UA 315 then UA 6093 at Houston
Tucson → Houston → Denver
Timetable, Houston time
10:53UA 315 from Tucson at the gate
13:11UA 6093 to Denver leaves the gate
2 h 18 apart on the timetable
The last days
UA 315 and UA 6093 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.