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DO-178C Plans & Standards Templates

DO-178C Plans & Standards Templates

Table of Contents

Introduction

DO-178C is a software standard developed by the Radio Technical Commission for Aeronautics (RTCA) that defines the guidelines for the development of safety-critical avionics software. It provides a framework for the certification of software used in airborne systems, ensuring that they meet stringent safety and reliability requirements. One of the key aspects of DO-178C compliance is thorough testing, including the measurement of structural coverage. This article explores the importance of testing and structural coverage in the context of DO-178C.

Understanding DO-178C

Overview of DO-178C

DO-178C, titled “Software Considerations in Airborne Systems and Equipment Certification,” is the current standard for developing and certifying software in airborne systems. It provides a framework for determining the safety, reliability, and compliance of software used in avionics systems. DO-178C replaces its predecessor, DO-178B, and introduces several enhancements and clarifications.

The Importance of DO-178C Compliance

Complying with DO-178C is essential for ensuring the airworthiness of avionics systems. The standard emphasizes a systematic and rigorous approach to software development, verification, and validation. Adhering to DO-178C not only helps identify and mitigate potential software defects but also promotes a comprehensive understanding of the software’s behavior, interfaces, and potential failure modes.

Testing in DO-178C

Verification Process

DO-178C outlines a comprehensive verification process that includes requirements-based testing, integration testing, and system testing. The aim of testing is to demonstrate that the software performs its intended functions correctly and reliably. The verification process consists of four distinct levels, each building upon the previous one: Level A (the most critical) to Level D (the least critical). Regardless of the level, testing is a vital component of the DO-178C process. 

Test Objectives

The primary objectives of testing in DO-178C are:

  • Demonstrate that the software complies with the specified requirements.
  • Identify and eliminate defects that could potentially compromise safety.
  • Provide evidence to support the certification of the software.

Test Techniques

DO-178C allows for various test techniques, including:

  • Functional Testing: Verifying the functional correctness of the software by executing test cases that exercise its features and capabilities.
  • Structural Testing: Focusing on the internal structure of the software, examining its paths, branches, and decision points to ensure that all logical outcomes have been exercised.
  • Performance Testing: Evaluating the software’s performance under different load conditions to ensure it meets the specified requirements.
  • Regression Testing: Re-running previously executed tests to ensure that modifications or enhancements do not introduce new defects.
  • Fault Injection Testing: Intentionally injecting faults or errors into the software to assess its robustness and ability to handle abnormal conditions.

Structural Coverage in DO-178C

Definition

Structural coverage, also known as code coverage, refers to the measurement of how much of the software’s code has been executed during testing. It helps assess the thoroughness of the testing process by identifying areas that have not been exercised. Structural coverage provides evidence that the software has been adequately tested and helps ensure that all possible outcomes of the software’s logic have been considered. 

Coverage Criteria

DO-178C specifies several coverage criteria that must be met during testing. These criteria include:

  • Statement Coverage: Ensures that every executable statement in the software has been executed at least once during testing.
  • Decision Coverage: Verifies that every decision point (e.g., if statements, switch statements) in the software has been exercised with both true and false outcomes.
  • Condition Coverage: Ensures that each Boolean condition within a decision point has been evaluated to both true and false values.
  • Modified Condition/Decision Coverage (MC/DC): This verifies that each condition independently affects the outcome of a decision.

Benefits of Structural Coverage

Structural coverage measurement offers several benefits within the DO-178C context:

  • Early Detection of Untested or Partially Tested Code: Structural coverage analysis helps identify areas of the software that have not been exercised by existing tests, allowing for more targeted testing efforts.
  • Risk Reduction: By ensuring comprehensive coverage, the likelihood of undetected software defects and safety-critical failures is reduced.
  • Certification Support: Structural coverage metrics provide objective evidence that the testing activities have been conducted in accordance with DO-178C guidelines, facilitating the certification process.
  • Enhanced Software Quality: By exercising all code paths and decision points, structural coverage testing helps improve the overall quality and reliability of the software.

Using Professional Tools Like Visure Solutions for DO-178C Testing and Coverage Process

Visure Solutions is a leading requirements management tool that provides end-to-end support for the entire software development lifecycle. It offers a collaborative and integrated platform for managing requirements, test cases, traceability, and documentation. Visure Solutions is designed to meet the stringent requirements of safety-critical industries, including aviation, where compliance with standards such as DO-178C is crucial.

Key Features of Visure Solutions for DO-178C Testing and Coverage

Visure Solutions offers a range of features specifically tailored to support the DO-178C testing and coverage process:

  • Requirements Management: Visure Solutions enables the capture, organization, and management of software requirements according to DO-178C guidelines. It provides traceability features to establish and maintain traceability links between requirements, design, test cases, and code.
  • Test Case Management: The tool facilitates the creation, management, and execution of test cases. Test cases can be linked to requirements, allowing for efficient traceability and verification of coverage.
  • Structural Coverage Analysis: Visure Solutions supports the analysis and assessment of structural coverage metrics, including statement coverage, decision coverage, and modified condition/decision coverage (MC/DC). It provides visual representations of coverage data, allowing developers to identify areas that require additional testing.
  • Traceability Management: The tool offers robust traceability management capabilities, ensuring that each requirement is properly traced to test cases and code artifacts. This traceability helps demonstrate compliance with DO-178C objectives and aids in the certification process.
  • Change Management: Visure Solutions includes change management functionalities that facilitate tracking and controlling changes to requirements, test cases, and other project artifacts. This ensures that changes are properly documented, reviewed, and approved, maintaining compliance with DO-178C configuration management requirements.

Benefits of Using Visure Solutions

  • Improved Efficiency and Collaboration – Visure Solutions streamlines the DO-178C testing and coverage process, improving efficiency and collaboration among team members. The tool provides a centralized platform for managing requirements, test cases, and traceability, reducing the complexity and time spent on manual administrative tasks.
  • Enhanced Visibility and Traceability – By leveraging Visure Solutions, development teams gain enhanced visibility into the entire software development lifecycle. The tool enables comprehensive traceability between requirements, test cases, and code, ensuring that each requirement is adequately tested and providing a clear audit trail for compliance purposes.
  • Accelerated Certification Process – Visure Solutions helps expedite the software certification process by providing structured and organized documentation that complies with DO-178C standards. The tool’s traceability features enable efficient and accurate reporting of requirements coverage and structural coverage metrics, facilitating certification activities and audits.
  • Compliance with DO-178C Guidelines – Visure Solutions is designed specifically to address the requirements of DO-178C. By utilizing the tool, organizations can ensure that their software development processes align with the standard’s guidelines and objectives. Visure Solutions provides built-in templates, workflows, and functionalities that are tailored to meet the DO-178C compliance requirements.

Conclusion

Testing and structural coverage are critical elements of the DO-178C standard for the development and certification of safety-critical avionics software. Rigorous testing, combined with comprehensive structural coverage analysis, helps ensure that the software meets the specified requirements and operates reliably in the intended environment. By adhering to DO-178C’s testing guidelines and achieving satisfactory structural coverage, aviation software developers can demonstrate the safety and reliability of their systems, ultimately contributing to safer air travel.

In the context of DO-178C testing and coverage, using professional tools like Visure Solutions offers significant advantages in terms of efficiency, collaboration, visibility, and compliance. The tool’s specialized features for requirements management, test case management, structural coverage analysis, traceability management, and change management streamline the entire software development process and facilitate adherence to DO-178C guidelines. Leverage Visure’s 30-day free trial to enhance your software development practices and achieve a higher level of confidence in the reliability and safety of their avionics systems.

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