Refractive surgery and flight safety

For both VFR and as IFR flight, visual assessment is the major source of information for the pilot. The new possibilities for change of refraction by means of corneal refractive surgery have led to an increasing demand from pilots for these new methods. Can these methods successfully be applied for aviation purposes? The valid regulations for medical standards of pilots, as well as the future international regulations such as JAR and ICAO, are explained in this respect. A report is given on the work of the Advisory Board of the German Federal Government Air Traffic Authority and on the cases treated so far and their outcome, and recommendations are expressed. Concerning the legal situation and clinical experience, advice for pilots, aviation medical examiners and ophthalmologists is given.     

Physiological indices of workload in a simulated flight task

The sensitivity of physiological measures to evaluate workload was investigated in a simulated flight task. Heart rate, blood pressure (from beat to beat), respiration and eye blinks were recorded in 14 subjects while they performed a complex task in a flight simulator. Workload was manipulated by introducing an additional task and by varying the task difficulty of segments of the flight scenarios. Heart rate and blood pressure were both affected by the different levels of task difficulty. Heart-rate variability was found to be confounded by respiration. Slow respiratory activity contributed considerably to heart rate variability, especially after periods of high workload (for example, after landing). The gain between blood-pressure and heart-rate variability (modulus) was sensitive to mental effort and was not influences by respiration. Eye blinks, in particular the duration, were specifically affected by the visual demands of the task and not by the workload in general. When subjects had to process visual information, the number and duration of blinks decreased.     

Risk factors for pilot fatalities in general aviation airplane crash landings

CONTEXT: Most pilots survive airplane crash landings in small airplanes. Factors associated with pilot death have not been well studied. OBJECTIVE: To identify factors associated with fatalities in general aviation airplane crash landings. DESIGN: Case-control study. SETTING: The United States. SUBJECTS: All pilots in general aviation crash landings of airplanes with 10 seats or fewer, from 1983 through 1992. MAIN OUTCOME MEASURE: Pilot death. RESULTS: Pilots died in 437 (5.2%) of 8411 crash landings. A fire or explosion on the ground was strongly associated with pilot death (relative risk [RR], 20.4; 95% confidence interval [CI], 15.5-26.9), adjusted for pilot age, pilot flight hours, type of landing gear, and the filing of an instrument flight plan. Pilots who failed to use both lap belt and shoulder harness were more likely to die (adjusted RR, 6.8; 95% CI, 1.8-25.5), as were those who used only the lap belt (adjusted RR, 1.7; 95% CI, 1.3-2.2), compared with pilots who used both restraints. CONCLUSION: Pilots may be able to reduce their risk of death in a crash landing by using lap and shoulder restraints.     

Electrophysiological, behavioral, and subjective indexes of workload when performing multiple tasks: manipulations of task difficulty and training

This study examined whether alpha event-related desynchronization (ERD) and theta event-related synchronization (ERS) could successfully measure changes in cognitive workload and training while an operator was engaged in a continuous, interactive, control task(s). Alpha 1 (8-10 Hz) ERD, alpha 2 (10-12 Hz) ERD, and theta (3-7 Hz) ERS were determined for a communications event that occurred during multiple task workload conditions or as a single task. Other measures (alpha and theta EEG power, heart rate, respiration, eye blinks, behavioral performance, and subjective workload ratings) were also evaluated. Results showed that alpha 2 EEG, heart rate, behavioral, and subjective measures were sensitive to changes in workload in the multiple tasks. In addition, eye blink rate and behavioral measures were sensitive to training. Alpha ERD and theta ERS were not sensitive to workload and training in our interactive, multiple task environment. However, they were effective indexes of cognitive/behavioral demands within an interactive single task.     

Shaping Indirect Flight Control System Properties for General Aviation Aircraft

This paper describes calculations and computer simulations concerning handling qualities of general aviation aircraft equipped with an indirect (fly-by-wire) control system. The main idea of this proposal is shaping small aircraft dynamic characteristics in a way that enables all general aviation aircraft to exhibit similar user-friendly properties from the pilot’s point of view. The natural solution of this problem is modifying aircraft dynamic properties to comply with the “ideal model” of a safe and easily controllable airplane. We can improve the handling qualities of an aircraft using the indirect flight control system. In this paper, the model following method was used for controller synthesis, with the purpose of obtaining qualitatively new handling properties and simplifying the control system for pilots with limited professional training. However, a control system designer has to assume responsibility for proper functioning of complex flight control systems. The properties of the optimal controller were calculated applying the indirect (implicit) model following method. In particular, the modified version based on the computer simulations was used. Model following method allows shaping properties of the flight control systems that satisfactorily approximate those of the desired model of controlled aircraft. In this way, the expected handling qualities can be reached.     

