Ensuring the Safety of Satellite Navigation Systems for Aviation

The European Geostationary Navigation Overlay Service (EGNOS) is Europe´s first venture into satellite navigation. EGNOS augments the existing GPS satellite navigation service by providing additional information to enable it to be used to support safety critical applications. Before it can be used there are a number of steps to be performed in order to demonstrate that the system has been designed, deployed and is operated in a manner commensurate with its intended use in such safety critical applications. This demonstration has been developed in the form of a System Safety Case showing that the system is compliant to key safety requirements, resulting in a ´safe´ navigation signal. This paper describes the challenges that must be faced to ´certify´ satellite navigation systems providing safety-of-life services throughout large geographical areas encompassing many countries. In particular this paper focuses on the use of EGNOS to support aviation applications; it describes the current aviation regulatory mechanisms and looks into the future at how these mechanisms may evolve to support the certification of such complex systems such as Galileo, Europe´s contribution to the second phase of Global Navigation Satellite Services (GNSS).