Originally Posted by
SparseFlyer
Having AC ticket ACXXXX operated UA is different than ticketing UAXXX with no AC flights though.
OP may be able to do it if he goes through a TA, if the AI fare allows plating on other Airlines, and I think AC has a plating fee.
I have regularly purchased 016 tickets on UA.com with no flights operated by UA.
I cannot recall if I've done it with no flights marketed by UA though.