AA 518 then UA 5191 at O'Hare
San Diego → Chicago → Lancaster
Timetable, Chicago time
12:42AA 518 from San Diego at the gate
08:50UA 5191 to Lancaster leaves the gate
20 h 08 apart on the timetable, overnight
UA 5191 leaves 20 h 08 after AA 518 arrives on the timetable: more than half a day, so not a connection we count.