UA 423 then AA 1869 at Houston
Philadelphia → Houston → Miami
Timetable, Houston time
15:29UA 423 from Philadelphia at the gate
13:20AA 1869 to Miami leaves the gate
21 h 51 apart on the timetable, overnight
AA 1869 leaves 21 h 51 after UA 423 arrives on the timetable: more than half a day, so not a connection we count.