  Safety standards prescribe change impact analysis (CIA) during evolution of
safety-critical software systems. Although CIA is a fundamental activity, there
is a lack of empirical studies about how it is performed in practice. We
present a case study on CIA in the context of an evolving automation system,
based on 14 interviews in Sweden and India. Our analysis suggests that
engineers on average spend 50-100 hours on CIA per year, but the effort varies
considerably with the phases of projects. Also, the respondents presented
different connotations to CIA and perceived the importance of CIA differently.
We report the most pressing CIA challenges, and several ideas on how to support
future CIA. However, we show that measuring the effect of such improvement
solutions is non-trivial, as CIA is intertwined with other development
activities. While this paper only reports preliminary results, our work
contributes empirical insights into practical CIA.

Software Engineering