Heart period variability and respiratory changes associated with physical and mental load: non-linear analysis

In the investigation of heart rate and heart rate variability, the discrimination between mental workload, physical activity and respiration is known to be methodologically difficult. At most, heart rate variability measures are more likely to be coarse-grained measures with variability confounded by heart rate. Moreover, the spectral analysis of heart rate variability shows broad-band frequency characteristics, pointing towards non-stationarity or non-linearity. From this it is suggested to focus on non-linear dynamic analyses that are variance-insensitive. The experimental section of the paper focuses on the estimation of two non-linear measures for both heartbeat dynamics and respiration, the correlation dimension indicating complexity and the Lyapunov exponents indicating predictability. The results indicate that the complexity of heart dynamics is related to the type of task and that the predictability of heart dynamics is related to the amount of load.     

Increase of heart rate and determination of W170 as a measure of physical working capacity in children 5 to 14 years of age (author's transl)

1. Exercise testing with stepwise increasing workload was performed in 257 healthy children (134 boys, 123 girls) on a bicycle ergometer, which was independent of variations in pedal speed within a certain range. The procedure of exercise was adapted to the children as far as possible. 2. Nomograms and standard values for heart rate during exercise and for physical working capacity at a heart rate of 170/min (W170) were established. The increase of heart rate (from 1.0 to 2.5 Watt/kg) was well correlated to the age, length, body weight and body surface. If heart rate, respectively W170 are related to workload per kg body weight, results are dependent on sex, but not on age. 3. By means of the new standard values a rough evaluation of cardiorespiratory condition is possible, if the heart rate is measured at moderate exercise during steady state. A more precise assessment of the cardio-respiratory fitness is granted by the W170. By this method physical working capacity can be determined in children with heart diseases in a relative simple manner. 4. Normally in stepwise increasing loads the exercise takes 6 minutes per workload. If this time is reduced, an underestimation of the expected heart rate, respectively an overestimation of W170 is observed, which depends on the extent of the shortening of exercise.     

Factors influencing mental workload indexes

Several findings of the author's own mental workload research are reviewed. Especially, factors, except task demand, influencing mental workload indexes are discussed. First, an experiment using the National Aeronautics and Space Administration Task Load Index (NASA TLX) is reviewed and the effects of a prior task load on a subsequent subjective workload are described. In a physiological measures section, the low reliability of the heart rate variability (HRV) parameters when the subjects' respiration pattern are highly irregular, and the existence of low sweat respondent, although perspiration seems to be sensitive to the workload, are indicated. Furthermore, results of the task specific physiological responses and of a HRV parameter affected by the individual characteristics, like type A behavior pattern, are shown. Discrepancy between autonomic nervous system activity measures may be solvable by introducing a new concept of autonomic space (synergism of sympathetic and parasympathetic nervous system). Finally, the need for strategies of data management concerning the individual differences is emphasized.     

Expertise in aeronautical weather-related decision making: A cross-sectional analysis of general aviation pilots.

Weather-related crashes continue to account for a significant proportion of general aviation (GA) accidents. In the present study, the decision-making performance and information acquisition strategies of inexperienced, intermediate, and experienced pilots were examined from a cognitive skill perspective. Data were obtained from information search patterns and verbal protocols during a series of 6 computer-based simulated flight scenarios. The results revealed both quantitative and qualitative differences between the strategies of experienced and inexperienced pilots. The implications of these results are discussed in terms of weather-related decision-making training and the validity of a cognitive skill model of aeronautical decision making. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Task difficulty, cardiovascular response, and the magnitude of goal valence.

Studied the impact of expected task difficulty on anticipatory cardiovascular (CV) responsiveness and the anticipatory reactivity under difficult task conditions in 64 female undergraduates. Ss performed an easy, moderately difficult, or extremely difficult memory task to earn a small incentive for good performance. CV and subjective measures were taken immediately prior to task performance. Both systolic blood pressure (SBP) responses and ratings of goal attractiveness were nonmonotonically related to expected task difficulty, with the most pronounced SBP elevations and highest goal attractiveness in the moderately difficult task condition. CV response measures revealed a strong positive association between systolic and diastolic pressure (but not heart rate) change in the easy condition, positive relationships among measures in the moderately difficult condition, and no significant correlations in the extremely difficult condition. Subjective measures of arousal were not affected by task difficulty. Principal findings are discussed in terms of J. W. Brehm's theory that motivation varies as a nonmonotonic function of the difficulty of goal attainment. Intercorrelations among CV response variables are considered in terms of their possible indication of the mechanisms underlying blood pressure changes associated with variations in motivation. (35 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Psychophysiological responses to changes in workload during simulated air traffic control

