AA 4156 then AA 3547 at O'Hare
Green Bay → Chicago → St Louis
Timetable, Chicago time
16:10AA 4156 from Green Bay at the gate
16:50AA 3547 to St Louis leaves the gate
40 min apart on the timetable
The last days
AA 4156 and AA 3547 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.