Good luck to the A380 - big shoes to fill.............
Average Mach no. for London-Sydney?
Quite slow, I would think - something like M 0.80 - cost index zero, or thereabouts. Cathay used CI 80 for most of the -400 ops although BA, Singair and me used to fly around at .86 which used to suit the wing and the schedule well. To stretch the flight where necessary, CI zero did work.