Is DO-331 applicable to UML diagrams used in the software design?

Question

DO-178C, Software Considerations in Airborne Systems and Equipment Certification is the primary document by which the certification authorities such as FAA, EASA, and Transport Canada approve all commercial software-based aerospace systems. The document is published by RTCA, Incorporated, in a joint effort with EUROCAE, and replaces DO-178B.

DO-331 is a supplement for DO-178C that discusses the use of model-based development and verification in the software life cycle for software that is produced in accordance with DO-178C.

In DO-331, it seems that model coverage analysis and simulation can only be achieved using advanced Model-Based Development Tools like SCADE/Simulink.

I would like to know if companies who design their software using simple UML tools and produce static UML diagrams need to apply DO-331 if they intended to comply with DO-178C?

This is assuming they do not use advanced Model-Based Development Tools like SCADE/Simulink.

Answer 1

It depends on how you use the UML models. For static models, I would say "no".

DO-331 covers the use of SysML and UML models. However, just because you are using SysML or UML doesn't mean DO-331 applies. It's one thing to use UML as a standardized graphical language support requirements or design description documentation. It's another thing to try to take credit for some verification and validation activities using model checking and simulation. The relationship between model and code also matters - models that are used to generate code or are reverse engineered from code are treated differently than pictures drawn that conform to a standard modeling language.

It's been a while since I worked in aerospace, and when I did, the systems I worked on were Level D and Level E systems. DO-178C was new, but there was no concern in the software engineering group about using UML models without following DO-331 as we were not using any kind of model checking, model simulation, or forward engineering of code from models. The UML models were included in requirements documentation and design description to help improve clarity and were covered during review and analysis of the artifacts.