B6 1621 then DL 514 at Boston
London → Boston → Phoenix
Timetable, Boston time
12:15B6 1621 from London at the gate
08:35DL 514 to Phoenix leaves the gate
20 h 20 apart on the timetable, overnight
DL 514 leaves 20 h 20 after B6 1621 arrives on the timetable: more than half a day, so not a connection we count.