Originally Posted by boerne

I had this issue a couple of weeks ago and FT is not clear on this that I can see. Perhaps others can share a newer link if it is. EF isn't clear either. Not all C space is the same according to 2 EXP agents when I was trying to use some SWUs. Links and pasted info to short explanations below. What I learned was that you do a test booking, and the note in blue on the left below will say something like System wide upgrades available. Or SWU available. If you can find the routes you want, then put them on hold. Then Call the EXP line to check to see if indeed they are available. The agent will go to the rate desk to confirm, then come back and book it. So I tried to book AUS-PHL-ZRH, and return next April. I found SWU availability for PHL-ZRH and return, but nothing else with AUS involved. So I put that on hold and called the EXP line. They confirmed the availability with the rate desk, came back and I booked it. Then I nested that flight with travel AUS-PHL before and after on a separate PNR. The best part was PE was not available on the PHL ZRH flight so all i had to do was buy cheap Y and upgrade to J. bam... Also have done the nesting thing several times before without problems. Many times, your upgrade will not be confirmed in advance and it will require you to be placed on an airport list, which is automatic if it doesn’t clear prior.