1. A method of performing real-time flight path selection and path planing for general aviation, comprising the following steps: using Digitized Terrain Elevation Data (DTED) to generate a terrain model; using this terrain model to provide a navigation space; accessing and retrieving terrain model to generate a terrain map; giving start and goal points on navigation space to determine a ground track of direct flight path on terrain map; identifying dangerous zone based on ground track and flight altitude; using said dangerous zone to allocate a set of way-points for avoidance; constructing a visibility graph of navigation space, in which is a set of collision free path segments; linking start point to goal point by flight path searching algorithm; and obtaining the terrain profile of flight path from terrain model.