Demonstration of Improved Trajectory Prediction Using Future Air Navigation Systems

Abstract

This paper aims to demonstrate how current technology can assist to improve ground-based trajectory prediction. The lack of accurate ground-based trajectory prediction is often associated with the inefficiencies resulting from current Air Traffic Control (ATC) practices. To this purpose, results from different ground-based Trajectory Predictors (TPs) – both standard and enhanced with Future Air Navigation Systems (FANS) data-link – are compared using operations into Los Angeles (LAX). At first sight, direct use of trajectory information down-linked through FANS from the aircraft’s Flight Management System (FMS) seems logical, but numerous arguments exist against that approach. Instead, this research inferred parameters as speed schedule and aircraft mass from the FMS down-linked trajectory. Contrary to the trajectory data itself, these parameters can be used as input to many legacy TPs and are often unknown such that nominal values must be assumed. This paper indicates that with use of this inferred information significant improvements in ground-based trajectory prediction can be achieved. The 95% spread in the estimate time of arrival and top of descent error were reduced by a maximum 79% and 86%, respectively. The predicted trajectories from some enhanced TPs were found to be even more accurate than the original downlink predictions on which the inferred information was based, providing arguments for a combined air-ground solution to trajectory prediction rather than reliance on solely airborne trajectory data.FANS is standard equipment on most wide-body aircraft, and fitting options exist on the major single-aisle aircraft fleet. With the infrastructure to obtain the required data already in place, the approach proposed in this paper is feasible today with minimum investment and aircraft system changes for airlines transitioning towards more advanced concepts and developing technologies.