BACKGROUND: Spatial disorientation, poor situational awareness, and aerodynamic stalls are often causal/contributory to general aviation accidents. To mitigate against the occurrence of these mishaps Cirrus Aircraft has, since 2002, introduced advanced avionics into their piston airplanes (Cirrus SR20/22). These airplanes are also certificated to more rigorous crashworthiness tests than legacy aircraft approved prior to these standards being codified. Herein, using for comparison two legacy aircraft fleets manufactured prior to 2002, we determined whether a reduced mishap rate for all accidents or relating to the aforementioned causes/contributing factors and/or diminished injury severity for survivable accidents were evident for Cirrus SR20/22 airplanes.METHODS: Accidents (2008–2017) involving Cirrus SR20/22 airplanes (manufactured 2002 or later) and Beechcraft 35/36 (Bonanza) and Mooney 20 models (both manufactured no later than 2001) (14CFR Part 91 rules) were identified (N = 136, 259, 164, respectively) from the NTSB database. Statistical analyses used Poisson distribution/contingency tables/ t- and Mann-Whitney tests.RESULTS: For each year within the 2013–2017 timespan the Cirrus SR20/22 all-accident rate was diminished 39–75% relative to both legacy fleets. Temporally, the fraction of fatal Cirrus SR20/22 accidents, initially higher, declined 50% achieving a lower, or comparable, proportion to the two legacy airframes. Fatal accident rates involving spatial disorientation/situational awareness/aerodynamic stalls were > 80% lower for Cirrus SR20/22 airplanes. For survivable mishaps, Cirrus SR20/22 aircraft showed a lower proportion (0.13 compared with 0.20–0.35) of fatal/serious injuries.CONCLUSION: Toward improving legacy aircraft safety, owners should be encouraged to upgrade their avionics for mitigating against the occurrence of such human-factor-related mishaps and install airbags to minimize injury severity.Boyd DD, Howell C. Accident rates, causes, and occupant injury involving high-performance general aviation aircraft. Aerosp Med Hum Perform. 2020; 91(5):387–393.

INTRODUCTION: Hypoxia can be a problem for warfighters, compromising visual and cognitive performance. One area of study has been hypoxia-induced decrements in color vision.METHODS: The present study examined how hypoxia affected the perception of wavelengths associated with unique green and with unique yellow as well as discriminability by the blue vs. yellow (b-y) and the red vs. green (r-g) spectrally opponent color channels while breathing O₂ levels found at sea level and at 5500 m. Measurements of wavelengths producing unique green (minimizing response by the b-y channel) and unique yellow (minimizing response by the r-g channel) preceded measurements of wavelength discriminability near those unique hues.RESULTS: Relative to sea level, unique yellow shifted to shorter wavelengths (0.54 nm) and unique green shifted to longer wavelengths (2.3 nm) under hypoxia. In terms of an equal psychophysical scale, both unique hues shifted by similar magnitudes. Wavelength discriminability of both color channels was compromised by statistically reliable amounts of 16–17% under hypoxia.DISCUSSION: These results were consistent with previous studies and the inference that postreceptor, M-cone neurons were differentially compromised by hypoxia. However, these measurable changes in color vision due to hypoxia were not perceived by the subjects.Bierman A, LaPlumm T, Rea MS. Declines in wavelength discrimination and shifts in unique hue with hypoxia. Aerosp Med Hum Perform. 2020; 91(5):394–402.

BACKGROUND: When a pilot is referred for presbycusis, his flight fitness may be questionable. The objective of this retrospective study was to describe a case series of presbycusis in a pilot population and to discuss the decisions about their flight waivers.METHODS: There were 19 pilots who were referred to the ENT-Head and Neck Surgery Department of the National Pilot Expertise Center. Their medical files were retrospectively examined.RESULTS: Of the 19 patients, 5 did not obtain flight fitness waivers. Among the 14 who received waivers, 7 had no restrictions on their flight fitness.DISCUSSION: Flight fitness was based on the maximum percentage of speech recognition and the slope of the curve for speech recognition in speech audiometry in noise and the follow-up of these findings. The results made it possible to determine a patient’s fitness to fly with a waiver, which may be associated with restrictions. In our series, only 5 pilots out of 19 did not obtain a flight fitness waiver. The few published studies on the resumption of flight for patients who had presbycusis and our experience in France with similar waivers in commercial and military aviation suggest that under certain conditions and after relevant cochlear assessment, presbycusis may allow for a safe pursuit of aviation activity.Ballivet de Régloix S, Genestier L, Maurin O, Marty S, Crambert A, Pons Y. Presbycusis and fitness to fly. Aerosp Med Hum Perform. 2020; 91(5):403–408.

