The generic software development situational factors model has been developed in order that environments within which software is developed can be profiled and better understood. Situational context is a complex concern for software developers, with a broad set of situational factors holding the potential to affect any one software development project. Safety critical software development is broadly similar to other kinds of software development / engineering. But there are some additional or more dominant situational factors. In this article we conduct a conceptual experiment to define safety critical software development context using situational factors. Eleven such factors are identified, with some of the factors requiring elaboration beyond the detail presently available in the generic situational factors model. We firstly discuss the appropriateness of the selected factors in generic safety critical software development context. Thereafter we apply the selected factors to the medical device and nuclear power domains. Selected situational factors can be used as a high level profile and starting point for more detailed process and safety assessment. Discussion about potential use cases and further development needs is also presented.