The issue of women flying military aircraft in a combat role has been very controversial. To succeed, female military aircrew are very similar to their male peers. We conducted a comprehensive anonymous questionnaire survey of all U.S. Army and U.S. Air Force rated female aircrew, with an equal number of age and duty matched male aircrew. We are reporting on the interpersonal relationship and prisoner of war (P.O.W.) responses here. Male and female aircrew respond in a similar manner to posed questions, although differences do exist. Women reported: unequal treatment by opposite gender peers; problems relating to peers, superiors and subordinates; their gender influences assignments; the need to perform to higher standards and the need to work harder to be accepted as equals; ability to bond equally to their own and opposite gender peers; improved squadron cohesiveness in mixed gender squadrons; problems with peers' spouses; and, in a P.O.W. situation, fear of rape and sexual abuse. Men reported: women get inappropriate privileges and get special “breaks” a gender difference in how flight duties are performed; worsened squadron cohesiveness in mixed gender squadrons; less likeliness to recommend their career path to their daughters; and a higher concern for welfare of families in a P.O.W. situation. Although responding in a similar manner to most questions, male and female military aircrew differ in the perception of their ability to function in mixed squadrons because of their gender. Some of these perceptions can be modified through training, others may need to be resolved through high level orders/policy; while in others, the military may have to accept women are different from men in some aspects.Abstract
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Experiments in the visual modality show that acute hypoxia slows the earliest stage of information processing-preprocessing. It is unknown, however, whether a later stage, feature extraction, is also slowed. To answer this question, an additive factors method (ARM) experiment was conducted which employed seven well trained subjects whose arterial oxyhaemoglobin saturation was controlled at 63% with low oxygen mixtures. The subjects responded to oddball names presented on a computer screen and both reaction time (RT) and the event-related brain potential P300 were measured. The luminance and quality of the names was varied factorially to influence the preprocessing and feature extraction stages, respectively. RT and P300 latency showed the same pattern of results: stimulus luminance and signal quality were additive, indicating that ArM assumptions were met; hypoxia and stimulus luminance were interactive but hypoxia and signal quality were additive. In conjunction with other evidence, we interpret these results to indicate that the locus of slowing produced by hypoxia is largely at the preprocessing stage, at least in the visual modality. Slowing at the preprocessing stage can be explained by hypoxia shifting the function relating RT and stimulus luminance to the right by a constant amount.Abstract
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The most common pharmacological agents for alleviating symptoms of motion sickness in the U.S. are over-the-counter antihistamines. Two example are dimenhydrinate (Dramamine) and cyclizine (Marezine). Dramamine and Marezine suppress overall motion sickness symptoms with equal effectiveness, but Dramamine affects the central nervous system (CNS), while Marezine affects the stomach directly. This study employed a double-blind, within-subject design to compare the effectiveness of Marezine (50 mg) and Dramamine (50 mg), in preventing subjective symptoms and gastric dysrhythmias associated with motion sickness. The sedative effects of the two drugs were also compared. Electrogastrograms (EGGs) were recorded from 23 subjects during 2 counterbalanced sessions for 3 trial periods: an 8-min pre-drug baseline, an 8-min pre-rotation baseline, which began 30 min after drug ingestion, and a 16-min period of exposure to a rotating optokinetic drum. Subjects reported any subjective symptoms of motion sickness (SSMS) and drowsiness before and during induction of motion sickness. There were no statistically significant differences between the two drug conditions for the overall mean SSMS scores. However, when the scores were divided into symptom groups, Marezine was associated with significantly lower scores than Dramamine for gastrointestinal (GI) symptoms. Also, Marezine was associated with significantly less drowsiness than Dramamine 30 min after ingestion. Power in both the normal (3 cpm) and tachyarrhythmia (4-9 cpm) ranges of the EGG increased significantly more during rotation compared to baseline in the Dramamine condition than in the Marezine condition. Marezine and Dramamine are similarly effective in preventing the overall subjective symptoms of motion sickness. While Dramamine's effectiveness may be related to its sedative properties, Marezine may work more directly on the stomach and thus be more effective in preventing gastric dysrhythmias and reports of GI symptoms.Abstract
