Loss of control testing of light aircraft and a cost effective approach to flight test

Abstract

Loss of control in Visual Meteorological Conditions (VMC) is the most common cause of fatal accidents involving light aircraft in the UK and probably worldwide. Understanding why LoC events occur and why there are apparent differences between aircraft types is currently under investigation by Brunel Flight Safety Laboratory (BFSL). Using a case study approach for selected light aircraft used in the training environment and based upon a 29 year study of UK fatal accidents, BFSL undertook a qualitative and quantitative review of fatal stall/spin accidents using a combination of statistical and qualitative analysis. Aircraft/model design differences and published material were reviewed with respect to performance and handling qualities for possible clues, and informal interviews were conducted with type-experienced students, pilots and flying instructors. A flight test programme was executed using multiple examples (for fleet-wide attributes) of aircraft models to enable assessment and comparison of flying qualities (both qualitatively and quantitatively). Working within the continuous budget constraints of academia, a creative and cost effective flight test programme was developed without compromising safety. The two-man team (TP & FTE) used standard (unmodified) flying club and syndicate aircraft in conjunction with non-invasive low cost flight test instrumentation. Tests included apparent longitudinal (static and dynamic) stability and control characteristics, stall and low-speed handling characteristics and cockpit ergonomics / pilot workload. During this programme, adaptations were also made to the classic Cooper-Harper “point tracking” method towards a “boundary avoidance” method. The paper describes tools and techniques used, research findings, the team's lessons learned and proposed future research. It also discusses the possible application of research results in aircraft, pilot and environmental causal factors, enabling a better understanding of LoC incidents and future avoidance within the light aircraft community.