Technical Reports

A technical report is a technical document that records and disseminates methods and results from research studies and research, development, test, and evaluation (RDT&E) activities. Technical reports are USAARL's principal method of in-depth reporting on technical subjects that are of interest not only to the department, agency, or command sponsoring the work, but also to external groups and laboratories in government, academia, and industry. Technical reports may vary in type, to include technical reports that present the findings of research or analyses or that provide guidance or instruction on matters important to the DoD, journal articles (open access and embargoed text) that have been published under an open access agreement with the publisher or published under a Creative Commons license, conference proceedings that include whole collections of papers presented at a symposium or workshop, and conference papers that could include an individual paper, briefing charts, or a poster presented at a workshop or symposium. For inquiries related to USAARL's technical report(s), contact usarmy-usaarl-library@health.mil.

Featured Reports

For more reports, please visit the technical reports archive page.

Download '2026-47' report PDF

SIZE:3.9 MB

DTIC #:AD1369816

TITLE:Head Impact Brain Health Thresholds Expert Panel: Summary Report

AUTHOR(s):Gleason, A., Johnson, B., McEntire, B. J., & Chancey, V. C.

ABBREVIATED ABSTRACT:Traumatic brain injury remains a significant threat to Warfighter brain health and military readiness. Although wearable sensors may improve detection of head acceleration events (HAEs) and reduce missed mild traumatic brain injury diagnoses, a 25-member expert panel convened by the U.S. Army Aeromedical Research Laboratory concluded that current science does not support a single linear or rotational acceleration threshold that can reliably predict concussion. The panel found that concussion risk is complex and individualized, affected by cumulative exposure, impact direction, location, frequency, and duration, as well as factors such as age, sex, prior concussion history, fatigue, hydration, sensor error, and limitations in clinical assessment. Wearable sensors are nevertheless useful for identifying high-risk environments and establishing baseline HAE exposure profiles.

KEYWORDS:head impact, brain health, Warfighter brain health, head acceleration event

Download '2026-46' report PDF

SIZE:3.5 MB

DTIC #:AD1369812

TITLE:Engineering Sleep Architecture for Better Performance Under Combat Stress

AUTHOR(s):Turovets, S., Luu, P., & Tucker, D. M.

ABBREVIATED ABSTRACT:The next generation of rotary-wing aircraft are anticipated to have advanced capabilities that will require aviators to fly for longer durations and impose a high demand in terms of cognitive workload. Given unavoidable stress and loss of sleep in the operational environment, we anticipate that this will increase the likelihood and prevalence of overloaded and fatigued aviators in the cockpit. The best method of counteracting fatigue induced by loss of sleep or circadian rhythm disruption is to have sufficient and good quality, preferably night-time, sleep. This is not always possible to achieve in aviation, however, especially during military deployments, as sleep in the field is often of less quality and duration than sleep at home. Moreover, performing operations at night and during sequentially long hours with limited opportunities of layover, pre-flight or in-flight rest maybe tactically necessary. This is why new technologies for improving sleep efficiency, including that through short naps, during military deployments may be a key strategy in boosting cognitive functions and operational readiness and eventually saving lives in the rotary-wing environment. The overall objective of this study is to review the recent promising advances in sleep stage engineering that may enhance the quality of deep sleep and lead to enhanced human cognitive performance. Day-time pre-flight naps, controlled in-flight rest on the flight deck or short in-seat cockpit naps are promising means of performance enhancement for aviators.

KEYWORDS:sleep, performance optimization, stimulation, napping, aviation

Download '2026-44' report PDF

SIZE:5.1 MB

DTIC #:AD1369801

TITLE:Mechanical Surrogates For Behind Armor Blunt Trauma

AUTHOR(s):Bass, C. R.

