UA 4179 then AA 2158 at O'Hare
Roanoke → Chicago → San Francisco
Timetable, Chicago time
07:44UA 4179 from Roanoke at the gate
21:31AA 2158 to San Francisco leaves the gate
13 h 47 apart on the timetable
AA 2158 leaves 13 h 47 after UA 4179 arrives on the timetable: more than half a day, so not a connection we count.