Originally Posted by
sbm12
You can, but it is not particularly easy or cost efficient. From Y to C you need to pay for a native Y or B fare and also pay miles per segment and also be able to find Biz award inventory. It sucks.
ETA: It also only works on most of the *A carriers; there are a few that don't participate in the program.
And it is worth it to note that full Y often is more expensive than Discount C, so if you want to fly in C, pay in C...