Enroute Mode - 5NM

Terminal Mode - 1NM

Approach Mode - 0.3NM

Ground-Based Augmentation Systems (GBAS) require no additional action on the part of the pilot other than those actions associated with instrument approach procedures. GBAS consists of ground-based equipment in the vicinity of airports that provides additional accuracy and integrity for aircraft GPS systems. This added accuracy allows for more precise GPS approaches.

GBAS only supports approaches down to Category I approach minima. The FAA intends to bolster GBAS capabilities across the country and provide Category III approach capabilities.

Uses WAAS to act like an ILS. Sensitivities change as the aircraft gets lower. Aircraft must be certified for LPV approaches (statement in flight manual or supplement).

Usually provided by Baro-VNAV. Internally generated glidepath.

Lateral only. No WAAS required.