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Total Performance System for GBAS based Automatic Landings

TOPGAL is an internal DLR project which investigates GBAS based navigation in conjunction with flight management and autopilot systems. A socalled Ground Based Augmentation System enables aircraft to use satellite navigation for guidance on a precision approach. It assures navigational accuracy and integrity all the way down to touch-down and roll-out and thus will in the future be able to replace the currently used instrument landing system (ILS).

This is a joint work of the DLR institutes of Communications and navigation (Lieder of the project), Flight Guidance, Robotics and Mechatronics and Atmospheric Physics which investigates this promising technology under several different aspects.

In a preceding project a GBAS ground station was set up at the research airport in Braunschweig and successfully tested to comply with the requirements for CAT-I (runway visual range not less than 550m, ceiling not lower than 200ft). Within the TOPGAL project the necessary enhancements and analyses to comply with the drafted CAT-III (no minimum visibility) requirements are carried out. This is mainly achieved through implementation of several new monitoring schemes on the ground and in the airborne system to detect and mitigate ionospheric anomalies.

The highly precise and robust navigation data are then forwarded to an enhanced autopilot. It can follow a predefined trajectory more precisely and thus reduce the dispersion of the touchdown points on the runway. In order to be able to determine the performance of the whole aircraft it is necessary to investigate navigation and flight control systems jointly. In simulations numerous influencing parameters such as wind and different navigation error modes are investigated and characterized. The results are then validated in flight trials.

Furthermore, the newly gained precision is exploited in advanced flight guidance procedures including not only positioning but also timing aspects. This allows highly flexible approach procedures with increased capacity and guidance on curved approach tracks. Hence, noise sensitive areas can be better avoided and shorter approach tracks help in saving fuel.

The research in DLR’s TOPGAL project concerning a series of technical and operational aspects is a valuable contribution to the introduction of this new technology.

Support:  internal project

Duration: 01.01.2010-31.12.2012

Boubeker Belabbas
German Aerospace Center

Institute of Communications and Navigation
, Navigation
Tel: +49 8153 28-1129

Fax: +49 8153 28-2328

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