Ground-Based Augmentation System (GBAS)

Ground Based Augmentation System (GBAS) is an alternative to Instrument Landing Systems (ILS).

Background

Since the 1960s, airports around Europe have relied on ILS for approach and landing guidance. The ILS is effectively two sub-systems:

  • a localiser to provide lateral guidance
  • and a glide slope antenna for vertical guidance.

Although ILS has proven itself as a reliable and functional system for many years, the availability of advanced satellite navigation systems provides the possibility to implement a system that overcomes some of ILS’ challenges, and to meet the more demanding needs of the future in a more cost-efficient way.

Implementation

Currently GBAS Category I operations are implemented at the following airports:

  1. Bremen,
  2. Malaga,
  3. Frankfurt,
  4. Zurich. 

Research and development

The Single European Sky ATM Research (SESAR Programme) is validating the  development of GBAS to support low visibility operations (so-called Category II/III).

In order to optimise low visibility operations using GBAS, it is recommended that users follow a “landing clearance line”  which is closer to the runway than ILS holding points; this helps the controller determine when an aircraft has vacated the runway. Reduced runway occupancy times are an additional benefit, as GBAS operations make for an immediate improvement in runway throughput in adverse weather conditions.

Benefits

With regard to airports, GBAS advanced operations based on increased glide slopes and adaptive runway aiming point are expected to:

  • Reduce runway occupancy times and a lower risk of wake vortex problems, due to displaced runway thresholds
  • Increase runway throughput in low visibility conditions and adverse weather conditions by supporting reduced spacing on final approach
  • Reduce noise concerns in the vicinity of airports through GBAS increase glide slopes and curved approaches

GBAS provides a cost-efficient solution, since only one ground station is needed to service multiple approaches to all runways at an airport.

GBAS-optimised low visibility operations primarily address busy airports with capacity limitations. GBAS advanced procedures can directly support airports seeking to address noise issues and efficient arrival paths.

Passengers can also benefit from the deployment of the GBAS concept as more flights could be flown.

The SESAR GBAS Community

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