In aeronautics, software development is submitted to strong constraints. The DO-178 certification standard specifies development and verification objectives. Moreover, its supplement DO-333 defines guidelines for the use of formal methods in this context. Formal methods are used in industry for different purposes and often require the intervention of experts for their processing. In this paper, we propose an approach to answer a certification objective using formal methods while keeping them usable for non-experts. We present an automatic method to check the compliance of a C source code according to its Low Level Requirements expressed as an UML state machine and we show how it addresses objectives of the DO-333.