Proceedings of the Human Factors and Ergonomics Society Annual Meeting

Years of research on feedback has not produced universal prescriptions for feedback during training. Results are split in two directions; those recommending more feedback during training and those recommending less. This has resulted in no unified theory and little understanding of other factors that might affect feedback mechanisms. The current experiment manipulated the cognitive load of the task and measured the working memory capacities of the learners to see whether forcing the learner to self-evaluate affects learning of a cognitive task and how this might be moderated by learner ability and task load. Results generally showed that reducing task load through supportive feedback resulted in more learning.

Older adults may benefit from using technology in their everyday lives. However, adults over 65 may need more training than their younger counterparts given they have had less experience with technology. In this study, 113 adults between the ages of 65 and 85 participated in focus group interviews discussing their training needs and preferences for technology items used in the home. Participants expressed an interest in receiving additional training, particularly for specific tasks. Participants also discussed preferences for various characteristics of training, such as who should conduct the training and for their preferred method of training. One of the most frequently discussed preferences was for self-training using text materials, such as a manual.

Breakdowns in complex systems often occur as a result of system elements interacting in ways unanticipated by analysts or designers. In systems with human operators, human-automation interaction associated with both normative and erroneous human behavior can contribute to such failures. This paper presents a method for automatically generating task analytic models encompassing both erroneous and normative human behavior from normative task models. The resulting model can be integrated into a formal system model so that system safety properties can be formally verified with a model checker. This allows analysts to prove that a human automation-interactive system (as represented by the model) will or will not satisfy safety properties with both normative and generated erroneous human behavior. This method is illustrated with a case study: the operation of a radiation therapy machine. In this example, a problem resulting from a generated erroneous human action is discovered. Future extensions of our method are discussed.

Up to 98,000 patients die because of human error in U.S. hospitals each year. Among the areas where errors occur frequently is the intensive care unit (ICU). Despite the impact of these errors, little research has identified the human factors that contribute to errors in the ICU. The current study uses the error-producing conditions (EPC) approach to help identify device-related factors that contribute to error. One result of the present study was the identification of the extent to which individual conditions contribute to the prevalence of error. In addition, we identified the contribution of certain devices to the prevalence of error. More importantly, the most critical devices for patient care were also identified as the devices that were rated highest in EPC prevalence. Developing medical devices designed to reduce the device-related potential for patient harm should be a primary goal in patient safety.

Health care practitioners need complete and accurate information to provide quality care to their patients. However, health information is considered to be highly private. Patients may have concerns about disclosing such information, especially if asked to provide this information using technology. The goal of this study was to investigate how participants' experience with a technology affect their level of disclosure in a health setting. Specifically, we were interested in understanding how the use of a health database system influences the disclosure of private health information. We asked 12 younger and 12 older adults to interact with a computerized health data entry system and then to rate the completeness and accuracy of their intended disclosures. Results indicate that, for the most part, participants would provide complete and accurate information using such a system. Younger adults were less likely than older adults to intend to disclose sensitive information, suggesting that additional information gathering may be appropriate for younger adults. The importance of providing a reason for the request of each piece of health information is discussed in relation to the setting where information is gathered.

Predicting failures in complex, human-interactive systems is difficult as they may occur under rare operational conditions and may be influenced by many factors including the system mission, the human operator's behavior, device automation, human-device interfaces, and the operational environment. This paper presents a method that integrates task analytic models of human behavior with formal models and model checking in order to formally verify properties of human-interactive systems. This method is illustrated with a case study: the programming of a patient controlled analgesia pump. Two specifications, one of which produces a counterexample, illustrate the analysis and visualization capabilities of the method.

