A model to 4D descent trajectory guidance

Current standard arrival routes or STARs will require in next years more flexibility to handle the increase of aircraft arrivals and to minimize the related environmental impact applying continuous descent trajectories at idle thrust. To do that, a global optimized 4D trajectory must be followed from the given aircraft position to the terminal gate and tracked in real time. 4D trajectory guidance is not an easy task (mainly at arrivals trajectories) due to the variability of the atmospheric and meteorological conditions with the altitude, which introduces discrepancies from the given reference trajectory and the real one. In this paper we present a new 4D trajectory guidance model focussed on the descent and arrival flight phase. This model has been designed as a 4D FMS which is part of an entire dynamic control system using the well established point mass model for the aircraft aerodynamic behaviour. The proposed 4D FMS compares the aircraft state vector with the reference trajectory and calculates the necessary control entrances to fit the actual response to the previously estimated one.