Abstract
In general, probabilities of overlap which are key parameters in a collision risk model can be estimated from the frequency distribution of navigational errors. However, it is very difficult to determine the distribution of vertical navigational errors because the assigned altitude of aircraft is given by an isobaric surface (flight level) whose height depends on the atmospheric conditions. This paper describes a method of estimating the probability of vertical overlap of an aircraft pair without knowing the distribution function of vertical navigational errors directly. Using a pair of observed heights of aircraft (this is defined as the relative vertical distance), the probability of vertical overlap can be estimated from its frequency distribution empirically. Several cases of samplings and some results of a computer simulation carried out for an assumed error distribution in order to verify this method are discussed herein.
