Industrial Challenges with Quality Requirements in Safety Critical Software Systems

Budget constraints and the difficulty to specify quality requirements, such as reliability, robustness, and safety present challenges to many software companies in particular if they develop safety-critical systems. Failing to specify this type of requirements properly can lead to misunderstandings between the developers and the customers, which can threaten the quality of the system. However, little information is available on how companies currently work with these requirements. This paper describes the state of requirements engineering practice and identifies challenges with quality requirements by conducting a requirements analysis on two projects, including 980 requirements, at a company developing safety-critical systems. We also compare to similar results for a company developing end user software. Problematic and ambiguous requirements have caused misunderstandings with the customers and introduced late and project-critical costs to the projects. The results show that despite a high percentage of quality requirements at the company, the majority of these requirements are non-quantified, which potentially leads to lower verifiability, high ambiguity and can create late-project delays in verification and validation. Our study adds empirical evidence on the characteristics and challenges of real-world requirements engineering for safety-critical systems.