To easily recognize a landing strip and after reaching in the adjacent to the landing strip, safely and surely guide a helicopter to the landing strip by actuating a control means by a common signal issued, when the helicopter reaches near the landing strip, and reducing the intensity of a light emitting means.

When a parent machine receives a primary command signal from a ground watchman by an antenna 7, it judges at its receiving part, whether it instructs to switch a light emitting state or not, If the primary command signal instructs the switching of the light emitting state, the information is sent to the control part as an output signal. The control part sends a command of transmitting a secondary command signal, whose content is changed to instruct a child machine to reduce the light, to a transmission part so that the transmission interval is shortened. At the same time, the control part of the parent machine reduces the own light intensity and emits the light of a light emitting tube 5 simultaneously with the transmission of the secondary command signal transmission command. This constitution provides the same situation substantially as continuously lighting a weak light.