The MiG-15UTI two-seat trainers were the most intensely operated aircraft in every Bulgarian fighter regiment in the 1950s and 1960s, used for the continuation training and proficiency checks of all pilots flying the MiG-15, MiG-17 and MiG-19. The two-seat MiG-15UTI ‘Midget’, used the basic airframe and powerplant of the single-seater, and had its second cockpit (occupied by the instructor) inserted in the place of the fuel tanks, thus reducing the internal fuel tankage. This aircraft wears a rare four-digit serial which tends to indicate that it was among the first delivered aircraft, taken on strength in 1951 or 1952. The VVS took delivery of no fewer than 61 two-seaters between 1951 and 1960, representing a mixture of Soviet- and Czechoslovak-built examples.