Dependability evaluation of an air traffic control computing system

As air traffic over France is growing rapidly, the existing air traffic con trol (ATC) system has to evolve to satisfy the increasing demand. The selec tion of the new automated computing system (denoted CAUTRA) is based, among other things, on dependability evaluation. This paper is devoted to the de pendability evaluation of the CAUTRA, however, emphasis is put on a subset: the regional control center (RCC). Starting from the analysis of the impac t of CAUTRA failures on air traffic safety, five levels of service degradat ion are defined for the global system grading the effects of these failures on the service delivered to the controllers to ensure traffic safety. The RCC failure modes leading to these degradation levels are then defined and evaluated using stochastic Petri nets. The modeling approach consists in mo deling the system as a set of modules interconnected via coupling mechanism s. The system model is constructed in several steps according to an increme ntal approach. Each step integrates the failure and recovery assumptions of an additional component and updates the model of the previous step by acco unting for the impact of the new component on the behavior of those already included in the model. The application of this approach to the CAUTRA allo wed us to analyze several configurations of the CAUTRA architecture and to identify improvement areas to minimize the impact of CAUTRA failures on air traffic safety. (C) 1999 Elsevier Science B.V. All rights reserved.