Gravity-induced Loss Of Consciousness Research Articles

Get on the Round Dial: Fighter Pilot Strategies for Recovering Situation Awareness After Disorienting Physiological Events

Despite decades of research and training, adverse physiological events continue to present a significant risk to pilots. This paper describes a naturalistic study of fighter pilot experiences with disorienting physiological events such as gravity-induced loss of consciousness (G-LOC), hypoxia, and spatial disorientation. We conducted a cognitive task analysis with 10 experienced fighter pilots to elicit incidents in which the pilot or another pilot in the flight experienced a physiological event, exploring how they recognized something was wrong, assessed the level of impairment, and regained situation awareness. We describe cognitive requirements, specific cues and strategies, as well as complexities associated with managing these disorienting physiological events. Implications for decision support design and training are discussed.

Physical strength, body composition, and G-test results of air force cadets based on nutrition knowledge differences

The Gravitational Acceleration Test (G-test) is a demanding, and sophisticated high-intensity physical activity, greatly influenced by individual body composition and physical strength. This study analyzed the general nutrition knowledge questionnaire (GNKQ) responses of Air Force cadets to identify the relationship between nutrition knowledge, body composition, physical activity, physical strength, and gravity-induced loss of consciousness. Based on the G-test results, 105 fourth-year Air Force cadets were divided into two groups: GP (G-test pass group) and GF (G-test fail group). The analysis items were GNKQ responses, body composition, and physical strength analysis, based on which independent sample t-tests , and logistic regression analysis were conducted. Physical activity according to the G-test results was statistically higher in the GP compared to the GF (vigorous activity reps/week, p = 0.017; mins/day, p = 0.011). The GP Group showed a statistically high GNKQ score compared to the GF Group: Overall (p = 0.003), Section 1 (p < 0.001), and Section 2 (p = 0.002). Based on this study, it can be deduced that analyzing the effect G-test through continuous research over the next years and applying them to physical training will have a greater impact on the cadets’ increased physical strength and their success on the G-test.

G-Induced Loss of Consciousness Prediction Using a Support Vector Machine.

INTRODUCTION: Gravity-induced loss of consciousness (G-LOC) is a major threat to fighter pilots and may result in fatal accidents. The brain has a period of 5-6 s from the onset of high +Gz exposure, called the functional buffer period, during which transient ischemia is tolerated without loss of consciousness. We tried to establish a method for predicting G-LOC within the functional buffer period by using machine learning. We used a support vector machine (SVM), which is a popular classification algorithm in machine learning.METHODS: The subjects were 124 flight course students. We used a linear soft-margin SVM, a nonlinear SVM Gaussian kernel function (GSVM), and a polynomial kernel function, for each of which 10 classifiers were built every 0.5 s from the onset of high +Gz exposure (Classifiers 0.5-5.0) to predict G-LOC. Explanatory variables used for each SVM were age, height, weight, with/without anti-G suit, +Gz level, cerebral oxyhemoglobin concentration, and deoxyhemoglobin concentration.RESULTS: The performance of GSVM was better than that of other SVMs. The accuracy of each classifier of GSVM was as follows: Classifier 0.5, 58.1%; 1.0, 54.8%; 1.5, 57.3%; 2.0, 58.1%; 2.5, 64.5%; 3.0, 63.7%; 3.5, 65.3%; 4.0, 64.5%; 4.5, 64.5%; and 5.0, 64.5%.CONCLUSION: We could predict G-LOC with an accuracy rate of approximately 65% from 2.5 s after the onset of high +Gz exposure by using GSVM. Analysis of a larger number of cases and factors to enhance accuracy may be needed to apply those classifiers in centrifuge training and actual flight.Ohrui N, Iino Y, Kuramoto K, Kikukawa A, Okano K, Takada K, Tsujimoto T. G-induced loss of consciousness prediction using a support vector machine. Aerosp Med Hum Perform. 2024; 95(1):29-36.

