A version of this article appears in the June 30 edition of Aviation Week & Space Technology.
Among European air navigation authorities, Britain is taking the lead in implementing a space-based means to ensure safer, more accurate vertically guided aircraft approaches at airports, including those where conventional precision landing systems are not always economically feasible.
Few argue that the safety-of-life service enabled by the European Geostationary Navigation Overlay Service (Egnos) system is a benefit to civil aviation: As Europe’s equivalent to the U.S. Wide Area Augmentation System (WAAS), Egnos allows aircraft to make precision approaches, rendering air navigation safer. It also helps reduce flight delays, diversions or cancellations and allows airports to increase capacity, cut operating costs and reduce Co2 emissions.
Led by the European Space Agency (ESA) and the European Commission, Egnos entered operational service in 2009. But while its safety-of-life signal has been available since March 2011, experts within Europe’s civil aviation community say its use is limited by a lack of guidance from international regulators and foot-dragging among civil aviation authorities within the 28-nation European Union, most of whom have yet to adopt the regulatory framework necessary for implementing LPV (localizer performance with vertical guidance) procedures.
“It’s been three years, but people forget we don’t have any technical issue anymore; the performance is good,” says Thierry Racaud, CEO of the European Satellite Service Provider (ESSP), the private company established to manage the EC’s Egnos service contract through 2021.
Using a combination of onboard avionics, procedures and pilot training to enable LPV approaches, Egnos comprises three satellites and a network of 40 ground stations that sharpen GPS signals and allow aircraft to perform near-precision approaches using vertical guidance.
Interoperable with WAAS and the Japanese Multi-functional Satellite Augmentation System, Egnos is a suitable alternative for regional, corporate and general aviation operators working in remote areas as well as for small airports that cannot afford ground-based instrument approach systems that use radio signals and lighting arrays to enable safe landing in inclement weather.
Speaking at the 2014 European Space Solutions Expo here, Racaud said the signal availability has been demonstrated at 99% reliability. To date, he says, ESSP has signed 20 agreements with countries seeking to implement space-based LPV procedures, and that 108 LPVs have been published at 77 airports in Europe. By the end of the year, he says, 180 LPV procedures will have been published, with a goal of EU-wide coverage by 2018.
“Today we have 15 operators who are using Egnos on a daily basis, regional and business operators as well as helicopters,” Racaud said, adding that most business aviation and high-end helicopter manufacturers are now building Egnos equipment into their aircraft.
“It’s going more slowly with commercial aviation,” Racaud said. “But we know for surewill have the equipped, and regarding military aircraft, the is also LPV-capable as well.”
The first commercial operator to use Egnos was Channel Islands-based Aurigny Air Services, which for the past two years has been relying on the satellite-based navigation system to sharpen U.S. GPS and Russian Glonass signals to less than 2-meter (6.5-ft.) accuracy.
The U.K. currently has 56 airports developing LPV procedures, with Bristol and Exeter scheduled to become effective in August and Southampton in December. For now, Aurigny remains the only European operator to use Egnos-enabled LPV in scheduled passenger service, though others are coming along, including Loganair, Hebridean Air Services,and Skybus.
“They all have the equipment onboard, but they need operational approval,” says Ken Ashton, an official with NATS, Britain’s largest air traffic control agency. “They haven’t progressed the operational approval because until you have a procedure published, why would you train people if they then can’t use it? You then have to go and train everybody again at a later date.”
Other countries are gradually following suit. Sweden, a nation that long held out in backing Egnos due to its northerly geographic location, is now a supporter. Because its airports are far north of the equator, acquiring satellite signals can be a challenge, a factor that led Stockholm to initially withhold funding for Egnos—the only ESA member to refuse.
“But we have changed our minds about that,” says Christer Ullvetter of the Swedish Transport Agency’s civil aviation authority.
Two years ago Sweden conducted Egnos trials using a Beechcraft B200 at 20 airports across the nation. The conclusion was that south of 60 deg. north, Egnos provides good service, but that north of 65 deg. it becomes marginal because satellite signals can be blocked by the aircraft’s fuselage.
However, he said another round of testing showed that with longer approaches, any glitches in the Egnos signal could be compensated for over time. He noted that with the right LPV procedures in place, “Egnos can be used at all Swedish airports.”
Paul Fraser-Bennison, a policy specialist with Britain’s Civil Aviation Authority, said the driving force behind the U.K. implementation was an International Civil Aviation Organization (ICAO) statement issued several years ago urging the world to implement LPV at runways by 2016.
Now, Fraser-Bennison says, ICAO needs to make space-based navigation a higher priority. “If a message goes out from this meeting, it should be to the air navigation panel of the ICAO to say a job card should be raised and that doc. 8168 [the ICAO standards on flight procedures] should be adopting a more permissive way of doing things.”