Ensuring the Compliance of Avionics Software with DO-178C

Given the needs to meet the most stringent requirements for reliability, safety, and security resulting in lengthy software development schedules, aerospace and defense projects have become among the most challenging to complete. In response to the increasing size and complexity of software used in airborne systems, the guidance document for certifying such systems has gone through numerous revisions with the latest being DO-178C.

Table 2-1 of the document dictates that for a system to be compliant, it has to be assigned one of five failure condition categories, proportionate to the hazard associated with system failure. Severity ranges from “Catastrophic”, which could involve multiple fatalities and the loss of the aircraft, to “No Effect” on safety. Each of these categories is mapped to an associated Design Assurance Level (DAL) from A (Catastrophic) to E (No Effect), such that the DAL assigned to a system is proportionate to the level of quality assurance required in its production. Objectives are detailed for each DAL throughout the development process including requirements specification, design, coding, life cycle traceability, and verification. Thorough, robust testing is a must, and a comprehensive suite of analysis, test and traceability tools is similarly essential.