Performance Analysis of GBAS Vertical Protection Levels for Civil Aircraft Precision Approach and Landing using GPS and GLONASS

Abstract

In this paper, an analysis has been performed to quantify and compare the Vertical Protection Levels (VPLs) performances using GPS (Global Positioning System) and GLONASS (GLObal NAvigation Satellite System - GLObalnaya NAvigatsionnaya Sputnikovaya Sistema) satellite navigation systems for the largest Turkish Airport (Istanbul Ataturk Airport – IST). The VPLs are position error bounds computed at aircraft with ensured high navigation performances for initiation of intendent precision aircraft approach and landing in the Ground Based Augmentation System (GBAS). The GBAS, therefore, is an advanced navigation system and designed to provide civil aircraft user with high navigation performances. All defined algorithms in GBAS are built entirely on the GPS positioning solutions. In this study, an alternative constellation of global satellite navigation system GLONASS is considered and its performances are quantified for potential usability in future. In this respect, IST is selected as an implementation site in analysis. Two approaches have been proposed in the quantification of system availability for the given site; a) full constellation with increased elevation mask, b) two satellite outages as a worst-case scenario in the quantification of system availability. Investigations have shown that the GPS could provide superior performance over GLONASS in compliance with the GBAS availability requirements (i.e., exhibits high performance). However, the outcomes are also promising for the prescribed GBAS VPL performance using an alternative constellation (GLONASS) for supporting a precision approach and landing of an aircraft at the IST.