The role of visual conditions and aircraft type on different aspects of pilot workload.

OBJECTIVE: The objective of our work was to assess the impact of flight conditions by aircraft type on the workload estimated using NASA-Task Load Index (NASA-TLX). BACKGROUND: Learning about subjective workload is important for assessing the impact of a pilot's work environment on their performance in the cockpit. This is an important element of flight safety and includes the prevention of aviation accidents. METHODS: The study included 146 military pilots that fly the following aircrafts: flying fast-jet (21), fixed-wing (24), and rotary-wing (101). The NASA-TLX questionnaire was used to assess workload and pilots were asked to determine the level of workload resulting from flying under the following conditions: daytime flight (VFR), night-vision flight performed under Night Visual Flight Rules (NVFR), and night-vision flight using night-vision goggles (NVGs). RESULTS: The highest level of workload was consistently attributed to flights performed under NVG conditions. NVFR conditions were rated as the most burdensome, while VFR conditions were rated as the least burdensome. Fast-jet pilots rated their mental performance and effort workload as significantly higher than pilots of other aircrafts. CONCLUSION: Pilots' perceived workload is influenced by both flight conditions and the type of aircraft they fly. Workload knowledge is important for flight safety and should be taken into account during training and flight-task planning. APPLICATION: The results of our study can be useful both in flight training and in work on the effectiveness of the human-machine interface. Awareness of one's own limitations due to the work environment can help improve flight safety.

An Attentive Blank Stare Under Simulator-induced Spatial Disorientation Events.

OBJECTIVE: This study investigated the effect of the spatial disorientation (SD) events on an attentive blank stare in the cockpit scene and demonstrated how much the flight task and visual delayed discrimination task were competing for the pilots' attention. BACKGROUND: SD in flight is the leading cause of human error-related aircraft accidents in the military, general and commercial aviation, and has been an unsolved problem since the inception of flight. In-flight safety research, visually scanning cockpit instruments, and detecting changes are critical countermeasures against SD. METHOD: Thirty male military pilots were performing a dual task involving piloting a flight simulator and visual change detection, while eye movements were obtained using an eye tracker. RESULTS: Pilots made more flight errors and spent less time gazing at the area of change in SD-conflict than in non-conflict flights. The vestibular origin SD-conflict led not only to deteriorated piloting and visual scanning but also to problems coordinating overt and covert attention, resulting in lower noticeability of visual changes despite gazing at them. CONCLUSION: Our study shows that looking at a given area in space is not a sufficient condition for effective covert attention allocation and the correct response to a visual stimulus. It seems to be important to make pilots aware of this during SD training. APPLICATION: To reduce change blindness, some strategies, such as reducing the number of secondary tasks is extremely valuable. Particular efforts should also be focused on improving the design of the aircraft cockpit by increasing the conspicuousness of critical information.

Influence of night vision goggles with white and green phosphor screens on selected parameters of the eye and fatigue.

In modern aviation, in particular in the military context, increasingly many aviation tasks are performed at night. To improve the safety of night flights, night vision goggles (NVGs) are commonly used. This study aimed to examine whether changes in ophthalmic parameters during NVGs use vary depending on phosphor screen type (green or white coded as P43 and P45 respectively). Thirteen participants were studied during a 2-h visual task in a night vision laboratory. Before and after NVGs use, we examined visual acuity, pachymetry, critical flicker-frequency thresholds, stereoscopic and contrast vision. During the use of NVGs, visual acuity, intra-ocular pressure and eye refraction were measured. We found no difference in visual performance between NVGs with green and white phosphor screens; however, NVGs use in general may lead to subjective eye fatigue, neck pain and headaches associated with the time of wearing and the weight of the helmet with additional equipment attached. Practitioner summary Night vision goggles (NVGs), widely used to improve the safety of night flights, were examined according to the applied type of the phosphor screen. There was no difference in visual performance between a white and green phosphor screens; however, NVGs and helmet manufacturers should strive to design these devices to be as lightweight as possible. Abbreviations: ANOVA: analysis of variance; CCT: central corneal thickness; CFF: critical flicker frequency; CNS: central nervous system; CS: contrast sensitivity; FOV: field-of-view; I2: image intensifier; IOP: intra-ocular pressure; NVGs: night vision goggles; SV: stereoscopic vision; VA: visual acuity; VAS: visual analog scale.

