DO-178C is the reference standard for certifying software embedded in aircraft. It defines the objectives a software development must meet to be accepted by certification authorities, with five levels of rigor, from DAL A to DAL E.
The level (Design Assurance Level) depends on the consequences of a failure: DAL A for software whose failure can be catastrophic, such as flight controls, down to DAL E when it has no effect on safety. The higher the level, the stronger the requirements for traceability, reviews, testing and code coverage.
Published by RTCA in the United States and EUROCAE in Europe (as ED-12C), it comes with supplements on formal methods, modeling and tools. It is found at aircraft manufacturers, equipment suppliers and their subcontractors, and it inspires other critical sectors.
Why it matters when hiring
A brilliant embedded developer with no DO-178C background will take time to adapt to the documentation rigor it imposes. Ask at which DAL level the candidate has worked, on which activities (development, verification, certification plans) and with which tools. Do not confuse it with DO-254, which covers electronic hardware. Verification and certification profiles are often the hardest to find.