The PAVE LOW III aircraft is a modified HH-53H helicopter that has a low altitude—below 30.48 m (100 ft)—night/day rescue mission. The desired night flying configuration is for the pilot to wear night vision goggles (NVGs) to fly the aircraft while the copilot, without NVGs, observes the video display and monitors the aircraft instruments. The problems of NVG incompatibility in the cockpit were successfully countered using several light control techniques. The light control modifications were evaluated on the ground in the PAVE LOW III helicopter at Kirtland AFB in April, 1980, by PAVE LOW instructor pilots. The evaluation results were extremely positive.Abstract
The use of an Aircrew Psychomotor Test Device and the Air Force Officer Qualifying Test have been proposed for the selection of U.S. Air Force pilot training candidates. Random samples of the U.S. Air Force Academy's class of 1978 and the class of 1979 were given the proposed tests and followed through undergraduate pilot training. The results cast serious doubt as to the utility of these tests in selecting U.S. Air Force Academy cadets for pilot training.Abstract
We gave 51 male and 52 female Air Force Academy Cadets a battery of five cognitive and three perceptual motor tests before they were taught four basic flight maneuvers followed by a complex chandelle maneuver. The results showed that the males were much faster in attaining the criterion level of performance on the flight tasks, and that some of the sex differences in the acquisition of task skills can be reduced by means of pretraining on specific cognitive and motor skills. In the prediction of trials to criterion (acquisition rate) of both the basic and the complex flight maneuvers, individually tailoring the regression equations by sex—as opposed to utilizing general overall regression equations—greatly enhanced the predictive capability.Abstract
The Army's aviator selection program began in the mid The first Flight Aptitude Selection Test (FAST) was implemented in 1966 and remained in use until 1980 when changes in personnel, aircraft, and tactics necessitated an improved or revised FAST (RFAST). This paper presents an overview of 1) the composition of the FAST and RFAST; 2) the advantages of the RFAST; and 3) the predictive validity estimates for the FAST and RFAST. Also presented are examples of current research projects which show promise for increasing effectiveness and for broadening the scope of the Army aviator selection program.Abstract
This paper presents the results of two experiments examining individual differences in multiple-task performance. In the first experiment, the subjects were classified according to the response strategy they used to perform two discrete tasks. The subjects then performed three different task combinations on four successive days. A multivariate analysis of variance revealed significant between-strategy group differences in multiple-, but not single-, task performance. The second experiment was designed to determine if the results of the first experiment reflected between-group differences in information processing. The analyses indicated that one strategy group processed multiple-task information significantly more poorly than the other two groups.Abstract
While the basic efficacy of antimotion sickness drugs is rooted in the reduction of motion sickness symptoms, adverse side effects are important practical considerations of their usage in aviation. This study examined the influence of three established antimotion sickness drugs on nystagmic eye movement responses to angular acceleration (whole-body movement) with vision either permitted or denied, and to optokinetic stimulation (visual field movement). Dimenhydrinate and promethazine hydrochloride, particularly at higher dose levels, reduced optokinetic nystagmus, thereby making less accurate the following ability of the eye. During whole-body motion in darkness, there was little placebo-drug difference in the vestibular response under alert conditions; under relaxed conditions, dimenhydrinate and promethazine hydrochloride produced significant declines in the vestibular eye movements. These same drugs also interfered with the ability of the individual to fixate adequately on a visual task during motion. Subjects who received a combination of promethazine plus d-amphetamine were able to suppress vestibular eye movements and maintain good visual fixation under the task condition. Thus, the effect of a drug on nystagmus may be a poor indicator of its value in preventing motion sickness. Moreover, assessments of antimotion sickness drugs for many practical situations should include, as a possible adverse side effect, the inability to maintain visual fixation during motion.Abstract
Impedance cardiography (IC) is a reliable noninvasive technique for monitoring stroke volume (SV) and cardiac output. Transthoracic impedance (Ze) is one variable in the equation used for the calculation of SV. Thoracic impedance reflects the resistivity offered by tissues and air and the length and cross-sectional area of the thoracic volume. The purpose of this study was to evaluate possible differences in Ze between men and women. Measurements (Mean ± S.D.) of Ze in 29 men (age 25.6 ± 4.6 yr) and 35 women (24.2 ± 6.0 yr) in the seated posture revealed Ze values were significantly (p < 0.05) greater for the women (31.5 ± 3.3 ohm) than the men (23.5 ± 1.84 ohm). The observed differences in Ze cannot be attributed to thoracic length; distances between the monitoring electrodes were similar for the men (25.1 cm) and the women (25.7 cm). We hypothesize that the greater Ze observed for women is due to a smaller thoracic cross-sectional area and greater resistivity resulting primarily from relatively more fat tissue, smaller heart size, and lessor central Mood volume as compared with men.Abstract
