A Case Study of Measuring Process Risk for Early Insights into Software Safety

Lucas Layman, Victor R. Basili, Marvin V. Zelkowitz, and Karen L. Fisher
Fraunhofer CESE, USA; University of Maryland, USA; NASA Goddard Spaceflight Center, USA

In this case study, we examine software safety risk in three flight hardware systems in NASA’s Constellation spaceflight program. We applied our Technical and Process Risk Measurement (TPRM) methodology to the Constellation hazard analysis process to quantify the technical and process risks involving software safety in the early design phase of these projects. We analyzed 154 hazard reports and collected metrics to measure the prevalence of software in hazards and the specificity of descriptions of software causes of hazardous conditions. We found that 49-70% of 154 hazardous conditions could be caused by software or software was involved in the prevention of the hazardous condition. We also found that 12-17% of the 2013 hazard causes involved software, and that 23-29% of all causes had a software control. The application of the TRPM methodology identified process risks in the application of the hazard analysis process itself that may lead to software safety risk.