High G Tolerance and Cardiopulmonary Reserve Function in Healthy Air Force Aviators.

INTRODUCTION: There is no consensus on whether cardiopulmonary reserve affects the risk of gravity-induced loss of consciousness (G-LOC) or almost loss of consciousness (A-LOC). Few previous studies have used cardiopulmonary exercise testing (CPET) to assess cardiopulmonary reserve function (CPRF) of fighter aviators. We compared CPET-related parameters in G-LOC/A-LOC and non-G-LOC/A-LOC fighter aviators to explore the effect of cardiopulmonary reserve function on G tolerance.METHODS: A total of 264 male fighter aviators with more than 500 h of flight experience participated in the study, all of whom underwent CPET and human centrifuge testing. We divided the aviators into two groups based on whether they experienced G-LOC/A-LOC during the human centrifuge test and compared the CPET parameters between the two groups.RESULTS: A total of 37 aviators (14%) experienced G-LOC/A-LOC. There were no significant differences in age (26.65 ± 4.30 vs. 26.01 ± 4.95), height (173.68 ± 4.21 vs. 173.55 ± 3.37), weight (69.51 ± 6.22 vs. 69.63 ± 6.01), or body mass index (23.06 ± 2.11 vs. 23.11 ± 1.82) between the two groups. Forced vital capacity (FVC) (4.95 ± 0.87 vs. 4.65 ± 0.79) and forced expiratory volume in 1 s (FEV1) divided by FVC (FEV1/FVC) (79.88 ± 7.24 vs. 83.72 ± 9.24) of pulmonary function of the G-LOC/A-LOC group was significantly lower than that of the non-G-LOC/A-LOC group. There was no significant difference in CPET-related parameters between the two groups.DISCUSSION: In conclusion, FEV1/FVC may be a factor affecting aviators' G-LOC/A-LOC, meaning aviators with slightly lower ventilation are more likely to experience G-LOC/A-LOC. However, oxygen uptake and exercise blood pressure, oxygen pulse, etc., may not be the main factors influencing G-LOC/A-LOC.Lan X, Zhu W, Du J, Wang J, Yang M, Xu Y, Cao Y. High G tolerance and cardiopulmonary reserve function in healthy air force aviators. Aerosp Med Hum Perform. 2023; 94(12):911-916.

The Effects of Body Composition, Physical Fitness on Time of Useful Consciousness in Hypobaric Hypoxia.

Several previous studies have reported that hypoxia accidents of fighter pilots are rarer than gravity-induced loss of consciousness and spatial disorientation; however, the risk is greater. Therefore, this study aimed to investigate the relationship between physical fitness and body composition on time of useful consciousness (TUC) in hypobaric hypoxia. Body composition and physical fitness testing on human participants were performed; subsequently, they were exposed to hypobaric hypoxia at a simulated altitude of 25,000 ft. Cognitive testing of the participants was accomplished by having them perform arithmetic task tables until they stopped writing for a period exceeding 5 seconds, at which point, they were placed on 100% oxygen. TUC was measured from the time the participants removed their oxygen masks to the time when the oxygen masks were placed back on them. Pearson's correlation was used to determine the relationship between TUC and other variables, and multiple regression was performed to determine the independent variables that best explain the TUC. TUC was positively correlated with the maximum oxygen uptake, stroke volume, arteriovenous oxygen difference, and endurance (sit-up and push-up). The maximum heart rate on the ground, high altitude, body fat mass, and percent body fat were negatively correlated with TUC. A regression analysis showed that 84.5% of the TUC can be explained by body composition and physical fitness. Our results revealed that increased cardiorespiratory fitness and decreased body fat mass could significantly impact the TUC. Therefore, for Air Force pilots who are frequently at high altitudes and at risk for exposure to hypoxia, aerobic exercise is significant to hypoxia tolerance.

