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 '2025-35' report PDF

SIZE:1.8 MB

DTIC #:AD1335770

TITLE:A Comparison of Cervical Transcutaneous Vagal Nerve Stimulation and Transcranial Direct Current Stimulation for Maintaining Aviator Performance

AUTHOR(s):Feltman, K., Duffy, M., Mackie, R., Wolf, S., Yue, X., & Turovets, S.

ABBREVIATED ABSTRACT:Two types of non-invasive brain stimulation methods were compared to evaluate their impact on aviator performance. These were transcranial direct current stimulation (tDCS) and cervical transcutaneous vagal nerve stimulation (tVNS). The study was done in two phases. The first phase evaluated methods of sham tVNS to be used in the comparison phase. In the comparison phase of the study, five participants completed the entire study. The effectiveness of the devices were evaluated using an aviation task, the Psychomotor Vigilance Task (PVT), and a number of side effects measures. The results of the study found evidence for potential performance improvements on the PVT and a reduction in feelings of fatigue with the lower intensity setting of the tVNS device. The lower intensity setting was intended to be the sham method for tVNS. Further research is required to systematically evaluate the impacts of different tVNS intensity settings on performance outcomes in healthy adults.

KEYWORDS:transcutaneous vagal nerve stimulation, transcranial direct current stimulation, aviator performance

Download '2025-33' report PDF

SIZE:1 MB

DTIC #:AD1335765

TITLE:Medical Causes of Temporary and Permanent Suspension of Flight Duty in Female Army Rotary-Wing Aviators

AUTHOR(s):Wolf, S., & Kelley, A.

ABBREVIATED ABSTRACT:Understanding disease prevalence specific to women in aviation service is the key to a comprehensive understanding of the occupational risk. Data were retrieved on 1386 female U.S. Army rated aviators from the Aeromedical Epidemiological Data Repository from the years 2015 to 2023. The dataset yielded a total of 6658 cases of waiver or suspension request. The top ten most frequently occurring diagnoses combining International Classification of Diseases (ICD) ninth and tenth revision codes and ICD chapter heading were calculated. The top three diagnoses associated with a waiver request were lumbar spine pathology (12.4%), cervical spine pathology (6.7%), and headache disorders (6.3%). The top three diagnoses associated with permanent suspension request were lumbar spine pathology (12.5%), depressive disorders (10.8%), and cervical spine pathology (7.8%). The top three ICD chapter headings associated with both waiver and permanent suspension request were diseases of the musculoskeletal system and connective tissue, mental, behavioral, and neurodevelopmental disorders, and diseases of the nervous system. Overall, the findings were consistent with a similar analysis of female aircrew data from 2005-2015. The results of this study show that no major changes are evident in the conditions impacting female Army aviators with respect to aeromedical disposition in the last eight years compared to the previous decade.

KEYWORDS:aviator, epidemiology, medical diagnoses

Download '2025-32' report PDF

SIZE:2.9 MB

DTIC #:AD1335761

TITLE:Multisensory Cueing

AUTHOR(s):Miller, J., McDermott, D., Gerstner, J., D'Alessandro, M., & Rupert, A.

ABBREVIATED ABSTRACT:The Multisensory Cueing (MSC) Title X project was initiated in response to an increase in U.S. Army Class A mishaps attributed to spatial disorientation (SD). These SD mishaps have historically been the leading cause of military aviation accidents and fatalities, with research indicating they account for approximately 30% of all Class A mishaps. The project aimed to highlight MSC capabilities in both simulator and in-flight environments, initially focusing on integration into the USAARL NUH-60 Black Hawk full motion simulator before developing an aircraft version for demonstration purposes. In this report, three complementary sensory systems to enhance situational awareness are highlighted: the Integrated Cueing Environment Threat and Hazard Cueing (ICE-TAHC), 3D audio, and the Tactile Situational Awareness System (TSAS). The ICE-TAHC system uses a trimodal approach incorporating visual, spatial-auditory, and tactile inputs to detect obstacle hazards. For threat detection, it switches to a bimodal approach focusing on visual and spatial-auditory cues. The 3D audio system creates spatially rendered sound cues that significantly improve pilots' speech recognition, reduce response times, and decrease perceived workload in complex environments. Furthermore, the TSAS consists of a torso-worn belt with vibrotactile arrays, supplemented by tactors in the seat cushion and shoulder restraints, providing intuitive awareness of orientation and threats. Research has consistently shown that both tactile and 3D audio cueing technologies enhance pilot performance by improving situational awareness and reducing cognitive workload. The ultimate goal of the MSC program is to provide intuitive awareness technologies that enhance both lethality and survivability in Army aviation missions. With continued development, including plans to implement Terma 3D audio in both simulator and helicopter environments, these multisensory systems represent the advancement in human-machine interface design for aviation.

