Originally Posted by
philemer
Unless someone here has actually upgraded with miles I don't believe it is possible. I've booked a lot of CF cert tickets & have never been given the option to upgrade except with GGU.
You can upgrade with miles. You must be booked into (or you can upfare into) one of the miles-upgradable fare codes (
Y, B, H, K or M). Contrast that to using a GGU, where you can book into
Y, B, H, K, M, L, V, S, or N.