LAAS operations in support of airport surface movement, guidance, control, and surveillance: initial test results

Currently, low visibility landing and surface operations are hampered by a lack of guidance in the cockpit while on the ground. Specifically, the current instrument landing system (ILS) can support near-zero visibility landings (CAT IIIB) but cannot aid the pilot in taxiing from the runway to the gate area. However, this situation is changing as the aviation community transitions from ground-based to space-based navigation, landing and surveillance systems. The satellite-based local area augmentation system (LAAS) is being considered for inclusion in the mix of systems which will support surface movement, guidance and surveillance functions. However, these types of operations represent a significant challenge. Multipath is the dominant error source in differential satellite-based navigation systems. For landing operations, the bulk of the multipath occurs at the differential ground station and this concern can be addressed through antenna design (i.e., the LAAS integrated multipath limiting antenna). However, for surface operations the multipath at the airplane is no longer negligible. In actuality, the multipath at the airplane is likely to be the dominant error source since multipath limiting antennas cannot be installed in an aircraft. This paper presents the results of the first test of LAAS for surface operations at a major airport. The results of a series of tests conducted at the Dallas-Fort Worth international airport in November and December of 1999 are discussed and analyzed. Special attention is given to the analysis of the multipath at the mobile unit since for surface operations these effects have not been well characterized previously