Abstract: A device for assisting a pilot in the navigation of a small aircraft which comprises a micro processor with a keyboard input device, a cathode ray tube as output and a mini-disc memory. The device is housed in a portable package which can be installed in the control panel of the aircraft.The data base comprises most of the information usually derived from a sectional aeronautical chart for the preparation of a flight plan, including location coordinates of airports and V.O.R. stations, transmitting frequencies and runways characteristics. The program library comprises dialectical routines for guiding the pilot through the preparation of flight plans, and the resolution of common navigational problems such as dead reckoning, wind effect, bearing correction, fuel consumption and range determination.