Results of a study performed to derive an automation and avionics integration design concept for the NUH-60 systems testbed for avionics research (STAR) aircraft are presented. The STAR aircraft is being developed by the US Army avionics research and development activity to provide a flight demonstrator and research vehicle for state-of-the-art cockpit technology. A goal was to determine cockpit design preferences associated with single-pilot performance of the US Army scout and utility missions. Emphasis was placed on high-workload phases of the missions during which eyes-out-of-the-cockpit and hands-on-controls performance capabilities would be most crucial. Cockpit design alternatives in the areas of communication, navigation, aircraft survivability equipment (ASE) operations, subsystem status monitoring, and aircraft performance computation and prediction were systematically derived

The paper discusses a two person development effort where one developer resided in San Francisco and the other was located in Cincinnati. The team met once at the beginning for two days and toward the end of the project for less than a day. The design was refined to its current form through prototyping and iterative usability testing. All levels of management and users have widely accepted the resulting product. The primary communication paths were the telephone and Lotus Notes. The resulting team synergy and critical success factors are further detailed

The interactive display design tool (IDDT), an attempt to resolve some of the difficulties inherent to part-task simulation development, is described. IDDT is a set of applicational programs that function as an interface between a display/part-task designer and a graphics processing system. IDDT allows individuals with no knowledge of computers or programming to interactively create, edit, save, and view graphic displays. As displays are saved at the end of an editing session, directly compilable software source code is generated that can be inserted into part-task simulation software. To date, IDDT has been in use for a ten-month period, during which, it has been used to generate approximately 20 display formats for incorporation into a part-task simulation system. Initial indications have been that display design and programming time is reduced by 40%-60%

Twenty-three participants (six air traffic control specialists, and 17 pilots trained in fundamental ATC skills), performed a simulation in which they were required to evaluate pilot requests for flight plan changes, issued by aircraft depicted on their display. Some requests could be safely granted, whereas others would bring about a mid-air conflict with other aircraft. Participants evaluated the requests in the context of an airspace depicted on either a conventional 2D planar display or a 3D perspective display. Requests were presented either as voice messages or were displayed visually. Visual requests were either printed at the bottom of the display or represented as vectors, emanating in the requested direction from the requesting aircraft.The results indicated that controllers performed more accurately than pilots, and that performance was generally equivalent with the 2D and the 3D display. Overall performance was best with the auditory-verbal request mode. It was considerably slower with the print mode, presumably because of the greater visual scanning required. The spatial vector mode offered performance that was faster than print, but considerably less accurate. Particular deficiencies were noticed with the vector mode when it was used to present complex 3-dimensional requests in the context of the 3-dimensional display. The results are discussed within the context of their relevance for data-link technology and advanced ATC display concepts.

This study investigated how the addition of enhanced perceptual detail in a navigation interface interacts with learner characteristics and ultimately impacts learning; specifically memory for a route on a map. Previous research has shown both facilitative and prohibitive effect of adding perceptual detail to user interfaces. However, it is not clear how adding this kind of resolution might also interact with learner abilities. This study evaluated how well routes were remembered from maps that were either enhanced with actual satellite photography or presented in more traditional (low resolution) form by learners who differed in spatial ability. Results indicated that learners recalled a mapped route significantly better in the low perceptual detail condition than in the high detail condition and spatial visualization ability significantly predicted success on these tasks whereas mental rotation ability did not. Thus, it appears that the addition of perceptual detail not only affects learning, but also interacts with learner ability.

Two rating scale techniques employing an absolute magnitude estimation method, were compared to a relative judgment method for assessing subjective workload. One of the absolute estimation techniques used was an unidimensional overall workload scale and the other was the multidimensional NASA-Task Load Index technique. Thomas Saaty's Analytic Hierarchy Process was the unidimensional relative judgment method used. These techniques were used to assess the subjective workload of various single- and dual-tracking conditions. The validity of the techniques was defined as their ability to detect the same phenomena observed in the tracking performance. Reliability was assessed by calculating test-retest correlations. Within the context of the experiment, the Saaty Analytic Hierarchy Process was found to be superior in validity and reliability. These findings suggest that the relative judgment method would be an effective addition to the currently available subjective workload assessment techniques.

The purpose of this analysis was to describe some of the errors that pilots make during flight under instrument flight rules (IFR). The data suggest that there is less risk during the approach and landing phase of IFR flights, as compared to operations under visual flight rules. During the 1980s, there was a large increase in the number of single-pilot IFR (SPIFR) accidents. Most of these were the result of an increase in air taxi accidents. But, because of the increase in air taxi operations, there was no change in the SPIFR rate. SPIFR accident rates continue to be higher than dual-pilot IFR, reflecting the high work load of IFR operations. Night SPIFR continues to be dangerous; its rate is almost 10 times the rate of day IFR, and twice that of day non-IFR operations. The relatively static nature of the statistics for IFR accident rates may be accounted for by (1) the fact that there has been little change in general aviation cockpit technology during the last 25 years, (2) training techniques have not had an impact on pilot operations, and/or (3) current display technology promotes certain types of pilot errors that are virtually immune to training.

