Which GNSS technology is developed for civil aviation?

The correct choice is WAAS, which stands for Wide Area Augmentation System. This technology was specifically developed to enhance the accuracy, integrity, and availability of GPS signals for civil aviation in North America. WAAS uses a network of ground reference stations that monitor GPS signals, correct for errors, and send this information to satellites, which then broadcast the augmented signals back to users. This is crucial for improving the precision of aircraft navigation, particularly for approaches and landings at airports, thereby increasing safety in aviation operations.

WAAS is part of a larger effort to improve GPS reliability for aviation purposes and has been instrumental in allowing for precision approaches in locations where traditional ground-based navigation aids may not be available. While other technologies like NDGPS (National Differential GPS), EGNOS (European Geostationary Navigation Overlay Service), and MSAS (Multi-functional Satellite Augmentation System) also support various applications, WAAS specifically focuses on meeting the stringent standards required for civil aviation in the U.S. and has been integrated into various navigation systems utilized by pilots.