WN 856 then WN 769 at Denver
Dallas → Denver → Boston
Timetable, Denver time
08:45WN 856 from Dallas at the gate
17:55WN 769 to Boston leaves the gate
9 h 10 apart on the timetable
The last days
WN 856 and WN 769 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.