I have no idea; I wasn't actually looking to book a seat, instead I was testing the qantas.com award application to see whether it was working properly or had the problems mentioned on this thread. It doesn't show fare class inventory, just award inventory -- which was surprisingly plentiful, in fact astonishingly so. I suppose I can thank FT for getting me to play with this tool; booking it with Aadvantage miles was quite easy, after finding the dates on qantas.com (at less than half the QFF cost; looks like Oneworld really does get the same award inventory).

I did see F awards available every week on the kangaroo route for 3 consecutive months (Feb-May 2009, or something like that); and at least one every month trans-Pacific. But probably only 1 per flight (but my theory is that all non-year out awards are trickled in 1 at a time). Got the A380 in F in both directions LAX-MEL-LAX, and on dates I wanted. Astonishing. I have found A and D to be hard to get in the past year (harder than this award) ... the strange world of FF plans.