GPS Solutions

, Volume 19, Issue 3, pp 393–401 | Cite as

GBAS ground monitoring requirements from an airworthiness perspective

Original Article


The ground-based augmentation system (GBAS) provides corrections for satellite navigation signals together with integrity parameters to aircraft and enables precision approach guidance. It will eventually replace the currently used instrument landing system. GBAS Approach Service Type C stations supporting CAT-I operations have been fully developed and certified, and first stations are operational. For the service type D, which is intended to support CAT-III operations including automatic approaches and landings, requirements have been drafted and are currently undergoing validation. One remaining issue is the requirement for monitoring of ionospheric anomalies in the ground subsystem. Large gradients in the concentration of free electrons in the ionosphere can lead to significant positioning errors when navigation is based on differential methods. We give a review of the derivation of currently proposed performance requirements for such a monitor. Next, we show that the required level of safety from an airworthiness perspective can be achieved even with relaxed monitoring requirements compared to the currently drafted standards. These relaxations result from satellite geometry assessments on the ground and actual approach characteristics toward a runway. We show that with this method, it is sufficient to monitor for gradients in the range of about 450–550 mm/km while current standards require detection already from 300 mm/km. A remote monitoring receiver near the touchdown point can monitor the post-correction differential range error and use it as test statistic for GBAS performance monitoring and protection against ionospheric disturbances.


GBAS Ionosphere monitoring Airworthiness assessment 


  1. Belabbas B, Meurer M (2012) Carrier phase and code based absolute slant ionosphere gradient monitor for GBAS, Proc. ION GNSS 2012, Institute of Navigation, Nashville, TN, USA, pp 2201–2208Google Scholar
  2. Boeing (2005) Determining the vertical alert limit requirements for a level of GBAS service that is appropriate to support CAT II/III Operations, D6-83447-4Google Scholar
  3. Burns J, Clark B, Cassell R, Shively C, Murphy T, Harris M (2009) Conceptual framework for the proposal for GBAS to Support CAT III Operations, ICAO NSP WGW November 2009Google Scholar
  4. Clark B, DeCleene B (2006) Alert limits: do we need them for CAT III? Deriving GBAS requirements for consistency with CAT III operations. In: Proceedings of ION GNSS 2006, Institute of Navigation, Fort Worth, TX, USA, pp 3070–3081Google Scholar
  5. Dautermann T, Felux M, Grosch A (2012) Approach service type D evaluation of the DLR GBAS testbed. GPS SOL. doi:10.1007/s10291-011-0239-3 Google Scholar
  6. European Aviation Safety Agency (EASA) (2003) Certification specifications for all weather operations (CS-AWO)Google Scholar
  7. Eurocae (2013) Minimum operational performance specification for global navigation satellite ground based augmentation system ground equipment to support category I operations, ED-114A, EUROCAEGoogle Scholar
  8. Federal Aviation Administration (FAA) (1999) Criteria for approval of category III weather minima for take-off, landing, and rollout (AC 120-28D). US Department of Transportation, WashingtonGoogle Scholar
  9. Federal Aviation Administration (FAA) (2010) Siting criteria for ground based augmentation systems (GBAS), Order 6884.1, US Department of Transportation, WashingtonGoogle Scholar
  10. Fujita S, Takayuki Y, Saito S (2010) Determination of ionosphere gradient in short baselines by using single frequency measurements. J Aero Astro AVI A-42:269–275Google Scholar
  11. Harris M, Murphy T (2007) Geometry screening for GBAS to meet CAT III integrity and continuity requirements. In: Proceedings of ION NTM 2007, Institute of Navigation, San Diego, CA, USA, pp 1221–1233Google Scholar
  12. ICAO (2010) GBAS CAT II/III development baseline SARPs—draft proposed changes to Annex 10, Volume I, ICAO NSP WGWGoogle Scholar
  13. Jung S, Lee J (2012) Long-term ionospheric anomaly monitoring for ground based augmentation systems. Radio Sci 47:RS4006. doi:10.1029/2012RS005016
  14. Khanafseh S, Pullen S, Warburton J (2012) Carrier phase ionospheric gradient ground monitor for GBAS with experimental validation. Navigation 59:51–60. doi:10.1002/navi.3 CrossRefGoogle Scholar
  15. Lee J, Seo J, Par YS, Pullen S, Enge P (2011) Ionospheric threat mitigation by geometry screening in Ground-Based Augmentation Systems. J Aircraft 48(4):1422–1433. doi:10.2514/1.C031309 CrossRefGoogle Scholar
  16. Mayer C, Belabbas B, Jakowski N, Meurer M, Dunkel W (2009) Ionosphere threat space model assessment for GBAS. In: Proceedings of ION GNSS 2009, Institute of Navigation, Savannah, GA, USA, pp 1091–1099Google Scholar
  17. McGraw GA, Murphy T, Brenner M, Pullen S, Van Dierendonck AJ (2000) Development of the LAAS accuracy models. In: Proceedings of ION GPS 2000, Institute of Navigation, Salt Lake City, UT, USA, pp 1212–1223Google Scholar
  18. Murphy T, Harris M (2006) Mitigation of the ionospheric gradient threats for GBAS to support CATII/III. In: Proceedings of ION GNSS 2006, Institute of Navigation, Fort Worth, TX, USA, pp 449–461Google Scholar
  19. Pullen S, Park YS, Enge P (2009) Impact and mitigation of ionospheric anomalies on ground-based augmentation of GNSS. Radio Sci 44:RS0A21. doi:10.1029/2008RS004084
  20. RTCA (2008a) GNSS-based precision approach local area augmentation system (LAAS) signal-in-space interface control document (ICD), RTCA DO-246D, Washington, DCGoogle Scholar
  21. RTCA (2008b) Minimum operational performance standards for GPS local area augmentation system airborne equipment, RTCA DO-253C, Washington, DCGoogle Scholar
  22. Schuster W, Washington O (2010) Harmonisation of category-III precision approach navigation system performance requirements. J Navig. doi:10.1017/S0373463310000287 Google Scholar
  23. Simili DV, Pervan B (2006) Code-carrier divergence monitoring for the GPS local area augmentation system. In: Proceedings of ION/IEEE position, location, and navigation symposium 2006, pp 483–493, ION/IEEE, San Diego, CA, USAGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  1. 1.German Aerospace Center (DLR)Oberpfaffenhofen, WesslingGermany
  2. 2.Korea Advanced Institute of Science and Technology (KAIST)DaejeonRepublic of Korea
  3. 3.Technische Universität München, Lehrstuhl für FlugsystemdynamikGarching bei MünchenGermany

Personalised recommendations