Understanding the human factors associated with Visual Flight Rules (VFR) into Instrument Meteorological Conditions (IMC) (DOT/FAA/AM-08/12). Washington DC: Office of Aerospace Medicine

Abstract

Work was accomplished under approved task AM-B-06-HRR 521. Abstract Visual Flight Rules (VFR) into Instrument Meteorological Conditions (IMC) accidents are a major concern in the aviation industry. More than 70% of the fatal weather-related accidents involved General Aviation (GA) pilots operating under visual flight rules (VFR) that continued into IMC. The purpose of this study was to pair GA accident causal factors that had been classified with the Human Factors Analysis and Classification System (HFACS) categories and traditional demographic data in an effort to present a more complete picture of VFR flight into IMC accidents. To accomplish this, GA accidents associated with VFR flight into IMC were examined to determine if there were any causal factors that set these accidents apart from the rest of GA (RoGA) accidents. GA accident data (14 CFR Part 91) from 1990-2004 were analyzed. The dataset was divided into accidents that had VFR into IMC (VFR-IMC; N = 609) cited as a cause or factor versus the rest of the GA accidents (RoGA; N = 18,528). Analyses were performed examining the human error associated with these accidents. The results indicated that skill-based errors were more prevalent in RoGA than in VFR-IMC (odds ratio = 4.167, 2 = 332.531, p <.001). VFR-IMC pilots were more likely to commit a decision error (odds ratio = 2.062, 2 = 77.961, p <.001); experience a perceptual error (odds ratio = 3.179, 2 = 118.350, p <.001); and commit a violation (odds ratio = 29.960, 2 = 2454.198, p <.001) than RoGA. The injury severity for VFR-IMC accidents was much greater than for RoGA (80.3% vs. 18.8%). RoGA pilots held a higher number of multiple certificates and earned more flight hours across the board than the VFR-IMC pilots. These data provide a more detailed view of the VFR into IMC accidents and will facilitate the development of future data-driven intervention strategies. Current interventions include weather cameras and other pilot aids for decision making with regard to weather