This version of SWEHB is associated with NPR 7150.2B. Click for the latest version of the SWEHB based on NPR7150.2C

SWE-160 - Safety Critical Classification

1. Requirements

3.5.5 If a software component is determined to be safety critical software then software component classification shall be Software Class D or higher.

1.1 Notes

NPR 7150.2, NASA Software Engineering Requirements, does not include any notes for this requirement.

1.2 Applicability Across Classes
























Key:    - Applicable | - Not Applicable
A & B = Always Safety Critical; C & D = Not Safety Critical; CSC & DSC = Safety Critical; E - H = Never Safety Critical.

2. Rationale

The level of rigor required to develop and assure safety-critical software requires that safety-critical software be classified at a sufficiently high level that the minimum set of applicable requirements help ensure the appropriate level of rigor is applied.

3. Guidance

Safety critical software is any condition, event, operation, process, equipment, or system that could cause or lead to severe injury, major damage, or mission failure if performed or built improperly, or allowed to remain uncorrected.  All safety-critical software development programs are to have a minimal set of required software engineering development requirements.

Once a software component is determined to be safety-critical (see SWE-133), the minimum software classification for that component is Class D.  There are no exceptions.  If the software is safety critical software, then the software development is expected to meet the requirements for Class D, at a minimum. 

Engineering Technical Authorities (ETA) check the accuracy of the project’s classification of software components, so they ensure this requirement is met. The Center ETA can also waive or tailor specific requirements if the project provides adequate justification (see SWE-126). 

During the software development life cycle, periodic re-evaluations of safety-criticality and classification occur (see SWE-021), so the project and Center ETA need to keep this classification “rule” in mind as those reviews occur.

Additional guidance related to safety critical classification may be found in the following related requirement in this Handbook:

4. Small Projects

No additional guidance is available for small projects.

5. Resources

5.1 Tools

Tools relative to this SWE may be found in the table below. You may wish to reference the Tools Table in this handbook for an evolving list of these and other tools in use at NASA. Note that this table should not be considered all-inclusive, nor is it an endorsement of any particular tool. Check with your Center to see what tools are available to facilitate compliance with this requirement.

No tools have been currently identified for this SWE. If you wish to suggest a tool, please leave a comment below.


6. Lessons Learned

There are currently no Lessons Learned identified for this requirement.

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