PURPOSE: To provide a method for allowing an operator to accurately grasp the flying position of a remote-controlled helicopter for dusting use to enable the uniform dusting of each part of a field with chemicals.

CONSTITUTION: A plurality of markers M are erected on a field. A helicopter remotely controllable by a transmitter having a display is provided with a position sensor to measure the distance between the helicopter and a reflector. The position of the helicopter over the field is calculated based on the distances measured by the position sensor and the calculated result is transmitted to the transmitter to display the position of the helicopter on the display.