How do older drivers perceive visual information under increasing cognitive load? Significance of personality on-road safety.

The ability to properly receive information and respond to stimuli is a prerequisite for road safety. The aim of this study was to determine the changes in oculomotor activity under conditions of increasing cognitive load depending on personality traits in older drivers (65 years and above). We assessed 44 male active drivers (M = 69, SD = 8.1) in a road traffic simulator in the dual-task paradigm: n-back reaction test (central task) and memory test (peripheral task). During the test in the simulator, oculomotor activity was recorded. Drivers' personality traits were determined using the EPQ-R questionnaire. With the increase of cognitive load in drivers with high levels of neuroticism and extraversion, the time of saccades and fixation significantly increased. The decrease in the effectiveness of visual attention shifting in older drivers intensified as the difficulty of performing tasks increased and manifested itself in longer saccade and fixation times. A higher level of neuroticism and the resulting stress and emotional tension can translate into a greater tendency to make mistakes in older drivers.

A survey of spatial disorientation incidence in Polish military pilots.

OBJECTIVES: The study aimed to establish the current incidence and severity of spatial disorientation (SD) in Polish military pilots when flying different aircraft types over their entire careers, and to determine how SD training and pilots' flight experience might benefit their recognition of situations that may cause SD. MATERIAL AND METHODS: Overall, 176 military Polish pilots (aged 33.8±7.72 years, the number of flying hours: 1194±941) flying different aircraft types, who attended the aviation medicine course, were surveyed and asked to report their episodes of SD. To collect anonymous data, a postal SD questionnaire (INFO PUB 61/117/5) was used. RESULTS: In the overall incidence rate of SD (96%), the most commonly experienced SD illusion was "loss of horizon due to atmospheric conditions" (81%). More SD incidents were reported by pilots who had received SD training. Some differences in the categories of the most commonly experienced SD illusion episodes between aircraft types were found. A severe episode adversely affecting flight safety was categorized by 10% of the respondents. CONCLUSIONS: In Polish military aviation, episodes of SD are a significant threat to aviation safety. There is evidence for the beneficial effects of SD training in the improvement of pilots' ability to recognize those factors that lead to SD. Int J Occup Med Environ Health. 2020;33(6):791-810.

Auditory Verbal Working Memory Load Effects on a Simulator-Induced Spatial Disorientation Event.

INTRODUCTION: Working memory is an essential executive function for flying an aircraft and its limitations may jeopardize flight safety. This function is particularly critical when pilots have to struggle with spatial disorientation (SD) cues. This research aimed to assess the combined effect of the auditory N-back task (NBT) and simulator-induced SD cues on pilots' flight performance.METHODS: Using an SD simulator, 39 male military pilots (control N = 20; age M = 31.6; SD = 8.22, experimental N = 19; age M = 26.9; SD = 8.67) were exposed to 12 flight sequences, where 6 contained an SD conflict-3 with vestibular illusions and 3 with visual illusions. Additionally, the pilots from the experimental group were asked to perform an auditory NBT involving sound stimuli (the sequential letter memory task) as they performed during oriented and disoriented flight conditions.RESULTS: Pilots' flight performance from the NBT group were significantly worse than the control group in the approach and landing profiles involving visual illusions (for both nonconflict and conflict flight), and in the profile involving the false horizon illusion (only for the conflict flight). No increase in a pilot's susceptibility to SD was observed with any other profiles.DISCUSSION: The current study provides support that pilots' cognitive workload can negatively impact flight performance. Pilots are not always aware of altered flight parameters, which may indicate that they have lost spatial orientation, mainly as a result of visual illusion. If problems occur in maintaining proper flight parameters, pilots should direct all available mental resources to regain their orientation and withdraw from any other parallel tasks.Lewkowicz R, Strózak P, Balaj B, Francuz P. Auditory verbal working memory load effects on a simulator-induced spatial disorientation event. Aerosp Med Hum Perform. 2019; 90(6):531-539.

Selective Auditory Attention and Spatial Disorientation Cues Effect on Flight Performance.

