DL 8840 then VS 1906 at San Francisco
Vancouver → San Francisco → Seattle
Timetable, San Francisco time
16:36DL 8840 from Vancouver at the gate
20:59VS 1906 to Seattle leaves the gatealso SK 3106, SK 3470, DL 3991
4 h 23 apart on the timetable
The last days
DL 8840 and VS 1906 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.