Application of causal analysis based on systems theory (CAST) to regulatory decision-making: A case study of the Sikorsky S92A

Ensuring aviation safety requires maintaining the integrity of product design and operations. The Federal Aviation Administration (FAA) regulates Transport Category rotorcraft design through 14 CFR Part 29, establishing Categories A and B of certification for multiengine rotorcraft, and requires aircraft to be operated according to the certified procedures in flight manuals. This paper presents a case study of the Sikorsky S92A, a Transport Category rotorcraft that is not certified for elevated helideck operations according to Part 29, but operates primarily in the offshore market through FAA-authorized exemptions from applicable regulation. To understand how this discrepancy between the aircraft's certification and operation came to be, a relatively new accident analysis methodology called Casual Analysis based on Systems Theory (CAST) is applied to a hypothetical accident involving an S92A, strongly based on a real incident described in a service difficulty report. The CAST results identify unsafe decisions on the part of flight crews, air operators, the aircraft manufacturer, and the FAA that contribute to the accident. We explain these contributions by identifying several systemic factors generalizable to the entire offshore rotorcraft industry that underlie unsafe decisions, and we propose a set of recommendations to address them.