UA 751 then UA 3907 at O'Hare
Charlotte → Chicago → Washington
Timetable, Chicago time
07:25UA 751 from Charlotte at the gate
12:00UA 3907 to Washington leaves the gate
4 h 35 apart on the timetable
The last days
UA 751 and UA 3907 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.