AA 1721 then UA 3312 at Charlotte
Myrtle Beach → Charlotte → Louisville
Timetable, Charlotte time
07:19AA 1721 from Myrtle Beach at the gate
21:00UA 3312 to Louisville leaves the gate
13 h 41 apart on the timetable
UA 3312 leaves 13 h 41 after AA 1721 arrives on the timetable: more than half a day, so not a connection we count.