ABBREVIATED ABSTRACT:Across modern conflicts, unprotected fatal wounds occur principally in the torso because this body region has a larger cross-sectional area and contains more vital organs than other body region. The largest threats for Warfighters and law enforcement personnel are from shrapnel and projectiles of higher energy and velocity than anticipated 53 years ago when the National Institute of Justice worked to standardize body armor. Modern body armor can defeat incoming pistol and rifle rounds by trading energy and momentum deposition into the armor for armor deformation. This deformation includes direct body armor deformation in soft body armor and deformation with fracture in hard body armor. This deformation in soft and hard body armor has the potential to create injuries behind the armor in the thorax that may be generally characterized as blunt trauma. These injuries are often termed behind armor blunt trauma (BABT). Backface deformation of the body armor over the thorax is sufficient to cause local and distant fractures, contusions, and hemorrhages; therefore, thoracic biofidelity is crucial when evaluating body armor. Many experiments have been completed to evaluate body armor protection, forecast realistic injury prediction, and examine the effects of BABT on the wearer. The surrogate thorax must respond like a real thorax, or the data collected is meaningless. Some aspects of biofidelity may include rib fractures, lung contusions, and internal organ damage. Biofidelity allows engineers to understand how injuries happen. Over the last 25 years, advanced biofidelic surrogates have started to incorporate innovative materials (e.g., viscoelastic materials, fluid filled bladders, rubber) and technologies (e.g., finite element analysis, 3D printing, pneumatics, embedded sensors). In addition, different chest sizes and stiffnesses have been incorporated to represent the wide range of human bodies. This paper reviews the animal, cadaver, and human surrogates used in the experiments that have contributed to this body of research. The paper focuses of a review of past and present human surrogates, reviews a selection of experiments conducted using biofidelic surrogates, and discusses the resulting data. This knowledge is essential for designing better protective systems and assessing the performance of newly developed materials and designs.

KEYWORDS:body armor, backface deformation, behind armor blunt trauma, biofidelity, human thorax, biofidelic human surrogates, animal models, anthropometric test devices, body armor testing

Download '2026-42' report PDF

SIZE:3.7 MB

DTIC #:AD1369795

TITLE:Progress Toward an Operator State Monitoring System for U.S. Army Aviation

AUTHOR(s):Feltman, K., Yue, X., Vogl, J., Atchley, J. A., Wilkins, J., Baugher, K., Basso, J., & Kelley, A.

ABBREVIATED ABSTRACT:The project covered within this report addressed a number of areas related to the development of an operator state monitoring system for U.S. Army aviation. These included a survey of current aviators, review of research studies, retrospective analysis, implementation of data synchronization techniques, collection of physiological data in operational scenarios, and using physiological data to predict flight-related performance outcomes. From these efforts we were able to confirm prevalent occupational stressors impacting performance include fatigue and degraded weather conditions. Airspeed and altitude were identified as consistent, measurable and meaningful performance outcomes across a range of simulated flight scenarios. We were also able to begin demonstrating the ability to collect usable physiological data within operational type settings and the ability to use physiological data to predict meaningful flight performance outcomes. While these are significant accomplishments that will contribute to the development of an operator state monitoring system, they are only a small piece of the overall puzzle. Ongoing work will be required to fully establish such a system.

KEYWORDS:operator state monitoring, physiological activity, aviation

Download '2026-41' report PDF

SIZE:3.4 MB

DTIC #:AD1368332

TITLE:Executive Summary: Measuring Operator Response to Simulated Adaptive Automation

AUTHOR(s):Vogl, J.

ABBREVIATED ABSTRACT:Over three years, this project moved adaptive automation from a broad design problem into a working USAARL research capability and a more clearly defined set of human-factors requirements. The strongest finding was not that automation should simply reduce workload, but that how work is transferred matters. Aviators trusted and used automation more when they retained authority over routine handoffs, even though making that decision added some momentary workload. Additional transparency was not consistently beneficial and could impose its own attentional cost. The flight simulator study further showed that adaptive systems should respond to a developing pilot-aircraft-automation state, rather than treating physiology as an isolated workload trigger. Together, the project produced practical guidance for automation design while leaving USAARL with the synchronized data, workload-modeling, automation, and high-fidelity simulation capabilities needed to continue toward prospective operator-state-driven automation.

