Aviation flight safety is largely ensured by the reliability and continuity of interactions between ground and airborne systems during data exchange in process of the flight. Modern avionics systems are built on a modular basis. The combination of technical and software components has led to the emergence of a new class of systems – integrated modular avionics. The article proposes an approach to the analysis of the dependability for ATC functionality failures for system with combination of hardware-oriented and software-based solutions. In the paper the Fault Tree Analysis method is used for building of failure tree for the indicated main interaction between infrastructure and software components which may contribute to failure of ATC part of data link system. In the paper the constructed fault tree is used for creation of model based on Petri nets for modelling the influence of various factors on the availability of the ATC hardware-software complex. The article describes the method of constructing a dependability model based on Petri nets.1. Introduction
Nowadays computer and information technology is widely applied in many domains, such as civil aviation,
spaceflight、electronic power etc. The software used in those domains is more and more complex and
costly , such as systems in air traffic control、patient watch、factory electronic watch and so on.
Great pressure is posted upon the air traffic control because of the greater demand for flight. Air Traffic
Control Automatic System (ATCAS) plays an important role in many aspects of ATC system, such as
improving the air traffic control efficiency, lightening controller’s burden, promoting safety of ATC and so
on. Its reliability affects air traffic’s safety directly. From 2005 to 2006,the fault of ATCAS occurs one
after another in GuangZhou Air traffic control center, which results in serious delay .So the reliability of
ATCAS comes to more and more important. The research on this area has been gotten left behind by other
domains, there are few studies on ATCAS[1]. At present ,many arithmetic are advanced in order to improve
the reliability of key software. As far as prediction is concerned, markov chain is an efficient model to
use[2]. In this paper markov chain is used to predict the reliability of ATCAS, the results of the trial come
out good which show that this method can be used for the future study.
Reliability is defined as: In given condition, given times, the ability to finish the special task. The
reliability of software is in given condition and given time, the probability of software run without error.
Due to the ability of ATCAS has the direct relation with the life of passenger, once the error occurs the
aftereffect is unthinkable. So the strict requirement is applied on the reliability . 2. Markov chain model
Markov chain model is a useful mathematic method in reliability researching[3]. Study of the system states
and the transition of these states is the main content of Markov chain model. When conditions which
determine a state were satisfied in a system, the system was deemed to in that state. Dynamic change in
system is designated as state transition. There are two basic kinds of model, one is discrete time model
(markov chain model), the second one is succession time model(markov process model)。The predict accuracy of ATCAS software reliability in December and November respective is 94%, 85%.
There are differences between the predict result and the actual result. The reason is that the reliability of
system is affected by human factor、environment factor and other factors, and the predict result is
practicable and reasonable.
References
[1] Wang Xinglong Software Reliability Prediction of ATCAS based on BP neural network modeling The 7th National
Youth Conference on Traffic and Transportation 2007，851-856。
[2] Sarukkai R R. Link Prediction and Path Anaysis Using Markov Chains[J]. Computer Networks, 2000, 33(1/6): 377-386
[3] YAN Cairong A Parallel Web Prefetching Model to Web Cluster Server Computer Engineering 2005 ,31 :47-49
[4] Liu CiHua Stochastic Process the second edition Wuhan Huazhong University of Science and Technology publishing
company 2005
[5] Yong An Li Zhong Jie Eurocat-X System Segment Specification[Z] PEOPLE’S REPUBLIC OF CHINA Beijing
2002,1:4
[6] Yong An Li Zhong Jie Integrated Logistic Support Plan[Z], PEOPLE’S REPUBLIC OF CHINA Beijing 2001.5.33
[7] Air traffic control base, Civil Aviation University of China .Guangzhou area control center system reliability evaluate.
Tianjin. 2005.11