The purpose of this paper is to show the performance during flight tests of the proposed GBAS Approach Service Type D navigation – intended to support autoland operations – in comparison to ILS.
An experimental GBAS station was installed at the research airport in Braunschweig. Data processing complied with the currently proposed requirements to support automatic landings. Corrections for GPS measurements and integrity parameters were sent to a research aircraft which was equipped with an experimental GPS receiver providing raw measurement data. The received data and measurements were then processed on board in real‐time and provide approach guidance information to the experimental pilot in form of a flight director indication. To evaluate system performance the authors create a truth reference track from a post processed carrier phase solution. Finally, the GBAS outputs and the received ILS signals are compared to the truth reference.
The system performed well within all specifications and showed full availability at all times during the flight. Compared to ILS, GBAS is significantly more precise and shows almost no noise.
The navigation solution was flown manually according to flight director displays, therefore no automatic approaches and landings could be performed.
It has been demonstrated that GBAS can support the intended operations under nominal conditions.
This work is part of the ongoing validation of the proposed standards for a satellite based landing system. It compares GBAS and ILS data from flight tests carried out with a representative aircraft.
