INTRODUCTION: Loss-of-control (LOC) is the major cause of transport airplane mishaps. There have been many published reports and papers examining these accidents. While these studies did mention spatial disorientation (SD) as a cause or a factor, none of them analyzed it further. The present study uses transport and commuter airplane mishap data for a recent 35-yr period and examines the results of those mishaps involving spatial disorientation.METHOD: We identified LOC and SD accidents from five national aviation accident organizations and two independent groups. Only “normal” operations (air carrier, noncommercial transportation, ferry flights, and training) were considered. We reviewed transport and commuter airplane accidents using the published reports and identified 94 involving SD.RESULTS: We found the distribution of SD mishaps differs from LOC mishaps. During initial climb, there were relatively fewer SD mishaps (16%) than LOC mishaps (31%). During enroute climb SD has relatively more mishaps (18%) than LOC (11%). During go-around or missed approach phases, there were relatively more SD mishaps (21%) than LOC mishaps (4%). Perhaps the most significant observation was an increasing number of SD mishaps during the period reviewed.DISCUSSION: There are several possible reasons for the increasing numbers of SD mishaps over the study period from 1981 to 2016. Somatogravic illusion during go-around or missed approach accounts for only some of this increase. There is insufficient data to determine the reason for the remaining increase.Newman RL, Rupert AH. The magnitude of the spatial disorientation problem in transport airplanes. Aerosp Med Hum Perform. 2020; 91(2):65–70.

INTRODUCTION: Individual motion sickness susceptibility can be rapidly estimated by the motion sickness susceptibility questionnaire (MSSQ), but its stability is affected by various factors. The purpose of this study was to investigate the involved predictive factors of motion sickness screened with uniform samples of Chinese college students and to verify the individual susceptibility difference in marine navigation.METHODS: A total of 1051 college students (719 men, 332 women; mean age: 18.32 ± 0.65 yr) completed the MSSQ. Another 42 men (mean age: 21.12 ± 1.10 yr) took part in 2 separate voyages. MSSQ data were collected before sailing and Graybiel motion sickness questionnaire (GMSQ) data were collected within 24 h after sailing and 24 h before landing.RESULTS: The internal consistency of the MSSQ was 0.685. The mean subscore of the MSSQ-A (18.47 ± 19.49) was significantly higher than that of the MSSQ-B (12.69 ± 14.97). Women had significantly higher MSSQ scores (38.29 ± 33.49) than men (27.87 ± 30.27). The mean MSSQ score of the inland subjects (33.97 ± 33.35) was significantly higher than that of the coastal subjects (27.81 ± 29.24). Nearly 93% of new seafarers experienced seasickness during their first navigation. The MSSQ score was positively correlated with seasickness symptoms (r = 0.706).CONCLUSION: Gender, age, and birthplace appear to be important predictors of motion sickness for Chinese college students. Specifically, women, younger people, and people who were born in inland China seem more prone to the syndrome. A high MSSQ score is a risk factor for seasickness. However, long-term voyages can lead to habituation, which reduces the occurrence of seasickness.Zhang X, Sun Y. Motion sickness predictors in college students and their first experience sailing at sea. Aerosp Med Hum Perform. 2020; 91(2):71–78.

INTRODUCTION: In Canada, aviators and seafarers are required to be medically fit by international and domestic standards to be issued a medical certificate by Transport Canada (TC). In the event of denial or restriction, individuals have the right to a review by an independent decision-maker with medical expertise/training in marine and/or aviation medicine. This paper presents the results of cases submitted to the Transportation Appeal Tribunal of Canada over 19 yr.METHODS: The Tribunal’s repository of medical records was searched and 112 adjudicated cases were reviewed.RESULTS: Since 2000, 55 (49%) cases were in the aviation sector and, since 2010, 57 (51%) cases were in the marine sector. The mean age of applicants was 49 and 54 yr for seafarers and pilots, respectively. Mental illness, cardiovascular disease, visual, and neurological disease were the most common reasons for a medical certificate restriction/denial. The Tribunal upheld the refusal to issue or renew a medical certificate in 89 (79%) cases and 23 (21%) cases were referred back to TC.CONCLUSIONS: Mental illness is the most frequent diagnosis that precipitates a request. The international literature is sparse on the number, causes, and results of the appeal process. Our findings and the application of the medical standards in Canada are generally comparable with those of the United Kingdom. It was not possible to make more than indirect comparisons to those of the United States.Brooks C, MacDonald C. Medical cases adjudicated by the Transportation Appeal Tribunal of Canada: 2000–2018. Aerosp Med Hum Perform. 2020; 91(2):79–85.

