DO-254: What is DO-254 and why is it important?
Even a tiny glitch in the software or hardware of an aircraft can lead to a bigger failure. That’s why it is important to follow some standard rules or guidelines while developing the aircraft.
DO-254 sets the rules for developing electronic hardware used in aircraft. It tells teams how to plan, design, test, and document each step, especially for components like flight computers and navigation systems.
In this blog, we’ll break down DO-254 in simple terms so you can understand what’s expected and how to avoid common mistakes.
What Is DO-254? A Quick Overview
DO‑254, or Design Assurance Guidance for Airborne Electronic Hardware, is a rulebook for building airborne electronic hardware (AEH). It provides a set of best practices for organizations to design, develop, and test aviation hardware items such as flight computers and custom chips.
- Brief history: DO-254 was developed and launched by the Radio Technical Commission for Aeronautics (RTCA) and EUROCAE in 2000. After that, it underwent several refinements, and the latest release was made in September 2021.
Following DO-254 standards can help organizations in getting a certificate for AEH from regulatory bodies like the Federal Aviation Administration (FAA) or European Aviation Safety Agency (EASA). So, companies manufacturing AEH should adopt it early to avoid costly fixes later.
Engineers often call DO‑254 the “little sibling” of DO‑178C: DO‑178C covers the safety standards of an aircraft’s software, while DO‑254 looks after the safety standards of circuit boards and logic that the software relies on.
Core Objectives and Importance of DO-254 Compliance
- Prioritizes the Safety of Hardware: By following DO-254, organizations make sure the hardware inside an aircraft does exactly what it’s supposed to do, without failure. It gives engineers a structured way to design and test each component with safety in mind.
- Ensures Reliability: The DO-254 compliance forces teams to double-check designs and test every function of hardware. Over time, this leads to more stable and reliable systems.
- Important to Get Airworthiness Certification: If you want to get airworthiness certifications like FAA or EASA for the aviation systems, adhering to the DO-254 compliance is a must during the development phase of aviation.
- Early Risk Identification: By following DO-254, teams can identify the risks in the early stages of the product development before they become expensive to fix.
- Promotes Traceability: DO-254 promotes the approach with end-to-end traceability for the hardware design, development, and verification. This way, organizations can ensure that hardware works as expected and trace the problem if any failure occurs.
Key Phases Involved in DO-254 Compliance
The DO-254 process includes several structured phases that guide hardware teams from planning to certification. Here, we have covered each phase:
1. Planning and Requirements Analysis Phase
The initial stage of the DO-254 compliance is the planning phase. In this phase, developers prepare the following documents that cover the strategy, processes, methods, etc., used during the different phases of the aviation hardware.
- PHAC (Plan for Hardware Aspects of Certification)
- HDP (Hardware Development Plan)
- HVVP (Hardware Verification and Validation Plan)
- CMP (Configuration Management Plan)
Developers also collect DO-254 requirements through stakeholder inputs, safety assessments, and system-level expectations in this phase. They need to ensure that every requirement is traceable, meaning it should be linked to its design and test results.
2. Design and Implementation or Development Phase
Once planning is done and requirements are ready, developers start preparing the architectural and detailed design of the hardware. Once the design is ready, they start the development. Also, developers are required to maintain traceability across all steps of design and development.
3. Verification and Validation (V&V)
In this step, the product development team confirms that the hardware works as expected under every situation.
- In the verification step, teams check if the design meets each requirement.
- During the validation step, teams ensure the final system performs its intended function in a real-world environment.
4. Reporting and Documentation
Throughout the entire DO-254 process, the comprehensive document is created in each phase. In this phase, developers are required to combine these documents and prepare reports. The document should demonstrate that DO-254 requirements are followed during the hardware development.
5. Certification Support
The final step is getting certified by the regulatory bodies before using the hardware in aviation systems. In this phase, you submit all documents to the certification authorities for review, and upon successful approval, the product can be used in aircraft.
Design Assurance Levels (DALs) of DO-254
In aviation systems, not all hardware is equally risky. For instance, if the flight control system or navigation system fails, it might lead to an aircraft crash or disaster, and airlines might need to stop their operations. But if the in-seat entertainment system fails, it won’t affect the safety of the aircraft.
DO-254 Design Assurance Levels (DALs) help in categorizing the hardware according to its criticality. Each level shows how serious the outcome would be if the hardware failed and how strict the development process should be.
Level | Impact of Failure | Examples |
|---|---|---|
DAL A | Could lead to a crash or major loss of life | Flight control system, auto-throttle |
DAL B | Serious injury or major system failure | Navigation logic, terrain warning units |
DAL C | Big inconvenience or reduced safety margin | Display units, sensor processing logic |
DAL D | Minor effect with no real impact on flight safety | Cabin alert systems, non-critical inputs |
DAL E | No safety effect if the hardware fails | In-seat entertainment, power status lights |
The higher the risk, the tighter the rules. Hardware in DAL A needs much deeper testing and documentation than something in DAL D or E. Knowing the DAL early helps set the right process from the start.
Top Challenges in DO-254 Compliance (And How to Overcome Them)
Following the DO-254 compliances looks straightforward, but in actuality, it’s a complex process if proper planning is not done and the right tools are not used. Here, we have covered a few challenges that aerospace hardware development teams might face and how to solve those challenges.
1. Managing Heavy Documentation Workloads
In every stage of the DO-254 process, development teams need to prepare and manage documents, such as development, testing, validation, etc., plans, and reports. Manually managing these documents can lead to version issues and missed updates.
How to fix it:
The “Smart Docs” module of the Modern Requirements4DevOps, the only requirements management tool within Azure DevOps, allows teams to create live-in requirements documents. It also offers a version control system, which allows teams to track different versions of the document.
2. Traceability Breakdowns Across Teams
It’s very important to maintain end-to-end traceability in every phase of the DO-254 process. However, many development teams generally rely on spreadsheets, which easily fall out of sync during design changes.
Modern Requirements4DevOps offers live traceability between requirements, tasks, test cases, and user stories. Even with the traceability matrices, teams can visualise the link between requirements.
Check out the tutorial to build traceability matrices in Modern Requirements4DevOps:
3. Writing Clear, Testable Requirements
Writing clear requirements that are testable and free from errors is also a challenge. Manually writing requirements can be time-consuming and prone to errors. So, teams can use Copilot4DevOps, an AI assistant that is a part of the Modern Requirements4DevOps, to generate requirements from the raw input data.
4. Toolchain Fragmentation
Most development teams use different tools for requirements and task management. Using multiple tools can make the overall development process complex.
For that, development teams can use Modern Requirements4DevOps, which can be directly used within your existing Azure workspace. So, teams don’t need to use external tools. This setup works especially well for teams in aerospace and product manufacturing, where tight process control is critical.
You can learn more about how Modern Requirements4DevOps supports requirements management in government and defense projects.
