NASA software safety requirements are documented in NPR 7150.2 083, and elaborated in the Software Assurance and Software Safety Standard, NASA-STD-8739.8A 278 . Design features are a small but important part of an overall software safety implementation. The driving requirement in this area is NPR 7150.2C, requirement SWE-134. The design principles that support specific provisions of SWE-134 are shown in the table below. A verified application of the NASA software design principles can help form the basis for demonstrating compliance with SWE-134. SWE-134 Sub-requirement Applicable Design Principle a. The software is initialized, at first start and restarts, to a known safe state. b. The software safely transitions between all predefined known states. c. Termination performed by the software functions is performed to a known safe state. d. Operator overrides of software functions require at least two independent actions by an operator. e. The software rejects commands received out of sequence when the execution of those commands out of sequence can cause a hazard. f. The software detects inadvertent memory modification and recovers to a known safe state. 9.09 Incorrect Memory Use or Access g. The software performs integrity checks on inputs and outputs to/from the software system. h. The software performs prerequisite checks prior to the execution of safety-critical software commands. i. No single software event or action is allowed to initiate an identified hazard. j. The software responds to an off-nominal condition within the time needed to prevent a hazardous event. k. The software provides error handling. l. The software can place the system into a safe state. 
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Software Design Principles and Software Safety
9.07 Fault Detection and Response2. Resources
2.1 References
9.02 Software Safety and Design Principles
Web Resources
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