Flight Sydney Airport departs from Sydney Sydney Airport at 19:50 and arrives at Cairns Cairns Airport at 23:00.
The flighttime is about 3h 10m. The distance travelled ("as the bird flies"): 1723 Km. So the average speed is roughly 544 Km.
The best month to arrive at Sydney is March and the most expensive month to fly is October. (Average prices, based on 616 datapoints.)
We have a lot more statistics for flights QF 930 and between Sydney and Cairns.