BACKGROUND: Spatial disorientation (SD) remains a significant cause of accidents and near accidents. A variety of training methods have been used to assist pilots to anticipate the SD problem. The value of such training in the prevention of disorientation has been difficult to assess.METHODS: To study transfer of SD awareness training, we related reported incidents to the content and frequency of SD awareness training received. The questionnaire was completed by 368 out of 495 pilots; 189 currently flying fixed-wing, and 150 flying rotary-wing aircraft. On average, their age was 38, and they had 2466 flight hours on-type.RESULTS: Respondents gave high ratings for the importance of SD training and their awareness of SD, the latter being one of the training objectives. The amount of SD training received by respondents was positively correlated with ratings for appreciation and importance. Self-rated awareness was positively correlated with the number of reported SD experiences. Although the correlations were below 0.50, the results provide an indication that SD training is effective. In total, respondents reported 5773 SD experiences, 195 of them resulting in a serious risk for flight safety. Narratives of these serious events show that, in many cases, pilots managed their SD by carefully checking the flight instruments, and also by good crew coordination.DISCUSSION: The results of the survey provide some evidence, although based on subjective reports, for transfer of SD training. The results of the SD experiences can be used to improve the SD training in terms of content and frequency.Pennings HJM, Oprins EAPB, Wittenberg H, Houben MMJ, Groen EL. Spatial disorientation survey among military pilots. Aerosp Med Hum Perform. 2020; 91(1):4–10.

INTRODUCTION: The evolution and preservation of venous gas emboli (VGE), as markers of decompression stress, were investigated during alternating high- and moderate altitude exposures, thus, simulating a fighter aircraft high-altitude flight, interrupted by refueling excursions to lower altitudes.METHODS: Eight men served as subjects during three normoxic simulated altitude exposures: High = 90 min at 24,000 ft; High-Low = three × 30 min at 24,000 ft, interspersed by two 30-min intervals at 15,000 ft; Low = 90 min at 15,000 ft. VGE scores were assessed by cardiac ultrasound, using a 5-grade scale. Respiratory nitrogen exchange was measured continuously using a modified closed-circuit electronic rebreather.RESULTS: Both High and High-Low induced persistent VGE, with no inter-condition difference either at rest [median (range): High: 1 (0-3), High-Low: 2 (0-3)] or during unloaded knee-bends [High: 3 (1-4), High-Low: 3 (0-4)], whereas VGE was considerably less in Low, both at rest [0 (0-1)] and during knee-bends [0 (0-2)]. In High-Low, VGE decreased temporarily during the 15,000-ft excursions, but resumed pre-excursion values upon return to 24,000 ft. During the final descent to ground level, VGE were more persistent following High-Low than High. In both High and Low, nitrogen was continuously washed out at altitude, whereas in High-Low, the washout at 24,000 ft was interrupted by nitrogen uptake at 15,000 ft.DISCUSSION: In normoxic conditions, long-duration flying at a cabin altitude of 24,000 ft is associated with substantial VGE occurrence, which is not abolished by intermittent excursions to a cabin altitude of 15,000 ft.Ånell R, Grönkvist M, Gennser M, Eiken O. Evolution and preservation of venous gas emboli at alternating high and moderate altitude exposures. Aerosp Med Hum Perform. 2020; 91(1):11–17.

BACKGROUND: Cognition is a neurocognitive test battery created at the University of Pennsylvania and adapted by the National Aeronautics and Space Administration (NASA). It comprises 10 neurocognitive tests that examine multiple domains, and has been validated in a normative sample of STEM-educated adults and compared to NASA’s WinSCAT battery.METHODS: The purpose of this study was to follow the original sample to assess Cognition and WinSCAT’s test-retest reliability and age, sex, and test-retest interval effects on performance.RESULTS: Performance on both Cognition and WinSCAT decreased with age but improved with repeated administration due to practice effects, and men had higher scores than women on tasks that required vigilant attention, spatial reasoning, and risk-taking behaviors. Assessment of test-retest reliability showed intraclass coefficients for efficiency ranging from 0.417 to 0.810, reflecting the broad nature of constructs assessed by Cognition.DISCUSSION: Results largely matched predictions, with some counter-intuitive results for test-retest reliability interval.Lee G, Moore TM, Basner M, Nasrini J, Roalf DR, Ruparel K, Port AM, Dinges DF, Gur RC. Age, sex, and repeated measures effects on NASA’s “Cognition” Test Battery in STEM educated adults. Aerosp Med Hum Perform. 2020; 91(1):18–25.

