The FAA is allowing San Francisco International Airport to implement a new instrument landing system the airport hopes will allow it to design approaches that reduce noise for its neighbors. The Ground-Based Augmentation System (GBAS) uses ground stations arrayed at the airport to make corrections to errors inherent in the GPS signals that are broadcast by the satellites. The corrected signals are then transmitted to aircraft, offering position accuracy to within an inch compared to 150 feet from regular GPS. That will allow for much higher precision for operations in bad weather.
This is a companion discussion topic for the original entry at https://www.avweb.com/aviation-news/faa-approves-more-precise-gps-at-sfo