VectorCAST and the RTCA/DO-178B Tool Qualification Process

The Requirements and Technical Concepts for Aviation (RTCA) Document Number RTCA/DO-178B specifies that qualification of a software tool is necessary when processes defined in the DO-178B document are eliminated, reduced, or automated by the use of a software tool without its output being verified. VectorCAST addresses the automation of the software verification process as defined by DO-178B. The qualification of a software verification tool is mandated by DO-178B Section 12.2.2 on a project by project basis. The qualification data produced for each project operating under the DO-178B guideline is done under the guidance of the project certification authority and Designated Engineering Representative (DER).

Responsibility for qualifying software verification tools (VectorCAST) is usually a joint effort between the prime contractor and the tool vendor. Based on a system safety assessment, failure condition categories are established. These failure condition categories determine the level of software integrity necessary for avionic safe operation. DO-178B classifies the software into five levels of criticality related to atypical software behavior that could cause or contribute to failure of a system function. The table below shows the relationship between the failure condition category and the structural coverage objective as defined by DO-178B.

In addition to providing all of the levels of code coverage required by DO-178B, VectorCAST also provides the following capabilities associated with structural level testing:

• Automatic generation and compilation of test stubs and driver programs
• Test cases based on min-mid-max and fixed increments through a range of values
• Interactive point-and-click and script generated test case construction
• Test case modification and re-execution without re-compilation
• Automatic regression testing
• Standards compliant test report generation
• Basis path analysis and cyclomatic complexity
• Test execution on both host and embedded target development systems

To qualify VectorCAST as a software verification tool, Vector Software produces the following information for each project that the tool is to be used on:

Tool Operational Requirements (TOR) Document includes:

• Tool's functionality in verifiable requirements
• Project operational environment
• Configuration management process
• Method for attaining verification that VectorCAST has been satisfactorily tested against specified requirements

Tool Qualification Document (TQD) includes:

• Tool qualification test data and results

The tool qualification process normally includes interaction with the qualifying user as well as the associated certification authority and/or DER.

• Vector Software delivers the customer a baseline "draft" version of the qualification material and solicits comments.
• Vector Software incorporates the changes to the documents and associated tests, if applicable.
• Vector Software executes the tool qualification test suite using the same compiler version and VectorCAST version that the customer is using.
• Vector Software delivers version 1.0 of the Tool Qualification Documents for final approval.
• Final delivery contains all of the test scripts necessary to re-execute the test suite at the customer's site, if desired.

Recent projects that have utilized Vector Software's Tool Qualification Delivery include:

• Rotor Ice Protection System (RIPS) Sikorsky S-92 Helicopter
• A380 Cabin Pressure Control System
• Traffic Collision Avoidance System
• Boeing 777 LR
• F/D 728 Jet Fuel, Proximity, and Steering Systems
• Agusta A109 Light Utility Helicopter

For more information on FAA topics related to Software Policy:

• FAA Aircraft Certification Products and Services
• FAA Certification Authorities Software Team (CAST)
• FAA Notice 8110.49, "Software Approval Guidelines," (June 2003)