An integrated system safety model of the national airspace system

The Federal Aviation Administration (FAA) is undertaking a National Airspace System (NAS) modernization effort known as NextGen. NextGen includes a significant number of new system acquisitions that must be integrated with legacy NAS infrastructure which is continuously undergoing modifications in parallel. Each change to the NAS requires a safety analysis to identify and control safety risks. The FAA commissioned a software tool to assist with evaluating these safety analyses so that oversight activities may be planned accordingly. To accomplish this mission, a model of system and safety data that identifies interdependencies between NAS systems and safety hazards was developed. This model, along with a taxonomy of the data captured, can be used to identify relationships and trends in system and safety data that might otherwise be overlooked in safety analyses prepared separately for each NAS change. This paper discusses the approach used to build the integrated system safety model, the data captured to-date, and preliminary findings and trends from analysis of the model. This model can be used by safety practitioners to evaluate system changes and their contributions to existing hazards in the NAS and to focus oversight activities on systems and changes with the greatest predicted impacts on NAS safety. (Note: The views, opinions, and findings contained in this paper are those of the author and should not be construed as an official FAA position, policy, or decision.).