AA 1948 then UA 3865 at Houston
San Diego → Houston → Chicago
Timetable, Houston time
23:51AA 1948 from San Diego at the gate
08:00UA 3865 to Chicago leaves the gatealso UA 3903
8 h 09 apart on the timetable, overnight
The last days
AA 1948 and UA 3865 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.