EC 7644 then U2 3876 at Lisbon
Zurich → Lisbon → Milan
Timetable, Lisbon time
12:40EC 7644 from Zurich at the gate
19:15U2 3876 to Milan leaves the gate
6 h 35 apart on the timetable
The last days
EC 7644 and U2 3876 weren’t both flown 15 min to 12 h apart in the last 21 days.
Statistics from past flights, not live flight information. Always check times and your connection with your airline, and don’t base travel or booking decisions on these numbers.