Derivation of a Point-Mass Aircraft Model used for Fast-Time Simulation

This document describes a closed-loop aircraft model for testing the performance of Flight-deck Interval Management (FIM) avionics. The derivation of a point-mass aircraft model with and without winds is presented. Guidance control laws used to track a four-dimensional trajectory, described as a reference horizontal path, a vertical profile, and an indicated airspeed command, are also presented. In particular, two speed management modes, used to control the aircraft’s speed during descent while also managing the aircraft’s altitude relative to the reference vertical profile, are described. The data format of the reference horizontal path is described in detail, including an algorithm for mapping the aircraft’s position in the horizontal plane onto the reference horizontal path. Lastly, parameters for representing different aircraft types using the general equations are enumerated.