AA 1618 then UA 3917 at Houston
Phoenix → Houston → Austin
Timetable, Houston time
13:48AA 1618 from Phoenix at the gate
07:30UA 3917 to Austin leaves the gate
17 h 42 apart on the timetable, overnight
UA 3917 leaves 17 h 42 after AA 1618 arrives on the timetable: more than half a day, so not a connection we count.