BACKGROUND: Reading a map requires the ability to judge one’s position in a large-scale space from information presented in a small-scale representation. Individuals are more accurate and faster in making judgments when the “up” direction on the map is the same as the “forward” direction of the environment, which is when a map is aligned with the perspective of the spatial layout they have learned (alignment effect). The aim of this study was to explore whether military pilots, who have high spatial abilities, would not show the alignment effect compared with nonpilots.METHODS: Recruited were 20 military pilots and 20 nonpilots. Mean flight hours were 418.75. Nonpilots without flight experience were matched for age and education with pilots. Subjects were asked to learn a map and to perform directional judgments to verify whether the alignment effect was present considering absolute angular errors.RESULTS: An ANOVA for mixed designs on absolute angular errors revealed a main “group” effect: pilots performed better than nonpilots (pilots: M = 22.60 ± 5.57; nonpilots: M = 82.59 ± 5.56). A main “directional judgments” effect was also observed: aligned judgements were easier than contra-aligned judgements (aligned, M = 9.277 ± 0.938; contra-aligned, M = 11.004 ± 0.805). ANOVA showed a significant “group × directional judgments” interaction: post hoc comparison showed that contra-aligned were more difficult than aligned judgments for nonpilots.DISCUSSION: High visuo-spatial abilities preserved pilots from having alignment effect bias. They performed directional judgments equally well, being less influenced by the increased cognitive effort requested by the changing perspective.Verde P, Angelino G, Piccolo F, Carrozzo P, Bottiglieri A, Lugli L, Piccardi L, Nori R. Spatial orientation and directional judgments in pilots vs. nonpilots. Aerosp Med Hum Perform. 2018; 89(10):857–862.

INTRODUCTION: A visual stimulus change detection is an extremely important pilot’s cognitive process. This is especially true when pilot errors caused by perceptual failures have a negative effect on his/her spatial orientation. The aim of this research was to investigate the effect of the change detection flicker task (CDFT) on pilots’ response to spatial disorientation (SD) events. We hypothesized that the additional cognitive processing, based on CDFT, produces more deterioration of the pilots’ spatial orientation.METHODS: Using an SD flight simulator, 50 male military pilots (M = 27.2; SD = 6.68) were exposed to 12 flight sequences. Of the 12 flight profiles, 6 involved an SD conflict, with 3 involving motion illusions and 3 with visual illusions. We measured and compared pilots’ flight performance in response to visual and motion illusion conflicts across two simulations (CDFT vs. control) and SD conditions (nonconflict vs. conflict).RESULTS: Of the six applied illusions, significant differences in pilot flight performance were found for three visual and one vestibular illusion (Coriolis). The differences were observed between control and CDFT groups for both nonconflict and conflict flight sequences, associated with the approach and landing maneuvers.DISCUSSION: The CDFT increased the pilots’ cognitive workload, affecting their flight performance and susceptibility to SD, especially in the approach and landing maneuvers. This partially supports our hypothesis that performing the CDFT leads to greater deterioration of pilots’ spatial orientation. We recommend that when problems in maintaining proper flight performance arise, pilots should not respond to external stimuli until they have recovered their spatial orientation.Lewkowicz R, Fudali-Czyż A, Bałaj B, Francuz P. Change detection flicker task effects on simulator-induced spatial disorientation events. Aerosp Med Hum Perform. 2018; 89(10):863–872.