INTRODUCTION: The auditory system is not as heavily involved in the pilot's spatial orientation as the visual and vestibular systems; however, it plays a significant role in the cockpit for communication and warning information. The aim of this research was to investigate the combined effect of selective auditory attention and simulator-induced spatial disorientation (SD) cues on pilots' flight performance. We hypothesized that the flight performance in both disoriented and oriented flight profiles would be impaired by selective auditory attention.METHODS: Using an SD simulator, 40 male military pilots (M = 31.9; SD = 7.41) were exposed to 12 flight sequences, where 6 contained a SD-conflict, 3 with motion illusions and 3 with visual illusions. The pilots performed a duration discrimination task (DDT) involving sound stimuli while completing these profiles under SD-conflict and nonconflict conditions.RESULTS: In five flight profiles tested, the DDT and SD cues increased the pilots' cognitive workload, adversely affecting their flight performance. In the approach and landing profiles involving visual illusions, significant differences between the control and DDT groups were found for both nonconflict and SD-conflict flight sequences, whereas differences were only significant between nonconflict and SD-conflict flights for the two vestibular SD profiles.DISCUSSION: The results obtained partially support our hypothesis that performing the DDT, even in the absence of SD-conflict, significantly affects pilots' flight performance. In some cases, despite the large increase in cognitive workload, pilots did not activate the "posture first" principle. Pilots should be trained not to respond to auditory stimuli until they have recovered their spatial orientation.Lewkowicz R, Strózak P, Balaj B, Francuz P, Augustynowicz P. Selective auditory attention and spatial disorientation cues effect on flight performance. Aerosp Med Hum Perform. 2018; 89(11):976-984.

Change Detection Flicker Task Effects on Simulator-Induced Spatial Disorientation Events.

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-Czyz A, Balaj B, Francuz P. Change detection flicker task effects on simulator-induced spatial disorientation events. Aerosp Med Hum Perform. 2018; 89(10):863-872.

Coping and Changes in Arousal After Exposure to +Gz Load.

BACKGROUND: Acceleration load causes several physiological changes that play important roles in pilot performance. One of the problems is determining individual factors responsible for the differences in changes in the level of central nervous system (CNS) arousal after exposure to acceleration loads. We were interested in whether the coping style and anxiety as a trait might differentiate the subjects in terms of reactions of the CNS to +Gz load-related stress. METHODS: Examined were 31 male volunteers with ages between 23 and 30 yr. Measurements were obtained under controlled conditions before, during, and every 2 min up to 12 min after centrifugation. The study was conducted using the Coping Inventory for Stressful Situations (CISS) and State Trait Anxiety Inventory. The value of Critical Flicker Fusion Threshold (CFFT) corresponded to the level of CNS arousal. RESULTS: Two significantly different trends of changes in CNS arousal were identified: class 1 (higher level of fatigue following +Gz load) and class 2 (lower level of fatigue following +Gz load). Significant differences were observed in CISS scores with Task-Oriented Coping value in class 1 (M = 65.94, SD = 5.47) being considerably greater than in class 2 (M = 62, SD = 4.37). For Emotion-Oriented and Distraction Coping, the mean value in class 1 (M = 29.53, SD = 7.72; M = 16.82, SD = 3.8) was significantly lower than in class 2 (M = 34.33, SD = 6.68; M = 19.42, SD = 3.4). DISCUSSION: The nature of the changes in CFFT values over time is associated with coping style. Coping styles are very valuable in the prediction of CNS arousal caused by exposure to +Gz stress.Biernacki MP, Lewkowicz R, Zielinski P, Wojtkowiak M. Coping and changes in arousal after exposure to +Gz load. Aerosp Med Hum Perform. 2017; 88(11):1034-1039.

Hypoxia and Coriolis Illusion in Pilots During Simulated Flight.

INTRODUCTION: Pilots' vision and flight performance may be impeded by spatial disorientation and high altitude hypoxia. The Coriolis illusion affects both orientation and vision. However, the combined effect of simultaneous Coriolis illusion and hypoxia on saccadic eye movement has not been evaluated. METHOD: A simulated flight was performed by 14 experienced pilots under 3 conditions: once under normal oxygen partial pressure and twice under reduced oxygen partial pressures, reflecting conditions at 5000 m and 6000 m (16,404 and 19,685 ft), respectively. Eye movements were evaluated with a saccadometer. RESULTS: At normal oxygen pressure, Coriolis illusion resulted in 55% and 31% increases in mean saccade amplitude and duration, respectively, but a 32% increase in mean saccade frequency was only noted for saccades smaller than the angular distance between cockpit instruments, suggesting an increase in the number of correction saccades. At lower oxygen pressures a pronounced increase in the standard deviation of all measures was noticed; however, the pattern of changes remained unchanged. DISCUSSION: Simple measures of saccadic movement are not affected by short-term hypoxia, most likely due to compensatory mechanisms.

