The Polikarpov Po-2 served as an all-weather multirole Soviet biplane, nicknamed Kukuruznik ("kukuruza" which means "maize duster" or "crop duster"), NATO reporting name "Mule". The reliable, uncomplicated concept of the Po-2's design made it an ideal trainer aircraft, as well as doubling as a low-cost ground attack, aerial reconnaissance, psychological warfare and liaison aircraft during war, proving to be one of the most versatile light combat types to be built in the Soviet Union. The Po-2 became known as the aircraft used by the 588th Night Bomber Regiment, composed of an all-woman pilot and ground crew complement. The unit was notorious for daring low-altitude night raids on German rear-area positions. Veteran pilots Yekaterina Ryabova and Nadezhda Popova on one occasion flew eighteen missions in a single night. As of 1978 it remained in production for a longer period of time than any other Soviet-era aircraft.