BACKGROUND: Given the challenges of collecting reliable Psychomotor Vigilance Task (PVT) data in the field, this study compared a 3-min PVT on a hand-held device and wrist-worn device vs. a standardized laptop.METHODS: The experiment utilized a randomized, repeated-measures design. Subjects (N = 36) performed the PVT on a touch-screen, hand-held device (HHD), a wrist-worn device (WWD), and a standardized laptop (L). Sleep was assessed using wrist-worn actigraphy.RESULTS: Compared to the L, the HHD was slower on average (∼50% longer reaction times; ∼34% slower response speeds; ∼600% more lapses in attention combined with false starts) and introduced a proportional bias that decreased the range of response speeds by 60%. Compared to the L, the WWD with the backlight on was faster on average (reaction time: ∼6%; response speed: ∼13%), but equivalent in lapses combined with false starts, and introduced a proportional bias that increased the range of responses by 60%.DISCUSSION: Compared to the L PVT, using a hand-held, touch screen interface to collect PVT data may introduce a large constant bias and a proportional bias that decreases the range of response speed. However, performance on the WWD closely mirrors performance on the L PVT and the proportional bias tends to be in favor of detecting individuals with slower responses. Researchers should avoid comparing PVT metrics between different device types. Reliability of PVT data from a WWD or HHD may be degraded when used in an operational setting with unpredictable environmental movement (such as a surface maritime setting).Matsangas P, Shattuck NL. Hand-held and wrist-worn field-based PVT devices vs. the standardized laptop PVT. Aerosp Med Hum Perform. 2020; 91(5):409–415.

OBJECTIVE: The purpose of this study was to investigate the comfort of aircraft passengers during long flights and to determine the effects of the seatback angle and the seat pitch on passengers’ upper body muscles (neck, shoulder, and lower back) and subjective comfort.METHODS: All subjects sat on an aircraft seat for 2 h with different levels of seatback angle and seat pitch. Subjective discomfort scores and root mean square (RMS) and mean power frequency (MPF) values were used to evaluate muscle fatigue, and all data were calculated for every 15-min interval.RESULTS: Significant increases of MPF for all three muscles were found at 30 min, along with significant increases in the perceived levels of discomfort (PLD) over 2 h. Besides, a 120° seatback angle and a 34˝ seat pitch resulted in lower PLD values for the lower back and hip areas than smaller ones (significant difference).DISCUSSION: It took around 30 min before pronounced discomfort in the upper body regions occurred during flight. The larger parameters of seatback angle and seat pitch may significantly contribute to the easing of subjective discomfort. Moreover, a decrease in MPF coupled with a concomitant increase in RMS does not appear to be a reliable indicator of discomfort rate. The need for further development of discomfort indicators which are more directly related to muscular activation is recognized.Pei H, Yu S, Ding M, Bai Z. Aircraft passenger comfort based on muscle activation and perceived discomfort during long flights. Aerosp Med Hum Perform. 2020; 91(5):416–421.

INTRODUCTION: The effects of long-duration (213.0 ± 30.5 d) stays aboard the orbital station Mir and short-term (∼10 d) spaceflights aboard the International Space Station (ISS) on the joint torques of various muscles and work capacity of knee extensors were studied in male cosmonauts.METHODS: Joint torque and muscle endurance testing was performed 30 d before and 3–5 d after a spaceflight, using a LIDO^® Multi-Joint Isokinetic Rehabilitation System (USA).RESULTS: Greater postflight changes in maximal joint torque were observed for back, knee, and ankle extensors compared with flexors, and the difference was especially clearly seen after long-term spaceflights. The decrease in maximal joint torque of hip extensors substantially varied, being the greatest in voluntary concentric movements in a low-velocity high-force mode at angular velocities of 30 and 60° · s⁻¹ (by 16 and 13%, respectively) and the lowest in high-velocity modes at velocities of 120 and 180° · s⁻¹ (by 9 and 11%, respectively). Muscle work capacity was inferred from the gradient of declining muscle force produced in a series of rhythmic voluntary concentric movements and was found to decrease after both short- and long-term spaceflights. The area under the muscle contraction curve decreased to a greater extent and in all regions of the curve after long-term spaceflights. The fatigue index averaged 0.90 ± 0.03 at baseline and remained much the same, 0.90 ± 0.04, after a short-term spaceflight. However, after a long-duration spaceflight, the fatigue index increased 14.1%.DISCUSSION: The finding that the contractile functions and work capacity of muscles decrease more after long-term than after short-term spaceflights in spite of the physical training program of a certain type gave grounds to assume that physical training employed in long-term spaceflights were insufficient to simulate the daily mechanical load that the cosmonauts had before a spaceflight.Koryak YA. Isokinetic force and work capacity after long-duration Space Station Mir and short-term International Space Station missions. Aerosp Med Hum Perform. 2020; 91(5):422–431.

