UA 574 then UA 3804 at Phoenix
Boston → Phoenix → Denver
Timetable, Phoenix time
19:31UA 574 from Boston at the gate
22:30UA 3804 to Denver leaves the gate
2 h 59 apart on the timetable
The last days
UA 574 and UA 3804 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.