There’s an interesting little conundrum with Table A-1 of DO-178B when it comes to Level D software. The first objective in the table requires that software development process activities are defined. However, given that A-1 #6 isn’t applicable to Level D, there is no requirement that the plans actually comply to DO-178B.
In the case of other Level D objectives, this can mean that the artifact doesn’t need to be created. For instance, none of the table A-4 objectives apply to Level D, save the one about partitioning integrity. This is usually interpreted to mean that low-level software requirements aren’t required for Level D software.
With planning documents, though, the bar is a little bit higher, since Table A-9 requires that independent assurance is obtained that the development and processes complied with the approved plans and standards.
Let’s just summarize it this way: For Level D software, you have to have a plan. And you have to follow the plan. You don’t have to show, however, that your plan complies with DO-178B. Non-intuitive, maybe – but simple enough.
