IB 646 then IB 421 at Madrid
Milan Linate → Madrid → Barcelona
Timetable, Madrid time
12:55IB 646 from Milan Linate at the gatealso VY 5124
18:00IB 421 to Barcelona leaves the gatealso LL 3021, VY 5122, AV 6170, QR 6971
5 h 05 apart on the timetable
The last days
IB 646 and IB 421 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.