131 Cognitive Workload Analysis of Fighter Aircraft Pilots in Flight Simulator Environment K. Mohanavelu #,@,* , S. Poonguzhali @ , D. Ravi $ , Pushpendar K. Singh $ , Mistu Mahajabin $ , K. Ramachandran $ , Upendra K. Singh # , and Srinivasan Jayaraman ! # DRDO- Defence Bioenginnering & Electromedical Laboratory, Bengaluru - 560 093, India @ Centre for Medical Electronics, Anna University, Chennai - 600 025, India $ DRDO-Defence Institute of Psychological Research Laboratory, Delhi - 110 054, India ! Medical Device and Development, Tata Consultancy Services, Bengaluru - 560 066, India * E-mail: mohanvelk@debel.drdo.in ABSTRACT Maintaining and balancing an optimal level of workload is essential for completing the task productively. Fighter aircraft is one such example, where the pilot is loaded heavily both physically (due to G manoeuvering) and cognitively (handling multiple sensors, perceiving, processing and multi-tasking including communications and handling weapons) to fulfill the combat mission requirements. This cognitive demand needs to be analysed to understand the workload of fighter pilot. Objective of this study is to analyse dynamic workload of fighter pilots in a realistic high-fidelity flight simulator environment during different flying workload conditions. The various workload conditions are (a) normal visibility, (b) low visibility, (c) normal visibility with secondary task, and (d) low visibility with secondary task. Though, pilot’s flying performance score was good, the physiological measure like heart rate variability (HRV) features and subjective assessment (NASA-TLX) components are found to be statistically significant (p<0.05) between tasks. HRV features such as SD2, SDNN, VLF and total power are found to be significant at all task load conditions. The features LFnu and HFnu are able to differentiate the effect of low visibility and secondary cognitive task, which was imposed as increased task in this study. This result benefits to understand the pilot’s task and performance at each flying phase and their cognitive demands during dynamic workload using HRV, which could assist pilot’s training schedule in optimal way on simulators as well as in actual flight conditions. Keywords: Pilot cognitive workload; HRV; NASA-TLX; Fighter pilots; Flight simulator 1. INTRODUCTION Over many decades, statistics on aircraft crash reveals 1,2 that the human error, particularly mental stress and loss of situational awareness experienced by pilots are the cause for plane crash. Though technology growth has contributed towards enhancement in aviation safety, the pilot’s workload requirements are superseded by the combat mission requirements. Pilots have to be trained efficiently to match with advancements in fighter aircrafts, handling weapons, communication systems in coordination with other pilots and ground control systems in increased tactical battlefield environments. In-field pilots were exposed to counter G forces (acceleration), which demands extreme physical and cognitive loading, if not countered properly, the pilot will enter into grey out, blackout zone and G-induced loss of consciousness 3 (G-LOC). As an effect, pilots may also experience various neurological symptoms, seizure, spinal compression and hemorrhages. So, it is essential to understand pilot’s cognitive workload (PCWL) during dynamic tasks and its influence towards performance. Several researches have been contributed to understand workload assessment, for car drivers, industrial workers, whose job nature follows a set routine with little variation 4-6 . To author’s knowledge, few research group have contributed to understand the cognitive role in fighter aircraft pilots, whose life is always under threat and high risk. Pilot uses past and current information to build a mental picture of the current and future events, where higher cognitive brain regions are involved for actions (top-down approach). It shall be stated that the workload of pilot is not an intrinsic attribute of a pilot’s brain, but rather appears from the requirements, challenges under which a task is performed, skills/training, behaviours and perceptions of the pilot. The level of effort (cognitive and physical) and attention resources expected to accomplish a task in combat mission may induce stress and fatigue due to high PCWL. It has been well accepted and reported in the scientific community that attention an indirect measure of performance and, could be assessed either by objective (performance score from simulator) or subjective techniques such as National Aeronautics and Space Administration Task Load Index (NASA-TLX) 7 , subjective workload assessment technique, Received : 12 May 2019, Revised : 08 August 2019 Accepted : 30 September 2019, Online published : 09 March 2020 Defence Science Journal, Vol. 70, No. 2, March 2020, pp. 131-139, DOI : 10.14429/dsj.70.14539  2020, DESIDOC