Four Pillars for Improving the Quality of Safety-Critical Software- Reliant Systems

Studies of safety-critical software-reliant systems developed using the current practices of build-then-test show that requirements and architecture design defects make up approximately 70% of all defects, many system level related to operational quality attributes, and 80% of these defects are discovered late in the development life cycle [Redman 2010]. Exponential growth in software size and complexity has pushed the cost for the current generation of aircraft to the limit of affordability. We present four pillars of an improvement strategy for an integrate-then-build practice that result in early defect discovery and increased confidence through incremental end-to-end system validation and verification throughout the life cycle (Figure 1). • Capture of mission and safety-criticality requirements in analyzable form; • Virtual integration of the physical system, hardware platform, and software architectures through consistent analyzable architecture models; • Static analysis techniques applied to the models and actual system implementation to complement testing; and • Incremental assurance of justified confidence through consistent end-to-end evidence throughout the development life cycle.