BACKGROUND: An airframe parachute (“Chute”) available in certain aircraft is designed to lower the airplane safely to the ground for emergency situations that occur 500 ft (152 m) above ground level (AGL): the “Chute altitude envelope.” This study will explore the change in Chute use before and after 2012 to better understand factors that increased usage and improved accident outcomes.METHODS: Using the public National Transportation Safety Board (NTSB) accident database from January 1, 2001, through August 31, 2018, a regression model was developed to identify factors that may predict Chute use.RESULTS: In accidents occurring after January 1, 2013, pilots were 5 times more likely to use the Chute, while 2.9 times less likely to use the Chute when the accident involved pilot-related causes. The presence of passengers did not predict Chute use. Injuries were likely to be more severe when the Chute was used outside the Chute altitude envelope.DISCUSSION: In contrast to General Aviation (GA) overall, accidents outcomes in aircraft equipped with a Chute have seen great improvements between 2013 and 2018, with increased use of the Chute and improved injury outcomes. Results suggest that changes to pilot training in 2012 have increased the social acceptance of Chute use. Results highlight increased risk of injury outcomes for Chute use in accidents that occur outside the Chute altitude envelope.Kirby J. Social acceptance of increased usage of the ballistic parachute system in a general aviation aircraft. Aerosp Med Hum Perform. 2020; 91(2):86–90.

INTRODUCTION: Spaceflight Associated Neuro-ocular Syndrome (SANS) results from long-duration spaceflight and presents with a constellation of signs (e.g., optic disc edema, choroidal folds, globe flattening, refractive error shifts, etc.). Optic nerve tortuosity (ONT) has been detected in approximately 47% of astronauts after long-duration spaceflight but has not yet been fully analyzed. This review examines terrestrial ONT in order to better understand how the condition is caused and measured.METHODS: References were identified by PubMed and ScienceDirect searches covering 1955 to October 2018 using the terms “optic nerve tortuosity,” “optic nerve kinking,” “optic disc torsion,” “optic kinking,” and “ocular torsion.” Additional references were identified by searching relevant articles.RESULTS: ONT measurements have evolved and become more objective. One measure consists of meeting two criteria: 1) lack of optic nerve congruity in >1 coronal section; and 2) subarachnoid space dilation. This “criteria measure” is objective, sensitive, and specific for determining the presence of tortuosity. Another measure is the tortuosity index, which offers additional benefits by measuring the degree of ONT, including the potential to track changes over time. There are numerous terrestrial ONT causes, including intracranial hypertension, hydrocephalus, Chiari malformation, neurofibromatosis, glaucoma, and progeria, among others.DISCUSSION: To accurately measure ONT, it is crucial to adhere to objective, standardized techniques. The tortuosity index offers the potential to measure intraindividual change in ONT. Among the varied conditions associated with ONT, one commonality is pressure change. The impact of intracranial pressure on the vascular system and vice versa may offer insight into what is occurring in space.Scott RA, Tarver WJ, Brunstetter TJ, Urquieta E. Optic nerve tortuosity on Earth and in space. Aerosp Med Hum Perform. 2020; 91(2):91–97.

BACKGROUND: In helicopter critical care and emergency medical services (HEMS) transportation, organizations aim for efficiency of the dispatch process. Most HEMS organizations do not provide transport under instrument flight rules (IFR), due to equipment and training cost. Boston MedFlight (BMF) provides IFR HEMS transport. We set out to determine if response time of IFR transport was superior to ground transport.METHODS: A retrospective analysis of quality improvement data was performed. Data was collected by two observers sitting in the BMF control room in varying shifts. A process map of the dispatch process, from the dispatch call to the vehicle en route was developed. Critical points in the dispatch process were determined and a variety of time differences to determine the length of processes in the dispatch calculated. We compared median time differences between visual flight rules (VFR) flight and IFR flight, between IFR flight and ground transport, and between VFR and Ground for these points using a Mann-Whitney U-test.RESULTS: During the study collection period, 443 transports occurred, of which 109 transports happened while the observers were present: 37 ground, 57 VFR, and 15 IFR. Due to weather, six IFR transports were declined. The overall time from dispatch call to vehicle en route was significantly increased for IFR flights [median: 30 min:8 s (interquartile range 19:06–49:04)] over both VFR flights [11:36 (9:24–17:06); P vs. IFR: 0.001] and ground transports [9:39 (6:59–14.51); P vs. IFR: 0.001]. Most of this increase was accounted for by increases in the time from dispatch to crew acceptance, and from rotor start to vehicle en route.DISCUSSION: IFR conditions resulted in significantly increased dispatch times over both VFR flight and ground transport. The increase is likely a result of weather check, filing an IFR flight plan, and IFR release. Dispatch algorithms should be adjusted for this time delay of IFR transports.Kamine TH, Thomas L, Davis C, Cohen J. Critical care transport time differences between ground, helicopter VFR, and helicopter IFR transports. Aerosp Med Hum Perform. 2020; 91(2):98–101.

