BACKGROUND: No upper age limit exists at which general aviation pilots are disallowed from exercising their flying privileges. Operating an aircraft, and landing in particular, requires high visual acuity, cognitive function, and eye-hand/foot coordination; i.e., functions which commonly deteriorate with age. No studies have addressed flight safety of airmen ≥ 80 yr of age (octogenarian+ or 80+) or whether such airmen are more landing accident-prone. This research seeks to answer these questions.METHODS: Accidents and private pilot-certificated airmen counts were obtained from the National Transport Safety Board accident database and the U.S. Civil Airmen Statistics, respectively. Contingency tables were used to determine differences in proportions. A Poisson distribution was employed to determine whether airmen count (80+ and 30–39 yr) and their accident rates differed over time. Differences in median values were tested with a Mann-Whitney test.RESULTS: The proportion of airmen 80+ years doubled and their accident rate increased (6 and 11 mishaps/1000 airmen, respectively) between 2002 and 2016. Landing accidents were over-represented for octogenarian+ pilots compared with airmen 30–39 yr (31 and 17%, respectively) and did not reflect inferior experience but were often due to an aircraft flaring deficiency. The proportion of fatal accidents was comparable (11 and 13%, respectively) for the older and younger age cohorts.CONCLUSION: A growing population and a climbing accident rate for octogenarian+ airmen were evident. The disproportionate count of pilots involved in landing mishaps raises a concern for an increase in such mishaps for octogenarian airmen opting for BasicMed due to less restrictive/frequent visual acuity tests.Boyd DD. General aviation accidents involving octogenarian airmen: implications for medical evaluation. Aerosp Med Hum Perform. 2018; 89(8):687–692.

BACKGROUND: Pain and discomfort reported during sitting is a significant problem for aviators during prolonged missions. Previous work has determined that areas of local pressure exist during prolonged sitting in UH-60 seat systems; however, no work has examined the effects of this local pressure on measures of neurological and circulatory function.METHODS: A total of 30 healthy subjects completed the study in which focal pressure was applied in three conditions (no pressure, pressure to the ischial tuberosity, and pressure to the posterior thigh). We applied pressure using a purpose-built pressure application system allowing subjects to sit in a position mimicking the sitting position in a UH-60 Black Hawk helicopter and measurements were taken before, during, and after pressure application. We measured neurological function with the soleus Hoffmann reflex and sural nerve conduction velocity, and circulatory function with dynamic infrared thermography.RESULTS: We found a decrease in soleus Hoffmann reflex by 0.87 V and 0.52 V during pressure application at the posterior thigh and ischial tuberosity, respectively. No changes in nerve conduction velocity were found among the conditions during or after pressure application. Limb temperature increased 0.42–0.44°C during pressure application, but began to return to baseline once pressure was removed.DISCUSSION: This study examined the development of neurological and circulatory alterations due to local pressure application in an aviation specific functional position. These results may be used in the development of future interventions to mitigate the negative effects of localized pressure in military aviators.Games KE, Lakin JM, Quindry JC, Weimar WH, Sefton JM. Local pressure application effects on neurological and circulatory function. Aerosp Med Hum Perform. 2018; 89(8):693–699.

BACKGROUND: PERCLOS is a metric that has been primarily studied in the domain of driver fatigue to predict performance decrements, but there is comparatively less research applying it to aviation, where hypoxia is a safety concern. Hypoxic exposure was expected to increase blink activity, possibly by means of impairing blink inhibition behavior, thereby leading to increased eyelid closure time.METHODS: PERCLOS, blink rate, and blink duration were measured using head-mounted eye-tracking on pilots using a flight simulator inside a hypobaric chamber. Pilot subjects were tasked with programming the autopilot of a G-1000 console according to instructions from a simulated air traffic controller. Data was collected at 5% decrements in blood oxygen saturation (S_po₂) through progressive decreases in hypobaric pressure to model slow-onset hypoxia.RESULTS: PERCLOS, blink rate, and blink duration increased significantly and linearly as a function of decreasing S_po₂, and largely recovered in the posthypoxia normoxia condition. The greatest change in PERCLOS relative to the prehypoxia baseline occurred in the 80% S_po₂ condition, whereas the greatest change in blink rate and duration occurred at 75% S_po₂. As S_po₂ decreased, a higher frequency of long blink durations was observed.DISCUSSION: The increase in blink rate and duration in the absence of task demand manipulation could suggest hypoxia-induced sympathetic excitation and impairment of adaptive blink inhibition behavior. The effect of hypoxia on oculomotor features is also likely task-specific. In consideration of the extensive demand made upon the visual modality in flight, increased PERCLOS may further tax visual information processing.Thropp JE, Scallon JFV, Buza P. PERCLOS as an indicator of slow-onset hypoxia in aviation. Aerosp Med Hum Perform. 2018; 89(8):700–707.

