Mission Aviation Fellowship

The return of UK SBAS?

US satellite communications company Viasat has demonstrated a satellite-based augmentation system (SBAS) for potential use at UK airports that could replace the European Geostationary Navigation Overlay Service (EGNOS) that the UK lost access to when it left the European Union.

Viasat demonstrated its system using Cranfield University’s National Flying Laboratory Centre’s Saab 340B twin-turboprop in January as part of a first step in providing validation of an alternative UK SBAS capability.

SBAS is a Safety of Life (SoL) service which provides more reliable navigation data by combining ground monitoring data with satellite connectivity, giving a greater level of navigational accuracy, essential in critical stages of flight such as landing.

Prior to Brexit, the UK had been a key player in the development of the EGNOS system, which enabled the use of localizer performance with vertical guidance (LPV) approaches at airports.

Some 19 airports around the UK had invested in LPV approach procedures as an alternative to more expensive landing systems such as the radio signal-based Instrument Landing Systems, but these were lost in June 2021 after the UK had left the EU and subsequently declined to pay the annual £25m-£30m fee to regain EGNOS membership.

At the time there were strong objections over UK Government’s apparent refusal to rejoin EGNOS, with Lord Davies of Gower, former DfT General Aviation Champion and chairman of the All-Party Parliamentary Group on General Aviation, co-authoring a report on why it was vital to retain a SoL service for the UK aviation industry. While membership of EGNOS appears to have remained off the table, the fact that the Department for Transport has part funded Viasat’s SBAS trial would appear to indicate that Government has got the message and agrees that satellite augmentation is an important requirement for the transport sector.

Commenting on the trial, Todd McDonnell, President, International Government, Viasat, said: “This trial on a sovereign UK SBAS is all about delivering trust. Trust for pilots in their tracking systems so they can stay safe in challenging conditions. Trust for the aviation industry more broadly so it can rely on data to operate more efficiently. And, in the future, trust that we can use highly accurate tracking to develop Britain’s transport system as new technologies come into play. We’re excited to continue the trial and see how far we can take it.”

Dean Thomas, Position, Navigation and Timing Lead at the UK Space Agency, added: “This testbed project is vital in helping Government understand the potential benefits of a UK SBAS. The flight trial both demonstrates the capability of UK industry in delivering space based PNT solutions and illustrates the benefits of delivering UK PNT projects facilitated by ESA, through the highly flexible NAVISP programme.”

Viasat said the UK SBAS generates an overlay test signal linked to the US GPS that is compliant with International Civil Aviation Organisation (ICAO) standards to enable assessment of more precise, resilient and high-integrity navigation for aviation users in UK airspace. The signal is being broadcast in coordination with the US Federal Aviation Administration (FAA), the European Space Agency (ESA) and the European Union Space Programme Agency.

The SBAS trials are being completed by a Viasat-led team of companies in the UK, including Goonhilly Earth Station, CGI UK, GMV, Ordnance Survey, Cranfield University, the Cranfield National Flying Laboratory Centre, and Pildo Labs.

Author: FTN Editor

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