The terrain system provides alerts for Forward Looking Terrain Avoidance (FLTA), Premature Descent Alert (PDA), as well as basic Ground Proximity Warning System (GPWS) modes. FLTA alerts are comprised of Reduced Terrain Clearance (RTC), Reduced Obstacle Clearance (ROC), Reduced Line Clearance (RLC), Imminent Terrain Impact (ITI), Imminent Obstacle Impact (IOI), and Imminent Line Impact (ILI) alerts. These FLTA Alerts are automatically suppressed within specific proximity to the airport environment to prevent potential nuisance alerts. Both FLTA and PDA alerts can also manually be inhibited by the pilot using the TAWS Inhibit function discussed in a later section.