BACKGROUND: Vo_2peak has traditionally been thought to be regulated by cardiac output and arteriovenous-oxygen difference. A “muscle-centric” view suggests the cardiovascular system is secondarily responsive to the primary driver: active muscle mass.METHODS: A total of 19 recreationally active men (N = 10) and women (N = 9) performed a Vo_2peak test, a Vo_2peak verification test on an electrically braked cycle ergometer on the same day, and a hydrostatic weighing test to assess fat free mass after providing written informed consent.RESULTS: Vo_2peak was significantly higher in men (3.74 ± 0.6 L · min⁻¹) than women (2.22 ± 0.30 L · min⁻¹). Whole body fat free mass explained 91% of the variability in Vo_2peak (R² = 0.91) in the men and women combined, 81% of the variability in Vo_2peak in men alone, and 46% of the variability in Vo_2peak in women alone. None of these subjects were highly trained.DISCUSSION: Fat free mass, a surrogate for muscle mass, was the primary predictor of Vo_2peak in this group of recreationally active men and women. Therefore, it appears that whole body fat free mass (a surrogate for muscle mass) is the primary driver for Vo_2peak in these recreationally active men and women. These data have implications as to the type of training NASA personnel should be undertaking: resistance training as opposed to aerobic training.Lambert CP. Whole body fat free mass and Vo_2peak in recreationally active men and women. Aerosp Med Hum Perform. 2020; 91(2):102–105.

BACKGROUND: High-altitude decompression sickness (HADCS) is a rare condition that has been associated with aircraft accidents. To the best of our knowledge, the present paper is the first case report of a patient treated for severe HADCS using recompression therapy and veno-venous extracorporeal oxygenation (VV-ECMO) with a complete recovery.CASE REPORT: After depressurization of a cabin, the 51-yr-old jet pilot was admitted to the Military Institute of Medicine with a life-threatening HADCS approximately 6 h after landing from a high-altitude flight, in a dynamically deteriorating condition, with progressing dyspnea and edema, reporting increasing limb paresthesia, fluctuating consciousness, and right-sided paresis. Hyperbaric oxygen therapy in the intensive care mode was initiated. A therapeutic recompression with U.S. Navy Treatment Table 6 was performed with neurological improvement. Due to cardiovascular collapse, sedation, mechanical ventilation, and significant doses of catecholamines were started, followed by continuous veno-venous hemodialysis. In the face of disturbances in oxygenation, during the second day of treatment the patient was commenced on veno-venous extracorporeal oxygenation. Over the next 6 d, the patient’s condition slowly improved. On day 7, VV-ECMO was discontinued. On day 19, the patient was discharged with no neurological deficits.DISCUSSION: We observed two distinct stages during the acute phase of the disease. During the first stage, signs of hypoperfusion, neurological symptoms, and marbled skin were observed. During the second stage, multiple organ dysfunction dominated, including heart failure, pulmonary edema, acute kidney injury, and fluid overload, all of which can be attributed to extensive endothelial damage.Siewiera J, Szałański P, Tomaszewski D, Kot J. High-altitude decompression sickness treated with hyperbaric therapy and extracorporeal oxygenation. Aerosp Med Hum Perform. 2020; 91(2):106–109.

INTRODUCTION: Dramatic increases in parachuting safety over the last three decades have been attributed to advances in technology and training for parachutists. However, very little is known about the physiological condition of skydivers making repeated, medium-altitude aircraft exits without using supplemental oxygen. As in aviation, human error is broadly responsible for the majority of skydiving mishaps, although it is unclear what role, if any, physiological factors contribute to these mishaps. Over the course of 2 d, a healthy, 50-yr-old male skydiver executed four normal exits (two jumps per day) from an aircraft between 13,500 and 14,000 ft (4115 and 4267 m) pressure altitude while wearing a helmet-mounted biomonitoring device (SPYDR, Spotlight Labs). On both days, after the subject’s second jump, he reported feeling lightheaded and dizzy, symptoms he experiences approximately once every five jumps, and had previously attributed to the excitement of the jump. Inspection of S_po₂ and pulse data revealed that the subject was mildly hypoxic at jump altitude (S_po₂ < 90%). For all four jumps, S_po₂ did not return to normal levels until under canopy. Previous studies have evaluated the cognitive impairment of general aviation pilots operating unpressurized aircraft above 12,500 ft (3810 m) without supplemental oxygen. Alarmingly, mildly hypoxic pilots exhibited twice the rate of procedural errors as compared to normally oxygenated subjects. This study found that the skydiver exited the aircraft with mild hypoxia, which has been associated with cognitive impairment in pilots and could possibly be linked to injuries and/or fatalities.Bradke BS, Everman BR. Mild hypoxia of a skydiver making repeated, medium-altitude aircraft exits. Aerosp Med Hum Perform. 2020; 91(2):110–115.

Flower A. You’re the flight surgeon: spontaneous pneumothorax. Aerosp Med Hum Perform. 2020; 91(2):116–118.