KEYWORDS:adaptive automation, cognitive workload, operator sate monitoring

Download '2026-39' report PDF

SIZE:3.8 MB

DTIC #:AD1369281

TITLE:Pilot Evaluation of the STEPS in a UH-60 Simulator

AUTHOR(s):Enzor, M., Kinsler, R., Ranes, B., Black, R., Price, B., Molles, J., & Lloyd, A.

ABBREVIATED ABSTRACT:The objective of this work was to evaluate the use of a proof-of-concept system, the STEPS, that presents flight restrictions to pilots compared to the current standard of verbal guidance from an onboard medic. Five U.S. Army UH-60M rated aviators completed simulated flights where they received flight restrictions either through a visual pilot aid or from a medic over the intercommunication system. While both configurations yielded 100% application accuracy and clinically insignificant differences, the STEPS configuration resulted in slightly longer average reaction times (13 vs. 7 s) and average application times (10 vs. 6 s) compared to the medic configuration, likely due to the partially obscured view of the pilot aid. Although subjects rated the medic configuration as more helpful and trustworthy, they recognized the operational utility of STEPS and recommended interface visibility improvements. The findings of this study help to inform the needed design modification for the continued development of STEPS while also highlighting opportunities for integration with autonomous platforms and unmanned aerial systems.

KEYWORDS:medical evacuation, MEDEVAC, casualty evacuation, CASEVAC, pilot evaluation, decision support, flight restrictions, flight constraints, flight optimization, en route care, patient outcomes, cabin altitude restriction, patient transport, UH-60

Download '2026-38' report PDF

SIZE:5.4 MB

DTIC #:AD1368328

TITLE:Effects of Altitude During Rotary-Wing Transport in a Large Animal Polytrauma Model

AUTHOR(s):Lloyd, A., Kroening, L., Kinsler, R., Mayer, A., Mackie, R., Grunig, C., McQuaid, J. R., van der Horn, H., Pacheco, M., Michaliszyn, N. J., & Molles, J.

ABBREVIATED ABSTRACT:This study evaluates how different rotary-wing flight profiles during aeromedical evacuation (AE) affect physiological recovery in patients suffering from combined traumatic brain injury and hemorrhagic shock. Using a validated 24-hour swine model, researchers compared the environmental and physiological impacts of three experimental conditions: standard evacuation flight (SEF), tactical evacuation flight (TEF), or mock AE flight. Full datasets were obtained for 20 animals (TEF [N = 7], SEF [N = 7], and mock [N = 6]). Environmental data analysis was completed on the Global Positioning System, altitude, temperature, sound level, and acceleration and rotation data. The mean arterial pressure and intracranial pressure values were calculated for key points in the data collection process, and compared to the environmental data for correlation. This study identified the transportation stresses of a polytrauma swine model in different AE configurations. In summary, though there were differences in rotary-wing transport flight profiles, the study did not determine significant statistical differences in physiological data between the different flight configurations.

KEYWORDS:traumatic brain injury, TBI, hemorrhagic shock, polytrauma, aeromedical evacuation, AE, vibration, transport, cerebral perfusion pressure, CPP, intracranial pressure, ICP, mean arterial pressure, MAP

Download '2026-37' report PDF

SIZE:4.8 MB

DTIC #:AD1366984

TITLE:Development and Evaluation of Methodologies to Statically Assess Restraint System Designs and Release Loads for Post-Crash Occupant Survivability

AUTHOR(s):Schlick, M., Melara, L., Rhodes, D., Willett, J., Utter, C., McGovern, S., & McEntire, B. J.

