Automated test suite generation is an optimization technique to reduce test effort and duration. Software Testing has traditionally been one of the main techniques contributing to high software quality and dependability. Testing performance consumes about 50% of software development resources, so any methods aiming at reducing software- testing costs are likely to reduce software development costs. So an automated generation of test cases is highly required. Modelling technology has been introduced into the software testing field. Even though how to perform the testing is difficult task, in this approach we are testing using simulation modelling and by using testing methods we are generating MC/DC test cases. In our approach, the first system is modelled in MATLAB using Simulink/Stateflow tool. After that we are generating code from the Simulink/Stateflow models. We use that code to generate the test data using Concolic tester CREST Tool. Concolic testing is used in avionics systems in an efficient way.