing agreements are not uncommon, irrespective of alliance, especially (and primarily) with a long haul international carrier when combined with a domestic segment by another carrier. You'll often find it deep in fare rules. Even if not in the fare rules, there's usually nothing to inhibit it on the same ticket, even if it isn't part of a combined fare. It will just price point to point for each segment.