Comparing Hazardous States and Trigger Events in Fatal and Non-Fatal Helicopter Accidents

Abstract

Helicopter safety literature generally focuses on identifying the causes and contributing factors for fatal accidents. It identifies the top mechanical and crew-related problems that lead to fatal accidents, and intervention strategies to reduce fatal accidents and improve cash survivability. In this paper, we argue that data from non-fatal accidents is an underused resource that could be used to better understand the reasons for several types of fatal accidents. If fatal and non-fatal accidents share similar stories, we can leverage information in non-fatal accident reports to reduce not just the number of fatal accidents, but rotorcraft accidents overall. We seek to identify and compare the top hazardous states (e.g., loss of control) and trigger events (e.g., incorrect cyclic input) in fatal and non-fatal accidents. We analyzed 5051 helicopter accidents that occurred in 1982-2008. Fatal accidents constitute a small proportion of accidents (15.2%), while the remaining 84.8% were non-fatal. Inflight loss of control (LOC), controlled flight into terrain/object (CFIT), weather, failure to maintain physical clearance/altitude from objects, and system/component failure comprised the top five hazardous states, which accounted for nearly 90% of fatal accidents. Poor inflight planning/decision making by pilots was most likely to trigger both fatal and non-fatal accidents LOC accidents. Decision-making errors also frequently triggered fatal CFIT accidents. The high proportion of non-fatal accidents provides an opportunity for in-depth interviews of pilots to understand the rationale behind the decisions and the actions that followed. Seven out of eight system/component failure trigger events involved the main rotor system and the rotor drive system, highlighting the importance of these systems for rotorcraft operations. Critical flight components such as tail rotor blades and gearbox, and transmission drives were equally likely to fail in both fatal and non-fatal accidents. In some cases the nature of terrain, phase of operation, and on-board protective gear were the difference between life and death. Nomenclature ASIASAviation Safety Information Analysis and Sharing CFIT Controlled Flight into Terrain or Object

Conceptual design and optimization of a sustainable and environmentally friendly archetypal helicopter within the selection criteria and limitations

“…Various improvements in terms of design are required for helicopter accidents, which occur in excess of 100 worldwide every year. Within the scope of design, the helicopter crashworthiness and survivability analysis study conducted by Purdue University [ 8 ] in 2016 was examined, and solutions were developed to minimize the possibility of errors and accidents in the system. In this study, it was concluded that accidents frequently occur due to obstacle impact, resonance, weather conditions, and visibility.…”