BACKGROUND: Whether the unique environment of space affects astronaut risk of venous thromboembolism (VTE) is not known. On Earth, it is known that use of combined oral contraceptives (COCs) doubles the risk of VTE. Since some female astronauts choose to use COCs, this retrospective study examined known risk factors associated with VTE risk to determine whether the available data suggested elevated VTE risk in female astronauts.METHODS: Longitudinal health data were requested for female astronauts who flew short and long duration missions between 2000 and 2014. Pre- and postflight hematological and biochemical blood markers were available and evaluated. Astronauts’ postflight measurements were compared to clinically relevant terrestrial high risk levels to determine any trend toward increased risk for VTE following spaceflight. Secondarily, a comparison of pre- and postflight changes was made, as well as an assessment of COC impact.RESULTS: A total of 38 astronaut-flights were included in this study and no VTE events were found. Analysis of potential VTE risk factors showed no evidence suggesting elevated VTE risk in female astronauts associated with spaceflight, regardless of contraceptive use.DISCUSSION: Arguably, all astronauts encounter many physiological stressors during spaceflight missions, but women using the combined contraceptive pill add a known risk factor for VTE. The risk factors analyzed within this study showed no trend toward an increased risk of VTE for female astronauts. This study provides an evidence base supporting the safety of COC use by female astronauts and also reinforces the importance of healthy lifestyle on VTE risk reduction.Jain V, Ploutz-Snyder R, Young M, Charvat JM, Wotring VE. Potential venous thromboembolism risk in female astronauts. Aerosp Med Hum Perform. 2020; 91(5):432–439.

INTRODUCTION: Fatigue is a critical safety issue to U.S. Air Force (USAF) flight and ground crew. Nearly 15 yr of mishap reports were analyzed to determine how fatigue affects USAF operations with the goal of improving fatigue risk management policies and tools.METHODS: Summary data for 19,920 aviation mishap reports dating back to 2003 were collected from the Air Force Safety Automated System (AFSAS). Fatigue-related mishaps were identified based on designations provided within AFSAS. Other metrics examined were characteristics such as timing, cost, and aircraft metrics, among others. Contingency tables built from these metrics were used to assess fatigue-related trends across the aviation community.RESULTS: While only 3.88% of all mishaps were identified as fatigue-related, they are associated with 2.1 billion of medical expenses and property damage, or 18% of the 11.7 billion total cost of all mishaps included in the study. Nearly a quarter of the fatigue-related mishaps fall into the most severe mishap category and more than half occurred between 0100 and 0700, local time. Fatigue-related mishaps tended to be more common for Remotely Piloted Aircraft (RPA) and ground operations.DISCUSSION: Fatigue is very costly to the USAF despite the relatively low incidence rate of fatigue-related mishaps. This is because larger proportions of severe mishaps were found to be fatigue-related. RPA and ground maintenance operators might be especially susceptible to fatigue and potentially lack adequate fatigue mitigation support and training tailored to their unique operational environment, suggesting a need to improve upon fatigue mitigation tools and strategies.Gaines AR, Morris MB, Gunzelmann G. Fatigue-related aviation mishaps. Aerosp Med Hum Perform. 2020; 91(5):440447.

BACKGROUND: Aerospace Medicine is a small medical specialty. With the increasing need for aircraft pilots, continued low Earth orbit NASA operations, and the emergence of commercial spaceflight, there is a necessity for recruiting and educating the next generation of Aerospace Medicine specialists. This study was designed to create and validate a short Aerospace Medicine curriculum.METHODS: Medical students at the University of Texas Medical Branch were recruited to attend a series of six 1-h meetings covering Aerospace Medicine career options and key Aerospace Medicine topics. A survey addressing student demographics, interest in a career in Aerospace Medicine, and knowledge of key Aerospace Medicine topics was administered at the beginning and end of the curriculum. Interest in pursuing a career in Aerospace Medicine pre- and postcurriculum was compared with an independent t-test. The knowledge-based portion of the survey was also evaluated using an independent t-test.RESULTS: There were 23 participants who were recruited and filled out the initial survey and 15 participants who attended the final meeting and filled out the postcurriculum survey. Mean interest in pursuing a career in Aerospace Medicine did not change significantly (75.45% before involvement in the curriculum and 83.08% after participation). Knowledge of foundational Aerospace Medicine topics increased from 64.25% before involvement in the curriculum to 73.33% at the end of the study. There was an average of 12 participants at each meeting.DISCUSSION: This demonstrates the utility of this curriculum as an educational tool for medical students. Future efforts will focus on dissemination of the curriculum nationally and internationally.Kreykes AJ, Petersen EH, Lowry CL. Expanding knowledge and exposure to aerospace medicine by creating a medical student curriculum. Aerosp Med Hum Perform. 2020; 91(5):448–452.

INTRODUCTION: The use of systemic corticosteroids for upper respiratory tract infections has become increasingly common, but remains controversial. Given their purported ability to decrease duration of illness and hasten recovery, systemic corticosteroids offer an attractive treatment modality for flight surgeons desiring to minimize DNIF (Duty Not Including Flying) time. This commentary presents an evidence-based approach to the use of systemic corticosteroids for upper respiratory tract infections in flyers, concluding that the current body of evidence and missional concerns justify their routine use in sore throat and acute rhinosinusitis.Tanael M. Systemic corticosteroids for upper respiratory tract infections in the flyer. Aerosp Med Hum Perform. 2020; 91(5):453–454.

Warneke JA, Pavelites JJ. You’re the flight surgeon: Raynaud’s phenomenon/hand arm vibration syndrome. Aerosp Med Hum Perform. 2020; 91(5):459–461.