I assume you would have seen Branson's Virgin airlines intro into Australia; and this was just an announcement ! Markets usually tend to overreact, bringing often some trading opportunities.

Two things to note in QAN:
1. The fall of Qantas came off a lower top. Indicates Branson's effect prior to the public announcement.
2 Possible / probable support at the mid point around $3.60 -$ 3.80.