加速度誘発性意識消失（Gravity-induced loss of consciousness：G-LOC）予測式作成の試み

加速度誘発性意識消失（Gravity-induced loss of consciousness：G-LOC）予測式作成の試み

Wearable bio signal monitoring system applied to aviation safety.

Pilots are required to have the ability to evaluate their own physical and psychological status to operate high performance aircrafts effectively. Existing studies have lacked consideration of applying bio signal of pilots in real time flight situation. The purpose of this study is to develop a wearable bio signal monitoring system that can measure the condition of pilots under an extreme flight environment to ensure flight safety. The wearable bio signal monitoring system consists of an algorithm for evaluating pilots' physiological stability, algorithms for detecting Gravity-induced Loss of Consciousness (G-LOC) prognosis, pilots' interaction module, and pilots' context awareness platform. The algorithm for evaluating pilots' physiological stability uses psychomotor cognitive test (PCT) and heart rate variability (HRV) to measure pilots' mission performance before flight. The algorithms for detecting G-LOC prognosis utilizes electromyogram (EMG) to generate warning signal during flight. The pilots' interaction module was developed for pilots to operate the system efficiently under flight environment. The pilots' context awareness platform was designed for the system to process multiple sensor signals in real time. This wearable bio signal monitoring system is expected to enhance flight safety and mission performance of pilots.

Shedding Light on the Tunnel and Light in Near-Death Experiences: A Case Study

Partial abstract: In this article, we present a case study of an adult male who experienced both gravity induced loss of consciousness (G-LOC) as a Korean War aviation cadet, including narrowing of his visual field to a point of light and also two subsequent transpersonal experiences -- a near-death experience (NDE) and an after-death communication (ADC) -- that both included a tunnel-and-light feature. His Near-Death Experience Scale scores for each experience and his comparison of the qualia of these experiences provide unique evidence in the debate about the nature and likely origins of such experiences. These data place more weight on the argument that the tunnel and light in transpersonal experiences cannot reasonably be attributed to loss of oxygen in the brain.

Physical Condition Does Not Affect Gravity-Induced Loss of Consciousness during Human Centrifuge Training in Well-Experienced Young Aviators.

BackgroundConsensus on whether physical condition affects the risk of gravity-induced loss of consciousness (G-LOC) has not been reached, and most previous studies about the issue did not include well-experienced aviators. We compared the physical conditions of well-experienced young aviators according to the occurrence of G-LOC during human centrifuge training.MethodsAmong 361 young male aviators on active flight duty with experience in high performance aircrafts for at least 2 years, 350 had full data available and were reviewed in this study. We divided the aviators into the G-LOC group and the non-G-LOC group according to their human centrifuge training results. We then compared their basic characteristics, body composition, physical fitness level, and pulmonary function.ResultsTwenty nine aviators (8.3%) who experienced G-LOC during human centrifuge training in their first trials were classified into the G-LOC group. There was no difference in physical condition of aviators between the two groups.ConclusionsYoung aviators with experience in G-LOC showed no difference in physical condition such as muscle mass, strength, and general endurance from the aviators with no such experience. Although more studies are needed, physical condition does not seem to be a significant determinant of G-LOC among the experienced aviators.

