DO-178C Explained

A brief history of DO-178C

The DO-178 Guideline

DO-178C, also known as “Software Considerations in Airborne Systems and Equipment Certification,” is a guideline developed by the Radio Technical Commission for Aeronautics (RTCA). It was first published in 1982 as DO-178 and has since undergone several revisions, with the latest version being DO-178C. Released in 2011, DO-178C replaced its predecessor, DO-178B, incorporating modern software development practices and addressing emerging technologies.

The development of DO-178C

The latest DO-178 version, DO-178C was developed in 2005 and formally published in 2013. Our DERs have provided input to DO178C and also participate in the ongoing committee meetings. With improved clarification on avionics object oriented technology, formal standards on avionics software modeling, coverage of avionics systems versus software boundaries, and many more improvements, DO-178C covers modern approaches and requirements for avionics software development.

The primary objective of DO-178C is to provide a standard for the development of airborne software that ensures the software’s safety, reliability, and effectiveness in Avionics systems. It was developed to establish a consistent approach to software development and verification processes across the aviation industry. Compliance with DO-178C is often required by regulatory authorities such as the Federal Aviation Administration (FAA) and the European Union Aviation Safety Agency (EASA) for certifying software used in aircraft.

Why use DO-178C?

While not the only means for fulfilling airworthiness regulations, DO-178C is the most up-to-date and comprehensive guide to software development in aerospace.

It’s highly flexible and record-driven foundation allows developers to apply their own approach to avionics software development. When using DO-178C, all activities and their parent processes require well defined entry and exit criteria, effectively forcing the project to those activities throughout its duration. In a nutshell, DO-178C is all about properly planning so you can properly build and manage your project.

Do DO-178-guided projects cost more?

Using DO-178 can add 30-150% to avionics software development costs, though typically it only adds 25%-40%. When you start with fundamental planning and approaches to software engineering, DO-178C cost increases are at a minimum. Our team of DO-178C DERs cover how to keep costs down in our DO-178C training workshops.

Are there certification risks?

When the right steps aren’t taken during the design and development phases of a DO-178C project, you’re likely to run into project delays. Budget overrun of 30-80% can easily occur, as well as invalid qualification results at later stages. That said, DO-178 training and FAA training significantly reduces all project risks.

Additional risks include:

Incomplete and general data within the five key DO-178 process plans prior to initiating those lifecycles
Missing design/low-level software requirements
Insufficient checklists for reviews
Incorrect or Incomplete traceability between components
Incomplete structural coverage for decision and MCDC coverage
Missing or improper tool qualification

Learn more about the benefits of DO-178C project training and ConsuNova’s unique approach to Avionics workshops.

I’m not familiar with DO-178, where do I begin?

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Key Terms in DO-178C

Software Level

DO-178C defines five levels (A, B, C, D, and E) to classify the criticality of software functions based on their potential impact on aircraft safety. Level A represents the highest criticality, requiring the most stringent development and verification processes, while Level E represents the lowest.

Software Planning Process

The software planning process involves creating a software development plan that outlines the approach, resources, and schedule for software development activities, including requirements, design, coding, testing, and verification.

Software Verification Process

This process ensures that the software requirements and design are correctly implemented and that the software performs its intended functions. It involves various activities such as reviewing documents, conducting inspections, and executing tests.

Software Configuration Management (SCM)

SCM refers to the process of managing and controlling software baselines, including version control, change management, and tracking of software artifacts, to ensure proper configuration control and traceability.

Software Quality Assurance (SQA)

SQA activities involve ensuring that the software development processes comply with DO-178C guidelines. It includes activities such as audits, reviews, and inspections to identify and rectify potential issues or deviations.

DO-178C Project Checklist

1. Determine Software Demand Level

Identify the software functions and their associated levels of criticality to determine the appropriate level of compliance required.

2. Build Software Development Plan

Create a comprehensive plan that outlines the software development and verification processes, including activities, resources, schedules, and quality objectives.

3. Define Software Requirements:

Clearly define and document the software requirements, ensuring they are complete, consistent, and traceable.

4. Design Software Architecture

Develop a well-defined software architecture that meets the requirements and supports the software level’s criticality, considering modularity, reusability, and maintainability.

5. Implement Software

Write code that adheres to coding standards, follows established guidelines, and incorporates appropriate error-handling mechanisms.

6. Perform Software Verification

Conduct various verification activities, including reviews, inspections, and testing, to ensure compliance with requirements and the software’s intended functionality.

7. Manage Configuration

Establish a robust configuration management process to control and track software baselines, changes, and versions, ensuring proper traceability and reproducibility.

8. Conduct Software QA

Perform regular audits, reviews, and inspections to ensure compliance with DO-178C guidelines and identify and address any non-compliance or deviations.

9. Document & Record

Maintain accurate and comprehensive documentation throughout the software development lifecycle, including requirements, design, tests, verification results, and any deviations or anomalies.

10. Prepare for Certification

Compile all necessary documentation and artifacts required for certification, including compliance reports, test results, and verification records, and collaborate with the appropriate regulatory authorities for certification processes.

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