FB 851 then AI 128 at Heathrow
Sofia → London → Mumbai
Timetable, London time
16:55FB 851 from Sofia at the gate
13:30AI 128 to Mumbai leaves the gate
20 h 35 apart on the timetable, overnight
AI 128 leaves 20 h 35 after FB 851 arrives on the timetable: more than half a day, so not a connection we count.