The effects of altering skin and core temperature by cold exposure and exercise on substrate mobilization and utilization were examined. Six subjects between the ages of 22-27 years rested and exercised in neutral and cold environments to produce 1) a neutral core and neutral skin temperature, 2) a neutral core and cold skin temperature, and 3) a cold core and cold skin temperature. Free fatty acid (FFA), glucose (GL), Lactate (LA), hemoglobin (Hb), and hematocrit (Hct) concentrations were measured along with heart rate (HR), respiratory exchange ratio (R) and oxygen consumption (VO2) after 30, 60, and 90 min of exposure to each condition. FFA, GL, LA, Hb, and Hct concentrations increased significantly during rest when both mean skin temperature (Tsk) and rectal temperature (Tre) were reduced. Plasma FFA concentration was also significantly elevated and R values were reduced during exercise when both Tsk and Ter were lowered compared to exercise in a neutral environment. No significant differences in substrate concentration, hemoconcentration, or R values were observed when Tsk alone was reduced at rest or during exercise. It is concluded that a preferential utilization of fat occurs during exercise in the cold when both Tsk and Tre. are reduced compared to exercise in a neutral environment.Abstract
It is the policy of the Federal Aviation Administration to medically certify individuals for flying who have medical deficiency or disease, provided such action does not compromise air safety. During recent years, for example, standards have been relaxed on contact lens use and medication has been allowed for control of hypertension. This descriptive epidemiologic study of the prevalence of pathology among active airmen as of Jan. 1, 1980—by major body system and for other selected pathologies of interest within the major body systems—used data from active computer files maintained by the Aeromedical Certification Branch of the Civil Aeromedical institute in connection with the certification program. Some 350,701 (42%) active airmen require correction for some visual deficiency. Of this total, 20,058 are contact lens wearers. After eye pathology, cardiovascular and abdominal pathology represent the most prevalent medical conditions among active airmen (3.7% and 2.6% respectively). Overall, disease prevalence is greater among currently certified airmen than among previous groups studied. This increase in prevalence is probably a reflection of more liberal standards more than any other single factor.Abstract
A lew cost, gas-dilution type, high-altitude simulator was developed and found to be a useful model for studying the effect of acute hypoxic exposure on food consumption in the rat. A distinct advantage of this system is that it provides access to the animals without disturbance to the gaseous atmosphere. The onset of hypoxic hypophagia was shown to occur within the first 3 h following abrupt ascent to a simulated altitude of 4419.6 m (14,500 ft). The magnitude of the anorexic effect was uniform throughout the first day of exposure to 12% O2; likewise, food consumption rapidly recovered following return to a sea level atmosphere. It was concluded that the hypophagic effect of hypoxia is not absolute and that the severity of the hypophagia can be reduced by prior food deprivation. However, the degree of attenuation of the hypophagic response was not directly related to the length of the deprivation period. Food deprivation may sufficiently enhance metabolic-induced food demand signals to partially override the inhibitory effect of hypoxia on feeding behavior. Alternatively, metabolic perturbations associated with the food-deprived state may, in some undefined manner, minimize the severity of acute hypoxic stress.Abstract
Oxygen saturation in six subjects wearing a nasal cannula at altitudes of 14,000 ft (4267 m), 20,000 ft (6096 m), 22,500 ft, (6858 m) and 25,000 ft (7620 m) was measured using an ear oximeter (Hewlett-Packard 47201A). Saturation was measured during four activities: at rest breathing through the mouth, at rest breathing through the nose, performing biceps-curls, and talking. Oxygen flow rates of 1.5-2.5 LPM NTPD were used. There was no difference in the saturation levels whether the subject breathed through the nose or through the mouth, and cannula position in the nose was critical to good oxygen saturation. During talking and while exercising, subjects' saturations varied more than during rest conditions, sometimes falling to unacceptable levels. Based upon the lack of hypoxia symptoms and the high levels of oxygen saturation up to 20,000ft (6096 m), it is concluded that at flow rates of 1.5-2.0 LPM NTPD the nasal cannula can be safely used to maintain adequate oxygenation in healthy individuals in hypobaric chamber operations, aircraft flight, and other operations at altitude. Above 20,000 ft (6096 m), the cannula does not provide sufficient oxygenation for persons to perform these physical activities.Abstract