Reaction time in pilots during intervals of high sustained g.

INTRODUCTION: An important problem for pilots is visual disturbances occurring under +Gz acceleration. Assessment of the degree of intensification of these disturbances is generally accepted as the acceleration tolerance level (ATL) criterion determined in human centrifuges. The aim of this research was to evaluate the visual-motor responses of pilots during rapidly increasing acceleration contained in cyclic intervals of +6 Gz to the maximum ATL. METHODS: The study involved 40 male pilots ages 32-41 yr. The task was a quick and faultless response to the light stimuli presented on a light bar during exposure to acceleration until reaching the ATL. Simple response time (SRT) measurements were performed using a visual-motor analysis system throughout the exposures which allowed assessment of a pilot's ATL. RESULTS: There were 29 pilots who tolerated the initial phase of interval acceleration and achieved +6 Gz, completing the test at ATL. Relative to the control measurements, the obtained results indicate a significant effect of the applied acceleration on response time. SRT during +6 Gz exposure was not significantly longer compared with the reaction time between each of the intervals. SRT and erroneous reactions indicated no statistically significant differences between the "lower" and "higher" ATL groups. CONCLUSION: SRT measurements over the +6-Gz exposure intervals did not vary between "lower" and "higher" ATL groups and, therefore, are not useful in predicting pilot performance. The gradual exposure to the maximum value of +6 Gz with exposure to the first three intervals on the +6-Gz plateau effectively differentiated pilots.

Back pain and its consequences among Polish Air Force pilots flying high performance aircraft.

OBJECTIVES: Back pain in Air Force fast jet pilots has been studied by several air forces and found to be relatively common. The objective of the study was to determine the prevalence and degree of the pain intensity in the cervical, thoracic and lumbar spine, subjective risk factors and their effect on the pilots' performance while flying high maneuver aircrafts and the consequences for cognitive deficiencies. MATERIAL AND METHODS: The study was designed as a retrospective, anonymous questionnaire survey, collecting data on the age, aircraft type, flying hours, pain characteristics, physical activity, etc. The study was participated by 94 pilots aged 28-45 years (mean age: 35.9 ± 3.3 years), actively flying fast jet aircrafts Su-22, Mig-29 and F-16. The estimates regarding the level of the subjective back pain were established using visual analogue scales (VAS). RESULTS: The values of the Cochran and Cox T-test for heterogeneous variances are as follows: for the total number of flying hours: F = 2.53, p = 0.0145, for the pilot's age: F = 3.15, p = 0.003, and for the BMI factor F = 2.73, p = 0.008. CONCLUSIONS: Our questionnaire survey showed a significant problem regarding spinal conditions in high performance aircraft pilots. The determination of the risk factors may lead to solving this problem and help eliminate the effect of the unfavorable environment on piloting jet aircrafts. Experiencing back pain during the flight might influence the mission performance and flight safety. The costs of pilots education are enormous and inability to fly, or even disability, leads to considerable economic loss. More research on specific prevention strategies is warranted in order to improve the in-flight working environment of fighter pilots.

Reaction time in pilots at sustained acceleration of +4.5 G(z).

INTRODUCTION: Pilots flying at very high speed are exposed to the effects of prolonged accelerations while changing their flight path. The aim of this research was to assess the impact of sustained accelerations on the visual-motor response times of pilots and the acceleration tolerance level (ATL) as a measure of pilots' endurance to applied +G(z). METHOD: The study involved 18 young pilots, 23-25 yr of age. The subjects' task was to quickly and accurately respond to the light stimuli presented on a light bar during exposure to acceleration at +4.5 G(z) and until reaching the ATL. Simple response time (SRT) measurements were performed using a visual-motor analysis system throughout the exposures, which allowed the assessment of a pilot's ATL. RESULTS: The pilots' ATL ranged from 270 to 366 s (Mean = 317.7 +/- 26.15 SD). The analysis of the SRT indicated a significant effect of duration of acceleration on the visual response time. The results of the post hoc comparisons showed that SRT increased with longer durations of the same level of +G(z) load and then decreased, reaching values similar to the controls. CONCLUSION: Exposure to prolonged acceleration of +4.5 G(z) significantly increases SRT. There was no statistically significant difference in SRT between the pilots with "short" and "long" time exposures. A pilot's SRT during a prolonged +4.5 G(z) exposure could be a reliable indicator of pilot G performance in the fast jet. Deterioration of SRT may be used to predict imminent +G(z) endurance limits between pilots with widely varying endurance abilities.