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In order to study relationships between acute mountain sickness (AMS) observations done both during a short-term hypoxic exposure in a hypobaric chamber, and in field conditions during a high altitude expedition, nine subjects were submitted to a 9-h hypoxic exposure in a hypobaric chamber. Then, they experienced a high altitude expedition in the Himalayas. The Lake Louise AMS scoring system was used to assess AMS in both conditions, especially the self report questionnaire. During the expedition, the mean self report score of each subject, defined as the ratio between the sum of daily self report scores and the duration of the expedition, appears to be correlated not only to the maximal self report score observed in altitude (r = +0.77, p > 0.05) but also to the self report and self report + clinical assessment scores observed at the end of the hypobaric chamber sojourn (r = +0.81, p > 0.01 and r = +0.75, p > 0.05, respectively). In conclusion, the Lake Louise AMS scoring system, especially the self report questionnaire, is relevant to assess AMS with simplicity and rapidity both in laboratory and in field conditions. Our study also suggests that AMS induced by a short term sojourn in a hypobaric chamber is related to AMS observed in field conditions.Abstract
The effect of anti-retroviral medications on the cognitive functions important in flying has not been determined. Anti-retroviral medications have no effect on the cognitive performance of individuals at the CDC 4C2 (symptomatic HIV disease with no illness indicative of full-blown AIDS) stage of infection. A two-group study using a cross-sectional design was used. The participants in each group represented a sample of convenience obtained from a larger, naturalistic study. Each group consisted of 10 HIV+ males at the CDC 4C2 stage of infection. The two groups were found to be comparable on age, education, pre-morbid intelligence, and ethnicity. All members of the anti-retroviral medication group.had been receiving medications for at least 3 mo. Those in the control group (no anti-retrovira[ medication) had received no anti-retroviral medications for at least 6 mo. Cognitive functioning was assessed using a computerized information processing battery that included tests similar to those under consideration for inclusion in military pilot selection batteries and a neuropsychological battery. As part of the larger study, the participants were carefully and repetitively screened on factors known to affect performance on neuropsychologica[ instruments. The groups showed little difference in cognitive functioning. Although more research is needed, anti-retroviral medication does not impair, and may improve, the cognitive processes of individuals with symptomatic HIV infection who do not have AIDS.Abstract
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There is a paucity of published work in which the performance of Emergency Underwater Breathing Aids (EUBA) has been examined in the wide range of scenarios in which helicopter underwater escape may be necessary. In the present investigation two EUBA were examined: the Air Pocket (AP) rebreather and the Short Term Air Supply System (STASS) mini SCUBA set. Young, healthy male subiects undertook simple simulated helicopter underwater escapes in water at 15° and/or 5° During the immersions the subjects attempted to remain submerged for 60s while traversing back and forth along a ladder secured at a depth of 1.25m. At each temperature the subjects used AP and STASS twice. The subjects were dressed in the Royal Navy winter sea helicopter aircrew equipment assembly and an aircrew helmet. Both AP and STASS significantly extended the underwater survival time of individuals when compared to their maximum breath-hold time (BHT). It is clear from the measurements made of gas concentrations in AP; the volume of air used from STASS; and subjective responses, that the 60-s submersions were achieved more easily with STASS than AP. It is concluded that in conditions similar to those of the present experiment STASS will give a longer underwater duration than AP, but this benefit must be offset against the possible risk of pulmonary barotrauma associated with the use of STASS, as well as increased training and maintenance costs. Irrespective of the EUBA which is provided, in-water training, preferably including exposure to cold water, will significantly improve the ability of an individual to use it.Abstract
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A comprehensive study of the effect of Head-Supported Devices (HSDs) on neck loading during helicopter accidents is presented. The new Articulated Total Body (ATB) model which treats the neck as a deformable segment was used for crash simulation. Different categories of human and manikin subjects were considered under several crash scenarios. Simulations were theoretically designed to include a wide range of HSDs by changing their weights and center of gravity (CG) locations relative to the head, and studying the effects of these changes. Since HSDs were only theoretically included in the model, detachment of specific detachable devices used in most military applications was not modeled in the study. Hence, two typical detachable devices were modeled and selected simulations were repeated and compared not only to provide a measure of accuracy for the original results but also to see the effect of separation of these devices from the helmet.Abstract
