Currently, there is no CAT III GBAS for commercial use. While the broadcast is good for CAT III, it still has not been certified for general use. CAT III GBAS is in use in some military operations.
There is no CAT III RNP AR. RNP is 250 HAT.
When looking at ILS vs GBAS, we are using the following cost estimates, although it certainly varies per location:
Typically, the cost for an ILS per runway end is around $500,000, with about $50,000 per year in operating costs. ( per CT, I guess the $75,000 is where the FAA is...)
The cost for a GBAS system, itself is about $1.5 million, with another $1 million for installation and validation exercises, for up to 23 runway ends. Annual costs were about $50,000 per year for the entire system.
It can also handle ARR and DEP from same runway end. ILS cannot do ARR and DEP from same end.
The bottom line is that with 4 runways ends, ILS and GBAS are about equal in cost to install. Annual costs escalate rapidly with ILS.
GBAS is a very accurate GPS correction that broadcast as a signal to the ac, and can be repeated to get distance. Unlike ILS beams, there are no issues with multiplex from structures or reflectivity from ac on the ground or in the air.
A GBAS system can broadcast multiple displaced threshold solutions for each runway end. This can be used for wake mitigation strategies. (or simply manage displaced thresholds) ILS does not have this capability.
We have GBAS broadcasts that include a turn to final. That is in validation, as well as the other solutions such as RNP AR transitions to GBAS final.. No way an ILS beams could include a turn, or an acceptable transition from RNP to ILS final.
What I find interesting is that Smartpath is 50% owned by ASA. I would think that GBAS would be all over AUS, go figure.
Last edited by underfire; 9th Jul 2017 at 11:36.