The increased use of UAVs has revealed an unanticipated problem. All of these unmanned air craft need an airfield, especially for landings (which are the trickiest part of their operation.) While the air strips don't have to be as long as for the larger manned aircraft, a straight, flat areas is needed. A portion of a road would do, but you have to make sure ground vehicles don't wander by while you are trying to land a UAV. Originally it was thought that the UAVs could operate from the same airfields as other army aircraft. But most army aircraft are helicopters (about 5,000) and the fixed wing (about 300) planes are usually far from the front. In fact, the army has so few fixed wing aircraft that it doesn't consider building air fields, but instead relies on civilian or air force air strips. UAVs, which are more prone to crashing or going out of control, are not always welcome at these air bases. So far, the UAV units have been improvising, but eventually there may be a demand for dedicated UAV air fields.