UA 3870 then AF 8943 at San Francisco
Xiamen → San Francisco → Atlanta
Timetable, San Francisco time
07:49UA 3870 from Xiamen at the gate
11:51AF 8943 to Atlanta leaves the gate
4 h 02 apart on the timetable
The last days
UA 3870 and AF 8943 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.