KEYWORDS:3D audio, multisensory cueing, spatial disorientation, situation awareness

Download '2025-31' report PDF

SIZE:2.1 MB

DTIC #:AD1335754

TITLE:The Integrated Cueing Environment Threat and Hazard Cueing (ICE-TAHC)

AUTHOR(s):Miller, J. D.

ABBREVIATED ABSTRACT:This report covers the fourth development iteration of the Integrated Cueing Environment's (ICE) collision avoidance system (CAS). The ICE CAS was developed by U.S. Army Development Command Aviation and Missile Center (DEVCOM AvMC) engineers and scientists for the Degraded Visual Environment Mitigation Program. The most recent iteration was developed in support of an operator state monitoring simulator study (Godfroy-Cooper et al., 2024; Godfroy-Cooper et al., 2022) performed for the Holistic Situational Awareness and Decision Making Program. The ICE CAS includes trimodal (visual, spatial-auditory, tactile) obstacle hazard cueing that provides 360° situational awareness about the ownship using a simulated bumper radar scanning three elevations. The simulated radar is based on the physical Echodyne radars that were flown in 2020 as part of the DVE-M flight trials (Miller et al., 2021). It scans 360° in azimuth in 4° increments at elevations -12°, 0°, and +12°. The simulated radar differs from the physical radar in that it is perfectly gimballed and scans the environment with a laser polygon hit test in place of the broad beam of a radar. In flight, the terrain and obstacle geometry database can be used in place of, or with, physical bumper radars. When used, geometry hit tests are ranked identically to radar hits. In addition to bumper radar hits, the ICE CAS indexes ownship location into an obstacle database to determine, and provide cueing for, the nearest power line segment. What follows is an abbreviated description of the cueing that focuses on the incremental changes from v3 (2020 flight trials; Miller et al., 2021) to v4 (the current effort). The development and evaluation of the first iteration is discussed in Miller et al. (2018) and Godfroy-Cooper et al. (2018) and the second iteration in Miller et al. (2019), Godfroy-Cooper et al. (2019), Feltman, Hartnett, et al. (2020), and Feltman, McAtee, et al. (2020). As part of the current design iteration, new visual-spatial-auditory Aircraft Survivability Equipment (ASE) threat cueing was added to the ICE obstacle display to present obstacle hazards and ASE threats with a unified and consistent interface. The paired cueing set is referred to as the ICE Threat and Hazard Cueing (ICE-TAHC). The ASE systems supported are the radar warning receiver (RWR), the missile warning system (MWS), and the laser warning receiver (LWR).

KEYWORDS:hazard cueing, threat cueing, multimodal cueing, augmented-reality cueing, spatial-audio cueing, tactile cueing, spatial audio, 3D audio, pilot evaluation

Download '2025-30' report PDF

SIZE:1.2 MB

DTIC #:AD1336495

TITLE:Head-Supported Mass and Cervical Spine Health: A Baseline Assessment of Non-Special Operation Forces Army Soldiers

AUTHOR(s):Fjerstad, M. M., Robinette, A. M., Prusia, M. E., Stewart, A. S.3, Brozoski, F. T., Madison, A. M., & Chancey, V. C.

