Introduction to RTCA DO-178C
DO-178C, “Software Considerations in Airborne Systems and Equipment Certification,” is part of a series of international functional-safety standards published by RTCA for the aerospace industry. DO-178C covers aspects of certification related to the production of software for airborne systems and equipment used on aircraft, engines, propellers and auxiliary power units: it is the main reference used by certification authorities (such as FAA, EASA and Transport Canada) to approve all commercial software-based aerospace systems.
DO-178C prescribes that tools must be qualified when they are used to eliminate, reduce or automate processes mandated by DO-178C and the output of the tool is not verified manually or with another tool. The recommended approach is to follow the recommendations of RTCA DO-330 “Software Tool Qualification Considerations”.
DO-178C prescribes the allocation of software levels to software components. The software level establishes the rigor with which compliance with DO-178C has to be demonstrated, and it is based upon the contibution of the software to system failure conditions and their severity. There are five software level: A, B, C, D and E. They are, respectively, for software whose anomalous behavior, as shown by the system safety assessment process, would cause or contribute to a failure of system function resulting in
- Level A: a catastrophic failure condition for the aircraft (multiple fatalities, loss of the airplane);
- Level B: a hazardous failure condition for the aircraft (serious or fatal injury to a relatively small number of the occupants other than the flight crew, large reduction in safety margins or functional capabilities, flight crew physical distress or excessive workload);
- Level C: a major failure condition for the aircraft (possible injuries, physical distress or discomfort to passengers, flight and cabin crew, significant reduction in safety margins);
- Level D: a minor failure condition for the aircraft (physical discomfort to passengers or cabin crew, slight increase in crew workload, slight reduction in safety margins or functional capabilities);
- Level E: no effect on aircraft operational capability or pilot workload.
For software components that are confirmed to be Level E according to DO-178C, DO-178C has no further prescription.
Role of ECLAIR in Ensuring Compliance with DO-178C/DO-330
The ECLAIR Software Verification Platform can be used to comply with several of the objectives of DO-178C Table A.5.
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