Non-Intrusive Fatigue Detection and Alerting for Pilots

Pilot fatigue represents a critical concern in aviation safety, as it can significantly impair cognitive functions, decision-making abilities, and reaction times. In addition to decreasing performance, chronic fatigue has negative long-term health effects. Possible causes of fatigue include sleep loss, extended time awake, circadian phase irregularities and workload. Conventionally, the risk due to fatigue in aerospace is reduced by limiting pilot's flying hours and controlled rest requirements. Despite regulations on flying hours and optimal rostering, fatigue cannot be prevented completely. Hence, there is need to detect pilot fatigue in real time, annunciate in cockpit and transmit the information to airliners post-flight for appropriate fatigue risk management. There is ongoing research to detect pilot fatigue using devices that can capture Electroencephalogram (EEG) and Electrocardiogram (ECG). Though these devices have high fidelity, they are intrusive and can limit pilot activity. This limitation could potentially be overcome by non-intrusive devices such as a smart watch/wrist band/goggles which can measure physiological parameters that provide insights into pilot’s mental health. One promising physiological marker is heart rate variability (HRV), which can be derived from raw Photoplethysmography (PPG) signals. Analyzing HRV provides insights into the autonomic nervous system, enabling the evaluation of physiological states. In this study, a wearable wristwatch was used to collect PPG data, while both time and frequency domain analyses were conducted to assess HRV indices. The examination of R-R intervals and the Low Frequency/High Frequency (LF/HF) ratio plots indicated distinctive patterns that differentiate alert pilots from fatigued ones. This research presents a reliable non-intrusive approach to detect pilot fatigue, contributing to enhanced flight safety.