UA 2124 then FX 9791 at O'Hare
Houston → Chicago → Anchorage
Timetable, Chicago time
12:45UA 2124 from Houston at the gate
04:00FX 9791 to Anchorage leaves the gate
15 h 15 apart on the timetable, overnight
FX 9791 leaves 15 h 15 after UA 2124 arrives on the timetable: more than half a day, so not a connection we count.