Originally Posted by bagold
If your ticket is already issued in 'U' class (award J), I believe that you can be booked in Y class, go to the airport and ask to be put on the waitlist for business. Since your ticket already shows 'U', CX will offer you a business seat if available.
This is based on my past experience on a F class award ticket and I believe will be the same for a J class award ticket.
However, if it was me, I won't risk taking economy over business for that route. business over first maybe, but not economy over business.
CX at HKG unfortunately is getting very sticky about tickets that show a different date from the one that you're attempting to get on. Waiting by the airport *might* work but there is no guarantee.
SYD flights are chock-a-bloc full the first few weeks of May. Don't know why.