The satellite navigation system for civil aviation must ensure to provide position information with the required integrity as well as position accuracy. The ICAO (International Civil Aviation Organization) defines GNSS (global navigation satellite system) as the satellite navigation system eligible to be used for civil aviation, which means GPS and GLONASS, operated by the US and Russia, respectively, with the appropriate augmentation necessary to achieve required performance in terms of integrity. Currently SBAS (satellite-based augmentation system), GBAS (ground-based augmentation system), and ABAS (airborne-based augmentation system) are defined as the augmentation system.

For SBAS and GBAS, it is possible to evaluate the performance of GNSS over the service area based on a geometry of GPS (or GLONASS) satellites and augmentation information because the international standards specify both the contents and usage of augmentation information. On the other hand, for ABAS, the international standards specify neither particular algorithm nor parameter set. This paper aims to describe theory and algorithms of ABAS, so that it is possible to evaluate the performance of GNSS with ABAS anywhere and anytime. The author reports an investigation of the baseline RAIM (receiver autonomous integrity monitoring) algorithm implemented almost commonly for certified airborne GNSS receivers equipped with ABAS function. Some parameter sets are also given and evaluated in terms of performance and the examples of response to anomalous events of GPS satellite are shown.

To enable a common operational picture between all related aviation stakeholders, a collaborative environment for system-wide flight and flow information exchange is required to improve strategic planning. Therefore, a globally harmonized System Wide Information Management (SWIM) for sharing a richer set of information before and during the flight between related stakeholders has been structured by the International Civil Aviation Organization (ICAO). However, due to different communication and process approaches between air and ground systems, it is difficult to assure the 4-Dimensional Trajectory (4DT) sharing and negotiation between an airspace user and corresponding air traffic management service providers. To clarify the operational concept and explore the impacts to different stakeholders and various systems, the project of international demonstration had been conducted. The Electronic Navigation Research Institute (ENRI) joined this project as a research and development leader of Japan Civil Aviation Bureau (JCAB). In this paper, based on the proposed Air-Ground SWIM integration architecture, the observations and analysis of technical experience consisting of scenario proposal and function development for the series of operational changes that will occur through the implementation are reported. Moreover, the collaborative operation process and coordination mechanism in the post-departure phase between related actors and systems to achieve 4DT sharing and negotiation are clarified. Finally, the considerations and challenges for flight and flow information exchange to include interactions of related stakeholders, systems, and services through a collaborative environment are discussed.