FR 3976 then UA 981 at Dublin
Barcelona → Dublin → Chicago
Timetable, Dublin time
13:30FR 3976 from Barcelona at the gate
10:40UA 981 to Chicago leaves the gate
21 h 10 apart on the timetable, overnight
UA 981 leaves 21 h 10 after FR 3976 arrives on the timetable: more than half a day, so not a connection we count.