Benefits of Satellite Navigation to U.S. Airports Using Ground Based Augmentation System (GBAS)

Abstract

The objective of this study is to evaluate benefits of the ground-based augmentation system (GBAS) at large U.S. airports that also use the traditional instrument landing system (ILS). Landing operations are analyzed at GBAS-equipped and non-GBAS-equipped airports and airlines to determine if there is any significant difference in their performance. After comparing performance of airports (GBAS- and non-GBAS-equipped) and airlines (one GBAS- and non-GBAS-equipped), we draw a comparison matrix for the following flight performance metrics: block delay, Expect Departure Clearance Times (EDCT) arrival delay, and gate arrival delay. The analysis results reveal that arrival delays are lower at GBAS-airports, while GBAS equipage onboard aircraft does not show any significance. This might imply that airports benefit more from GBAS than airlines. Considering the fact that airports and private entities are responsible for major expenses of GBAS airport equipment, these study findings can be used in cost-benefit analyses when considering GBAS purchasing. Since an ILS system consists of many components located around a runway, this study also evaluates the reliability and availability of ILS systems across Tier 1 U.S. airports; and it compares their performance at GBAS- and non-GBAS-equipped airports using the following metrics: mean time between outages (MTBO), and outage downtime. The analysis results reveal the following: (1) at GBAS-equipped airports, ILS components have longer MTBO when compared to non-GBAS airports, implying that these components fail less frequently; and (2) glide slope (GS) and runway visual range (RVR) outage downtimes at GBAS airports are shorter than at non-GBAS airports, while Localizer (LOC) downtimes at GBAS airports are longer. Since LOCs are mandatory for precision and non-precision approaches, the fact that LOC downtimes are longer at GBAS airports than at non-GBAS airports might imply that because GBAS airports can utilize CAT I precision approaches without using LOCs, LOC failures don’t have to be repaired as quickly as at non-GBAS airports.