+Gz load and executive functions.

BACKGROUND: Pilots are constantly exposed to a number of environmental factors, which include +Gz load. Physiological changes evoked by +Gz stimuli have already been well investigated in aviation medicine. However, the influence of +Gz stimulation on executive functions in pilots has not yet been thoroughly explored. METHOD: There were 20 pilot cadets between the ages of 19 and 22 yr who volunteered to participate in the experiment. The subjects were divided into two groups: the G-load group, which was exposed to accelerations in the centrifuge, and the control group, which did not undergo this stimulation. Executive functions were assessed by means of the Schulte tables and the Rey-Osterrieth complex figure test. RESULTS: +Gz load exposure significantly improved attention switching. This relationship was valid for performance speed (M = 268.09 s in the pretest in the G-load group; M = 228.09 s in the posttest in the G-load group) and for the cumulative time of mistakes (M = 26.73 s in the pretest in the G-load group; M = 12 s in the posttest in the G-load group), whereas reproduction of visuospatial stimuli from memory deteriorated significantly under the influence of +Gz stimulation (M = 17.18 points in the posttest in the G-load group; M = 28.18 points in the posttest in the control group). CONCLUSION: These results suggest that the impact of +Gz load is not homogenous and unidirectional, since it improves attention switching but visuospatial working memory decreases under its influence. These aspects are particularly important for understanding the mechanisms responsible for maintaining situational awareness during the flight.

Back pain in Polish military helicopter pilots.

OBJECTIVES: Low back pain in pilots of military helicopters is widely discussed in the world literature. Vibrations and improper seat configuration cause that cervical, thoracic and lumbar spine might be exposed to overloading. The aim of the study was to determine the incidence and intensity of pain in the spine as well as to identify subjective risk factors of back pain and its effect on the pilot's actions while flying a helicopter. MATERIALS AND METHODS: 112 pilots, aged 25-56 years (mean age: 34.8 ± 6.3 years), actively flying helicopters, participated in the questionnaire survey. The questionnaire containing five groups of questions, elaborated by the authors, was used. RESULTS: 70% of the pilots reported pain complaints. Pain was localized in different parts of the spine. Uncomfortable body posture during prolonged flights resulting from the lack of lumbar support exerted the highest effect on pain provocation. CONCLUSIONS: This questionnaire survey enabled to determine the prevalence of pain, its type and intensity. Knowledge on low back pain imposes the necessity to eliminate the negative environmental effect on helicopter pilotage. Elimination of risk factors is possible through appropriate physical exercises and adjustment of pilots' seats. The authors plan to conduct--in the future--detailed annual examinations among pilots with back pain and, based on the results, to elaborate a prophylactic program containing simple forms of isometric and isotonic training involving paravertebral and deep abdominal muscles designed specifically for pilots of military helicopters.

+Gz centrifugation and mood.

BACKGROUND: Physiological effects of +Gz centrifugation are well known. Psychological functioning combined with +Gz centrifugation also appears to be important, but has not yet been sufficiently studied. This study was designed to evaluate whether mood (energetic arousal, tense arousal, and hedonic tone) is influenced by a centrifuge run with +Gz stress. METHOD: We examined subjects' mood four times: 2 h prior to the centrifuge run, 2 min before and after centrifugation, and again 30 min afterwards. Energetic arousal (EA), tense arousal (TA), and hedonic tone (HT) assessments were conducted by the self-reported UWIST Mood Adjective Check List (UMACL). RESULTS: Centrifugation explained 31.6% of EA and 56.9% of TA variance. EA level increased 2 min before centrifugation and remained so until the last measurement. TA was high 2 h prior to the centrifuge run, rose sharply 2 min before centrifugation, and lowered considerably after cessation of the run. The HT level was stable throughout all measurements. CONCLUSION: The centrifuge run with +Gz acceleration may evoke changes in arousal, but not in subjective enjoyment. Alterations in arousal levels triggered by centrifugation were positive, increasing energy and reducing tension.