The machine we communicated to through switches and dials responds. It will present us with meter readings, flashing lights, or alarms. Lights tell them if the engines are running properly. Alarms sound as the plane approaches stall speed.
Video screens display the information gathered by the radar system.
In our automobiles, gauges and lights are also used to communicate. The fuel gauge tells the driver when to buy more gasoline. The oil light warns the operator of low oil pressure. A blue light tells the driver that the headlights are on high-beam.