Flight Testing

Flight testing inherently exposes programs to unforeseen phenomena and risks not encountered in standard operations, demanding a more robust approach to error management than conventional methodologies provide. This paper introduces the Flight Test Error Matrix (FTEM), a conceptual framework designed to systematically classify, mitigate, and learn from errors in this demanding environment. The FTEM is built upon two interrogative pillars: “Do we know the error?” (knowability) and “Do we expect it to happen?” (expectancy). By analyzing errors along these dimensions, the framework identifies three primary classifications: Known-Expected errors, which are anticipated and managed through discipline; Known-Unexpected errors, which are understood in principle but whose occurrence is unforeseen, often driven by the “normalization of deviance”; and Unknown-Unexpected errors, which represent the most significant danger as they are entirely outside the organization’s risk awareness.

Response

This paper validates the FTEM by applying it to three seminal case studies: the Bell X-2 inertia coupling incident (Known-Expected), the Space Shuttle Challenger disaster (Known-Unexpected), and the X-31 crash (Unknown-Unexpected). The analysis reveals that the underlying causes, danger levels, and required mitigations are fundamentally different for each category. For effective safety management, it is required that these distinctions are not only identified, but that tailored strategies are also implemented—from the enforcement of discipline for known risks to the establishment of robust “lessons learned” cycles for unforeseen events. Ultimately, this research posits that the key to enhancing flight test safety lies in building resilient learning organizations capable of adapting to inherent risks and ensuring that every historical lesson contributes to a more secure and disciplined future.

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