In this investigation, eight Air Force air traffic controllers (ATCs) performed three scenarios on TRACON (Terminal Radar Approach Control), a computer-based air traffic control (ATC) simulation. Two scenarios were used each with three levels of difficulty. One scenario varied traffic volume by manipulating the number of aircraft to be handled and the second scenario varied traffic complexity by manipulating arriving to departing flight ratios, pilot skill and mixture of aircraft types. A third scenario, overload, required subjects to handle a larger number of aircraft in a limited amount of time. The effects of the manipulations on controller workload were assessed using performance, subjective (TLX), and physiological (EEG, eye blink, heart rate, respiration, saccade) measures. Significant main effects of difficulty level were found for TRACON performance, TLX, eye blink, respiration and EEG measures. Only the EEG was associated with main effects for the type of traffic. The results provide support for the differential sensitivity of a variety of workload measures in complex tasks, underscore the importance of traffic complexity in ATC workload, and support the utility of TRACON as a tool for studies of ATC workload.     

Prevention of visual anxiety and proficiency problems in the senior air transport pilot

Several actual cases were presented to show the problems encountered with flight deck vision in the middle-age presbyopic pilot both in the simulator and in flight. We have gained useful knowledge in the proper flight-deck needs and optical corrections for these pilots, which should be passed on to aviation examiners, eye specialists, and pilots themselves. This would relieve a great deal of unnecessary lost time and anxiety which results when the pilot has a correction unsuited for the cockpit and encounters extreme difficulty in simulator work and in actual flight conditions which he does not understand and which can become very frustrating and a source of anxiety because his career is at stake. This anxiety may lead to other functional ocular problems, is unnecessary, and can be prevented.     

Health of the pilots and flight safety

Pilots and other aviation personnel meet physicians on different terms depending on the purpose of the medical consultation: Whether it is a periodical medical examination by an appointed medical examiner required for renewal of flight licence, or whether the pilot consults the physician on a health problem. The physician has different roles in these two types of consultation. This article is a short introduction to physicians outside the aviation community on health problems among pilots with regard to flight safety.     

Weatherwise: evaluation of a cue-based training approach for the recognition of deteriorating weather conditions during flight

Inappropriate and ineffective weather-related decision making continues to account for a significant proportion of general aviation fatalities in the United States and elsewhere. This study details the evaluation of a computer-based training system that was developed to provide visual pilots with the skills necessary to recognize and respond to the cues associated with deteriorating weather conditions during flight. A total of 66 pilots were assigned to one of two groups, and the evaluation process was undertaken at both a self-report and performance level. At the self-report level, the results suggested that pilots were more likely to use the cues following exposure to the training program. From a performance perspective, there is evidence to suggest that cue-based training can improve the timeliness of weather-related decision making during visual flight rules flight. Actual or potential applications of this research include the development of computer-based training systems for fault diagnosis in complex industrial environments.     

Enhanced anticancer therapy mediated by specialized liposomes

OBJECTIVES: To determine whether instrument-proficient pilots would more safely manage a flight into unplanned instrument meteorologic conditions (IMC) than would nonproficient pilots. METHODS: A controlled experimental study was performed using a full-motion helicopter simulator. Participants were emergency medical services (EMS) pilots with commercial licenses and previous simulator experience who were blinded to the study design and hypothesis. During a simulated EMS mission, cloud ceiling and visibility were decreased until IMC prevailed, and pilot actions were recorded. Data included the altitude at which the aircraft entered IMC, and whether the pilots maintained control of the aircraft, flew within aviation standards (i.e., bank angle, airspeed), and safely landed. RESULTS: Twenty-eight pilots (13 instrument-proficient, 15 nonproficient) participated; they had a median of 6,300 hours of helicopter experience. Two pilots crashed, both from the nonproficient group. The instrument-proficient pilots lost control less often (15% vs 67%, p < 0.05), maintained instrument standards more often (77% vs 40%, p < 0.05), and entered IMC at a higher altitude (689 feet vs 517 feet, p < 0.05) compared with the nonproficient pilots. Instructor comments indicated that the nonproficient pilots made more errors than did the instrument-proficient pilots. CONCLUSIONS: Instrument-proficient pilots more safely manage an unexpected encounter with IMC. Helicopter EMS programs should strongly consider maintaining instrument proficiency to enhance safety.     

The influence of expertise and task factors on age differences in pilot communication.

The influence of expertise and task factors on age differences in a simulated pilot–Air Traffic Control (ATC) communication task was examined. Young, middle-aged, and older pilots and nonpilots listened to ATC messages that described a route through an airspace, during which they referred to a chart of this airspace. Participants read back each message and then answered a probe question about the route. It was found that pilots read back messages more accurately than nonpilots, and younger participants were more accurate than older participants. Age differences were not reduced for pilots. Pilots and younger participants also answered probes more accurately, suggesting that they were better able to interpret the ATC messages in terms of the chart in order to create a situation model of the flight. The findings suggest that expertise benefits occur for adults of all ages. High levels of flying experience among older pilots (as compared with younger pilots) helped to buffer age-related declines in cognitive resources, thus providing evidence for the mediating effects of experience on age differences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of scenery, lighting, glideslope, and experience on timing the landing flare.

