AV 2191 then UA 3853 at San Francisco
Sydney → San Francisco → Houston
Timetable, San Francisco time
06:25AV 2191 from Sydney at the gate
16:15UA 3853 to Houston leaves the gate
9 h 50 apart on the timetable
The last days
AV 2191 and UA 3853 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.