This presentation concentrates on knowledge acquisition and its application to the development of an expert module and a user interface for an Intelligent Tutoring System (ITS). The Systems Test and Operations Language (STOL) ITS is being developed to assist NASA control center personnel in learning a command and control language as it is used in mission operations rooms. The objective of the tutor is to impart knowledge and skills that will permit the trainee to solve command and control problems in the same way that the STOL expert solves those problems. The STOL ITS will achieve this object by representing the solution space in such a way that the trainee can visualize the intermediate steps, and by having the expert module production rules parallel the STOL expert's knowledge structures.

Little work has empirically examined the cognitive construct of situation awareness (SA) in driving tasks involving the use of advanced in-vehicle automated technologies and personal communication devices. This research investigated the effects of an adaptive cruise control (ACC) system, and cell phone use in driving, on a direct and objective measure of SA, and assessed the competition of multiple driving and communication tasks for limited mental resources in terms of driving performance. Eighteen participants drove a virtual car in a driving simulation and performed a following task involving changes in speed and lateral position. Half of the participants were required to respond to cell phone calls and all completed trials with and without use of the ACC system. Task performance was measured in terms of lane deviations and speed control in tracking a lead vehicle, as well as headway distance in the following task. SA was measured using a simulation freeze technique and SA queries on the driving situation. Subjective workload was measured using a uni-dimensional mental workload rating. Results indicated use of the ACC system to improve driving task SA under typical driving conditions, and to reduce driver mental workload. However, the cell phone conversation caused deleterious effects on driving SA and increased driver mental load. The cell phone conversation (secondary task) competed for limited mental resources of drivers, leading to less attention to, and accurate knowledge of, the driving situation. Results also revealed the ACC system to improve driving performance along multiple dimensions; however, the cell phone did not have an effect. The latter result may be attributed to a short duration of the cell phone conversations during the experiment. This study has implications for the implementation of in-vehicle automation to support driver SA under normal driving conditions and regulations on the use of cell phones while driving.

This report describes a preliminary investigation of the use of perturbed visual feedback during the performance of simulated space-based remote manipulation tasks. The primary objective of this NASA evaluation was to determine to what extent operators exhibit adaptive strategies which allow them to perform these specific types of remote manipulation tasks more efficiently while exposed to perturbed visual feedback. A secondary objective of this evaluation was to establish a set of preliminary guidelines for enhancing remote manipulation performance and reducing the adverse effects. These objectives were accomplished by studying the remote manipulator performance of test subjects exposed to various perturbed camera-viewing conditions while performing a simulated space-based remote manipulation task. Statistical analysis of performance and subjective data revealed that remote manipulation performance was adversely affected by the use of perturbed visual feedback and performance tended to improve with successive trials in most perturbed viewing conditions.

Age-related changes in trunk kinematics in lifting have received little attention despite a documented increased risk of musculoskeletal injury with age. This study examined the responses in trunk kinematics and ground reaction forces of older and younger subjects during lifting. Ten older (55–63 years) and ten younger (19–29 years) adults performed lifting tasks in six different conditions. A lumbar motion monitor was used to measure the subjects’ trunk kinematics and a force platform was used to measure the ground reaction forces during the lifting motion. The results of this study showed that age had a significant (p<0.05) effect on the transverse plane (axial twisting) trunk kinematics variables (peak velocity and peak acceleration) but did not affect ground reaction forces or other trunk kinematics variables. The peak transverse velocity was 40% lower and peak transverse acceleration was 30% lower in the older subjects as compared to the younger subjects.Relevance to industryThis study presents the postural adaptation of older subjects to dynamic lifting tasks. Results can be used to understand the risks of older work population in manual material handling tasks.