BACKGROUND: Adequate instrument scanning is considered an important countermeasure against spatial disorientation (SD). Remarkably, literature on the relation between SD and pilots’ visual scanning is scarce. The objective of this simulator study was to investigate the influence of SD on pilots’ visual scanning and flight performance.METHODS: In a ground-based SD simulator, 10 novice military pilots were asked to manually fly 3 circuits. Unknowingly to the pilots, the final circuit contained one visual and four vestibular SD events. Simulator motion, flight performance, pilots’ gaze direction, and control inputs were recorded and analyzed. Afterwards the pilots filled in a questionnaire about their recognition of events.RESULTS: Three of the five SD events significantly affected pilots’ flight performance and gaze behavior. First, the false horizon during the cloud leans induced an unintended roll rate, 0.41 ± 0.36° · s⁻¹, when the pilots were looking out the window. Second, the Coriolis illusion caused a 0.44 ± 0.18 s delay in the first glance to the attitude indicator and triggered an unintended roll rate, 1.25 ± 1.33° · s⁻¹, and bank angle deviation of 3.4 ± 3.7° during the coordinated turn. Third, the somatogravic illusion affected pilots’ pitch inputs on the stick, but this seems to be confounded by inaccurate simulation of the illusion.DISCUSSION: This study provides direct experimental evidence that SD can evoke inappropriate control inputs and can influence the pilots’ scanning behavior, even when SD is not recognized. We conclude that gaze tracking provides useful feedback on the pilot’s instrument scan during SD simulator training when using appropriate scenarios and simulator motion.Ledegang WD, Groen EL. Spatial disorientation influences on pilots’ visual scanning and flight performance. Aerosp Med Hum Perform. 2018; 89(10):873–882.

BACKGROUND: Skeletal muscle atrophy is a striking example of the multiple changes in the physiological state of humans and animals induced by microgravity. Previous studies have shown that a blood circulation disorder may be a cause of this atrophy, and traditional Chinese medicine has been regarded as a potential countermeasure to reverse the atrophy in China. This study was carried out to test the effects of Xuefuzhuyu capsules (XFZY) on the skeletal muscle atrophy induced by simulated microgravity.METHODS: The mass and cross-sectional area of the soleus muscle were compared in rats treated with XFZY that were hindlimb unloaded for 30 d (XFZY-TS group), untreated rats that were hindlimb unloaded for 30 d (TS group), and control rats (CON group). The expression and phosphorylation levels of key proteins of the sarcoplasmic reticulum stress system were also measured.RESULTS: Treatment with XFZY attenuated the loss of muscle mass and cross-sectional area induced by hindlimb unloading. Western blot analysis showed that the phosphatidyl-inositol-3-kinase/phospho-Akt (PI3K/p-Akt) pathways were down-regulated after 30 d in the TS group compared with the CON group. This effect was partly reversed by XFZY. Hindlimb unloading increased the expression of glucose-regulated protein 78 (GRP78), cytosine-cytosine-adenosine-adenosine-thymidine/enhancer-binding protein homologous protein (CHOP), C-Jun N-terminal kinase (JNK), and Caspase 12. Treatment with XFZY alleviated this increased protein expression.DISCUSSION: Our results suggest that XFZY could partially reverse the effects of hindlimb unloading on muscle atrophy and perhaps target the sarcoplasmic reticulum stress system, possibly through the GRP78-CHOP-JNK-Caspase 12 pathway.Zhang S, Yuan M, Cheng C, Xia D, Wu S. Chinese herbal medicine effects on muscle atrophy induced by simulated microgravity. Aerosp Med Hum Perform. 2018; 89(10):883–888.

INTRODUCTION: The prevalence of flight-related neck pain in all Royal Air Force (RAF) aircrew is 66% and 70% in UK fast-jet aircrew. The RAF Aircrew Conditioning Programme (ACP) has been designed to enhance pilot performance through reducing fatigue and strain injuries, particularly to the neck. Content validity of the ACP was assessed to determine the appropriateness for delivery to aircrew.METHODS: Six international medical experts reviewed level two of the ACP, which is delivered to student aircrew who have completed basic instruction in cervical spine stability, core stability and initial technique instruction for strength training. Content validity on overall exercise approach (5 items) and specific exercise session (24 items) was rated on a 4-point Likert-type ordinal scale for Relevance and Simplicity. Four reviewers had experience of delivering an exercise program to aircrew. The item-content validity index (I-CVI) was the proportion of experts rating an item/exercise as acceptable (score 3-4) while protocol-CVI was the average I-CVI across items.RESULTS: Of the suggested exercise sessions, 20 reached an excellent I-CVI (1.00) for Relevance (4 reached acceptable I-CVI (0.83)), and 21 reached an excellent I-CVI (1.00) for Simplicity (3 reached acceptable I-CVI (0.83)). Protocol-CVI for the ACP was excellent for Relevance (0.90) and good for Simplicity (0.83). The need for sufficient supervision during the exercises was recommended for safe exercise execution and to maintain adherence.CONCLUSION: The ACP demonstrated excellent relevance for the target population. The aircrew require additional supervision with the more complex neck exercises to enhance simplicity with the ACP.Slungaard E, Green NDC, Newham DJ, Harridge SDR. Content validity of level two of the Royal Air Force Aircrew Conditioning Program. Aerosp Med Hum Perform. 2018; 89(10):896–904.

