AA 1239 then FX 9791 at O'Hare
Boston → Chicago → Anchorage
Timetable, Chicago time
10:30AA 1239 from Boston at the gate
04:00FX 9791 to Anchorage leaves the gate
17 h 30 apart on the timetable, overnight
FX 9791 leaves 17 h 30 after AA 1239 arrives on the timetable: more than half a day, so not a connection we count.