Thirty pilots flew a simulated VFR cross country flight with one of three levels of display support: a control display with standard instruments, a synthetic vision systems (SVS) display depicting terrain and a highway in the sky (HITS), and a configuration in which the same SVS/HITS display was augmented by an electronic moving map depicting weather. The flight path directed for all three groups penetrated bad weather (IMC) near the destination airport. Results revealed that nearly all pilots in the control condition avoided penetrating the IMC clouds. Significantly more pilots in both SVS conditions penetrated the clouds before diverting to a lower altitude. Their failure to notice the deteriorating weather outside the cockpit was documented by a dominance of head down scanning for the pilots in these two groups who penetrated the weather. Even pilots who did avoid the clouds, looked outside only 1/3 as frequently as those in the control group. The presence of the moving map weather display did not mitigate these manifestations of attentional tunneling. Possible solutions related to display design and training are discussed.

This study proposes a methodology for characterizing the causal context and consequences of procedural interrupts in ground operations tasks. Behavioral science researchers observed 26 tasks at NASA's Kennedy Space Center. From these tasks, 81 procedural interrupts were identified and coded for the following information: source of the interrupt, circumstances surrounding the interrupt, and consequences of the interrupt. We found that more interrupts were equipment or personnel-related than procedure-related. More interrupts were due to unavailable resources or resources being incorrect than resources being inaccessible, and most interrupts resulted in some action being taken. Variation in duration of procedural interrupts across causal categories was also examined. The characterization process helps to identify those interrupts that are disruptive, those that cannot be avoided, and those that may have been prevented through better planning or scheduling of resources. Implications for the use of the methodology and suggestions for further research are discussed.

Display evaluation has generally been performed using reaction time experiments or subjective evaluations to determine which display is better suited for a particular application. A new testing procedure combined with two analysis techniques of scanning behavior have been used to evaluate two alternative display designs in a realistic setting. Tests were conducted in the Langley Research Center's General Aviation Simulator. The results indicated that a new bargraph type of vertical speed indicator located between the attitude indicator and the altimeter is looked at more quickly, appears to lower cognitive workload slightly, and was preferred over a conventional vertical speed indicator.

A computer program has been written which contains a model of the procedures used in normal operation of a twin engine aircraft. This model, from examining the current and recent aircraft state, can determine when a procedure (or checklist) should be or is invoked and when each step (detectable by a change in the aircraft state) is completed. Thus. the program tracks the flight crew through changes in the aircraft state. The computer program is intended to aid the flight crew by detecting errors. Omitting procedure steps (or entire procedures), changing the aircraft configuration improperly, and executing procedure steps out of order are all errors the program is able to detect. The program will be evaluated on data from a previous experiment on a Link GAT-II simulator. One data set was used to test the program. The program was run unmodified on the second. The errors it found are compared with manual analysis that has been reported by Rouse and Rouse [1983].

The development and evaluation of the Knowledge Aided Display Design (KADD) system is described. Developed to investigate several designer support concepts in the context of the design of computer-generated displays, KADD's implementation uses technology from several disciplines of computer science including data base design and management, graphics, expert systems, and real-time simulation. This paper discusses KADD's goals and concepts, the implementation of the system, and the results of a two-part evaluation to determine the effectiveness of the KADD concepts.

Objective: The paper studies aircraft ghosting on a radar display as a potential means to support air traffic controllers with late merging operations in approach control. Background: A formerly presented late merging concept has pointed out operational benefits in terms of fuel efficiency and noise reduction. A first exploratory study has shown that the concept puts high task demands on the air traffic controller to achieve necessary precision. The provision of a ghosting system is considered as a potential automation tool which supports the controller in merging traffic. Methods: A microworld simulation of approach control was used to study the effect of two potential ghosting solutions (time-based vs. distance based ghosting) on control performance while executing late merging operations. Objective performance, situation awareness (SAGAT), and subjective ratings on the ghosting system were the main evaluation criteria. Results: The results confirm the hypothesized positive effects of both ghosting solutions on objective merging performance. Under certain conditions, ghosting had a negative effect on situation awareness as regards the position of real aircraft. Finally, the majority of participants reported that time-based ghosting support is less strenuous and more helpful for merging operation than distance-based ghosting. Conclusions: Ghosting brings about performance benefits. Yet, SA of real aircraft has to be ensured. Application: Results will inform the system design and experimental design for follow-up studies in the full mission simulator.

