VS 3 then DL 4915 at JFK
London Heathrow → New York → Chicago O'Hare
Timetable, New York time
12:25VS 3 from London Heathrow at the gate
15:21DL 4915 to Chicago O'Hare leaves the gate
2 h 56 apart on the timetable
The last days
VS 3 and DL 4915 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.