SQ 1539 then AS 1340 at San Francisco
Boston → San Francisco → Seattle
Timetable, San Francisco time
09:40SQ 1539 from Boston at the gate
17:42AS 1340 to Seattle leaves the gatealso QR 3438, AA 7579
8 h 02 apart on the timetable
The last days
SQ 1539 and AS 1340 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.