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Writing efficient plans (vs. ARP-4754A, DO-178C, DO-254)

Based on our cumulative experience of hundreds of aeronautical projects, we observe that the plans are often incomplete but also contain useless or too complex information.



Our opinion is based on decades of experience, either as designers or as certification auditors. In the minds of many people, the documentation to be produced, especially the plans but not only, is seen as unnecessary to the project. As if, in the end, this documentation was only there to satisfy the regulator. Consequently, it is thought that the more you put in, the better it is. This does not prevent essential aspects from being missed. This is primarily due to a lack of understanding of the certification context and expectations. This situation inevitably leads to wasted energy and a significant impact on project costs and deadlines. We have already seen several projects delayed by 2 to 5 years, directly linked to this lack of understanding.


Here are some basic tips for writing plans vs ARP-4754A, DO-178C, DO-254/AMC 20-152A.


Tip #1: Take a day to understand


Have a specialist explain the context of certification, the basics of safety analysis, the grading of effort according to criticality, the responsibility of individuals in the design of critical systems. Have the entire project team participate. This is a recommended preliminary before even getting into specific ARP-4754A or DO-178C/DO-254 training.


Tip 2: Check what is mandatory


Keep in mind that plans, once approved, will have to be implemented and that this implementation will be verified by an authority or its representative.

Make sure you have only processed what is required. Nothing prevents you from doing more than what is required, but if you do, handle it outside the plans produced for certification. Get help if you are unsure.

« Don't make it harder for yourself »

Tip 3: Keep it simple and clear


Do not duplicate the information in several plans, otherwise you can be sure that in later changes there will be differences and it will be difficult to determine what is applicable. For example, if you have a PSAC and a SCMP, the following text is sufficient in the PSAC under "Configuration Management":

The SCMP (Software Configuration Management Plan), reference XXX, defines the software configuration management activities:

- Configuration item identification and traceability

- Baselines and traceability

- Problem reporting, tracking and corrective actions

- Change control and change review

- Configuration status accounting

- Release

- Storage and retrieval

- Software load control


Don't make convoluted, ambiguous, or incomplete descriptions. For example, don't say in an audit plan "we will write test cases" without further explanation. The person in charge of this activity should not let his or her imagination run wild in accomplishing this task. One to two pages of description are needed to explain how the test cases will be written and will contribute to the coverage of the requirements.


Stick to the objectives, don't make useless sentences to make a document per Kg. For example, this has no interest in a PSAC, or even in a SQAP or HPAP: "our company has significant experience in the fields blah blah blah..., which leads us to a high level of blah blah blah..., we are certified EN9100 since 5 years and blah blah blah...".


In conclusion, aim for effectiveness


If you are not experienced with the aspects of aviation certification, don't go it alone, chances are you are wasting energy, either by doing too much or not enough (in the latter case you might find out too late vs. your schedule).

We can help you at any stage of development, whether it's through gap analysis, training (https://www.certaero.com/en/training), consulting (https://www.certaero.com/en/services), or document templates (https://www.certaero.com/en/products).

We welcome your feedback. Do not hesitate to contact us.

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