Originally Posted by
Andrew Yiu
At last check, not all booking classes are upgradeable on an International flight no matter what your tier is or whether you're using SWU or miles or miles + copay.
And to ensure that all Mileage Plus members have a chance to experience the new international first and business class, beginning July 1, 2009, all paid international Economy-class tickets can be upgraded with miles and a co-pay.