At 1 hour out from SYD the run time remaining to DXB would have been 13.5 hours chock to chock, not 8 hours and probably more with 1 mill deadheading.
Is it possible that the fuel useage compensating for the dead #3 engine along with the drag for rudder deflection for compensating for the thrust imbalance may have made the potential range of the aeroplane a factor?
Probably something I shouldn't throw into the mix but just interested. I was always told and taught that a clean well trimmed aeroplane was a fast and fuel efficient one.
best all
EWL