The U.S. Army’s Future Vertical Lift program will introduce the next generation of U.S. Army aircraft. The complexities of the newly automated systems will increase speed and range during operational missions. Spatial disorientation has historically been a main concern during flight, often leading to loss of control that can result in death when an aviator succumbs to it. While working with the complex systems, the increase in tasks and operational tempo may result in greater risk for aviators experiencing SD. The risk of SD is elevated during upsets (nose low vs. nose high), including unusual attitudes or speed conditions. Biomedical sensors used to monitor pilots’ physiology during flight have the potential to predict the onset of human error. The U.S. Army has been working to develop methods of in-flight physiological monitoring to mitigate performance decline in preparation for the advanced battlefield.
For example, electrocardiogram measures heart activity. In some ways, ECG acts like a mind-stress level indicator by monitoring heart activity. The simplest thing ECG measures is heart rate, the speed of the heartbeats over time, by counting how often the heart beats each minute. Looking only at heart rate doesn’t give us the full story, though. A more insightful measure of ECG is heart rate variability, which looks at the changes in the time between heartbeats and shows us how regular or irregular the beats are. HRV is great for understanding how mentally engaged or stressed someone is. Generally, as heart rate increases, HRV decreases, indicating more stress. By monitoring heart activity in-flight, we might be able to identify periods of time when an aviator is overly stressed and make recommendations for changes, either to training, alerting, or perhaps even the addition of automated features that can take over some tasks, and decrease stress.
To help us further understand the physiological changes that occur in flight, the U.S. Army Aeromedical Research Laboratory partnered with Aviation Performance Solutions, LLC to collect physiological data from Army pilots participating in APS’s fixed-wing upset prevention and recovery training. APS’ UPRT is intended to increase safety, stress management, decision making, and manual handling skills in pilots, providing hands-on training for pilots to respond to dangerous scenarios. The UPRT consisted of five flights featuring different emergency scenarios performed at various attitudes. Pilots were trained on proper maneuvers and stalls in response to the upsets. Specific maneuvers included inverted flight, a Cuban eight, and skidded cross-controlled stalls to safely recover the aircraft. While participants in the APS program completed the training flights, USAARL researchers recorded physiological data from the pilots affiliated with the Army.
During the UPRT, USAARL found that average HRV significantly decreased as G-forces increased. This implies that higher G-forces might be linked to increased stress levels in some maneuvers. Furthermore, USAARL observed that the irregularity in heartbeat patterns (the standard deviation of HRV), increased with higher G-forces, indicating that the heart not only beats faster (HRV decreases) but also more erratically under stress, pointing toward increases in mental workload during challenging flying conditions. These findings suggest that stressed physiological states in pilots can be predicted, allowing proactive planning for techniques, tactics, and potentially automated assistance during adverse events.
Disclaimer
The views, opinions, and/or findings contained in this article are those of the author(s) and should not be construed as an official Department of the Army position, policy, or decision, unless so designated by other official documentation. Citation of trade names in this presentation does not constitute an official Department of the Army endorsement or approval of the use of such commercial items.
About USAARL
USAARL is a world-class organization of subject matter experts in the fields of operator health and performance in complex systems; the en route care environment; blunt, blast, and accelerative injury and protection; crew survival in rotary-wing aircraft and combat vehicles; and sensory performance, injury, and protection. USAARL engages in innovative research, development, test and evaluation activities to identify research gaps and inform requirements documents that contribute to future vertical lift, medical, aviation, and defense health capabilities. USAARL is a trusted agent for stakeholders, providing evidence-based solutions and operational practices that protect joint force warriors and enhance warfighter performance. USAARL invests in the next generation of scientists and engineers, research technicians, program managers, and administrative professionals by valuing and developing its people, implementing talent management principles, and engaging in educational outreach opportunities.
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