A simulator study of the five airline flight crews engaged in various enroute planning activities has been conducted. Based on a cognitive task analysis of this data, a flight planning workstation has been developed on a Mac II controlling three color monitors. This workstation is being used to study design concepts to support the flight planning activities of dispatchers and flight crews in part-task simulators.

Computerized aids may be used to support decision-making and control in a variety of complex, dynamic arenas. For instance, such systems have been introduced into industrial settings as the means to implement automated control or support decision-making activities such as fault detection and recovery. Of interest in these systems is the extent to which operators utilize and trust such systems, in terms of their ability to successfully control systems, or the information or decision support they provide, particularly under conditions of potential failure. A theoretical framework to describe potential factors affecting these issues, and an experiment to investigate the role of failure cause on trust and system utilization, are described. Results provide some support for factors in the theoretical framework, and also demonstrated the use of an empirically developed trust scale.Relevance to industryAs manufacturing environments increasingly rely on computerized and automated systems for control and human operator support, it is necessary to understand the situational factors which could impact operators’ use of such systems. This paper describes a framework which could be used to investigate trust in industrial automation settings, as well as a rating scale which could be applied.

An increasing level of automation in the flight cockpit more and more prevents pilots from receiving direct feedback from the aircraft. This lack can result in deficient situation awareness, which can degrade the dependability of the pilot-aircraft system. To assist the pilot in maintaining a high level of situation awareness, it has been proposed to develop a system monitoring the pilot’s gaze behavior, comparing it with a model, and reacting appropriately, if meaningful deviations occur. Therefore, the impact of the aircraft’s states and the communication with the air traffic control on the gaze behavior has been investigated previously. The study’s conclusions are, however, only based on one professional pilot, which impedes generalization. This is why this paper aims (a) at replicating the effects of the aircraft’s states and communication efforts on pilots’ gaze behavior and (b) at analyzing whether there are interindividual differences in the gaze patterns of pilots. For this purpose, a study with twelve professional pilots has been conducted during which two scenarios where flown while the states of the aircraft, the communication with the air traffic control, and the pilot’s gaze behavior were recorded. Data analytic procedure revealed significant interindividual differences: Visual attention on the center pedestal and a navigation display varied between persons. In addition, the results replicated the findings of the one-participant study: It is especially the altitude of the aircraft and the communication, which impact the pilots’ visual attention.

Airborne self-separation is one of the concepts which is currently under discussion as a key feature in NextGen/SESAR's future air-transport system. Self-separation of aircraft is expected to provide higher capacity and safety levels as well as a better consideration of the different needs of airspace users. However, in order to become operational self-separation requires certain airspace structures and procedures. Compared to earlier studies by FAA and NASA which are based on the concept of shared control by ATC and flight crews, our approach uses a transfer of control concept where the control authority for aircraft separation tasks is shifted from ATC to flight crews and back to ATC. In order to better understand possible roles and role changes of future aviators, we conducted an integrated simulation study with 15 airline pilots and five air-traffic controllers on a low-cost simulation platform called AviaSim. In an experimental design with repeated measurements, the subjects flew three scenarios with and without control shift for self-separation. The findings show that operators' workload and situation awareness scores are better balanced under the shift-of-control condition compared to the traditional ground-control condition. Additionally, effects of transfer of control on preferred separation tactics and safety indicators are examined.

This study explored the use of cockpit traffic displays for aircraft separation in instrument conditions. This is a new concept termed EFR for electronic flight rules. Four groups of three general aviation, instrument-rated pilots flew cross-country flights in twin engine simulators in the Multi-Cockpit Facility at NASA Ames. They were required to maintain two miles horizontal and 500 feet vertical separation from all other aircraft. There were 24 different geometries, or traffic situations, repeated randomly for each of the four experimental conditions for each group. Of 1152 aircraft encounters 12.8% were in violation of separation minimums. Eighteen of these were closer than 400 ft vertically or 1.6 nm horizontally. The minimum separation of all aircraft pairs was 293 ft and .13 nm. The type and time of evasive maneuvers showed no effect when sensor noise was simulated in the displayed traffic information. When pilots were able to communicate and coordinate their maneuvers, the time to resolve the conflict was reduced. Subject groups varied significantly in: time of conflict resolution, frequency and type of maneuvers, control activity, reported amount of threat, confidence, and satisfaction they perceived, and appraisal of the efficacy of their communications.

