A team of researchers at Osaka University, together with Rediscovery of the wheel Inc., and JFE Shoji Electronics Corporation, has developed an ultra-wideband radar system, which can be mounted on drones. With the cooperation of the Tokuyama Plant of Idemitsu Kosan Co., Ltd., a drone equipped with the radar was flown in a chimney with a height of 150 m during a regular inspection period (Fig. 1). The researchers have succeeded in inspecting the thickness of the lining material, which covers the chimney wall as a protection layer.