In this paper we present how to use an Unmanned Aerial System in remote sensing. The system is specifically designed for forest fire management, as a support tool for the Fire Services to improve their tactical decisions. The system payload includes two cameras: a thermal camera and a visual camera. A simple image processing algorithm is applied to the thermal images in order to detect hot areas. In case of detecting a hot spot, it raises an event and notifies the geographical position of the spot, so that the firemen manager can know the hot spot position as soon as possible. On demand, the system also provides the visual image of the area with the shape of the detected hot spot marked on it. The visual images of the surroundings of the fire can help experts to discard false positives and to make faster and more accurate decisions.