Stochastic models of aircraft flight paths and a method for deriving such models from recorded air traffic data. Each stochastic model involves identifying the flight plan for one or more aircraft; identifying important parameters from each flight plan, such as aircraft type, cruise altitude, and airspeed; optionally identifying flight plan amendments for each flight; representing each route of flight as a series of navigational fixes; representing at least one aircraft flight parameter probabilistically; modeling realistic differences in at least one dimension between each planned route of flight and the flight path as it might actually be flown; and communicating the modeled deviations or simulated flight paths to the user. At least one aircraft flight parameter is represented as a random variable with a particular statistical distribution, such as a normal (Gaussian), Laplacian, or logistic distribution; or with a more complex algorithm containing one or more random elements. The modeled flight parameters may be any of lateral position, longitudinal position, climb altitude, descent altitude, climb airspeed, descent airspeed, cruise airspeed, cruise altitude transition, or response time to a flight plan amendment.