Research On Testing And Diagnostic Method For Reducing The Risk Of TCAS

Traffic Alert and Collision Avoidance System (TCAS) is very important to flight safety, it can instruct the pilot to avoid the danger through detecting the nearby aircraft conflict and predicting potential hazard in future, and help the crew maintain the safety interval with other aircraft. However, because of false alarms, aircraft performance limitations, and other potential risk factors, there would be risk on TCAS itself.In this thesis, first we discussed the major risks of TCAS, and aiming at these risks, we proposed some aspects to improve in the designing, testing, and operating of TCAS, which could be helpful to reduce its risk, further to assure flight safety.Then in the proposed measures, we put the focus on the simulation test and rapid fault diagnosis of TCAS to start our study.On simulation test, we applied simulation test framework based on embedded software to TCAS system, and we put the focuses on the design of use case model of TCAS. First, we analyzed functional requirements of TCAS and its cross-linked environment, built the functional model of TCAS and its cross-linked environment models, and put up TCAS simulation test environment, then we got the test-space model and testing strategy of TCAS. Finally, we proposed a method of use case model designing of TCAS. Based on combinatorial testing and the Lincoln Laboratory's Quickly Encounter Model, we designed 10 kinds of track combination as the use case model for TCAS simulation test. On fault diagnosis, first we built the fault tree of TCAS, based on risk analysis of TCAS we had done. TCAS fault would be summed up as 16 kinds of fault modes. Then, we studied several samples of TCAS fault phenomena and the corresponding reasons, ultimately matched to 16 kinds of fault modes. We collected TCAS faults to establish the fault dictionary database of TCAS, and designed the inference engine according to the logic of the fault causes and symptoms, accomplished a simple expert system for TCAS fault diagnosis.Finally, the works were summarized and prospected at the end of the paper.