DL 939 then B6 515 at JFK
Los Angeles → New York → San Francisco
Timetable, New York time
20:59DL 939 from Los Angeles at the gate
20:15B6 515 to San Francisco leaves the gate
23 h 16 apart on the timetable, overnight
B6 515 leaves 23 h 16 after DL 939 arrives on the timetable: more than half a day, so not a connection we count.