Study On Minimum Longitudinal Separation For Aircrafts Crossing Flight Levels

Contradiction between the increasing of flight flow and the limited airspace resources has become the major factor restricting the development of China's civil aviation industry. In order to increase airspace capacity and improve ATC's work efficiency, it is very necessary to define the required minimum longitudinal separation for aircrafts cross through flight levels.In this paper, a model of aircrafts cross through flight levels is established. The disturbances that affect the flight of aircrafts are considered including the flight technical errors, navigation errors and surveillance errors, then simulations of aircrafts cross through flight levels can be done with Monte-Carlo method. The required minimum longitudinal separation for aircrafts cross through flight levels can be calculated through extensive simulations.A model of aircrafts cross through flight levels is established according to the relevant separation standards and the process of controllers commanding aircrafts cross through flight levels. Then several factors which affect the size of safe separation are analyzed. With the assumption of flat earth, coordinated turns and added to potential error sources, a set of three-dimensional point-mass equations of motion for a commercial aircraft can be derived and on this basis the models of trajectory controls can be developed by using the method of feedback linearization. The aircraft flight simulation is designed modularly using Matlab/Simulink based on mathematical models, including modules of aircraft dynamics,modules of aircraft kinematics, modules of trajectory deviation and modules of trajectory control. The fourth-order Runge-Kutta numerical integration method in Matlab is used to numerically integrate the differential equations forward. Programming with Matlab according to actual requirements, on the one hand it might be used to generate random numbers; on the other hand many simulation experiments can be realized in the form of cycle call simulation model. The probability of conflict between two aircrafts in different initial separations can be done with Monte-Carlo method. Through extensive simulations and considering the impact of radar surveillance position errors, the required minimum longitudinal separation for aircrafts cross through flight levels can be calculated.The results of this study are very helpful to revise separation standard and controllers command aircrafts cross through flight levels.