Changing safety-critical software

Changing software to implement new features, correct problems, update functions, or replace obsolete hardware components (e.g., microprocessors) is a way of life in today's industry. A systematic software change process is essential for the maintenance and reuse of safety-critical software. This paper presents activities to consider when changing software in safety-critical systems. The focus is on the aviation industry; however, the concepts are also applicable to other safety-critical domains, such as medical or nuclear.