The US Federal Aviation Administration (FAA) is developing and planning to field the Local Area Augmentation System (LAAS). LAAS is a Ground-Based Augmentation System (GBAS) to GPS, and is designed to serve all categories of precision approach. The purpose of this paper is to provide the latest technical and status information on the LAAS programme. The technical aspects of the LAAS specification are discussed, followed by a description of specification validation field testing and results. Institutional and programmatic aspects are then summarized along with a chronology of events leading up to the Government Industry Partnership (GIP) for the initial development and fielding of LAAS.

This paper, and the following six papers, were presented during the NAV 98 Conference held at Church House, Westminster, London on 9th and 10th December 1998. A full listing of the Conference, and how to obtain a copy of the proceedings, is shown on Page 300.

The existing Loran-C and Chayka infrastructure can, with some minor changes, become a very powerful augmentation system for GNSS (GPS, GLONASS and the future Galileo). Delft University initially proposed the Eurofix concept in 1989. Although the necessary modification to the LF navigation systems are minimal, the GNSS user may get significant benefits from the Eurofix signals in terms of accuracy, integrity and availability. The reason is the high signal structure, signal propagation, and the operations dissimilarity of both systems. The broadcast correction and integrity data improves GNSS accuracy down to the metre level. In this way, the measured Loran-C and Chayka ranges are continuously updated. Thus, in the case of GNSS signal interruptions, highly calibrated Loran-C/Chayka may take over the navigation function. Tests carried out in Europe at the Loran-C station at Sylt (Germany) drew large international attention, leading to further tests in the USA by the US Coast Guard in 1998. Recently, a Dutch–Russian consortium implemented Eurofix on the Chayka transmitter at Bryansk (Russia) which is now successfully broadcasting DGPS as well as DGLONASS correction data. This paper highlights some on-air Eurofix DGPS performance experiments carried out in Europe and the USA. With all the European Loran-C and Chayka transmitters modified, Eurofix can be used all over the European continent. As multiple stations can normally be received simultaneously, the user may locally apply networked DGNSS, which may reduce spatial decorrelation effects significantly. Post- processed results of this Regional Area Augmentation System are presented.