Ground-Based Augmentation Systems in the National Airspace System Implementation Act or the GBAS Act This bill requires the Department of Transportation to award grants for deploying ground-based augmentation systems (GBAS) at airports and in aircraft. GBAS augment the Global Positioning System (GPS) used in U.S. airspace to improve the accuracy of, and provide integrity for, an aircraft's GPS navigational position when the aircraft is near an airport.