Flight Brisbane Airport departs from Brisbane Brisbane Airport at 05:00 and arrives at Melbourne Melbourne Airport at 08:25.
The flighttime is about 3h 25m. The distance travelled ("as the bird flies"): 1343 Km. So the average speed is roughly 393 Km.
The best day to arrive at Brisbane is Thursday and it would be best to avoid Saturday, as prices are on average 67.68% higher than on Thursday. (Average prices, based on 1151516 datapoints.)
We have a lot more statistics for flights QF 605 and between Brisbane and Melbourne.