Research On Minimum Safety Distance In Free Flight Based On CNS Performance

The pilot can be more flexible to choose flight track,speed and heading in free flight than in present flight mode,which will increase the probability of conflict. Research on minimum safety distance under the free flight can ensure flight safety of the free flight, so as to provide theoretical support for the implement of free flight.The main work is as follows:First, establishing calculation model of the minimum safety distance based on CNS performance and velocity error.For the condition that aircraft fly in the same plane, through the analysis of the impact CNS performance and velocity error on aircraft actual position,the two-dimensional plane collision risk model is established using the knowledge of probability theory.Then the minimum safety distance can be calculated by using optimal eighth-order Steffensen iterative method.Then, establishing calculation model of the minimum safety distance based on conflict area.For the condition that aircraft fly on different height and have vertical movement, to build a kind of cylindrical conflict area,and then to establish the collision risk model by analyzing the relationship between the minimum safety distance and collision risk.Then the minimum safety distance is optimized using the hill-climbing algorithm for a given security target.Finally,establishing the minimum safety distance calculation model based on stochastic delay differential equations.The influence of CNS performance on flight safety is divided into two aspects- position error and time delay, which are respectively expressed with the random term and delay term in the stochastic delay differential equations.The minimum safety distance under a given security target levels could be calculated by using full implicit Euler method.