Tool Qualification Level
TQLSection 08: Software Certification (DO-178C)
Definition
A designation under DO-330 / DO-178C that defines the qualification effort required for a software development or verification tool based on the potential impact of the tool on the airborne software. Five TQL levels are defined: TQL-1 (most rigorous) applies to tools whose output is part of the airborne software and that could insert errors, when used for Level A software; TQL-2 through TQL-4 apply to lesser combinations of tool impact and software level; TQL-5 (least rigorous) applies to tools that automate processes but whose output can be verified by other means. The TQL determines which DO-330 objectives must be satisfied for the tool qualification.
Where This Shows Up
Tool qualification is necessary because modern development processes rely heavily on automated tools. A compiler translates source code into object code — if the compiler introduces an error, the airborne software could be defective. A test tool that fails to detect a failure could allow a defective software item to be certified. DO-330 provides the framework for assessing and mitigating these tool-related risks. The TQL is determined by two factors: the tool's potential to introduce or fail to detect errors, and the software level of the airborne software being developed.
Primary Sources
Defines Tool Qualification Levels and the criteria for determining the applicable TQL.
Addresses tool qualification requirements within the software certification context and references DO-330.
Related Terms
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