How does WAAS and GBAS fit into the FAAs future NAS architecture?
A. When the final WAAS architecture is in place, users in the NAS will be able to use GPS/WAAS as a stand-alone navigation aid for en route through GLS precision approach operations. Like WAAS, GBAS relies on GPS for basic navigation signals. GBAS will operate independently from WAAS, while at the same time complementing WAAS by providing additional GPS augmentation to support airport requirements for CAT-II/III precision approach operations. GBAS will also provide a GLS capability at locations where WAAS cannot, as well as provide a signal, which could be used, for surface navigation in the terminal area.