Here at Honeywell we have been banging the GBAS drum for nearly 10 years now, and momentum behind the technology is now really starting to pick up around the world. The traditional Instrument Landing System (ILS), which provides a glideslope and localizer to guide aircraft into land, has started to show its limitations when tasked with managing the high traffic volumes of today’s airports. This of course is not surprising -- the principles of ILS date back to the 1930s when no-one could have imagined the number of aircraft that use hub airports today, nor the level of infrastructure and other obstructions around the terminal environment that can cause interference with the ILS beam.
GBAS gets around these challenges by augmenting satellite navigation signals to make them accurate for precision landings. The infrastructure required for such approaches is relatively simple -- you need a ground station such as our certified SmartPath system, which can receive satellite signals, process the data and make necessary error corrections before broadcasting out to aircraft transitioning from en-route to terminal airspace via VHF. And you therefore need GNSS (Global Navigation Satellite System) Landing System (thankfully shortened to “GLS”) airborne equipage for the aircraft, so that it can receive these signals.
Honeywell has been pioneering this infrastructure in Europe through its SmartPath ground station and also in terms of avionics under the European Union’s Single European Sky ATM Research initiative’s 9.12 work package. This work package is designed to validate GBAS for use in Europe’s future ATM ecosystem down to CATII/III - that is, an approach and landing with very low visibility. This dramatically lowers the decision height whereby the pilots must abort their landing if they cannot see the runway from the cockpit at a given altitude.
To enable an aircraft to be accurately and safely guided by satellite right down to the runway takes some serious engineering and consequently a lot of validation and certification processes. It’s something Honeywell’s Advanced Technology Europe group has been working on in terms of avionics under SESAR and alongside our work package partners for four years now. And on 25th September at Frankfurt International, Germany, the team reached a significant milestone - the program’s first CATIII approach and landing managed solely by GBAS.
This initial test was an overwhelming success, and in the week that followed we completed a total of 38 other successful GBAS approaches at Frankfurt, as well as at Toulouse, France. These successes were made possible by the one thing that epitomises SESAR -- collaboration. Through Honeywell Advanced Technology Europe’s partnership with Airbus, Germany’s DFS, NATMIG, Eurocontrol, DSNA and Thales, we were able to consistently land Honeywell’s Falcon 900EX business jet using a mix of satellite guidance and autopilot with a high degree of integrity and accuracy well within requirements.
The key objective of these validation exercises was not simply to see whether the landing was accurate enough but was to test interoperability of each component. Over the past 10 months we have been working with our partners to ensure our airborne VIDL-G for CAT III avionics receiver prototype ingrates seamlessly with their prototype ground stations and airport air traffic control infrastructure. We also test flew a range of different conditions and scenarios during the trials, including multipath evaluations, tested full scale deviations and CATII/III regression testing, in order prove the GBAS’ validity.
The interoperability of our VIDL-G receiver performed exactly as it was designed to, integrating seamlessly with the different ground stations at Frankfurt and Toulouse. While this initial test was conducted using a business jet, the results are applicable to commercial platforms too, making this an important leap towards the end goal of revenue-generating GBAS flights in Europe.
Of course, it would be great to say that we have now fully validated CATIII GBAS for Europe as a result of these trials but in reality there is still some way to go. In the short-term the team will process the data from the first round of tests, captured by the sophisticated test set-up, in order to further enhance the airborne receiver’s functionality, support baseline Standards and Recommended Practices (SARPS) validation, as we as validate our simulation tools.
In the medium to longer term, as well as further testing of the current trial systems at Frankfurt and Toulouse (the next of which is scheduled for mid-2014) we expect to conduct further tests of our airborne receiver against other ground stations, including airports equipped with our own CATI-certified SmartPath system. Honeywell’s Advanced Technology Europe group is also exploring with SESAR the potential for future extension of the 9.12 work package for multi-constellation multi-frequency GBAS, which would lead to an even more robust system suitable for use virtually anywhere in the world as a replacement for existing ILS.
Despite the work still left to do, the results of our initial flight tests have proved that GBAS is a viable alternative to ILS, bringing additional benefits including lower maintenance costs, easier installation paths, reduced tarmac and approach congestion and a greater range of complex and straight-in approaches to European airports. And for us at Honeywell it has shown that whether we are providing GBAS capabilities on the ground or in the sky, our systems are reliable and interoperable. I see GBAS as one of the most exciting prospects in the future of ATM and one that we at Honeywell are very proud to be pioneering.