UA 503 then DL 169 at Boston
Newark → Boston → New York JFK
Timetable, Boston time
09:17UA 503 from Newark at the gate
12:52DL 169 to New York JFK leaves the gate
3 h 35 apart on the timetable
The last days
UA 503 and DL 169 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.