UA 3879 then DL 1216 at Houston
Amarillo → Houston → Los Angeles
Timetable, Houston time
17:48UA 3879 from Amarillo at the gate
07:00DL 1216 to Los Angeles leaves the gate
13 h 12 apart on the timetable, overnight
DL 1216 leaves 13 h 12 after UA 3879 arrives on the timetable: more than half a day, so not a connection we count.