BACKGROUND: Flight crew fatigue is an important factor in aviation, leading organizations to implement fatigue risk management programs to reduce risk. The U.S. Air Force Air Mobility Command (AMC) has implemented the Aviation Operational Risk Management (AvORM) program to aid mission schedulers and flight crews in mitigating flight risks and identifying appropriate levels of risk. The AvORM program uses a scheduling tool and underpinning biomathematical fatigue model. This study examined self-reported fatigue-related incidents within AMC, which provides some indirect and anecdotal evidence as to the effectiveness of the scheduling tool.METHODS: Archival data from the AMC Aviation Safety Action Program (ASAP) Safety Reporting System was examined. Report content themes were created through an inductive approach in terms of fatigue prevalence, antecedents, and consequences.RESULTS: Fatigue was estimated as a factor in 4% of the reports. The two most commonly referenced fatigue antecedents were associated with mission/duty length and mission scheduling/planning factors. Factors associated with aircraft operation violations were the most cited consequences of fatigue. Fatigue was almost twice as likely to be reported as a secondary rather than primary contributing factor. Aircrew reported both positive and negative aspects of AvORM resources in mission planning and fatigue mitigation.DISCUSSION: Examination of ASAP reports suggests that fatigue is a contributing factor to safety incidents. Although the AvORM program highlights potential flight risks by utilizing a scheduling tool built upon an underlying biomathematical fatigue model, human fatigue continues to impact safety, suggesting an ongoing need for improved fatigue risk management and mitigation.Morris MB, Wiedbusch MD, Gunzelmann G. Fatigue incident antecedents, consequences, and aviation operational risk management resources. Aerosp Med Hum Perform. 2018; 89(8):708–716.

BACKGROUND: There is a need to develop noninvasive methods to monitor intracranial pressure (ICP). Pupillary reactivity decreases in patients with elevated ICP with demonstrated cerebral edema. We sought to determine whether pupillary reactivity is affected when ICP is elevated in the absence of brain edema.METHODS: Healthy subjects and individuals with idiopathic intracranial hypertension (IIH) underwent pupillometry in different positions (upright, supine, and head-down tilt) and during different physiological maneuvers. A separate group of healthy subjects were tested in the upright resting position only. The pupillary dynamics were measured with a pupillometer.RESULTS: Healthy and IIH subjects were enrolled. In the healthy subjects the change from upright to head-down tilt led to a Neurological Pupil Index (NPI) decrease from 4.30 to 4.12, while maximum pupil size and minimum pupil size increased from 4.74 to 5.19 and 3.04 to 3.44, respectively. In the IIH group the maximum pupil size, minimum pupil size, and latency increased in magnitude with a decline in head tilt. The mean NPI of IIH subjects, 4.37, was greater than the healthy mean, 4.25. Also, the mean IIH Max and Min, 5.02 and 3.25, were greater than the healthy mean, 4.62 and 2.92.DISCUSSION: We observed changes in the pupillary reactivity in all subjects based on changes in position and task. There were also differences between the healthy and IIH subjects. This is consistent with our hypothesis that elevated intracranial pressure may result in decreased pupillary reactivity even in the absence of brain edema.Soeken TA, Alonso A, Grant A, Calvillo E, Gutierrez-Flores B, Clark J, Donoviel D, Bershad EM. Quantitative pupillometry for detection of intracranial pressure changes during head-down tilt. Aerosp Med Hum Perform. 2018; 89(8):717–723.