ABBREVIATED ABSTRACT:U.S. Army aviators may be exposed to various potentially harmful in-flight or impact events during their missions. In mishap scenarios, the restraint system is designed to secure the occupant to the seat and minimize collisions with the cabin, preventing injuries by maintaining spinal alignment (Willett et al., 2022). Even with the introduction of the U.S. Army Aircraft Crash Survival Guide in 1989, the lower extremities, head, thorax, and spine remain the leading injured body regions in mishaps (Desjardins et al., 1989; Labun, 2014). The first objective of this research aimed to develop a methodology to statically assess occupant restraint systems under 1 G loading, where 1 G represents an acceleration of 32.174 feet per second squared (ft/s2) and evaluate the new method. A conventional five-point restraint system and a Parachute Restraint Harness Assembly-56 Personal (PCU-56\P) torso harness (TH) were used to restrain a test surrogate in a seat inversion wheel fixture for testing. The second aim of this research was the development and execution of a restraint system release assessment methodology. A conventional five-point restraint with a quick release (as described in MIL-S-58095A (AV) was used to evaluate the assessment.Both assessments identified a need to design occupant restraint systems to prevent lateral flail in rotary-wing mishaps. The increased risk of injury during lateral flail, indicated in the static 1 G loading, combined with the risk identified with the five-point release mechanism further emphasized the need for a lateral dynamic seat performance requirement to assess injury risk to the upper extremities, which may prevent egress.

KEYWORDS:Occupant flail, static 1G loading, torso harness, 5-point restraints, seat restraint system, static testing

Download '2026-36' report PDF

SIZE:3.6 MB

DTIC #:AD1366982

TITLE:Preliminary Findings from an Investigation of the Influence of HSM and Inertial Loading Direction On Cervical Spine Injury Risk

AUTHOR(s):Rhodes, D., Brozoski, F. T., Brown, B. A., Johnson, B., Daniel, R., Rooks, T., & Chancey, V. C.

ABBREVIATED ABSTRACT:Current military HSM guidelines for acute injury risk are based primarily on vertical loading in a helicopter crash environment (i.e., loading in the Gz direction) (McEntire & Shanahan, 1998). Research using HSM under longitudinal (-Gx) and lateral (Gy) loadings is becoming increasingly important with future U.S. Army air and ground vehicles incorporating side-facing seats. However, no current guidelines exist for longitudinal (±Gx) inertial loadings, such as those experienced during frontal impacts, or lateral (Gy) loadings for side-facing occupants, such as those experienced during a side impact. The objective of the current study was to investigate the effects of HSM on injury severity under frontal (-Gx) and lateral (Gy) exposures. Observed injuries and kinematics measured at the junction of the seventh cervical and first thoracic vertebra (C7/T1) were documented and compared between HSM groups and loading directions, and initial qualitative impressions are presented. Future research will quantify the influence of HSM and loading direction on cervical spine injury risk.

KEYWORDS:acute injury, lower neck injury, lateral impact, frontal impact, Gx exposure, Gy exposure, neck injury severity

Download '2026-35' report PDF

SIZE:3.7 MB

DTIC #:AD1366974

TITLE:Expert Panel Feedback on Fatigue Impacts on Cognitive and Functional Performance of Flight Paramedics

AUTHOR(s):Kelley, A., Kinsler, R., Lloyd, A., Enzor, M., Molles, J., Duffy, M., & Feltman, K.

ABBREVIATED ABSTRACT:The objective of this expert panel was to identify medical scenarios, tasks, and measurable outcomes for use in an upcoming prolonged en route casualty care study. The discussion yielded key takeaways such as the type of tasks to employ (those requiring critical thinking skills such as medication and dosing calculations, ventilator management, troubleshooting and response to alarms, and documentation), and the implementation of multiple patient scenarios and extended durations to exacerbate fatigue effects.

KEYWORDS:en-route care, flight paramedics, performance

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