ABBREVIATED ABSTRACT:There is a limit to how much head-supported mass (HSM) a Soldier can wear during operational exposures before the risk of cervical spine injury and performance degradation outweighs the intended protection and capability. For rotary-wing aviators, these limits have been defined for 25 years and are being reassessed with the introduction of more complex helmet systems and changing mission requirements. Dismounted Soldiers, however, do not yet have similar HSM guidelines. Additionally, while the effect of HSM on acute cervical spine injury has been studied, the research is lacking in longitudinal studies assessing HSM effects on chronic cervical spine injury. There is a need for further research to examine HSM effects combined with specific occupational factors that contribute to chronic cervical spine injury. This research is part of a larger research effort, "Examining the Effects of Head-Supported Mass on Cervical Spine Biomechanics and Injury Risk in Special Forces Operators," which is being led by Atrium Health, in collaboration with Duke University and the U.S. Army Aeromedical Research Laboratory (USAARL). The USAARL was tasked with collecting data describing cervical spine injury, range of motion, and strength in a healthy, non-Special Operations Forces (SOF) Army population with limited exposure to HSM and vibration environments. The USAARL enrolled and evaluated 60 subjects, assessing and recording their cervical spine range of motion (CROM) and cervical spine strength. Averaged CROM data and the neck strength data are presented as a baseline metric to compare with data from experienced HSM wearers. The data from this report will contribute to a greater understanding of HSM effects on chronic cervical spine injury risk for SOF Soldiers.

KEYWORDS:head supported mass, HSM, Special Forces, SOF, Soldiers, cervical range of motion, neck strength, cervical spine, biomechanics, injury risk, neck injury

Download '2025-29' report PDF

SIZE:2.4 MB

DTIC #:AD1335741

TITLE:Comparison of Visual Outcomes Between Wavefront Optimized LASIK and SMILE

AUTHOR(s):Trinh, T., Capo-Aponte, J., & Turovets, S.

ABBREVIATED ABSTRACT:Small incision lenticule extraction (SMILE) is a minimally invasive, flapless laser refractive surgical procedure with less propensity for dry eye and better preservation of corneal biomechanics compared to laser-assisted in situ keratomileusis (LASIK). However, its benefits in terms of superior visual outcomes remain inconclusive due to study design variability. The preliminary results show that both procedures significantly decrease refractive error, resulting in a mean uncorrected distance visual acuity (UDVA) better than 20/20 by post-operative week 2 (POW2). LASIK eyes had slightly less residual manifest cylinder than SMILE eyes. There was no significant difference between LASIK and SMILE eyes in terms of reported or measured dry eye parameters in this study. Overall, we found no statistically significant differences between LASIK and SMILE across all measured visual and refractive parameters.

KEYWORDS:wavefront optimized LASIK, SMILE, corneal refractive surgery

Download '2025-28' report PDF

SIZE:2.4 MB

DTIC #:AD1335738

TITLE:Small Arms Noise Dose Escalation Research Project: Experimental Blank Discharge Apparatus Operational Manual

AUTHOR(s):Jones, H., Sept, W., Zollinger, L., Bertsch, B., Ohnstad, T., & Flamme, G.

ABBREVIATED ABSTRACT:The current technical report describes the construction of the blank discharge apparatus (BDA) designed for conducting research to identify the maximum tolerable dose (MTD) for impulse noises produced by small arms. Exposure to impulsive noise from small arms is a significant risk factor for auditory injury. Injuries to the auditory mechanism can lead to hearing loss and tinnitus, which can interfere with operational communications, situational awareness, and ultimately, mission success. Temporary threshold shifts compromise Service Member readiness, lethality, and survivability. The design and procurement of weapons and hearing protection, health hazard evaluations, and training and operational doctrine should include the goals of reducing the risk of auditory injuries and avoiding temporary reductions in hearing sensitivity. The Small Arms Noise Dose Escalation Research (SANDER) project will prospectively determine the candidate damage risk criteria (DRC) that returns the maximum safe allowable number of rounds in quasi-free field and reverberant environments without exceeding the MTD. The SANDER project will use the BDA device to identify the DRC that comes closest to predicting the empirical MTD without exceeding it. The results of this project will inform acquisition, training, and doctrine regarding the impact of small arms impulsive noise on auditory and other blast injuries.

