UA 4189 then WN 1638 at Detroit
Newark → Detroit → Denver
Timetable, Detroit time
15:23UA 4189 from Newark at the gate
16:15WN 1638 to Denver leaves the gate
52 min apart on the timetable
The last days
UA 4189 and WN 1638 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.