A number of MiG-3s were found to have unacceptable performance at high altitudes despite being designed as a high-altitude interceptor. The oxygen supply was often insufficient and the stall and spin characteristics were very dangerous, especially to inexperienced pilots. This was demonstrated on 10 April 1941 when three pilots of the 31st Fighter Regiment of the Air Defenses (IAP PVO) attempted to intercept a German high-altitude reconnaissance aircraft over Kaunas, Lithuania flying at . All three aircraft entered irrecoverable spins and the pilots were forced to bail out, one being killed. The NII VVS sent an engineer to investigate and he found that the pilots had flown very few hours on the MiG-3 and that that was their first high-altitude sortie. Other problems included insufficient fuel and oil pressure at altitude due to problems with the pumps.