My dad is not having a lot of luck with an attempted redemption.

He wants to fly NW DTW-PDX, for July 22-July 30.

There are flights available, but they are only offering Frontier and HP/US.

A quick look at ITA reveals that Frontier and HP/US are the cheapest available fares for those dates. So this is in keeping with our previous experiences - they will tend to offer cheapest flights.

But when he tried to search FNT-PDX on the same dates, TY Network is only offering him AA - even though NW is now the cheapest airline. This is frankly surprising and had not been my experience up until this point. Any insights?