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Biomedical subjects

G W McCarthy

Publications and source records attributed to G W McCarthy.

7 recordsLinked to original sources
PubMed1997

Review of major injuries and fatalities in USAF ejections, 1981-1995.

Our laboratories are examining injuries and deaths resulting from mechanical forces applied to aircrew members in the course of Department of Defense aviation operations. In this paper we report only on bodily injuries sustained during ejection from US Air force, aircraft for the fiscal years 1981-1996, that is, major injuries and fatalities resulting directly from seat acceleration forces, from aerodynamic forces applied to crew members during escape through the effects of windblast and parachute opening shock; from direct contact: and from parachute landing injuries. Such injuries occur typically to the head, neck, cervical spine, thorax, thoracolumbar spine, ribs, pelvis, and the upper and lower extremities. Injuries are usually caused by anomalies in the ejection sequence or by delaying ejection until too close to the ground. Conversely, a planned ejection in a modern ejection seat in controlled, low speed flight imposes forces well below injury thresholds. In the USAF, 10-50 aircrew eject yearly, with a decline since 1991. We conclude that the risk of fatality is 0-11% and of major injury is 2-25%. Both are remarkably low and decreasing in the later years of this study period. The absolute number of head, neck, and spine injuries is 0-10 yearly and similarly decreasing. The results of this study are intended to provide a basis for estimating potential savings in deaths, injuries, and costs expected from the development of improved protective measures.

Accidents, Aviation↗
PubMed1995

Flying therapy for flying phobia.

INTRODUCTION: Optimum treatment for aircrew who have developed anxiety associated with flight includes a flying phase for desensitization. However, standardized flight profiles are not found in the literature. In this study, a method of desensitization flying, which may increase the probability of a return to productive flying, was devised and assessed. METHOD: Seven aircrew were referred for flying desensitization. Behavioral therapy (relaxation training, imaginary flying, and thought switching) was usually continued by the Medical Officer (Pilot) (MOP). These aircrewmen flew 2-16 sorties in the RAF IAM Hawk or Hunter aircraft with the MOP. Each flight was structured with three purposes: to approach by increments the flight conditions in each victim's anxiety hierarchy, to regulate the amount of low workload, anxiety-vulnerable time during each sortie, and to practice relaxation techniques in the air. RESULTS: In all referred aircrewmen, anxiety was controllable in flight at IAM. Somatic signs diminished and no sortie was terminated early. All returned to operational flying. Anxiety recurred in one fast jet pilot while flying solo, and in one navigator, both of whom requested a change to transports. A transport pilot had recurrent uncontrollable anxiety at high altitude and is grounded. At 9-24 months follow-up, 5/7 were flying comfortably with rare, controllable anxiety. We conclude that actual exposure to flying is usually necessary for aircrew to recover from anxiety associated with flight.

Adult↗
PubMed1994

In flight verification of the inversion illusion.

Pilots' sensations of orientation while pushing over (bunting) are inconsistent. We flew 13 aircrew or naive subjects individually in a Hawk or Hunter jet training aircraft. With sun visor down and eyes closed, each was asked to report what the aircraft was doing. After unaccelerated level flight for 30 s, the aircraft was accelerated in level flight from 200 to 250 kts at +0.15 to +0.25 Gx, and gently pulled into a stable 250-kt, 3000 ft/min climb. After 30 s, it was pushed to -1 G during 3 s. Minus 1 G was then held for a further 3 s. Of 30 maneuvers, 14 produced sensations of inversion in 9 of 13 subjects. Two subjects reported feet-up rotation to the inverted; one felt a rotation of indeterminate direction; five felt sudden inversion. This illusion was experienced by 3/3 naive non-pilots, 6/8 pilots, and 0/2 test pilots. We conclude that the "inversion illusion" exists, and that the postulated sensation of backward rotation is often not perceived.

Acceleration↗
PubMed1994

The effect of a new ejection seat headbox and high G garments on head mobility during air combat.

Full coverage anti-G trousers, a chest counter pressure garment for positive pressure breathing for G tolerance, and a smaller ejection seat headbox have been developed for future agile aircraft. The hypotheses that the new headbox might improve, and that the more restrictive high G garments might compromise, pilot head mobility were tested. The RAF institute of Aviation Medicine Hawk aircraft was equipped with a wide angle video camera facing the front seat pilot. Two experimental conditions were compared to the control air combat sortie: 1. standard garments and the smaller headbox; 2. high G garments and the smaller headbox. Data were recorded from five instructor pilots during three scheduled air combat training sorties. Their helmets were marked with 10-mm white dots in a standardized pattern. Software for recording helmet dot positions from single frame video images, and a trigonometric method for calculating head rotation and translation from changes in the helmet dot positions were devised. No differences were found between headboxes or garments at the three extremes of head movements analyzed. Observed neck rotations were similar to maximal seated norms. Optimal head and neck extension is impeded by the ejection seat headbox. Pilots' head movements are not restricted during air combat at moderate G levels.

Aerospace Medicine↗
PubMed1988

USAF take-off and landing ejections, 1973-85.

Ejection on or near the ground appears potentially injurious, especially since the survival rate decreases as altitude of ejection decreases. Ejection data from 1973 through 1985 were reviewed to analyze whether ground-level take-off and landing ejections posed an increased risk of injury or death. This review included only ejections clearly requiring a decision between ground egress and ejection. There were 15 aircraft with 25 crewmembers identified; 22 of them had ejected. Ejection systems performed as designed 91% of the time. Three crewmembers were killed during ejection, yielding a survival rate of 86%. Four ejectees suffered spinal compression fractures from ejection force. Two of these also fractured other vertebrae during the parachute landing fall, for a major injury rate of 21%. In only 33% was ground egress probable. Survival and injury rates for ejection on the ground did not differ significantly from those above 500 ft (p less than 0.05). Ejection during take-off and landing phases is as safe as ejection above 500 ft. safer than other ejections below 500 ft, and does not result in excess injury rates. Ejection systems are sometimes damaged by impact or fire. In the emergencies considered, ejection offered greatly increased chances for survival over ground egress.

Accidents, Occupational↗