UA 3988 then UA 665 at Charlotte
Houston → Charlotte → Newark
Timetable, Charlotte time
10:49UA 3988 from Houston at the gate
15:00UA 665 to Newark leaves the gate
4 h 11 apart on the timetable
The last days
UA 3988 and UA 665 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.