DL 8939 then VS 1906 at San Francisco
Phoenix → San Francisco → Seattle
Timetable, San Francisco time
14:57DL 8939 from Phoenix at the gate
20:58VS 1906 to Seattle leaves the gatealso SK 3106, SK 3470, DL 3991
6 h 01 apart on the timetable
The last days
DL 8939 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.