A meteorological sounding system, consisting of a miniature robot plane, an air-craft-borne digital sonde unit, and a ground-based subsystem. The flight of mini aircraft is controlled by an onboard auto-control system according to a pre-designed navigation line under the guidance of Global Position System (GPS) data. Flight tracking and air sounding data can be transmitted in real time to ground receiver. The ground-based subsystem would process the received data with a computer and display the geographic position and height of the aircraft and meteorological parameters observed. The ground based subsystem can also send command to the aircraft to manipulate its flight in a remote-control manner. The sonde unit measures temperature, pressure and humidity. Wind speed and direction are derived from GPS data.