Because restricted visibility has been implicated in the majority of commercial and general aviation accidents, solutions will need to focus on how to enhance safety during instrument meteorological conditions (IMC). The NASA Synthetic Vision Systems (SVS) project is developing technologies to help achieve these goals through the synthetic presentation of how the outside world would look to the pilot if vision were not reduced. The potential safety outcome would be a significant reduction in several accident categories, such as controlled-flight-into-terrain (CFIT), that have restricted visibility as a causal factor. The paper describes two experiments that demonstrated the efficacy of synthetic vision technology to prevent CFIT accidents for both general aviation and commercial aircraft.

Traditionally, community aircraft flyover annoyance has been studied in the absence of other noises. However, the importance of considering the flyovers along with other community noise sources is gaining increasing awareness. To investigate annoyance of multiple noise sources, two experiments were conducted. The first experiment used 48 subjects, and the second used 216 subjects. The first experiment was designed to establish annoyance-noise level functions for three community noise sources presented individually: jet aircraft flyovers, air conditioner, and traffic. This experiment provided baseline data for a second experiment which is currently being conducted to investigate (1) effects of background noise on aircraft annoyance as a function of noise level and spectrum shape; (2) the relative contributions of background noises and aircraft noise to overall annoyance; and (3) effect of type of annoyance rating: overall or source specific. In the second experiment, the subjects were required to make either overall or source specific annoyance ratings or a combination of the two. Both experiments used two dependent measures: rated annoyance and amount of subconscious body movement or fidgeting. Results of the first experiment indicated that the slope of the annoyance-noise level function for traffic was significantly different from the slopes corresponding to flyover and air conditioner noise. This added further justification to the need to determine the influence of different background noises on aircraft noise annoyance (e.g., experiment two). Preliminary body movement analysis indicated no relationship of body movements to source noise level. Results of the second experiment showing differential effects of signal-to-noise ratio and background source type across total noise level will be presented and discussed. Results will also be presented to illustrate the effects of all the sources (flyover, air conditiner, and traffic) on relative annoyance as a function of the type of annoyance questionnaire. Further data on the correlation of movement with source noise level will be discussed. However, based on the results of the first experiment, little relation to annoyance is expected. All results will be applied in an effort to develop an improved model of human response to community noise.

Maintenance operations incidents submitted to the Aviation Safety Reporting System (ASRS) between 1986-1992 were systematically analyzed in order to identify issues relevant to human factors and crew coordination. This exploratory analysis involved 95 ASRS reports which represented a wide range of maintenance incidents. The reports were coded and analyzed according to the type of error (e.g, wrong part, procedural error, non-procedural error), contributing factors (e.g., individual, within-team, cross-team, procedure, tools), result of the error (e.g., aircraft damage or not) as well as the operational impact (e.g., aircraft flown to destination, air return, delay at gate). The main findings indicate that procedural errors were most common (48.4%) and that individual and team actions contributed to the errors in more than 50% of the cases. As for operational results, most errors were either corrected after landing at the destination (51.6%) or required the flight crew to stop enroute (29.5%). Interactions among these variables are also discussed. This analysis is a first step toward developing a taxonomy of crew coordination problems in maintenance. By understanding what variables are important and how they are interrelated, we may develop intervention strategies that are better tailored to the human factor issues involved.

