UA 3752 then QF 3669 at San Francisco
Denver → San Francisco → Seattle
Timetable, San Francisco time
13:00UA 3752 from Denver at the gate
17:42QF 3669 to Seattle leaves the gate
4 h 42 apart on the timetable
The last days
UA 3752 and QF 3669 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.