Anti-G 슈트 공압 제어를 위한 제어법칙 개발

F-22, F-16 및 F-15와 같은 고성능 전투기는 전투성능의 극대화를 위해 고기동성(highly maneuverable)을 보유하고 있다. 이로 인해 고기동 시에 조종사는 고중력가속도(high gravity acceleration)에 노출되고 피로도(fatigue)의 증가로 임무효율의 저하가 발생하며, 심할 경우에는 의식상실(Gravity-induced Loss Of Consciousness, GLOC)에 직면할 수 있다. 선진 항공업체에서는 조종사가 고중력가속도에 견딜 수 있는 내성을 향상시켜 의식상실에 진입하는 것을 방지하는 다양한 기술을 항공기에 적용하고 있다. 특히, 가속도방호복(Anti-G Suit)은 GLOC으로 인한 의식 상실을 방지할 수 있을 뿐만 아니라, 전투 기동 시에 조종사의 피로를 감소시킴으로써 임무성공률을 향상시킬 수 있다. 본 논문에서는 초음속 고등훈련기 모델을 기반으로 하여 고기동 시에 중력가속도의 증가에 따라 AGS에 최적의 공기압을 제공할 수 있는 제어알고리즘을 개발하고 검증하였다. 이러한 결과는 추후에 체계개발이 진행될 한국형전투기개발사업(Korean Fighter eXperimental, KF-X)에서 핵심기술을 개발하는데 기여하리라 기대한다. The highly maneuverable fighter aircraft such as F-22, F-16 and F-15have the high maneuverability to maximize the combat performance, whereas the high maneuver characteristics might degrade the pilot's mission efficiency due to fatigue's increase by exposing him to the high gravity and, in the worst case, the pilot could face GLOC (Gravity-induced Loss Of Consciousness). The advanced aerospace company has applied the various technologies to improve the pilot's tolerance to the gravity acceleration, in order to prevent the pilot from entering the situation of the loss of consciousness. Especially, the Anti-G Suit(AGS) equipment to protect the pilot against the high gravity in flight could improve the mission success rate by decreasing the pilot's fatigue in the combat maneuver as well as prevent the pilot from facing GLOC. In this paper, a control algorithm is developed and verified to provide an optimal air pressure to AGS according to the gravity increase during the high performance maneuver. This result is expected, as the key technology, to contribute to the KF-X(Korean Fighter eXperimental), project in the near future.

Formal Verification of a Gravity-Induced Loss-of-Consciousness Monitoring System for Aircraft

Military-related industries have developed many high-gravity aircraft, such as high-performance fighters and aerobatic aircrafts, which can maneuver beyond the acceleration tolerance limit of human beings. Gravity-induced loss of consciousness (GLOC) due to blood draining away from the brain is one of the main reasons for many high-gravity maneuvering aircraft accidents with many pilots losing their lives. Therefore, many automatic GLOC-monitoring systems have been proposed to prevent these accidents. However, it's not a trivial task to ensure system safety by ordinary simulation or testing methods. This article presents a case study to verify a GLOC monitoring system by using a model-checking technique. As a result of this verification, the authors report a case where the GLOC monitoring system misses, in which a pilot loses consciousness after some intentional movements.

중력 가속도로 인한 의식상실 감지 및 자동 회복 시스템 개발

For many years, many lost their lives and aircrafts due to GLOC(Gravity-induced Loss Of Consciousness). Due to the emergence of high-gravity maneuvering aircraft such as the F-16, F-15 and T-50, the automatic GLOC detection and recovery systems are necessary to increase the aircraft safeties even when the pilot loses his consciousness due to high-G maneuvering. This paper addresses the design of GLOC detection, warning and recovery algorithm based on a model of supersonic jet trainer. The system is solely controlled by the pilots control input(i.e., control stick force) and aircraft status such as attitude, airspeed, altitude, altitude and so forth. And, moreover, it does not depend upon any pilot physiological condition. The test evaluation results show that the developed system supports the recovery of an aircraft from the unusual aircraft attitude and imporves the aircraft safeties even when the pilot loses his consciousness due to high-G maneuvering.

