Evaluation of GBAS Flight Tests with respect to GAST-D Requirements

The German Aerospace Centre (DLR) is operating an experimental GBAS station at the research airport in Braunschweig. It currently consists of three reference receivers with multipath limiting choke ring reference antennas. The system was originally designed and built to support CAT-I approaches (which corresponds to the so called GBAS Approach Service Type C, GAST-C) and has been upgraded within the last year to almost fully comply with the more stringent requirements for CAT-III operations (referred to as GAST-D) in real time. This service type is foreseen to provide corrections and integrity parameters to meet the safety objectives for guiding aircraft on final approach including automatic landings. The required change according to RTCA DO-253C and ICAO draft SARPS includes addition of several new monitors and processing schemes, both, on the ground and in the airborne subsystem. We present the outputs of the airborne monitors during flight trials performed with DLR’s VFW 614 research aircraft and evaluate their performance with respect to the requirements concerning navigation and total system performance