Originally Posted by
jsloan
That… isn’t true. It is possible that it couldn’t be purchased with YYZ-YYT UA codes, but even then I doubt it. Alaska cruises that depart Vancouver are allowed to transport people from a stopover in Juneau to a stop in Anchorage.
It definitely isn’t true with AC codes; anyone can go in and buy a domestic AC flight with MileagePlus miles with no cabotage issues at all.
UA is acting as an agent for AC, and AC can operate the flight legally.
Mileage flights are treated differently from revenue fares. Domestic US-48 and US-Canada fares do not allow stopovers, so it's not possible in this case. You can potentially book stopovers in EU on TATL fares, but cheapest fares often do not permit stopovers and you may have to book both a higher class fare that allows stopovers and pay a stopover fee. In many cases, it's cheaper to simply book intra-EU flights on separate partner tickets.