Abstract
The fundamental tendency of deviation from a curved approach trajectory is investigated through a series of basic numerical simulations using a simplified aircraft model subject to wind disturbance. A set of numerical simulations has revealed that a large lateral deviation during a curved trajectory is inevitable, and that the lateral and vertical deviations correlate to each other. It is also revealed that the distribution of the flight trajectory deviation has an asymmetry; aircraft deviate inside of the average trajectory on the curved leg in the majority of simulation cases. Once the flight speed of an aircraft deviates from the reference value by some wind turbulence, it tends to be lower than the reference value because it is more difficult to accelerate than to decelerate because of the difference of the drag coefficient change amount between the faster and slower speed cases. This results in the distribution asymmetry of the trajectory deviation toward the inside of a curved leg, and quite large deviations toward the outside of the curved trajectory inevitably occur. From these results, it is considered that the protection space to assure the collision clearance should be defined so as to reflect the deviation tendency.
