UA 3909 then DL 8844 at San Francisco
Cancún → San Francisco → Los Angeles
Timetable, San Francisco time
15:10UA 3909 from Cancún at the gate
16:40DL 8844 to Los Angeles leaves the gate
1 h 30 apart on the timetable
The last days
UA 3909 and DL 8844 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.