TP 239 then B6 134 at San Francisco
Lisbon → San Francisco → Boston
Timetable, San Francisco time
15:45TP 239 from Lisbon at the gatealso EY 2796, B6 6734
22:10B6 134 to Boston leaves the gatealso SQ 1544, EY 8386
6 h 25 apart on the timetable
The last days
TP 239 and B6 134 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.