INTRODUCTION: We evaluated the reproducibility of two portable, self-administered autorefractors (Netra and SVOne Pro) to assess the time course of visual changes on the ISS.METHODS: We measured cycloplegic refractive error at 5 visits at least a week apart in 13 subjects (6 women, 7 men, 30 ± 9 yr) using both devices seated and also prone with lower body positive pressure (LBPP) applied. Axial length was measured with an optical biometer. Subjects completed a questionnaire on device preferences.RESULTS: The SVOne seated intrasession reproducibility coefficient (RPC) was 0.37 diopters (D), while the Netra’s was 0.41 D. Intersession seated results were: RPC = 0.67 D for the SVOne and RPC = 0.54 D for the Netra. The average seated to prone LBPP differences were significantly different from zero for both the SVOne and Netra. The SVOne was preferred in four out of five categories on the questionnaire and took half the time to complete a measurement set compared to the Netra.DISCUSSION: Users preferred the SVOne and it took less time. An SVOne refraction change of 0.67 D from baseline would happen by chance less than 5% of the time. If multiple separate measurements were taken, the detection limit could be reduced (e.g., three repeated measurements could reduce it to 0.38 D). Since astronauts with visual changes show spherical equivalent changes of 0.5 to 1.0 D, in-flight autorefractors could help determine the time course of refractive changes in space from which changes in axial length could be inferred.Masterova KS, Anderson AP, Cowan DR, Fellows AM, Zegans ME, Buckey JC. Portable autorefractors for detecting axial length changes in space. Aerosp Med Hum Perform. 2018; 89(8):724–730.

INTRODUCTION: The National Academy of Medicine called for increased research on nutritional supplement use among military members. Current research has suggested potential health risks posed by energy drink consumption. The purpose of this study was to examine the relationship of energy drink consumption and beliefs about nutritional supplements in a U.S. military population.METHODS: Data were collected by means of an anonymous 44-item survey that was administered to and completed by 302 naval aviation candidates (100% response rate) enrolled in aviation preflight indoctrination (API) at Naval Air Station Pensacola, FL.RESULTS: Bivariate correlations indicated a statistically significant relationship between beliefs regarding the safety of energy drinks, energy drink consumption frequency, and personal beliefs regarding supplements [r(202) = −0.23]. The negative correlational coefficient indicated an inverse relationship between favorable perceptions on supplements and energy drink consumption.DISCUSSION: This study assessed beliefs about the safety of nutritional supplements among API candidates and to examine if a relationship between nutritional supplement beliefs and energy drink consumption exists. Results indicated a significant inverse relationship between API candidates’ beliefs regarding consumption frequency and safety of energy drinks as well as beliefs regarding supplement use. Results also suggested that the more positively an API candidate perceived nutritional supplements, the less frequently energy drinks were consumed. The findings of this study indicated a weak inverse relationship between the beliefs/use of energy drinks and beliefs regarding the effectiveness of nutritional supplement use among naval aviation candidates.Sather TE, Woolsey CL, Delorey DR, Williams RD Jr. Energy drink and nutritional supplement beliefs among naval aviation candidates. Aerosp Med Hum Perform. 2018; 89(8):731–736.

INTRODUCTION: The aim of this study was to evaluate the ability of eight color vision tests to screen for and accurately measure hereditary color-deficiency in order to improve color vision assessment methods for aircraft pilots.METHODS: This prospective study included 29 color-deficient subjects and 23 healthy subjects. All performed the following tests: Ishihara plates, Farnsworth D15, Lanthony desaturated 15 Hue, Munsell 100 Hue, Beyne and Fletcher-Evans CAM lanterns, Nagel anomaloscope, and the Color Assessment and Diagnosis (CAD) test. The sensitivity and specificity of color-deficiency diagnosis were evaluated for each test, as well as the test’s relevance for assessing aircraft pilots.RESULTS: The Ishihara plate test demonstrated a sensitivity of 0.97 and a specificity of 1.00 for color-deficiency screening. The CAD test and anomaloscope showed both a sensitivity and specificity of 1.00. The Beyne lantern, Fletcher lantern, Farnsworth D15, and the Lanthony 15 Hue tests all showed a specificity of 1.00 and sensitivities of, respectively, 0.69, 0.97, 0.58, and 0.79. During aircraft pilot selection tests, the CAD test classified 10% of color-deficient subjects as safe to fly, the anomaloscope 17%, and the Beyne and Fletcher lantern tests, respectively, 31% and 3%.DISCUSSION: The discrepancy in results confirms that current color vision test protocols need to be reassessed. The CAD test could be an interesting alternative to the series of tests used to assess flight crew, but it seems more selective than current tests.Marechal M, Delbarre M, Tesson J, Lacambre C, Lefebvre H, Froussart-Maille F. Color vision tests in pilots’ medical assessments. Aerosp Med Hum Perform. 2018; 89(8):737–743.

