SQ 1539 then AS 9790 at San Francisco
Boston → San Francisco → Seattle
Timetable, San Francisco time
09:40SQ 1539 from Boston at the gate
09:00AS 9790 to Seattle leaves the gate
23 h 20 apart on the timetable, overnight
AS 9790 leaves 23 h 20 after SQ 1539 arrives on the timetable: more than half a day, so not a connection we count.