UA 6138 then AA 6445 at Charlotte
Houston → Charlotte → Knoxville
Timetable, Charlotte time
15:54UA 6138 from Houston at the gate
15:35AA 6445 to Knoxville leaves the gate
23 h 41 apart on the timetable, overnight
AA 6445 leaves 23 h 41 after UA 6138 arrives on the timetable: more than half a day, so not a connection we count.