This study examined three visual strategies for timing the initiation of the landing flare based on perceptions of either: (a) a critical height above ground level; (b) a critical runway width angle (Ψ); or (c) a critical time-to-contact (TTC) with the runway. Visual displays simulated landing approaches with trial-to-trial variations in glideslope, lighting, and scene detail. Twenty-four participants (8 private pilots, 8 student pilots, and 8 nonpilots) were instructed to initiate the flare when they perceived that their TTC with the runway (30 m wide by 840 m long) had reached a critical value of 2 seconds. Our results demonstrated a significant effect of flight experience on flare timing accuracy and dominance of the height-based strategy over the runway-width-angle and TTC-based strategies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual elements in flight simulation

Flight simulators have been in use for many years and their value has been amply proven. Many of today's simulators are very expensive, but they can pay for themselves by decreasing cost and increasing safety in training pilots to fly complex and expensive modern aircraft. Some aspects of aircraft control depend on an exterior view from the aircraft to the outside visual world. Training in these aspects of flight in a simulator requires simulation of the visual world to the extent that cues derived from it need to be employed by the pilot. A number of maneuvers cannot be performed without direct visual contact under normal circumstances in commercial as well as in military aviation. The importance of including a simulation of the external world is not acknowledged. Unfortunately, there is currently no solid scientific basis for cataloging visual cues with respect to their importance in aircraft control. This report recommends research topics, techniques, and strategies that should receive more attention.     

Explanatory factors for the geographic distribution of U.S. civil aviation mortality

BACKGROUND: State-specific aviation-related mortality rates differ substantially between various geographical regions of the United States. PURPOSE: The purpose of this study was to ascertain important explanatory factors that account for the geographical distribution of mortality. METHODS: National Center for Health Statistics sources were used to calculate state-specific, age-adjusted mortality rates. Fatalities studied were those attributed to select civil aviation-related causes (ICD-9 E-codes 840.2-.6, 841.2-.6, 842.2-.6) that occurred from 1979-89. State-specific information on a variety of selected variables was obtained from census, commerce, and Federal Aviation Administration (FAA) sources. Multiple linear regression techniques were used to assess the relationship between selected variables and state-specific mortality rates. RESULTS: There were 13,048 deaths for a U.S. 11-year mean mortality rate of 4.9 deaths/1,000,000 general population. Mountainous states of the western U.S. had the highest 11-year mean mortality rates (range 8.6-79.6 deaths/1,000,000). Mid-Atlantic states had the lowest rates (range 1.6-2.9 deaths/1,000,000). Regression analysis identified pilot density (number of pilots per 1,000,000 general population), top elevation (highest point of land within state boundaries), and flight intensity (number of general aviation flight hours flown per pilot) as important factors in explaining 92% of state mortality differences. CONCLUSIONS: Highest aviation-related mortality rates are found in states with expanses of mountainous terrain, and relatively high pilot densities and flight activity levels.     

Task engagement, cerebral blood flow velocity, and diagnostic monitoring for sustained attention.

Loss of vigilance may lead to impaired performance in various applied settings including military operations, transportation, and industrial inspection. Individuals differ considerably in sustained attention, but individual differences in vigilance have proven to be hard to predict. The dependence of vigilance on workload factors is consistent with a resource model of sustained attention. Thus, measures of attentional resource availability may predict the operator's subsequent vigilance performance. In this study, we investigated whether a diagnostic battery of measures of response to a cognitive challenge would predict subsequent sustained attention. Measures that may relate to the mobilization of resources in response to task demands include subjective task engagement and coping, and a novel psychophysiological index, cerebral bloodflow velocity (CBFV). A two-phase design was used. First, participants were exposed to a challenging battery of short tasks that elevated CBFV. Second, participants performed a 36-min vigilance task. Two subgroups of participants performed either a sensory vigilance (N = 187) or a cognitive vigilance (N = 107) task. Measures of task engagement, coping, and CBFV response to the short task battery were compared as predictors of subsequent vigilance. Both subjective and CBFV indices of energization predicted sensory and cognitive vigilance, consistent with resource theory. Structural equation modeling was used to develop a latent factor model of influences on sustained attention. It is concluded that measures of resources, conceptualized as multiple energization processes, are potentially useful for diagnostic monitoring in applied settings. Use of a diagnostic task battery in military and transportation settings is discussed, along with some potential limitations on validity of the diagnostic test. (PsycINFO Database Record (c) 2010 APA, all rights reserved)