DL 1909 then DL 4915 at JFK
Salt Lake City → New York → Chicago O'Hare
Timetable, New York time
05:00DL 1909 from Salt Lake City at the gate
15:21DL 4915 to Chicago O'Hare leaves the gate
10 h 21 apart on the timetable
The last days
DL 1909 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.