Guidance characteristics of GNSS landing systems

Technical and operation concepts for precision landing have evolved around the signal in space characteristics of the Instrument Landing System (ILS). For the Global Navigation Satellite System (GNSS) Landing System (GLS), many of these characteristics will be dependent on computational processes inside the airborne receiver. Development of GLS standards creates an opportunity to improve on inherent ILS limitations while retaining useful features. This paper compares proposed GLS guidance algorithms including an approach where nominal ILS features are reproduced as well as alternatives proposed to eliminate features seen as undesirable. Simulated deviation outputs are derived for various maneuvers, including orbits, on-path, and near-path approach trajectories. The potential impact of alternative approaches on aircraft performance during capture, flare, and rollout is shown. Additional considerations addressed include the impact of changes of field verification and flight inspection and the applicability of these concepts to the Multi-Mode Receiver (MMR).