What does tier qualification mean?

Tier qualification happens when you have collected enough Tier Miles or you have flown enough qualifying flights to either keep your tier or move up to the next level. 

At the time of your review, we count up how many Tier Miles you have accumulated or how many qualifying flights you have taken. If you have enough, we then promote you to the next status level or keep you in your current tier. If you haven’t qualified, you drop a tier level.