UA 177 then FR 1644 at Fiumicino
Denver → Rome → Vienna
Timetable, Rome time
11:55UA 177 from Denver at the gate
09:05FR 1644 to Vienna leaves the gate
21 h 10 apart on the timetable, overnight
FR 1644 leaves 21 h 10 after UA 177 arrives on the timetable: more than half a day, so not a connection we count.