Technology independent assurance method

Avionics software and hardware must, like all engineered products, be fit for use. The recently published SAE ARP4754A [1], “Guidelines for Development of Civil Aircraft and Systems,” addresses this obligation in the context of system development. Model-Based Development has been widely adopted in civil aeronautics and blurs traditional distinctions between systems-engineering disciplines on the one hand and software/hardware disciplines on the other. One consequence of that blurring has been loss of clarity in the guidance associated with design assurance. This paper seeks to resolve such questions. The Technology Independent Assurance Method (TIAM) is proposed as a straightforward extension of previous engineering strategies and is intended to span a given product's development cycle from concept to production readiness. TIAM generalizes the recognition that development is a progressive activity with an initially unknowable number of successive refinements that proceed from the more abstract to the less abstract. TIAM identifies, articulates, and preserves the integrity of each intellectual abstraction along that path, highlighting all required relationships of each abstraction to its predecessors and successors. At each step, developers are free to choose appropriate processes and tools. This paper provides an overview of TIAM. In addition, this paper illustrates TIAM's applicability to certain real-world challenges arising from Model-Based Development as currently applied to airborne hardware and software by systems engineers.