KEYWORDS:hearing, hearing protection, hearing health hazard assessment, damage risk criteria

Download '2025-27' report PDF

SIZE:1.2 MB

DTIC #:AD1333081

TITLE:Toward Data Synchronization and Real-Time Processing Methodologies for Operator State Monitoring at USAARL

AUTHOR(s):Vogl, J., Atchley, A., Persson, I., Mackie, R., & Feltman, K.

ABBREVIATED ABSTRACT:The development of an operator state monitoring system for Future Vertical Lift aviators has been an ongoing program of research at the U.S. Army Aeromedical Research Laboratory. However, development of such a system requires the development of robust algorithms that can take data from physiological measures and use them to predict states indicative of performance degradations. The development of algorithms requires large quantities of data. The researchers at the laboratory intended to combine datasets from previous studies to achieve a larger pool of data for this purpose. However, it was determined that doing so is not feasible given several limitations of the archived datasets. This report details those limitations and provides a solution that will mitigate this from occurring with future datasets. The solution outlined includes the integration of Lab Streaming Layer software into the laboratory's simulator and physiological measurement devices.

KEYWORDS:operator state monitoring, algorithm development, aviation, Lab Streaming Layer

Download '2025-26' report PDF

SIZE:871 KB

DTIC #:AD1333079

TITLE:The Effects of Whole-Body Vibration on Critical Care Tasks and Possible Mitigation Strategies for En Route Care: Subject Matter Expert Review

AUTHOR(s):French Krahn, H. A., Stewart, A. S., Barazanji, K. W., Wagner, C. E., Crowley, J. S., Chancey, V. C., & Rooks, T. F.

ABBREVIATED ABSTRACT:Military medical personnel are required to perform life-saving, invasive, medical interventions requiring visual perception and fine motor control while under vibration from ground and air evacuations. As evacuation durations and distances grow, there is a need to develop the capability to perform advanced critical care tasks while en route. The primary objective of this work was to identify: (1) critical care tasks performed en route affected by vibration and (2) learned mitigation strategies to cope with the effects of vibration. The study employed a semi-structured interview surveying subject matter experts (SMEs) in the community. SMEs also completed a task analysis of the standard medical operating guidelines focusing on those susceptible to vibration. SMEs (N=21) commonly reported cricothyroidotomy, gaining intravenous access and use of sharps, rapid sequence intubation, and use of monitoring equipment as the most challenging tasks. The most common mitigation strategy was to leverage stabilization techniques, such as finding anchor points, propping the patient on a padded surface, or bracing against the aircraft.

KEYWORDS:whole body vibration, combat medic, ground evacuation, air evacuation, critical care, en route care, mitigation strategies stabilization techniques

Download '2025-25' report PDF

SIZE:1.1 MB

DTIC #:AD1333074

TITLE:Evaluation of Novel Adaptive Optics for Aviators

AUTHOR(s):Turovets, S., & Trinh, T.

ABBREVIATED ABSTRACT:Adjustable focus eyewear, also known as variable focus or self-adjusting glasses, is an innovative type of eyewear that allows users to modify the focal length of the lenses to see clearly at various distances. This technology is particularly beneficial for individuals with presbyopia, an age-related condition where the eye struggles to focus on close object, but it also serves as a versatile solution for other vision needs. As of 2025, adjustable focus eyewear has been available on the market for several years and continues to advance with new developments. The goal of the proposed activity is to explore the existing technological landscape of adaptive eyewear for presbyopic aviators, the currently existing market of the adaptive eyewear, and conduct engineering tests of a few adaptive glasses available in regards of their performance and declared eyewear specifications independently at the USAARL optical laboratory. The findings of the study indicate strengths and limitations of each assessed prototype of eyewear in an operational setting and result in recommendations on utility of adaptive eyewear for presbyopic aviators in the future.

KEYWORDS:adaptive optics, adjustable focus, manually adjustable glasses, fluid-filled lenses, smart electro-optical glasses, auto-focus, added optical power, astigmatism

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