INTRODUCTION: Orientation in a 3-dimensional environment increases demands on the vestibular system. The anterior, lateral, and posterior semicircular canals sense pitch, roll, and yaw acceleration, respectively. The macular end organs sense linear acceleration and provide gravity reference. Creatures that evolved to fly (birds) share the same sensory systems and probably the same limitations as creatures that did not evolve to fly. However, bird semicircular canals have been noted for their large size relative to body mass since 1907.METHODS: A brief literature review was conducted regarding the morphological structure of the vestibular systems in birds, and their evolutionary and functional significance as compared to that in humans.RESULTS: For any given body mass, qualitatively more “agile” species have semicircular canals with larger radius of curvature. Specifically, the anterior and lateral canals were found to be preferentially larger than those of nonavian theropods and humans. Avian canals rarely approach circularity and all three canals typically undergo torsional excursions out of their respective planes.DISCUSSION: Increase in the length of the semicircular canal is associated with greater sensitivity to rotational stimuli. Highly maneuverable birds of prey have the largest overall canal dimensions relative to body mass, most plausibly to match the rapid body rotations that characterize variable speed maneuvering during pursuit. By comparison, the semicircular canals in humans are relatively smaller and lack the adaptive morphological asymmetry in agile flying species. This teleological symmetry may present another inherent but less understood vestibular limitation during aerobatic maneuvers, which could lead to spatial disorientation.Cheung B, Ercoline W. Semicircular canal size and shape influence on disorientation. Aerosp Med Hum Perform. 2018; 89(8):744–748.

BACKGROUND: Motion sickness remains a significant and unpredictable problem during spaceflight. One of the major difficulties in understanding the etiology of space motion sickness has been a lack of data at the time the symptoms occur, i.e., immediately after entry into space and during return to Earth; in these phases of the mission is when critical operational tasks are performed.CASE REPORT: We report here the case of a crewmember who experienced severe motion sickness symptoms immediately after launching into space and for several days into the mission. Verbal reports recorded during and immediately after the flight describe in detail the symptoms and their underlying causes. The prominent cause was oscillopsia that was induced by moving the head, wearing prescription eyeglasses, and translating the whole body.DISCUSSION: In this case, space motion sickness was sudden and induced by voluntary or involuntary head or body movements in any plane. These head movements caused a visual disturbance that induced the perception that the environment was oscillating. The exaggerated motion perceptions suggest an increased vestibular sensitivity and/or decreased pursuit-optokinetic mechanisms in orbit and immediately after landing.Reschke MF, Wood SJ, Clément GR. A case study of severe space motion sickness. Aerosp Med Hum Perform. 2018; 89(8):749–753.

INTRODUCTION: Although cardiac arrest during airline flights is relatively uncommon, the unusual setting, limited resources, and the variability of the skills in medical volunteers present unique challenges. Survival in patients who suffer a witnessed arrest with a shockable rhythm who are treated promptly has improved since the advent of widely available automated external defibrillators (AEDs). In general, the chances of survival from an out-of-hospital cardiac arrest (OHCA) are greater when ventricular fibrillation (VF) is seen as the initial rhythm or if there is return of spontaneous circulation (ROSC). Not all in-flight cardiac arrests are witnessed because cabin crew or fellow passengers might simply assume that the victim is sleeping. Based upon a review of the literature on resuscitation after OHCA, we recommend that automatic external defibrillators be carried on all commercial airline flights, regardless of duration. Patients presenting with shockable rhythm (e.g., VF, unstable ventricular tachycardia) have the best prognosis for survival and usually require diversion of the aircraft for advanced cardiac life support (ACLS). Because diversion may require interruption of cardiopulmonary resuscitation (CPR) and may impact flight safety, the volunteer rescuer, cabin crew, flight crew, and medical consultation services should discuss the possible outcome and operational considerations before recommending a diversion for a patient with a nonshockable rhythm. The recommendations in this article were developed by members of the Air Transport Medicine and Aerospace Human Performance Committees and approved by the Council of the Aerospace Medical Association.Ruskin KJ, Ricaurte EM, Alves PM. Medical guidelines for airline travel: management of in-flight cardiac arrest. Aerosp Med Hum Perform. 2018; 89(8):754–759.

Nussbaum L. You’re the flight surgeon: loss of consciousness while exercising. Aerosp Med Hum Perform. 2018; 89(8):760–762.