BACKGROUND: The aim of the study was to determine the characteristics of cervical muscle activity in different head movements when using helmet mounted display in air combat maneuvering.METHODS: Cervical EMG was measured with eight F/A-18 pilots using the Joint Helmet Mounted Cueing System (JHMCS) during air combat maneuvering. In-flight G_z acceleration and continuous head position were recorded. Muscular activity was compared between head movements in isolation and combined with torso movement. In addition, the effect of the direction of head movements and the use of head support of the ejection seat on muscle activity was determined.RESULTS: Muscular loading increased in the cervical flexors and extensors when using the torso during targeting beyond the field of vision in the neutral sitting posture; the difference was significant in the flexors, but activity levels were higher in the extensors. Cervical muscles are loaded to a lesser extent if the head is kept in a stable position during G_z loading. Muscular activity in the neck muscles was higher when the pilot was moving the head out of neutral posture rather than toward neutral posture. The use of the headrest as a support decreased muscle activity in the extensors, but resulted in higher activity in the flexor muscles.DISCUSSION: All analyzed conditions were significantly affected by an increase in G_z. An increase of muscle activity with torso movements is considered as a positive factor as it reflects maintained muscular support for the cervical spine. Presented results may be helpful when specific conditioning programs and cockpit ergonomics are developed for fighter pilots.Sovelius R, Mäntylä M, Huhtala H, Oksa J, Valtonen R, Tiitola L, Leino T. Head movements and neck muscle activity during air combat maneuvering. Aerosp Med Hum Perform. 2020; 91(1):26–31.

BACKGROUND: The aim of this study was pure tone audiometry (PTA) evaluation in normal individuals exposed to hypobaric hypoxia, taking into account the influence of air rarefaction on sound transmission via a standard earphone.METHODS: The study was conducted in a hypobaric chamber using a standard audiometer and a TDH-39P earphone whose performance at altitudes was analyzed in a previous research. Eight male volunteers underwent PTA testing at ground level and at 15,000 ft under normoxia (via an oxygen mask) and after 20 min of hypoxia. Auditory threshold at 500, 1000, 2000, and 4000 Hz was recorded from the right ear while monitoring arterial oxygen saturation (S_ao₂). The PTA data obtained at high altitude were corrected according to a specific recalibration table.RESULTS: During hypoxia, a significant threshold shift was observed only at 4000 Hz, with respect to ground level recording, for the sole not-corrected data. At the same frequency a significant threshold shift was also observed between the ground level recording and normoxia at 15,000 ft, confirming the presence of a hypobaric effect not related to hypoxia. After the recalibration procedure, this hearing impairment was not significant. No correlation with S_ao₂ levels was observed.DISCUSSION: The mild and not significant presence of high altitude-induced PTA derangements in healthy normal individuals was documented, although a stimulus recalibration was needed for a correct interpretation of our data.Lucertini M, Lancia S, Sanjust F, Guadagno AG, Lucertini L, Sisto R. Lack of significant audiometric changes under hypobaric hypoxia at 15,000 ft. Aerosp Med Hum Perform. 2020; 91(1):32–36.

BACKGROUND: Migraine is a common condition with features that can adversely impact aviation activities. The diagnosis of migraine is often compatible with civil aviation training, but is much more concerning for military pilot applicants. A history of migraine headache traditionally medically excluded potential military pilot applicants due to unpredictability of occurrence and potential for operational distraction or incapacitation. Medical standards and policy applications have been quite variable, ranging from total exclusion for even one headache occurrence to as low as a 1-yr migraine-free period before consideration. In many instances, policy application has been subjective and not based on objective evidence. This presents a challenge to waiver authorities and also potentially sends a mixed message to command authorities. There is essentially no current literature evidence applicable to the aviation population on migraine occurrence risk.METHODS: This study reviewed 71 U.S. Air Force pilot applicants who were diagnosed with migraine and had been granted waivers to assess any predictive factors for migraine recurrence and its aeromedical impact.RESULTS: Only three applicants had recurrence after waiver was granted, with two of these occurring within 2 yr of their last reported migraine event, and all recurrences noted within 3 yr.DISCUSSION: Data indicated favorable risk with suitable migraine-free observation before military pilot training, which could be incorporated into aeromedical standards and policies.Hesselbrock RR, Haynes JT. Migraine history and recurrence in military pilot applicants. Aerosp Med Hum Perform. 2020; 91(1):37–40.

INTRODUCTION: There are knowledge gaps in spaceflight pharmacology with insufficient in-flight data to inform future planning. This effort directly addressed in-mission medication use and also informed open questions regarding spaceflight-associated changes in pharmacokinetics (PK) and/or pharmacodynamics (PD).METHODS: An iOS application was designed to collect medication use information relevant for research from volunteer astronaut crewmembers: medication name, dose, dosing frequency, indication, perceived efficacy, and side effects. Leveraging the limited medication choices aboard allowed a streamlined questionnaire. There were 24 subjects approved for participation.RESULTS: Six crewmembers completed flight data collection and five completed ground data collection before NASA’s early study discontinuation. There were 5766 medication use entries, averaging 20.6 ± 8.4 entries per subject per flight week. Types of medications and their indications were similar to previous reports, with sleep disturbances and muscle/joint pain as primary drivers. Two subjects treated prolonged skin problems. Subjects also used the application in unanticipated ways: to note drug tolerance testing or medication holiday per research protocols, and to share data with flight surgeons. Subjects also provided usability feedback on application design and implementation.DISCUSSION: The volume of data collected (20.6 ± 8.4 entries per subject per flight week) is much greater than was collected previously (<12 per person per entire mission), despite user criticisms regarding app usability. It seems likely that improvements in a software-based questionnaire application could result in a robust data collection tool that astronauts find more acceptable, while simultaneously providing researchers and clinicians with useful data.Wotring VE, Smith LK. Dose tracker application for collecting medication use data from International Space Station crew. Aerosp Med Hum Perform. 2020; 91(1):41–45.

