Podcast Series Focuses on DO-178C for RTOS
A new three-episode podcast series explores the intersection of DO-178C certification and real-time operating systems (RTOS). The series delves into best practices for certifying real-time embedded software for aerospace applications. Topics covered are expected to include requirements traceability, partitioning strategies for mixed-criticality systems, and audit preparation.
- The DO-178C standard, jointly issued by RTCA and EUROCAE, is the primary means by which certification authorities like the FAA and EASA approve all commercial software-based aerospace systems. The current version, DO-178C, was released in December 2011 to replace DO-178B and address advances in software technology. - Software is categorized into five Design Assurance Levels (DALs) based on the potential consequences of a failure, from Level A (Catastrophic) to Level E (No Safety Effect). The DAL determines the level of rigor required in the development and verification process; for Level A, the most stringent processes are applied. - A key function of a Real-Time Operating System (RTOS) in this context is providing deterministic scheduling to ensure tasks execute within strict timing deadlines. Another critical feature is robust time and space partitioning, which prevents faults in one software component from affecting another, a concept standardized by ARINC 653. - The cost of DO-178C certification can be substantial, estimated to range from $25 to $100 per line of code, and requires highly specialized expertise. The process involves extensive documentation, rigorous testing, and complete traceability from requirements to the executable object code. - Several commercial and open-source RTOSs are widely used in certified avionics systems, including Wind River VxWorks 653, Green Hills Integrity-178, DDC-I Deos, and the open-source RTEMS, which is common in space missions for NASA and the ESA. - The transition from DO-178B to DO-178C introduced supplements to provide guidance on modern software development techniques, including model-based development, formal methods, and object-oriented technology. It also added a companion document, DO-330, which outlines qualification considerations for the software tools used in the development and verification process. - For military applications, the principles of DO-178C are often applied with a greater focus on mission success probability and harsher operational environments, referred to as "Military Compliance" rather than FAA/EASA certification.
