Welcome to FT!

Upgrade clearing on this route depends on your fare class, the day of the week and time of year. I am 100% in the past 18months over about 15 round trips (but then I'm UGS and have sometimes been the only upgrader to C). If you're 1K not buying a B fare, your chances go down quickly. Weekend flights (Fri/Sat from US, Sat/Sun/Mon from AU) are much worse for clearing. Also, the extra flights over the AU summer period provides more opportunities for upgrade.