Concerns about relationship between the geometry of internal jugular vein during anti-G straining maneuver and gravity-induced loss of consciousness

It is with great interest that we read the recent report from Choi et al. focusing on the relationship between the shape and size of internal jugular vein during anti-G straining maneuver (AGSM) and gravity-induced loss of consciousness (G-LOC) in human centrifuge in trainee pilots (Choi et al. 2010). We would like to comment on the experimental design and conclusion made by the authors. A sustained positive Gz load may result in a sudden and dangerous grey-out, black-out and Wnally loss of consciousness due to cerebral blood pressure and cerebral blood supply drop (Wood et al. 1963). The incidence of G-LOC reported by the US Air Force, the US Navy, and the military of other countries clearly reveals the importance of G-protection methods to prevent the hazards of G-LOC (Chen et al. 2004; Rudnjanin et al. 2006). The AGSM is one of the eVective G-protection measures. It involves repeated Valsalva manoeuvres for 3 s every Wfth second with semiclosed or closed (Balldin 1986; Shubrooks and Leverett, 1973) glottis, while straining the muscles in the leg, abdomen and arms. When performing AGSM, the increased intrathoracic pressure is directly transmitted through the neck blood vessels to the vessels at the headlevel and causes a very fast increase in retinal and cerebral blood pressure, which thus counteracts the reduced blood pressure during increased G-loads, moreover, the muscle contractions may increase the blood-pressure through vasoactive reXexes to cause vasoconstriction as well as a better venous return with an active muscle pump (Balldin 1986; Eiken et al. 2007; Yang et al. 2007). As a result, AGSM can reduce the risk of black-out and G-LOC (MacDougall et al. 1993). The AGSM may increase the mean G-tolerance by as much as 4G if the pilots perform this maneuver in an extremely eVective manner (Chen et al. 2004). As a kind of a learned skill involving a forced exhalation against a partially or completely closed glottis combined with straining of limb and abdominal muscles, education is important to shorten the learning curve. In the study of Choi et al. (2010), however, all the subjects were trainee pilots; they had not experienced high-performance aircraft and were not familiar with AGSM skills. How could they perform AGSM in an extremely eVective manner, and how to make the same eYciency for centrifuge AGSM and precentrifuge AGSM? In their study, the performing form of AGSM and self-sensation of trainee pilots in +1Gz environment might be quite diVerent with those in human centrifuge high +Gz environment, and the geometry of internal jugular vein during AGSM in +1Gz environment may not be similar to the geometry of internal jugular vein when AGSM was performed in human centrifuge. Accordingly, the conclusion that “concave contour and smaller cross-sectional area of internal jugular vein during AGSM were associated with G-LOC” was ambiguous. The eVectiveness and eYciency of the AGSM is of critical importance in increasing high G-tolerance and preventing the occurrence of G-LOC. The purpose of performing the AGSM is to maintain suYcient cerebral blood Xow; this Communicated by Susan Ward.

Ultrasonographic finding of internal jugular vein during anti-G straining maneuver: is it associated with gravity-induced loss of consciousness?

Gravity-induced loss of consciousness (G-LOC) is caused by loss of cerebral blood flow during high +Gz (head-to-foot inertial forces). The resistance of the jugular vein is a significant factor in decrease in cerebral blood flow. Ultrasonography of thoracic inlet veins, including internal jugular vein, is feasible to visualize the internal jugular vein and hemodynamic information. Anti-gravity straining maneuver (AGSM) was widely recognized as one of the important factors in preventing G-LOC. The purpose of this study was to evaluate the relationship between the ultrasonographic shape and size of internal jugular vein during AGSM and G-LOC. 47 trainee pilots who participated in human centrifuge education program were enrolled. They were all men, and their mean age was 23.9 +/- 1.38 years. Questionnaire sheets were used to collect information about well-being sensation, smoking, drinking, height, and weight. Using ultrasonography, we monitored shape and size of internal jugular vein during AGSM. After ultrasonographic examination, 47 subjects underwent human centrifuge on the same day. The protocol of human centrifuge training was maximal 6G with sustaining time of 30 s. G-LOC occurred to ten out of 47 subjects in human centrifuge. To find presumptive variable associated with G-LOC, we performed logistic regression analysis. Concave contour and smaller cross-sectional area of internal jugular vein during AGSM were associated with G-LOC.

