AC 1919 then AC 1558 at Montréal
Sydney → Montréal → Newark
Timetable, Montréal time
07:10AC 1919 from Sydney at the gate
13:10AC 1558 to Newark leaves the gate
6 h apart on the timetable
The last days
AC 1919 and AC 1558 weren’t both flown 15 min to 12 h apart in the last 21 days.
Statistics from past flights, not live flight information. Always check times and your connection with your airline, and don’t base travel or booking decisions on these numbers.