Possibly, the aspiration to glance for horizon was peculiar to commanders of all times. It is not surprising, that investigation became the first application of airplanes in military science. Prompt development of fighting aircraft has demanded acceptance of measures for reduction of probability of sudden occurrence of planes of the enemy over the territory. Receipt on arms in the late thirties of land radar stations became the present revolution in this business. There were also first plane radars. The groundless locator has shown considerable advantages before land as to it to a lesser degree stirred a relief of a terrestrial surface.