Aircraft employ satellite navigation too: Europe’s EGNOS augmentation system sharpens the accuracy and reliability of GPS signals so they can safely be used for landing approaches across a growing number of European airports. But aviation is a global enterprise – so the aim is to develop a seamless network of augmentation systems in future.
That is the task of an international group of experts, the Satellite Based Augmentation Systems (SBAS) Interoperability Working Group (IWG), whose 27th meeting took place in Tampa, Florida on 8-10 September, hosted by the US Institute of Navigation.
Satellite augmentation systems combine dedicated ground stations and satellite transponders to sharpen satnav accuracy and provide ‘integrity’ data – providing continuously updated reliability levels – across given geographical regions.
These systems are based on the US GPS for now, but with plans to move to a multi-constellation design in the post-2020 era, making use of Europe’s Galileo, China’s Beidou and Russia’s Glonass systems as well.
SBAS systems enhance any type of location-based satnav use, but in practice aviation is the main driver. The ESA-developed European Geostationary Navigation Overlay Service, EGNOS, commenced its general-public Open Service in 2009, with the Safety-of-Life Service for aircraft vertical landing approaches following in 2011.
For next-generation SBAS systems, the IWG are designing a multi-constellation and dual-frequency standard for heightened accuracy and reliability, building up to offering SBAS coverage on a worldwide basis.
Didier Flament, representing ESA – which co-chaired this IWG meeting with the US Federal Aviation Authority – commented: “Among the achievements of the Tampa IWG has been the presentation of an ongoing review of a standard message definition for the new and second SBAS channel – known as L5 – of the second-generation SBAS system, to be used along with the current L1 signal.
“A single definition coordinated between ESA and the European Commission on one side and the US Federal Aviation Administration on the other, is progressing. The formal IWG review loop has started, with the aim of finalising the convergence for early 2015.
“The aim is to have it ready to submit to the international SBAS standardisation bodies – the International Civil Aviation Organisation (ICAO), the US Radio Technical Commission for Aeronautics and the European Organisation for Civil Aviation Equipment – in the first quarter of next year.”
The meeting also introduced two new SBAS development projects, adding to the five existing projects presented at IWG 26.
The first was presented by the Agency for Air Navigation Safety in western Africa and Madagascar (ASECNA), a public international organisation with 18 member states.
ASECNA’s project aims to take a two-step approach, commencing with EGNOS-style vertical landing guidance for selected airports, based on EGNOS constituents, with a tentative schedule of 2018, moving to upgrade to the dual-frequency multi-constellation service across the whole of ASECNA airspace after 2020.
The second new project is China’s own BeiDou SBAS. After discussions at ICAO level, China has committed to delivering SBAS services over China that are fully compliant with ICAO standards.
“This new plan has been highly welcomed by the aviation community and other SBAS providers,” Didier added. “Chinese representatives have also confirmed their intention to become part of the SBAS IWG and contribute to the work done to finalise the future standard.”
The follow-up IWG meeting will take place in February 2015 and will be hosted by ASECNA in Dakar, Senegal.
EGNOS, the European Geostationary Navigation Overlay Service, is Europe’s first venture into satellite navigation. Its development was managed by the European Space Agency (ESA) under a tripartite agreement with the European Commission (EC) and the European Organisation for the Safety of Air Navigation (Eurocontrol).
The ownership of the EGNOS assets was transferred from ESA to the EC in April 2009 and EGNOS officially entered service on 1 October 2009. The service is delivered, through a contract with the European GNSS Service Agency (GSA), by the European Satellite Services Provider, ESSP SaS, founded by seven air navigation service providers. ESA is the design and procurement agent for EGNOS on behalf of the EC.