UA 3878 then AA 1618 at Houston
IAB → Houston → Phoenix
Timetable, Houston time
22:40UA 3878 from IAB at the gate
14:19AA 1618 to Phoenix leaves the gate
15 h 39 apart on the timetable, overnight
AA 1618 leaves 15 h 39 after UA 3878 arrives on the timetable: more than half a day, so not a connection we count.