A theory of performance measurement for operator controlled systems is presented. The theory permits synthesis of a system performance measure which scores performance on successive data samples based on the impact of the sampled performance on the overall summary of performance. Since performance is measured and evaluated on each sample, the dynamics of the controlled element, i.e., the aircraft, are effectively removed from the measurement eventhough the pilot (operator) continues to control the aircraft. While the theory directly applies to problems where the performance limiting factors are known, the method has been extended to apply to problems where the performance limiting factors are not known explicitly, but are known to be implicit in the performance data. This paper documents the development of measures for aircraft carrier landings for the glide path and angle of attack control channels. Flight data obtained from the Visual Technology Research Center, Naval Training Equipment Center, Orlando, Florida, was analyzed using the measures. The data on carrier landings were available on 9-track magnetic tape consisting of flights by four subjects each performing on 42 flights. Each flight was performed on a particular combination of glide path error display and day/night combination. Two types of glide path displays were used, resulting in four treatments (two displays and two light conditions). One display was the conventional glide path display and the other was a command display which incorporates error rate information with glide path error presentation. Each subject controlled the aircraft to a carrier landing three times with each treatment. The resulting performance scores were aggregated by subject, treatment, range to carrier deck, and error and error rate cells. The results suggest that the command display offers improved glide path control especially during day light conditions. Further, the measurement technique was shown to permit determination of the relationship between performance and factors that change during the flight - such as error and error rate magnitudes. The measurement technique bypasses the time delays due to aircraft dynamics - by accounting for them - permitting evaluation of performance on short (less than a second) intervals of flight. Consequently, observed differences in performance at different error and error rate magnitudes were detected suggesting that significant non-linear control techniques may have been exhibited by the pilots.

Information theoretic analysis and subjective paired-comparison and task ranking techniques were employed in order to scale the workload of 20 communications-related tasks frequently performed by the captain and first officer of transport category aircraft. Tasks were drawn from taped conversations between aircraft and air traffic controllers (ATC). Twenty crewmembers performed subjective message comparisons and task rankings on the basis of workload. Information theoretic results indicated a broad range of task difficulty levels, and substantial differences between captain and first officer workload levels. Preliminary subjective data tended to corroborate these results. A hybrid scale reflecting the results of both the analytical and the subjective techniques is currently being developed. The findings will be used to select representative sets of communications for use in high fidelity simulation.

This research, performed as a part of NASA Langley's Faultfinder project, investigated display implementation issues related to the introduction of real time fault diagnostic systems into next generation commercial aircraft. Three major issues were investigated: visual display styles for presenting fault related information to the crew, the form the output from the expert system should take, and methods for filtering fault related information for presentation to the crew. Twenty-four flight familiar male volunteers participated as subjects. Five subjects were NASA test pilots, six were Commercial Airline Pilots, seven were Air Force Lear Jet pilots, and six were NASA personnel familiar with flight (non-pilots). Subjects were presented with aircraft subsystem information on a CRT screen. They were required to identify the subsystems presented in a display and to remember the state (normal or abnormal) of subsystem parameter information contained in the display. The results of the study indicated that in the simpler experimental test cases (i.e., those involving single subsystem failures and composite hypothesis displays) subjects' performance did not differ across the different display formats. However, for the more complex cases (i.e., those involving multiple subsystem faults and multiple hypotheses displays), subjects' performance was superior in the text- and picture-based display formats compared to the symbol-based format. In addition, the findings suggest that a layered approached to information display is appropriate.

The events which have led to the intensive study of aircraft structural problems have contributed in no less measure to the study of human factors which influence aircraft maintenance and inspection. Initial research emphasis on aging aircraft maintenance and inspection has since broadened to include all aircraft types. Technicians must be equally adept at repairing old and new aircraft. Their skills must include the ability to repair sheet metal and composite materials; control cable and fly-by-wire systems; round dials and glass cockpits. Their work performance is heavily influenced by others such as designers, technical writers, job card authors, schedulers, and trainers. This paper describes the activities concerning aircraft and maintenance human factors.

Aircrew effectiveness in coping with emergencies has been linked to captain's personality profile. The present study analyzed cockpit communication during simulated flight to examine the relation between captains' discourse strategies, personality profiles, and crew performance. Positive Instrumental/Expressive captains and Instrumental-Negative captains used very similar communication strategies and their crews made few errors. Their talk was distinguished by high levels of planning and strategizing, gathering information, predicting/alerting, and explaining, especially during the emergency flight phase. Negative-Expressive captains talked less overall, and engaged in little problem solving talk, even during emergencies. Their crews made many errors. Findings support the theory that high crew performance results when captains use language to build shared mental models for problem situations.