It has been suggested that meticulous preflight medical screening of airline passengers would prevent most in-flight medical emergencies and it has been estimated that medical assistance is sought on around 1 in 50 international flights on wide bodied domestic aircraft. It was considered that the legal implications of such screening needed to be determined. A literature review of current legislation, court cases, and legal and medical journals was conducted. It was found that the legal problems with preflight medical screening fell into three areas: discrimination, right to free movement, and guidelines to medical contraindications to flying. It was considered that precluding someone from flying on medical grounds could in certain circumstances be construed as discriminatory or a breach of the basic human right of freedom of movement and, thus, unlawful. Current guidelines on medical contraindications to flying vary and there are presently no internationally agreed or legally enforceable protocols on the subject. Pre-flight medical screening of civil airline passengers may offer a means of reducing in-flight morbidity, but the complexity of the legal issues involved are such that it is unlikely to be introduced in the near future.Abstract
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In light of greater emphasis on global reach, fatigue has a real potential to negatively impact the U.S. Air Force (USAF) mission. Sustained operations and extended air missions will become ever more common and critical in a smaller USAF and human performance may be the most important limiting factor in the effectiveness of advanced weapons systems. Pharmaceuticals may be considered for fatigue countermeasures. A literature review was conducted to examine the potential of zolpidem as a pharmaceutical countermeasure against fatigue in USAF operations. Zolpidem is a hypnotic which appears to cause less global impairment than benzodiazepines during peak effect, and is free of persistent performance decrement or hangover effect. Few adverse effects have been reported. Several studies suggest a benefit of effective sleep produced by hypnotics on next day performance compared with sleep of questionable quality using no medication. The USAF should conduct further investigation into the potential safety and efficacy of zolpidem during sustained operations and extended air operations.Abstract
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Fatigue is an insidious threat to aviation safety because of the impairments in alertness and performance it creates. The fatigue associated with sleep loss, shift work, and long duty cycles can cause aviators to become sloppy, inattentive, careless, and inefficient. The only cure for fatigue is adequate sleep; however, gaining sufficient amounts of sleep is often difficult because of work requirements, family demands, or poor sleep habits. Although it may not be possible to avoid some of these problems, pilots can improve their sleep habits and thus gain more restful and restorative sleep by using self-administered relaxation therapy, establishing consistent and soothing bedtime routines, and avoiding certain activities and substances immediately prior to sleep. When opportunities for adequate sleep are not available because of work-related factors, prophylactic naps can sustain performance until sleep is possible.Abstract
The history of disqualified (DQ) subjects from 1973-1993 at Armstrong Laboratory, Wright Patterson AFB, is presented for both sustained and impact acceleration panels. Candidate and subject medical records were reviewed for screening results, recommendation for panel duty, and any follow-up medical findings. The generation and interpretation of the medical screening criteria and DQ rates are discussed. Medical Screening The mechanisms for change, those factors influencing change, and the interpretation of the screening criteria for Armstrong Laboratory's acceleration panels determine the panel's composition, which is reflected in the DQ rates. The centrifuge had a 5% (7/132) disqualification (DQ) rate from 1973-93 with 29% (2/7) due to musculoskeletal and 71% (5/7) for medical reasons. All were DQ during 1973-88. The impact parcel had a DQ rate of 18% (36/195) with 71% (24/34) DQ due to musculoskeletal and 29% (10/34) for medical reasons. Only 28% (10/36) were DQ during 1973-88, while during 1989-93, 72% (26/36) were DQ. The differences in DQ rates between the centrifuge and impact facility were due to the variability or conservatism of individual physicians, interpretation of the medical screening criteria, and the type of research being done. These factors effect the composition of the human subject panels. This determines to which target population the research data can be applied. If the subjects do not represent pilots due to inappropriate screening, then there is no benefit from the research and, therefore, there can be no risk incurred by the subjects.Abstract
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In recent years, aircraft manufacturers have been considering a very large airplane with a capacity of 600-1000 passengers. The human factors aspects of such an unprecedented enterprise demand that the aerospace medicine community take an active role early on in the design phase. Consequently, the Aerospace Medical Association formed an international task force to prepare a paper containing pertinent human factors recommendations for the manufacturers. This paper, including the recommendations herein, has been forwarded to Boeing and Airbus as well as to 50 major airlines of the world.Abstract