Physiological Fitness of U.S. Army Aviators Compared to the U.S. General Population.

INTRODUCTION: U.S. Army aviators are required to maintain a level of physiological fitness as part of their qualifying process, which suggests that they are generally physically healthy. However, it has not been statistically proven that they are more "physiologically fit" than the general population.METHODS: This retrospective study compares physiological measurements of U.S. Army aviators from the Aeromedical Electronic Resource Office database to the U.S. general population using the Center for Disease Control's National Health and Nutrition Examination Survey data. To enable an accurate comparison of physiological metrics between U.S. Army aviators and the U.S. general population, aviators were categorized into the same age groups and biological genders used for segmentation of the national population data.RESULTS: On average, pulse rate was 4.85 bpm lower in male aviators and 6.84 bpm lower in female aviators. Fasting glucose levels were, on average, 10.6 mg · dL-1 lower in aviators compared to the general population. Key metrics like pulse rate and fasting glucose were lower in aviators, indicating cardiovascular and metabolic advantages. However, parameters like cholesterol showed less consistent differences.DISCUSSION: While aviation physical demands and administrative policies selecting for elite physiological metrics produce improvements on some dimensions, a nuanced view accounting for the multitude of factors influencing an aviator's physiological fitness is still warranted. Implementing targeted health monitoring and maintenance programs based on assessments conducted more frequently than the current annual flight physical may optimize aviator safety and performance over the course of a career.D'Alessandro M, Mackie R, Wolf S, McGhee JS, Curry I. Physiological fitness of U.S. Army aviators compared to the U.S. general population. Aerosp Med Hum Perform. 2024; 95(4):175-186.

Aviation Maxillofacial Shields and Blunt Impact Protection in U.S. Army Helicopter Mishaps.

BACKGROUND: Maxillofacial shields (MFSs) are an available piece of aviation protective equipment designed to integrate into aircrew helmets and protect the face from wind and flying debris. Aviators have anecdotally reported that MFSs have provided blunt impact protection during impact events (i.e., a crash); however, no such cases have been formally documented in the literature.CASE REPORTS: Two cases were identified where aircrew wearing MFSs were involved in mishaps resulting in maxillofacial blunt impacts. In the first case, an OH-58 pilot struck the cyclic with his head/face during a crash. In the second case, a CH-47 crew chief was struck in the face by a maintenance panel dislodged from the aircraft. In both cases the MFS was damaged, but neither service member experienced injuries as a result of impact to the face.DISCUSSION: The cases illustrate the effectiveness of the MFS against blunt impact during aviation mishaps. While MFS use is currently optional for aircrew, it is believed that increased MFS use would result in fewer or less severe facial injuries as well as decrease the associated time and monetary losses due to injury.Weisenbach CA, McGhee JS. Aviation maxillofacial shields and blunt impact protection in U.S. Army helicopter mishaps. Aerosp Med Hum Perform. 2021; 92(1):5053.

Retrospective Assessment of U.S. Army Aviator Anthropometric Screening Process.

INTRODUCTION: The current U.S. Army aviator anthropometric screening process for rotary-wing cockpit compatibility was codified over 30 yr ago. Critical to the process are the anthropometric standards that define what is acceptable for U.S. Army flight school applicants. The purpose of this study was to assess and optimize the efficiency of the standards in screening for anthropometric cockpit compatibility while maintaining safety.METHODS: A retrospective analysis was performed. Anthropometry and disposition data of flight school applicants from 2005 to 2014 were taken from the Aeromedical Electronic Resource Office database to determine efficiency of the process. Data on mishaps from 1972 to 2017 were retrieved from the Risk Management Information System database to determine the safety benchmark of the existing process, to which adjusted standards would be held. Adjustments to standards were modeled that would more efficiently pass applicants over the period studied without exceeding the established acceptable safety level.RESULTS: There were 40,136 (98.28%) applicants who passed the standards, while 702 (1.72%) failed. Most (98.52%) applicants who failed the standards and applied for an anthropometry exception to policy (ETP) received one. The models would pass up to 396 (99.25%) applicants who received ETPs without exceeding the established number of mishaps attributable to the anthropometry standards, which was found to be zero.DISCUSSION: The screening process is efficient and effective, but could be improved. Adjusting the standards could increase process efficiency by passing more applicants during their flight physical and widening the applicant pool, while maintaining the current level of safety.Moczynski AN, Weisenbach CA, McGhee JS. Retrospective assessment of U.S. Army aviator anthropometric screening process. Aerosp Med Hum Perform. 2020; 91(9):725731.

Common mental disorders among US army aviation personnel: Prevalence and return to duty.

OBJECTIVES: Assess the prevalence of US Army aviation personnel with common mental disorders, the percentage that return to duty following mental health treatment, and predictors of return to duty. METHODS: Examined the prevalence over a 5-year period. The percentage of personnel who were granted a waiver to return to flying duty following treatment was also determined. RESULTS: The results revealed a 5-year prevalence of 0.036 (95% CI = 0.034-0.038) for personnel experiencing one or more of the mental disorders (N = 1,155). Prevalence was highest for adjustment disorders and for nonpilot participants. Overall, personnel were granted a waiver 55.3% of the time and suspended or disqualified 44.7% of the time. Waivers were more likely to be granted for an adjustment disorder and for pilots. CONCLUSIONS: Discussion focuses on the importance of aviation personnel receiving mental health treatment when problems are not severe to maximize the likelihood of returning to duty.

