AC 3997 then LA 7046 at San Francisco
Boise → San Francisco → Boston
Timetable, San Francisco time
09:23AC 3997 from Boise at the gatealso UA 4639
12:40LA 7046 to Boston leaves the gate
3 h 17 apart on the timetable
The last days
AC 3997 and LA 7046 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.