• SJU reference # 119 /Release 10
  • Stakeholders
    ANSP
    AO
    AU
  • Benefits Capacity
  • Status Available for industrialisation/deployment
  • Maturity Level V3/TRL6

The solution improves resilience in low visibility conditions enabling GLS CAT II operations, including CAT II Autoland, based on an enhanced GAST-C ground equipment:

  • Automatic Approach and Landing down to Cat II for Mainline Aircraft;
  • Automatic Approach and Landing down to Cat II minima for Business and Regional Aircraft;
  • DH = 100 & 300 m < RVR < 550m;
  • GBAS GAST C/CAT I equipment is sufficient.

While solution #55 “Precision approaches using GBAS CAT II/III” addressed CAT II/III operation based on GAST-D, solution #119 addresses CAT II operations based on the existing single frequency GPS L1, GBAS GAST-C and SBAS messages. Unlike for GAST-D, in the standard GAST-C the integrity requirements associated with detection of anomalous ionospheric conditions that could induce an erroneous GBAS position outside the Protection Levels (therefore undetected by the system) are not monitored on board. Instead, with the enhanced GAST-C ground station, they are monitored on the ground and, when the GBAS position is properly bounded, CAT II operations can be performed (this is referred to as GAST-C Service Level B). When the integrity levels are not fulfilled e.g. severe anomalous ionospheric conditions, protection levels are inflated, and only CAT I operations are supported (this is referred to as GAST-C Service Level A).The aircraft needs to be equipped for GAST-C but does not need to be equipped for SBAS. SBAS messages are used by the ground in order to monitor the integrity of the GAST-C service. From the ATC perspective, the CAT II operations based on GAST-C Service Level B are the same as CAT II operations based on GAST-D, except that an approach category indication (GLS CAT I/II) is needed. Like for GAST-D availability, GAST-C GBAS availability levels will be broadcast in the ATIS, and if the ATIS has not yet been updated after a Service Level change, controllers will pass the information directly to pilots over R/T. From the flight crew perspective, CAT II operations based on GAST-C are the same as CAT II operations based on GAST-D. However with GAST-C there is no possibility for on-board service level degradation alert like it can happen in GAST-D, so in GAST-C information on service level degradation will always come from ATC.

Datapacks

CN Solution #119 GLS CAT II operation using GBAS GAST-C 
SESAR 2020 AAL2 DEMO Report  
Appendix A to SESAR 2020 AAL2 DEMO Report 
Appendix B to SESAR 2020 AAL2 DEMO Report 
Appendix C and D to SESAR 2020 AAL2 DEMO Report 
Appendix E to SESAR 2020 AAL2 DEMO Report 
Appendix F G H and I to SESAR 2020 AAL2 DEMO Report 
Appendix J K and L to SESAR 2020 AAL2 DEMO Report