INTRODUCTION: The special issuance (SI) waiver is the primary mechanism for U.S. pilots who do not meet FAA standards to obtain a medical certificate. About 34,000 pilots possess an SI waiver, but there is a large gap in knowledge of the relationship of SI waivers to aviation safety.METHODS: All FAA pilot medical exams from 2002 through 2011 were matched to the National Transportation Safety Board accident database. The association of an SI waiver with accidents was explored using logistic regression models. Accident rates were also calculated using a novel technique based on pilots’ reported flight times on their applications for medical certification.RESULTS: For third-class flight exams overall, the presence of an SI waiver is associated with 8.7% lower odds of an accident than regular issuance exams. The calculated overall accident rate was 6.6 per 100,000 h. For the first and second-class exams, there was no significant association of SI waivers with safety for the overall group. The oldest and youngest pilots in the third-class group and the younger pilots in the first and second-class groups had somewhat elevated accident odds. The significance of these higher odds is uncertain, especially for the younger pilots who have a probable flight time bias.DISCUSSION: The overall FAA program of special issuance waivers shows no detrimental effect on aviation accidents and enables a large number of pilots to safely continue their aviation pursuits in spite of failure to meet specific regulatory medical standards.Mills WD, Davis JT. The U.S. experience with special issuance waivers. Aerosp Med Hum Perform. 2018; 89(10):905–911.

BACKGROUND: For many years, anticoagulant therapy had been deemed unacceptable for civilian pilot medical certification in the United Kingdom under the Joint Aviation Authorities Requirements and, therefore, mechanical valve implants were disqualifying. In 2012, this restriction was removed by implementation of the European Union requirements. This study was undertaken to assess the medical evidence available to develop a certificatory policy following mechanical valve implants in the United Kingdom.METHODS: A literature review was performed for complication rates following the implantation of mechanical aortic and mitral valves. This study was confined to the three major types of valve commonly used in current clinical practice: the ATS, the Carbomedics, and the St. Jude Medical valves.RESULTS: We identified 28 papers on aortic valve replacements and 22 papers on mitral valve replacements. Data were extracted for the late complication rates for endocarditis, paravalvular leak, thromboembolism, hemorrhage, and structural valve dysfunction. The total calculated incidence of a late complication was 3.8% per annum for aortic valves over a mean follow-up period of 57 mo and 5.2% per annum for mitral valves over a mean follow-up period of 61 mo. Both of these exceed the maximum 1% per annum medical incapacitation risk considered acceptable for professional multicrew pilot operations.CONCLUSION: Confounders and sources of error in estimating the risks and methods to mitigate these are considered. A certificatory policy is proposed and the UK experience of mechanical valve replacements is described.Jagathesan T, O’Nunain S, O’Brien M. Aeromedical certification following mechanical aortic and mitral valve implants in the United Kingdom. Aerosp Med Hum Perform. 2018; 89(10):912–917.

INTRODUCTION: While NASA requires that commercial spaceflight vehicles provide onboard emergency oxygen supplies for crew, there are currently no requirements in place regarding thermal constraints of delivered gas. The question has been raised whether or not onboard emergency oxygen supplies must be warmed prior to administration to the crew, as inclusion of warming capabilities will increase the complexity and mass of life support systems in the vehicle. We sought to identify the risk of various inhaled oxygen temperatures and resultant pulmonary inflammatory response in potentially injured crewmembers.METHODS: A systematic review of published literature was conducted concerning thermal regulation of inhaled gases, reactive airway response, and inflammatory reactions. In particular, we sought literature that correlated inhaled gas temperature to airway response to identify a temperature threshold that would avoid deleterious sequelae.RESULTS: Cold air inhalation can induce acute bronchoconstriction, increased respiratory rate, and associated dyspnea and hypoxia. Physiological response to cold air varies between healthy lungs and injured tissues, and increased inflammation is associated with increasing airway reactivity. Most studies suggest that inhaled gas temperatures below 10°C may induce deleterious physiological sequelae.DISCUSSION: Best practices would include maintenance of inhaled gas temperatures to >10°C to avoid poor physiological response, preferably as close to physiological norms as possible. Given that inhaled gas temperature may be altered by transit through an oxygen delivery system, measurement of actual delivered gas temperature should occur at the point of crewmember inhalation.Pattarini JM, Blue RS, Alexander DJ. Thermal regulation of emergency oxygen supplies in commercial space vehicles. Aerosp Med Hum Perform. 2018; 89(10):918–922.

