Originally Posted by
LHR/MEL/Europe FF
1300 scheduled arrival, with a 50 minute delay gives me a new scheduled arrival time of 1350.
Not really. Even before the aircraft arrived in SYD it would've had an updated arrival time into AKL...and that arrival time would be taking into account the anticipated duration of the flight. Clearly on the day, the actual operational specifics could be taken into account rather than the published schedule.