On Wednesday 2 April, QF4 (B789 VH-ZNB, the 1920 hours JFK-AKL-SYD) was airborne at 2005 hours but on Friday 4, it diverted to CHC. It then flew (empty?) to SYD as QF6005, taking off from Christchurch at 1205 and arriving in SYD at 1308 hours.
It then formed QF27, the 1130 hours SYD-SCL...