On Tracking the Course of Cerebral Oxygen Saturation and Pilot Performance During Gravity-Induced Loss of Consciousness

The aim of this study was to track the course of cerebral tissue oxygen saturation (rSO2) and pilot performance during an episode of gravity-induced loss of consciousness (GLOC). GLOC, a major problem facing pilots of high-performance aircraft, is brought about by a sudden reduction in rSO2 as a result of increased +Gz force. It consists of 24 s of complete functional impairment followed by a prolonged period of performance recovery. This study tested the hypothesis that delayed recovery in GLOC is caused by a slow return of rSO2 following removal of the g-force that induced the episode. GLOC was induced in U.S. Air Force personnel via a centrifuge with math and tracking tasks emulating flight performance. A near-infrared spectroscopy unit provided the rSO2 measure. Declines in rSO2 from baseline pinpointed when pilots would cease active flight control and when GLOC would set in. Counter to expectation, rSO2 returned to baseline levels shortly after the centrifuge came to a complete stop following GLOC onset. Nevertheless, performance deficits continued for 49.45 s thereafter. The prolonged performance recovery time in GLOC cannot be attributed to delays in the return of rSO2. This finding explains why previous ergonomic efforts to shorten the duration of GLOC episodes by increasing the rate of return of rSO2 have not been fruitful. Evidently, another approach is needed. Such an approach might use the close linkage between loss of rSO2, performance deterioration, and GLOC onset to develop a warning system that would permit pilots to take effective action to avoid GLOC incapacitation.

Negative Acceleration and Adaptive Automation Approaches to Counter the Effect of Acceleration Induced Loss of Consciousness

Gravity-induced loss of consciousness (GLOC) is a major human factors problem facing fighter pilots today. A recent study by Tripp et al. (2006) reported that the GLOC episode consists of 24 sec of unconsciousness and confusion/disorientation followed by 55 sec in which performance efficiency is compromised. Hence, fighter pilots in the throes of GLOC can travel 12 miles while not in control of their aircraft. Using a centrifuge to simulate gravitational forces together with tracking and math tasks to simulate flight control and navigation, this study attacked the GLOC problem in two ways: (1) by employing negative acceleration following GLOC onset to decrease GLOC recovery time and (2) by assessing the utility of a of cerebral tissue oxygen saturation (rSO2) measure as a possible triggering mechanism for an adaptive automation recovery system. Negative acceleration had no significant effect on the duration of the GLOC episode. Declines in rSO2 from baseline pinpointed when pilots would cease active flight control and when GLOC would set in. Thus, the rSO2 measure may be of effective value as an adaptive automation GLOC recovery system trigger. The rSO2 measure also showed that loss of blood oxygen is not the sole factor underlying performance deficits in GLOC. Tissue oxygen saturation retuned to baseline levels shortly after the centrifuge came to a complete stop following GLOC onset but the performance deficits continued for 55 sec after rSO2 returned to baseline. Cleared for Public Release Distribution Unlimited

+Gz Acceleration Loss of Consciousness: Use of G-suit Pressurization and Sensory Stimulation to Enhance Recovery

Gravity-induced loss of consciousness (GLOC) is the second largest human factors problem facing fighter pilots today. Whinnery, Burton, Boll, and Eddy, (1987) found that the GLOC event consists of a 24-sec period of total incapacitation involving unconsciousness and confusion. A study by Tripp, et al. (2006) found that the GLOC problem was much worse that originally thought with total performance incapacitation lasting for 87 sec. The two studies described herein were designed to decrease the time required to recover from the GLOC event. Toward that end, the first study employed an anti-G suit inflation technique while the second study exposed participants to accessory auditory, visual, and tactile stimulation following GLOC. Both procedures significantly reduced the duration of the GLOC episode but the reductions were not substantial enough to be functionally effective.

