Originally Posted by
Adam Smith
It's very closely correlated with R space. J space won't really help you. If it's J9 R0, you won't be able to IKK.
True, however it is important to note that if one finds themselves in this position then
Option # 1: A->B J9R0
Option # 2: A->C->B J2R1
Use Priority Rewards to redeem Option #2 , then show up at the airport at position A and then pay the same day change fee to then fly A->B direct (Option #1 ). This option is available as long as economy class (Y) is not oversold and there is positive business class inventory. (J>=1)