Human Factors Analysis and Classification System as a Potential Confounder in Army Aviation Mishap Analysis

Introduction: The U.S. Department of Defense has utilized the Human Factors Analysis and Classification System (HFACS) in its various iterations since 2004 to classify and codify the causation of military mishaps. The purpose of this study is to examine the likely accuracy of the HFACS coding of U.S. Army Aviation mishaps. Methods: The U.S Army Combat Readiness Center (CRC) database was queried for the fiscal years (FY) 2012-2022, the class A and B aviation mishaps were collated with their associated HFACS codes, and the mishap narratives were examined by an expert panel of senior mishap investigators, aviators, and aeromedical practitioners. The resultant disparities between the CRC coding and the assessed causative factors with special reference to spatial disorientation (SD) were then examined. Results: In the period under examination (FY 2012-2022) there were 184 class A and B helicopter mishaps recorded in the CRC database. Of those, 106 had HFACS version 7.0 codes assigned to them with 52 unique codes used. With specific reference to SD causation, only 3 of the 7 SD-related codes in HFACS version 7.0 were found to have been used; misinterpretation of instruments, misperception of changing environment, and SD. Combined, these amounted to 36 of the 537 codes used (6.7 ). The expert analysis of the 106 mishaps coded showed 58 with no SD component (54.7 ), 29 with SD as a contributory factor (27.4 ), and 25 where SD was assessed as being causal (23.6 ). By contrast, the HFACS coded SD causation in 4 of 106 (3.8 ) mishaps. Discussion: The review of CRC codes versus expert opinion suggests that the coding does include elements that are very common in SD mishaps but without the final step to assign an SD code to a specific mishap. Thus, the information being presented to Army aviation senior leadership is providing at best, an incomplete picture and at worst, a significant distortion of mishap causation.