I searched/still searching the forum. Find no clue. At co.com, there is a ticker for u/g using miles, and I guess it's not the same as the (old) SWU's can u/g any revenue fare. And co.com does not have the "expert" mode that let you looking at F9, C9, Y9, B9,...up to NC0, XY0,...
So how do you check the availability of the u/g space?
Thanks
Since they changed the method in the last few month, this is how I used SWU for u/g. On the main page of CO.com, enter your search and click on Advanced Search.
At the bottom of Advanced Search page, check OnePass Reward Upgrade box (you are actually not using reward for your upgrade, just finding out which flights are upgradable.
Note those flight, go back to the main page and purchase you flight. Once purchased, you can go through and upgrade your flight using SWU. It might clear immediately or put you on waitlist.