A man was accidentally decompressed to an altitude greater than 22,333 m (74,000 ft) in an industrial vacuum chamber. He experienced burst lung, massive decompression sickness, and sustained ebulism. He remained at altitude for a period of 3-3 min. By 5.5 h following the accident, he was still profoundly unconscious. He was subsequently treated in a hyperbaric chamber with recompression on a modified U. S. Navy Table 6A and had eventual clinical recovery. The CFK peaked at 8000 units 2 d after the accident, demonstrating substantial barotrauma to the tissues.Abstract
In medical fitness examinations of commercial pilots, extensive vestibular investigations should be conducted. In particular, the pendular test, as a weak rotational stimulation method, can disclose central vestibular disorders. Thus, the central nystagmus tracing can be considered as a sign of irritation of vestibular centers, most frequently as a consequence of head trauma, a finding that may influence the decision in the enlistment of the pilot. In contrast, a small nystagmus amplitude tracing is observed in cases of insufficient blood supply, occurring mostly in elderly persons. Therefore, this finding helps to demonstrate and treat arteriosclerotic dizziness in elderly pilots. Cervical-nystagmus— elicited by neck-torsion while keeping the labyrinth fixed at rest-is an objective demonstration of a cervical-spine-syndrome. Aimed therapy, namely chiropractic manipulation, may help the pilot become fit to fly again. Further processing of the data from the vestibular investigations by means of a computer and plotting can provide the so-called cumulative eye position. This enables one to evaluate the compensation capacity which is a measure of the intensity of the vestibular response, important in the assessment of normal function of the vestibular system.Abstract
Aerospace design engineers have long sought concrete data with respect to the thermal safety of materials in contact with human skin. A series of studies on this subject has been completed and some of the results have been reported earlier. In these studies over 2,000 observations were made of pain threshold during contact with materials at elevated temperatues. Six materials were used representing the full range of thermal properties from good conductors to good insulators. Previous reports gave methods for determining the maximum permissible temperatures for any material in safe contact with bare skin for 1-5 s solely from a knowledge of its thermal properties. This report presents the comparison of the theoretical and experimental contact temperatures at pain threshold and provides a method for deriving the skin temperature productive of threshold pain from the thermal properties of any material within the range of those studies. Ratios reflecting the heat transfer coefficient associated with the materials in contact are related to their thermal properties so that the skin temperature at pain threshold may be determined from that calculated from heat transfer theory. Tabular and graphical representation of these data permits interpolation within the range of properties so that any material of known thermal conductivity, density and specific heat may be assessed with respect to its effect on the skin temperature during contact to the end point of pain. These data, in conjunction with those already reported, constitute a system for the complete assessment of the thermal aspects of practically any material suitable for construction and manufacturing applications with respect to safe contact with human skin.Abstract
Negative transfer is defined in the context of this paper as the transfer from one cockpit to another—of different design or configuration—of habits or responses which were appropriate in the former but are inappropriate in the latter, thereby posing a threat to flying safety. This danger has been demonstrated not only experimentally but also in a number of aircraft accident investigation reports. As new aircraft become available to the commercial, military, and private sectors and pilots consequently must transition from older to newer models, the phenomenon of negative transfer becomes increasingly significant. To illustrate the concept of negative transfer and aviation, the author compares the cockpits of two USAF aircraft and how their differences could adversely affect pilot performance. Recommendations are then made on ways organizational flight surgeons can minimize the negative transfer threat to aviation.Abstract
Safety attitudes were elicited by forced-choice questionnaire responses obtained from 141 general aviation pilots in Ohio. The developed questionnaire was pretested on experienced pilots. Specific attitudes in five major categories significant to flight safety were surveyed: aerodynamics, meteorology, preflight activities, flight operations, and aeromedical factors. All pilots were active members of the Dayton Pilots Club. Two levels of concern were identified through the study: the first relates to those areas that are of extreme importance to safety; the second covers items that constitute a safety hazard when combined with other factors.Abstract
This feature is a self-assessment program consisting of questions/answers/references covering all disciplines of aerospace medicine for your continuing medical education. Questions each month will be randomly selected from different subject areas. This is a service brought to you by the Aerospace Medical Association. Take advantage of it.Abstract