AA 9817 then DL 1827 at O'Hare
London → Chicago → New York LaGuardia
Timetable, Chicago time
13:35AA 9817 from London at the gate
17:40DL 1827 to New York LaGuardia leaves the gate
4 h 05 apart on the timetable
The last days
AA 9817 and DL 1827 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.