The first VI-100 prototype was demonstrated publicly during the 1940 May Day parade, flown by Maj. Stefanovsky, as Petlyakov and his team watched on from the roofs of their "sharashka". During testing in 1940, the second prototype VI-100 suffered a cockpit fire due to an improperly tightened nut in the fuel supply and crashed into a kindergarten, killing a group of young children and a teacher. Despite the loss of the second prototype and several defects being found in the first prototype, the VI-100 was judged satisfactory and suitable for further development. Its performance was superior to other Soviet high altitude fighters such as the Mikoyan-Gurevich I-200 (the future MiG-3), and compared favourably with contemporary aircraft such as the Potez 630, Messerschmitt Bf 110 C, and Bristol Beaufighter Mk. I. However, events were to lead to substantial changes in the direction of the VI-100 project.