BACKGROUND: Humans detect motion and gravity via the labyrinthine system of the inner ear, which consists of the vestibule and the semicircular canals. The vestibular system provides three major functions for maintaining balance and orientation. First, it maximizes the effectiveness of the visual system. Second, it provides orientational information necessary for performing both skilled and reflexive motor activities. Third, in the absence of vision, the vestibular system provides a reasonably accurate perception of motion and position. Although these organs provide important cues for basic orientation on the ground, they often provide misleading information during flight. A superior semicircular canal dehiscence can cause an individual to experience disorientation and vertigo-like symptoms.CASE REPORT: A 30-yr-old male student pilot experienced airsickness on his first several flights in the T-6A Texan II aircraft. Airsickness is common among student pilots in the early stages of flight training; however, the subject pilot’s symptoms lasted well beyond the normal 24 h, and included vertiginous symptoms lasting days after his last flight. His persistent symptoms required he be held out of training for further evaluation. Comprehensive vestibular and audiological testing were normal; however, a CT scan of the temporal bones showed a left superior semicircular canal dehiscence, and he was diagnosed with left labyrinthine fistula as the cause of his vertigo. He was medically eliminated from pilot training and permanently disqualified from U.S. Air Force flying duties.DISCUSSION: Spatial disorientation remains one of the deadliest factors related to aircraft mishaps every year. In this case, an abnormal presentation of airsickness that prompted further evaluation may have prevented a dangerous situation in the air. In standard airsickness, the goal is to keep the pilot flying to expedite adaptation, so this case highlights the importance of distinguishing between normal airsickness and a spatially disorienting medical condition.Dreibelbis JA, Organ BE. Semicircular canal dehiscence syndrome and vestibular dysfunction disqualify a military student pilot. Aerosp Med Hum Perform. 2018; 89(10):923–926.

INTRODUCTION: Effective voice communication is essential when operating aircraft. Because of the loud operating environment in fighter cockpits, it has been a challenge to provide effective communication while simultaneously protecting the hearing sense. The objective of this study was to determine the feasibility of using bone conducting transducers (BCT) in place of legacy communications systems in fighter cockpits.METHODS: A military flight helmet was modified and outfitted with BCT and air-conducting speakers. BCT were independently tested against air-conducting speakers using a clinical audiometer under three conditions: without earplugs, with earplugs, and with earplugs in the presence of 100-dB broad-spectrum noise. Three test subjects were given an audiological examination using tones of varying intensity ranging from 100 Hz to 8000 Hz. The lowest hearable intensity indicated by button press was recorded for each frequency.RESULTS: In the presence of 100-dB ambient noise, bone conducting transducers performed better than air-conducting speakers at all frequencies. Hearability of BCT by audiogram was, on average, 10–20% lower intensity (dB) than air-conducting speakers.DISCUSSION: Currently, USAF pilots wear two layers of hearing protection; i.e., the helmet's integrated earcup and some form of ear plug (e.g., foam earplug or custom-molded earbud). Our results suggest that bone conducting audio transducers may be better for layered hearing protection than air-conducting speakers when used with foam earplugs. Given the cost, complexity, and non-interoperability of custom-molded earphones, helmet-integrated bone conducting transducers and foam earplugs may be a better option for sustained airborne operations.Bradke BS, White Z, Poston J. Bone conduction as a viable alternative to current communications systems in fighter cockpits. Aerosp Med Hum Perform. 2018; 89(10):927–930.

Levy B. You’re the flight surgeon: alcohol-induced psychosis. Aerosp Med Hum Perform. 2018; 89(10):933–935.