Business & GA

AAL Project Gives Positive Results for Satellite-based Navigation

By Woodrow Bellamy III  | December 12, 2016
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[Avionics Magazine 12-12-2016] A two-year study featuring 360 trial flights has shown the ability of augmented navigation and vision technologies to improve airport access and reduce aircraft environmental impact at numerous European airports. Avionics Magazine recently caught up with Jean-Phillippe Ramu, flight crew and project manager at NetJets Europe, to discuss what the results of the Single European Sky ATM Research Joint Undertaking (SESAR JU) co-funded Augmented Approaches to Land (AAL) project will mean for the future use of advanced aircraft navigation technologies to improve approaches into different airport environments.
The FalconEye Combined Vision System (CVS), developed by Elbit Systems, was one of the technologies validated for augmented approaches during the AAL trials. Photo: Elbit Systems.
The AAL project was first launched in 2015, as part of a 15-company, eight-country alliance seeking to validate the ability of augmented vision and satellite-based navigation technologies to improve aircraft access at various airports throughout Europe and around the world. More than half of AAL’s 360 trial flights were performed by European carriers Lufthansa and Swiss on revenue flights using Airbus A320s, A380s and Boeing 747-800s among other aircraft types. NetJets Europe acted as the projects’ consortium coordinator. AAL focused on testing advanced aircraft navigation procedures using five different technologies: Required Navigation Performance (RNP) paths, Ground and Satellite-Based Augmentation Systems (GBAS and SBAS), Enhanced Flight Vision Systems (EFVS), and Synthetic Vision Guidance Systems (SVGS). German and Swiss Air Navigation Service Providers (ANSPs) Deutsche Flugsicherung (DFS) and Skyguide, in collaboration with Fraport and Zurich Airport implemented new flight procedures to support the AAL flights in Frankfurt, Zurich and Bremen. 
Trial flights were also performed at regional airports in in Brno, Ostrava and Karlovy Vary to evaluate Honeywell’s SmartView SVGS; and Dassault Aviation Falcon 7X flight test aircraft performed another nine trial flights to evaluate its FalconEye Combined Vision System (CVS). AAL trial flights using SVGS and CVS showed that both technologies can be successfully used to provide access to small and regional airports as well during low visibility conditions. These technologies were tested at Bordeaux, Bergerac and Perigueux airports.
According to Ramu, AAL is one of the first projects to widely demonstrate in a real-life environment the transition from curved satellite-based navigation to the Ground Based Augmentation System (GBAS) precision landing capability. 
“Air Traffic Management is a complex socio-technical system where the design of procedures is only one part of the equation. The procedures developed in Frankfurt, Zurich and Bremen are better in terms of noise abatement, and also shorter by 20 to 40 percent. But the translation of shorter procedures into fuel savings in operations depends on how these procedures are used by controllers, who also need to consider other factors such as traffic sequencing,” said Ramu.
The NetJets Europe flight crew project manager also noted that AAL procedures using GBAS Category II/III (CAT-II/III) standards will enable an increase in capacity at large airports and the use of SBAS Localizer Performance with Vertical guidance  (LPV) supported by augmented vision can support increased accessibility at smaller airports.  
The FAA describes GBAS as a ground station capable of providing corrections to aircraft in the vicinity of an airport in order to improve the accuracy of, and provide integrity for the aircrafts’ GPS navigational position.  Unlike Instrument Landing System (ILS) — which requires one frequency per system — a GBAS only requires one VHF assignment for up to 48 individual approach procedures, the agency says. GBAS usage worldwide is relatively low, limited to 15 locations in Russia, as well as airports located in Bremen and Frankfurt, Germany; Sydney, Australia; Malaga, Spain; and Zurich, Switzerland. In the U.S., only two locations, Newark Liberty International Airport (EWR) and Houston George Bush Intercontinental Airport (IAH), have GBAS stations.
Navigation procedures used on AAL flights were designed with an increased glideslope of 3.2-degrees, steeper than the standard 3-degrees glideslope used on most ILS-equipped airports. Procedures designed for AAL for Frankfurt Airport were published in the International Civil Aviation Organization (ICAO) Aeronautical Information Publication (AIP), meaning any operator could request to fly them. Ramu said aircraft equipped with avionics approved to fly ILS, LPV or Ground-Based Landing System (GLS) procedures were capable of flying them. 
ANSPs and operators looking to fly AAL approaches at other airports though will come up against unique challenges that vary on a case-by-case basis.
“Each location might have different requirements. A small airport might just choose to redesign its procedure without RF Legs, because noise abatement does not require a complex trajectory. Also, if the traffic is not so dense, it might not require RNP, and [Area Navigation] RNAV can be sufficient provided a controller can monitor the aircraft trajectory. We can say that the concept of RNP to [non-linear curved path] XLS is an optimization of the operation, taking full benefit of some aircraft functions available today,” said Ramu. 
The results of the project have produced recommendations that will be forward to aviation standards organizations and civil aviation regulatory authorities. An example Ramu gives is procedure design recommendations maximize the benefit of using satellite-based navigation in terminal areas, taking full advantage of its flexibility, while ensuring interoperability between the several landing systems such as ILS, LPV and GLS.
On the use of augmented vision, operational credits demonstrated by AAL flights will need to be standardized and supporting regulatory material developed. Ramu says that by 2020, operators of aircraft equipped with augmented vision systems technologies will be able to gain new operational approvals. 

“In anticipation of the European mandate to deploy performance-based navigation including [Radius to Fix] RF Legs in the 25 major European airports by 2024, this project will help airports to redesign their procedures efficiently,” said Ramu. 

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