Initial analysis of archived non-human primate frontal and rear impact data from the biodynamics data resource.

OBJECTIVE: The research objective was to conduct an initial analysis of non-human primate (NHP) data from frontal and rear impact events archived in the Biodynamics Data Resource (BDR) records of the Naval Biodynamics Laboratory (NBDL). These rare data, collected between 1973 and 1989, will inform the safety community of upper-end tolerance limits of NHP and may be related to severe crash scenarios. METHODS: Data from frontal and rear acceleration tests to 93 macaque NHP were examined. Each NHP was fully torso restrained, whereas the head-neck complex was unrestrained. Each NHP underwent between 1 and 21 total runs; 2 total runs was most common-a low-level run and then a high-level run. Following each impact exposure, the NHP was evaluated using a series of medical examinations. Now part of the legacy collection in the BDR, these evaluations were used to assess NHP exposures to be in one of 3 categories: noninjurious, injurious, or fatal. Using reported peak sled acceleration values, data were amenable to survival analysis statistical methodology to derive injury probability curves (IPCs). IPCs were derived for injury and fatality outcomes. RESULTS: Fatal injuries for both frontal and rear impacts were mostly at the cranio-vertebral junction. In addition to hemorrhage, fatal frontal and rear impact tests both produced predominantly atlanto-occipital dislocations, with and without spinal cord transection. After exclusions, IPCs were derived for frontal and rear impact for both (1) fatal outcome and (2) injurious outcome (any injury including fatal injury). For frontal impact, 53 NHP qualified with 5, 25, and 50% risk for fatality at 89, 105, and 114 peak sled Gs, respectively, and for injurious outcome at 70, 92, and 106 Gs, respectively. For rear impact, 34 NHP qualified with 5, 25, and 50% risk for fatality at 96, 122, 138 peak sled Gs, respectively, and for injurious outcome at 75, 99, and 115 Gs, respectively. CONCLUSIONS: The majority of injuries were at the cranio-vertebral junction, indicating that the inertial head mass caused a tensile loading mechanism to the cervical spine. These data may be used in conjunction with finite element modeling to estimate risks to the human population. The most direct application in the automotive environment could be to the well-restrained child. The Nij neck injury criteria, currently based on data from piglet studies, could also benefit because the NHP is a more accurate human surrogate. These types of tests are likely to never be repeated and will form an upper bound of tolerance information valuable to safety system designers.

Evaluation of Head and Brain Injury Risk Functions Using Sub-Injurious Human Volunteer Data.

Risk assessment models are developed to estimate the probability of brain injury during head impact using mechanical response variables such as head kinematics and brain tissue deformation. Existing injury risk functions have been developed using different datasets based on human volunteer and scaled animal injury responses to impact. However, many of these functions have not been independently evaluated with respect to laboratory-controlled human response data. In this study, the specificity of 14 existing brain injury risk functions was assessed by evaluating their ability to correctly predict non-injurious response using previously conducted sled tests with well-instrumented human research volunteers. Six degrees-of-freedom head kinematics data were obtained for 335 sled tests involving subjects in frontal, lateral, and oblique sled conditions up to 16 Gs peak sled acceleration. A review of the medical reports associated with each individual test indicated no clinical diagnosis of mild or moderate brain injury in any of the cases evaluated. Kinematic-based head and brain injury risk probabilities were calculated directly from the kinematic data, while strain-based risks were determined through finite element model simulation of the 335 tests. Several injury risk functions substantially over predict the likelihood of concussion and diffuse axonal injury; proposed maximum principal strain-based injury risk functions predicted nearly 80 concussions and 14 cases of severe diffuse axonal injury out of the 335 non-injurious cases. This work is an important first step in assessing the efficacy of existing brain risk functions and highlights the need for more predictive injury assessment models.

Refractive surgery policy and its effect on visual acuity qualification rates for the 2004 and 2011 Army ROTC flight applicant pools.

OBJECTIVES: The goal of this study was to ascertain the effect of recent U.S. Army Aviation corneal refractive surgery (CRS) policy changes on the size of flight school applicant pools by comparing statistics from the 2004 and 2011 Warrior Forge Army Reserve Officers' Training Corps training camps. METHODS: A retrospective chart review was performed using the United States Army Aeromedical Activity's Aeromedical Electronic Resource Online database. RESULTS: Of the 607 applicants from 2004, 100 (16%) were disqualified for decreased visual acuity and had refractive errors correctable by CRS. Thirty-four cadets (6%) had prior CRS, and 21 qualified for flight school in 2004. Of the 625 applicants from 2011, 105 (17%) were disqualified for decreased visual acuity and had correctable refractive errors. Sixty-four applicants (10%) had prior CRS, and 54 subsequently qualified in 2011. CONCLUSIONS: Changes to Army Aviation CRS policy over the last decade have been associated with an increased number of initial flight applicants who now meet visual acuity standards. However, only a small percentage is using this resource. Army Aviation has the potential to significantly widen its applicant pool if more candidates are made aware of accepted CRS techniques that can help them to meet rigorous vision standards.