WN 3097 then UA 3913 at San Francisco
Denver → San Francisco → Washington
Timetable, San Francisco time
12:00WN 3097 from Denver at the gate
16:00UA 3913 to Washington leaves the gate
4 h apart on the timetable
The last days
WN 3097 and UA 3913 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.