Frontal cortical oxygenation changes during gravity-induced loss of consciousness in humans: a near-infrared spatially resolved spectroscopic study

Gravity (G)-induced loss of consciousness (G-LOC), which is presumably caused by a reduction of cerebral blood flow resulting in a decreased oxygen supply to the brain, is a major threat to pilots of high-performance fighter aircraft. The application of cerebral near-infrared spectroscopy (NIRS) to monitor gravity-induced cerebral oxygenation debt has generated concern over potential sources of extracranial contamination. The recently developed NIR spatially resolved spectroscopy (SRS-NIRS) has been confirmed to provide frontal cortical tissue hemoglobin saturation [tissue oxygenation index (TOI)]. In this study, we monitored the TOI and the standard NIRS measured chromophore concentration changes of oxygenated hemoglobin and deoxygenated hemoglobin in 141 healthy male pilots during various levels of +G(z) (head-to-foot inertial forces) exposure to identify the differences between subjects who lose consciousness and those who do not during high +G(z) exposure. Subjects were exposed to seven centrifuge profiles, with +G(z) levels from 4 to 8 G(z) and an onset rate from 0.1 to 6.0 G(z)/s. The SRS-NIRS revealed an approximately 15% decrease in the TOI in G-LOC. The present study also demonstrated the TOI to be a useful variable to evaluate the effect of the anti-G protection system. However, there was no significant difference found between conditions with and without G-LOC in subjects with terminated G exposure. Further studies that elucidate the mechanism(s) behind the wide variety of individual differences may be needed for a method of G-LOC prediction to be effectively realized.

+Gz Acceleration Loss of Consciousness: Time Course of Performance Deficits With Repeated Experience

We examine the time course of performance recovery from gravity-induced loss of consciousness (GLOC) and evaluate the utility of exposing participants to repeated bouts of GLOC in promoting recovery time. A substantial number of accidents among fighter pilots have resulted from episodes of GLOC. U.S. Air Force doctrine holds that when pilots experience GLOC, impairment lasts for 24 s, in which there are 12 s of complete unconsciousness and 12 s of confusion. However, there is reason to suspect that performance efficiency associated with GLOC is degraded well before unconsciousness sets in and that more than 24 s are required for performance efficiency to return to baseline levels. Additionally, there is a belief that repeated exposure to GLOC will reduce recovery time. Centrifuge simulators were used to induce GLOC in U.S. Air Force personnel with math and tracking tasks employed to emulate flight performance. Participants were tested once per week for 4 consecutive weeks. On average, performance deficits appeared 7.44 s prior to the onset of unconsciousness and persisted for 55.6 s following the GLOC event. Repeated exposure failed to moderate these results. The temporal course of performance deficits produced by GLOC far exceeds prior estimates. The problem is more serious than previously envisioned and it is not alleviated by repeated exposure to GLOC. U.S. Air Force doctrine regarding the severity of GLOC and the utility of repeated exposure to this problem needs to be revised and these data incorporated into future aircraft auto recovery systems.

+Gz Acceleration Loss of Consciousness: Time Course of Performance Deficits with Repeated Experience

Pilots of modern fighter aircraft encounter episodes of gravity-induced loss of consciousness (GLOC) consisting of complete unconsciousness and subsequent confusion. According to Whinnery, Burton, Boll, and Eddy (1987), pilots are totally incapacitated for 24 sec during such episodes. Using centrifuge simulators to induce GLOC and math and tracking tasks to emulate flight performance, this study confirms the duration of total incapacitation described by Whinnery et al. (1987) and also indicates that the GLOC problem is more serious than they envisioned. Performance efficiency deteriorates from 3.20 to 7.44 sec prior to the onset of unconsciousness and does not return to baseline levels until 55.5 sec after the confusion phase has ended. Thus, at speeds of 500 mph typical of modern fighters, pilots can travel 12.1 miles while not in control of their aircraft. These effects do not appear to be reduced by repeated encounters with GLOC.