Complex sentence: Bhatti who was a Flight Lieutenant in No.15 Squadron at Sargodha at that time, after completing his regular duty 0400--1200 hours asked to be allowed to continue for another shift.
Split into simpler sentences: Bhatti who was a flight lieutenant in No.15 Squadron at Sargodha at that time. After completing his regular duty 0400--1200 hours, he asked to be allowed to continue for another shift.