In order to adjust the luminance of indicator lights of a piece of monitoring and control equipment for an airplane, the control for regulating luminous intensity of legends and displays is used to act on the luminance value of the indicator lights. When the indicator lights are illuminated in a "day" mode, the luminance of the indicator lights is independent from the regulation of the luminous intensity of legends and displays. When the indicator lights are illuminated in a "night" mode corresponding to a reduced luminance of the indicator lights relative to the "day" mode, the luminance of the indicator lights can take at least two values according to the luminous intensity regulation value of the legends and displays.