Extending access to localizer performance with vertical guidance approaches by means of an SBAS to GBAS converter

Abstract

Currently, many commercial airline aircraft cannot perform three-dimensionally guided approaches based on satellite-based augmentation systems. We propose a system to rebroadcast the correction and integrity data via a data link as provided by the ground-based augmentation system such that aircraft equipped with a GPS landing system (GLS) can use the wide-area corrections and perform localizer performance with vertical guidance (LPV) approaches while maintaining the same level of integrity. In consequence, the system loses some availability and the time to alert is slightly increased. We build a prototype system and present data collected for one week, confirming technical feasibility. There is a loss of 5.3 percent of availability during a 1-week data collection cycle in which we compared our system to standalone LPV service. We tested our prototype with two commercially available GLS receivers with positive results and successfully demonstrated the functionality with a conventional Airbus 319 equipped with a standard GLS receiver.

Benefits for Greek Regional Airports Through Innovative Approach Technology Using an LPV to GLS Converter: A Case Study for Corfu and Thessaloniki

“…In this snapshot, we can observe that the protection levels behave as expected from [11]. The VPL obtained by the uninflated GLASS system is slightly larger than the pure SBAS VPL due to addition of the along track error component to the vertical error estimate, caused by the aircraft descending on an angled glide path and the larger K multiplier required by GBAS.…”

“…As a cost-efficient solution mainly for regional airports, [11] we describe a system that enables aircraft equipped with a GLS capable MMR to receive correction data as generated by a SBAS system via the GLS data broadcast system. The system is called GLASS and schematically illustrated in Figure 1.…”

“…Then, the availability of the system with protection level inflation and without was assessed. In [11], the inflation introduced in the protection level calculation was described, in order to fully reproduce SBAS protection level in the converter system. However, since GBAS actually only "cares" about the cross track component in the horizontal, plus a percentage of the along track component mapped to the vertical due to the glide path, this inflation is strictly not necessary for safety considerations.…”

“…Protection Levels (PLs) estimate the position uncertainty at the allocated integrity risk bound at any measurement epoch. This calculation is a requirement for any airborne GNSS receiver (details can be found in [4], [11] and the references therein). The red line is the standard SBAS VPL as computed by a pure SBAS receiver certified according to [4].…”

Performance improvement of the GAGAN satellite-based augmentation system based on local ionospheric delay estimation in Thailand

“…Moreover, Weng and Chen (2019) investigated the vertical integration of the SBAS service and a local monitoring station to reduce vertical protection levels (VPL). Dautermann et al (2020) proposed to rebroadcast the corrected parameters of the SBAS service via the Ground-Based Augmentation System (GBAS) to the aircraft. Interestingly, based on the assumption that the DFMC SBAS system may not be operating soon, the modification of broadcast correction data frames is proposed by Reid et al (2013).…”