DO-178C and DO-254 Explained

Written by: Hanna Taller

Read Time: 3 minutes

Three key standards which regulate the development of aviation systems compliance are DO-178C, DO-254, and ARP4754A. DO-178C and DO-254 are standards that provide guidance for the safe development of software and hardware, while ARP4754 focuses on the system aspect. Although organizations working in avionics development are likely to be more familiar with DO-178C, DO-254 compliance nowadays is just as important. Read on to discover what each standard requires and our top tips for a smooth compliance journey.

Aircraft and defense systems are made up of many different parts, including highly complex software and hardware components. Since many of these qualify as mission-critical applications whose faults can have deadly consequences for passengers and crew, avionics is a very heavily regulated industry. This means that in order for an aircraft to go to market, it must undergo a long certification process to be considered airworthy. The certification process includes submission to the relevant regulatory authorities in order to get a test certificate (FAA in the US, EASA in the EU). Then manufacturers go through rounds of design approvals, simulations, prototype model testing, structural tests, and in-flight tests to make sure the aircraft is safe for use. 

DO-178C explained

Published by RTCA with EUROCAE, DO-178C (Software Considerations in Airborne Systems and Equipment Certification) is the most widely used approach for demonstrating the airworthiness of an avionics or aerospace system. In other words, using this standard to guide your design process is the main way to ensure that your airborne software development is producing an aircraft that is fit for flight – and for going to market internationally.

The origins of this standard date back all the way to the 1970s, when manufacturers began to increase the amount of integrated software and hardware in aircrafts. This led the industry to create what was (at the time) a quite prescriptive set of design assurance processes to ensure aircraft safety. Over time, the standard has become less prescriptive and more objective-based, which gives companies a bit of flexibility in terms of how they achieve the recommended guidelines.

DO-178C is based on a fundamental framework for defining Development Assurance Levels. There are five different levels, each one relating to the gravity of what happens if the software fails, ranging from Level A (Catastrophic) to Level E (No effect on safety). The higher the risk, the more rigorous the certification process is and the more safety standards you need to comply with. The standard also describes the required stages for planning, development, and implementation when it comes to safe design assurance processes for delivering high-quality avionic software.

DO-254 explained

Meet DO-178C’s ‘Little Sibling’ standard, also known as the DO-254. DO-254 Design Assurance for Airborne Electronic Hardware is the go-to guideline for manufacturing airborne electronic hardware. Although it is often considered the ‘Little Sibling’ counterpart to the DO-178C, it is no less complex. 

The standard kicks off with a classification system that allows you to separate electronic hardware items into simple or complex categories, and then provides systematic design guidelines for both. DO-254 is similar again to DO-178C in that it uses a Design Assurance Level (DAL) framework as well. DO-254 uses a range of 5 levels too, ranging from A-E, with the most severe being A and the least impactful being E. Again, the efforts needed in order to achieve compliance scale along with the amount of damage a hardware failure can cause.

DO-254, like DO-178C, was also published in conjunction with the RTCA and EUROCAE. It is a bit younger than its counterpart, however – it was formally recognized by the FAA in 2005 in order to respond to the increasing use of varied electronic hardware included in airborne systems. The problem was that the European Aviation Safety Agency (EASA) didn't make the same decision. Therefore up to the recent past, there were confusions and many discussions regarding the need for compliance with DO-254 in airborne systems, especially in the case of simple hardware. 

This was recently clarified via EASA AMC 20-152A which brings:

  • Formal recognition and clarification on the use of DO-254
  • New modern classification of airborne electronic hardware
  • New compliance objectives for individual types of airborne electronic hardware
  • Harmonization with the FAA as there should be an equivalent document released soon

Advantages of DO-178C compliance and DO-254 compliance

DO-178C/DO-254 compliance can be a lengthy and expensive process, so it’s no wonder that some working in avionics development wonder what the point is. However, if you are prepared with the right information, processes, and tools, DO-178C compliance and DO-254 compliance can be extremely beneficial for your organization. First of all, this level of airborne systems compliance helps you create products that put passenger, crew, and operator safety first. 

It also strengthens the health of your organizational business practices, which can be helpful in many different areas. And finally, it gives your organization a competitive edge as some projects require DO-178C/DO-254 compliance capabilities, and you will have an advantage compared to other manufacturers and developers who don’t offer it.

Of course, you need to know how to keep the costs down as much as possible in order to reap these benefits. And it’s difficult to be as productive and systematic as possible with your resources if you’re still using manual documentation processes or legacy tooling. 

The challenge of paper-based documentation systems in aviation software development

Some organizations nowadays still use a paper-based documentation process. This can make it extremely difficult to stay on top of changes and give the whole team, stakeholders, and external partners the visibility needed to manage change and collaborate effectively. The result? Long review cycles, an increased chance of human error, costly fixes, and client approval delays that slow the project down overall. 

Legacy tooling in aviation systems development isn’t much better

So it may not be paper-based, but imagine this: endless different versions of documents shared back and forth by email or consumer-grade file-sharing platforms, or outdated tools which are still considered mission-critical but are difficult to update and integrate with new systems. Some may even not have customer service available anymore. Using various systems with incomplete data migration and unnecessary administration can create just as much of a visibility and traceability gap as a paper-based documentation system can. Inevitably, the team spends a lot of time on non-critical work, which becomes costly in terms of both time and resources.

Avionics systems compliance: tooling makes all the difference

An easy way to streamline the development of airborne products, aviation software, and embedded avionics systems is by using an Engineering Lifecycle Management platform like Codebeamer with capabilities specifically geared towards the needs of the aviation industry.

The capabilities of Codebeamer allow you to leverage the high level of traceability, transparency, and documentation you need to make your DO-178C, DO-254, and ARP4754A compliance efforts as smooth as possible. Using our preconfigured template for DO-178C compliance enables you to achieve efficiency in fulfilling the objectives of this aviation regulation.


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Tags: Application Lifecycle Management (ALM) Codebeamer

About the Author

Hanna Taller

Hanna Taller is a content creator for PTC’s ALM Marketing team. She is responsible for increasing brand awareness and driving thought leadership for Codebeamer. Hanna is passionate about creating insightful content centered around ALM, life sciences, automotive technology, and avionics.