These Are The Four Categories of DO-178c Tests According To Avionics Leader AFuzion

Avionics leader, AFuzion, is a boutique company specializing in the training and dissemination of technical knowledge to develop more efficient, safe, and certified aircraft and aviation systems. They have over 30 years of experience and knowledge developed and copyrighted, also providing Gap Analysis, Whitepapers, Checklists, and Templates. 

The AFuzion team has assisted over 90% of the world’s aviation development systems, and trained 23,000 engineers, which total to more than their competitors combined. Additionally, AFuzion is the only company permanently selected by conferences like the Society of Aerospace Engineers (SAE), Digital Avionics Systems Conference (DASC), Aerospace Tech Week and Electronics Valley and over twenty governmental organizations with links to Military agencies. 

Key avionics certifications that AFuzion focuses on are software and hardware development compliance, notably the DO-178C (software) and DO-254 (hardware), among others.  The DO-178C (Software Considerations in Airborne Systems and Equipment Certification) is referred to by many in the industry as the bible of Avionics software development and with valid reason. Developed in the 80s, the DO-178C has been the de facto standard applied to software in systems where safety is a critical factor.

AFuzion’s DO-178C training has a three-tiered development process, which starts with Planning, Development, and Correctness and this, in turn, is dependent on the five ‘criticality’ levels, referred to as the DAL (Development Assurance Level), which start from Level E (No Effect) to Level A (Catastrophic). The Planning process is done as a first step to create a stable foundation for development, and to indicate the standards and checklists for testing. 

Testing is a crucial step in the DO-178C development process, and as the founder of AFuzion, Vance Hilderman, says, ‘software testing should not be considered a luxury but rather a necessity. DO-178C requires a variety of necessary testing, with increased rigor per increased criticality’. However, there are many that believe software testing is a big line-item expense, but as Hilderman points out, ‘devoting upfront time to develop a test automation framework can provide the single largest expense reduction ability’.  

Four Categories of DO-178C Tests

There are four categories that comprise the DO-178C tests, these combine white-box (focusing on the internal software code, requiring programming knowledge) and black-box (focusing on how the software acts, as well as its requirements) testing methods. The four testing categories are as follows:

  1. Functional Tests – these cover all requirements, which fall under High-level and Low-level requirements. 
  2. Normal Range Tests – these are referred to as ‘Sunny Day’ conditions.  
  3. Robustness Tests – these tests are referred to as ‘Rainy Day’ conditions and Performance/WCET tests.
  4. Structural Coverage Analysis – these tests cover all code per requirements, which include DAL, C, B, and A.  

Final Takeaway

While there is more to the DO-178C software development process, the above categories  indicate essential aspects relating to the benefits of placing relevant importance and focus on software development when it comes to safety-critical systems like aircraft. Visit AFuzion’s website for more DO-178C resources, free to download.