GBAS CAT II/III Business Aircraft Flight Trials and Validation – Phase 1

摘要

The development of new GNSS based technologies that will enable precision approaches down to CAT II/III minima is currently in the operational validation phase. After years of technical feasibility assessments by the community of the GPS L1 based augmentation system, operational validation focusing on specific solutions is at its final stages. The objective of this paper is to describe the activities conducted with respect to the validation of the GBAS CAT II/III concept for business aircraft, the results from flight trials and feedback on feasibility of requirements from the airborne perspective. The focus is on the avionics receiver prototype (providing equivalent functionality to the Multi-mode receiver known from air transport aircraft) upgraded to GBAS CAT II/III (GAST D) capability. The paper focuses on Phase 1 of validation activities starting with the integration into Honeywell experimental business aircraft, Falcon F900EX. The test setup includes prototype avionics receiver with GBAS GAST D capability coupled with the autopilot of the aircraft to enable autonomous approaches to CAT II minima. Additional multi-mode receiver is placed on board of the experimental aircraft, to check for interoperability and consistency of results of two GBAS capable receivers. Dual-frequency Novatel receiver, connected to the same antenna as the other two receivers, provides centimeter level accuracy after post processing with another Novatel receiver based on ground with surveyed antenna location, to provide the truth to which the performance of the system is compared. In order to verify the VDB transmission from the ground station, as well as airborne reception (i.e. with respect to number of CRC errors) a Telerad receiver is placed on board and connected to the same VHF antenna as the other two GBAS capable receivers. The recording equipment enables to record all the aircraft data relevant for validation of models, as well as data from all the receivers (both ARINC 429, as well as internal data including GBAS specific monitors status) needed for verification and validation of the overall GBAS CAT II/III concept based on GPS L1. An experimental display which can overlay the primary flight display on one pilots' side and which can be turned on and off, subject to pilots' needs, was updated to provide status of the GBAS solution (supported modes GBAS CAT I or CAT II/III, as well as information on service downgrade). Deviations based on the outputs of the tested receiver were displayed together will all the usual information based on legacy display.