B6 8359 then AA 2578 at Boston
New York JFK → Boston → Chicago O'Hare
Timetable, Boston time
08:32B6 8359 from New York JFK at the gate
15:31AA 2578 to Chicago O'Hare leaves the gate
6 h 59 apart on the timetable
Boston’s board gives an arrival time for only about 58% of its flights, so many days show no gate time.
The last days
B6 8359 and AA 2578 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.