The argument is that there was work to be carried out (deferred defects, a checks, c checks, storage checks etc), Qantas just chose to not do the work. The precedent set in the past court cases is that a company can't just choose to stand down full time employees when business is slow even if the work isn't considered urgent. If there is work available, you can't stand people down. The ALAEA is arguing that there was work to do from what I understand.