When compared to current precision approach systems – GLS is a much more flexible system ready to meet the needs of the air transport community for the future. Initial GLS sytems will emulate the ILS but GLS has capabilities such as curved or segmented approach paths, different glide path angles, off set thresholds, which means that one single GBAS will be able to meet all of the needs for all users at an airport.
When compared to GLS, ILS has one significant advantage, ILS is already installed at most airports that require a precision approach and all aircraft are already equipped. In order to replace ILS any new system must be able to offer significant advantages.
One GBAS – Multiple approaches
One single GBAS will have the capability to provide up to 48 approach procedures. This means that one GBAS will be able to provide precision approach capability to all runway ends at an airport.
Flexible Siting requirements
The GBAS GPS reference receivers can be placed at an optimal location to avoid any possibility of multi-path interference. Siting is not referenced to a runway and so there will be no restrictions on aircraft movements
No need to protect runway ends
Impoved Accuracy of Positioning Service
Use of differential GPS corrections in the coverage area will improve the accuracy of Navigation error, potentially bringing improved R-NAV (RNP) performance to a greater number of users.
Reduced building restrictions
Construction of new terminals and hangars at many airports are restricted due to possible impact on ILS. Due to the flexible siting requirements of GBAS this will not be an issue, reference receivers can even be installed on the roof of airport buildings.