Certifying safety critical software and ensuring its safety requires checking the conformance between safety requirements and design decisions. Increasingly, the development of such systems relies on modeling, and the System Modeling Language (SysML) is now commonly used in many industry sectors. Inspecting safety conformance by comparing design models against safety requirements requires inspectors to browse through large models and is consequently very time consuming and error-prone. To address this, we have devised a practical set of mechanisms to establish traceability between requirements and SysML design models to extract design slices (model fragments) that filter out irrelevant details but keep enough context information for the slices to be easy to inspect and understand. In this paper, we report on a controlled experiment assessing the impact of such traceability and slicing mechanisms on inspectors’ conformance decisions and effort. Results show a significant decrease in effort and an increase in decisions’ correctness and level of certainty.