BACKGROUND: Gradual ascent is impractical for personnel deploying to the South Pole due to logistical challenges. Prevention of altitude illness relies on prophylactic medications such as acetazolamide and behavioral modifications including hydration and avoidance of overexertion. We present three recent cases of altitude illness that occurred in previously healthy individuals at the South Pole.CASE REPORTS: 1) A 52-yr-old woman not on prophylactics presented with headache and intractable vomiting 7 h after arriving and hiking around the station. She was treated with acetazolamide, dexamethasone, oxygen, and supportive care. Her symptoms resolved during the evacuation flight. 2) A 23-yr-old man presented with dyspnea at rest 3 d after arriving without prophylactic treatments. He had a S_ao₂ of 49%, wheezes and crackles on lung exam, and interstitial infiltrates on chest X-ray. His treatment included oxygen, nifedipine, acetazolamide, and dexamethasone. His symptoms resolved during the evacuation flight. 3) A 40-yr-old man presented with dyspnea after a series of strenuous workouts since his arrival 5 d prior. He had a S_ao₂ of 41%, and his chest X-ray was consistent with high altitude pulmonary edema. He was treated with oxygen, nifedipine, and fluids before descent to sea level, where his symptoms fully resolved 4 d later.DISCUSSION: These patients illustrate that altitude illness may develop despite medical screening, participant education, and availability of prophylactic medications based on published guidelines. These cases could be attributed to noncompliance and misinformation, bringing to light some of the challenges with managing more diverse populations that deploy to remote environments.Rose JS, Law J, Scheuring R, Ramage MH, McKeith JJ. Serious altitude illness at the South Pole. Aerosp Med Hum Perform. 2020; 91(1):46–50.

BACKGROUND: The risks associated with high positive G_z (+G_z) aerobatic flight, especially with respect to +G_z-induced loss of consciousness (G-LOC), are well known. Less appreciated is the effect of negative G_z (−G_z) flight on subsequent +G_z maneuvers, known as the “push-pull effect.” This is an example involving the loss of an F-16 and pilot that was caused by the push-pull effect.CASE REPORT: The mishap pilot (MP) was killed during a training flight when his F-16 crashed without an ejection attempt. The MP, while transitioning from prolonged −G_z flight to sustained +G_z flight, maneuvered the mishap aircraft (MA) from −2.06 G_z to +8.56 G_z in less than 5 s. At this point, there were only minimal control inputs for 5 s, indicating the MP experienced transient incapacitation, most likely due to G-LOC or almost loss of consciousness (A-LOC). The MP’s subsequent recovery attempt was interrupted by ground impact. The Accident Investigation Board (AIB) concluded the MP experienced G-LOC due to the push-pull effect.DISCUSSION: Since this is not the first time the push-pull effect has resulted in G-LOC mishaps, the adverse effects of such maneuvers should continue to be emphasized during military physiological training, as well as during general aviation (GA) aerobatics training. Furthermore, A-LOC, instead of being considered a discrete phenomenon, may need to be included in a broader G-LOC definition that encompasses the entire continuum of G-LOC and A-LOC.Metzler MM. G-LOC due to the push-pull effect in a fatal F-16 mishap. Aerosp Med Hum Perform. 2020; 91(1):51–55.

INTRODUCTION: In this article, we recount some aspects of the tremendous life of Don Shields. As a young Air Force pilot, Don Shields flew the B57 aircraft through the actual nuclear cloud during nuclear weapons blast explosions in Operation Dominic. The data he collected was of vital importance to our country's nuclear weapons program. Don Shields knew of the tremendous risk of radiation but served our country at the call of duty. After his military service, Don Shields served as the subject matter expert for the Apollo lunar module and worked directly with Commander Neil Armstrong and lunar module pilot Buzz Aldrin in training them on the module. During the Apollo 11 mission, Don Shields was being interviewed by Walter Cronkite on the epic Moon landing coverage. Unfortunately, later in life Don Shields suffered from cataracts and leukemia, both of which are known to be related to high radiation exposures. During his old age, Don Shields volunteered at the NASA Ames Museum and inspired generations of young individuals towards the space mission.Douglas DB, Cagle Y. The life of Don Shields: from atmospheric nuclear tests to the lunar module. Aerosp Med Hum Perform. 2020; 91(1):56–58.

Radigan M. You’re the flight surgeon: hyperparathyroidism. Aerosp Med Hum Perform. 2020; 91(1):59–61.