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| Safety Engineering |
Safety analysis and engineering seeks to reduce risk by anticipating points of failure, and proposing changes that eliminate or mitigate the consequences of such failures. Safety analysts identify and evaluate safety risk areas; and develop options to mitigate or reduce the consequences of those risks. Safety engineers evaluate those options and develop engineering solutions for those areas; and ensure that a life-critical component behaves as needed even when parts of the system fail. Safety engineers also analyze system designs to find what faults can occur, and then propose changes to make the system more redundant, resulting in a safe architecture. Together, safety analysts and engineers establish safety requirements, set safety criteria, mitigate non-safe areas, design safety architectures, and adopt safety processes to ensure that a system will be developed according to the safety architecture.
ISI is a pioneer in the development of safety requirements and studies for the implementation of satellite navigation in civil airspace. Robert Loh, the president of ISI, was involved in developing initial satellite navigation safety requirements starting in the 1980s. In 1994, ISI led the development of safety and certification requirements for the implementation of the WAAS, the first large, distributed navigation system—except for systems contained in aircraft—that used concepts of system safety and software based on SAE ARP 4754/4761 and RTCA DO-178B. Since then, ISI has worked on safety, certification, and commissioning for the WAAS, LAAS, GPS III, and MSAS (the Japanese equivalent of WAAS) programs.
To describe the interactions of safety, certification, and commissioning, ISI developed a ten-step process from identifying system safety requirements to verifying the successful operational implementation of a safe system in the National Airspace System (NAS). ISI is one of the few companies that can provide lessons-learned and best-practices in sorting out and using the different safety standards and guidance documents from the RTCA, the SAE, military standards (MILSTD) and the new FAA Safety Management System and its various processes and guidance documents.
On our GPSTAC contract and its predecessors, ISI has been involved in the entire safety, certification, and commissioning process, starting with defining safety requirements and ending with developing safety criteria for the operational procedures of pilots using GPS, WAAS, and LAAS as navigational aids, such as US Terminal Instrument Procedures (TERPS) or the equivalent International Civil Aviation Organization (ICAO) PANS-OPS.
On our GPS III contract, ISI supported Lockheed Martin in GPS III aviation navigation capability development, including defining GPS III civil aviation integrity and continuity requirements; developing GPS III aviation integrity architecture; developing GPS III aviation navigation safety assurance processes; and conducting multiple aviation navigation safety assessments during Phase A. ISI led the Lockheed Martin Aviation Safety and Certification Team by developing a draft aviation Operational Services and Environment Definition (OSED); a draft aviation Operational Hazard Assessment (OHA); a draft aviation Functional Hazard Analysis (FHA); and supported various developments of the GPS III space and ground segments draft Failure Mode Effects Analysis (FMEA), with recommendations for design and architecture changes.
On our MSAS contract, ISI worked with NEC, Raytheon, Lockheed Martin, and the Japanese Civil Aviation Bureau (JCAB) as the lead safety, certification, and commissioning expert for NEC. ISI developed the safety architecture; the certification plans for the MSAS and LAAS; the commissioning plans for the MSAS and LAAS; the ten-step integrated safety, certification, and commissioning plan; the configuration management and change process for the integrated safety architecture; and the safety integration/interface with the Japanese satellite providing the MSAS integrity signals. Since MSAS was built by the same manufacturer as WAAS (Raytheon), ISI concentrated on the safety issues that emerged due to different architecture components between the FAA’s WAAS and the Japanese MSAS. Those issues included use of Ku frequency band versus C band for the satellite data link and sharing navigation and communications functions in the same ground-earth antenna in the MSAS. |
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