DL 9970 then UA 3919 at San Francisco
Seattle → San Francisco → Denver
Timetable, San Francisco time
11:15DL 9970 from Seattle at the gate
14:00UA 3919 to Denver leaves the gate
2 h 45 apart on the timetable
The last days
DL 9970 and UA 3919 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.