Advanced Surface Movement Guidance and Control Systems (A-SMGCS) comprise a range of new technologies for both the flight deck and ground air traffic control and is supposed to enable increased safety and a more efficient throughput at presently highly congested major airports. A flight deck A-SMGCS module is the onboard guidance system TARMAC-AS. This module consists of controller pilot data link communication (CPDLC) and an electronic moving map (EMM), which also serves as a cockpit display of traffic information (CDTI). TARMAC-AS is evaluated in an investigation involving 49 commercial pilots who performed a series of approach, landing and taxiing simulation trials under varied visibility, which were completed in a fixed-base cockpit simulator. Results support the notion that an EMM + CPDLC + CDTI improve the effectiveness of taxi navigation. A potential negative impact of observed increased head-down times to the compelling TARMAC display on unexpected outside scene obstacle detection was not substantiated.

A research effort has been undertaken to determine the feasibility of employing a forward-looking cockpit display to provide information that would enable aircraft to utilize reduced separation, and hence increased runway capacity, through the application of multiple-glide-path approach techniques. The current study was an initial exploration into this concept in which traffic information was added to a HUD format to allow the pilot to monitor the traffic situation and to self space on a lead aircraft during a simulated single glide-path approach. The results of this study indicate that this display concept can provide sufficient information to the pilot for traffic monitoring and self separation. Additionally, the pilots noted that an increase in situational awareness, relative to conventional instrument flight, was provided by the traffic information on the display.

The paper aims at understanding crucial variables that influence the control of visual attention of tower controllers. Novel concepts for aerodrome control of regional airports consider to remotely control two or more airports at a time from one remote center. A simulation experiment was set up where 12 professional tower controllers operated parallel traffic of two airports. Eye gaze recording and questionnaires were used. Two feedback loops are considered to influence the controllers monitoring behavior: The accessibility of the information of the “far-view” and controller strategies. The results show that both variables have a crucial influence on how often the controller updates the information of one airport. This implies that monitoring performance depends on system design and behavioral strategies. These dependencies can be applied to the design of novel ATC-workplaces.

In the near future, conventional radio communications, currently the primary medium for the transfer of information between aircraft and ground stations, will be replaced by digital data link. This paper briefly describes this technology and summarizes what are believed to be the principal human factor issues associated with data link implementation in the airspace system. Integration of data link communications with existing systems on the flight deck and in the Air Traffic Control system is discussed with regard for both near term implementation and longer term operational issues.

As part of an ongoing program to develop a Computer Aided Engineering (CAE) system for human factors engineers, a Human Performance Expert System, Human, was designed. The system contains a large database of human-performance equations derived from human performance research reported in the open literature. Human accesses these data to predict task performance times, task completion probabilities, and error rates. A problem was encountered when multiple independent data sets were relevant to one task. For example, a designer is interested in the effects of luminance and font size on a number of reading errors. Two data sets exist in the literature: one examining the effects of luminance, the other, font size. The data in the two sets were collected at different locations with different subjects, and at different times in history. How can the two data sets best be combined to address the designer's problems?On the basis of an extensive review of the human performance literature and statistical procedures, four combining algorithms were developed. These four algorithms were tested in two steps. In step one, two reaction-time experiments were conducted: one to evaluate the effect of the number of displays being monitored. The four algorithms were used on the data from these two experiments to predict reaction time in the situation where all three independent variables are manipulated simultaneously. In step two of the test procedure, a third experiment was conducted. Subjects who had not participated in either Experiment 1 or 2 performed a reaction-time task under the combined effects of all three independent variables. The predictions made from step one were compared to the actual empirical data collected in Experiment 3. The best predictor of the mean in Experiment 3 was an unweighted average of the means in Experiments 1 and 2; the best predictor of the standard deviation in Experiment 3 was an unweighted average of the standard deviations, (S.D.s) in Experiments 1 and 2. Based on these results, Human uses an average of the means to combine the results from multiple independent data sets.

This paper proposes a generic human-computer software user interface design, called the Resource Allocation Planning System (RAPS), designed to support a person making resource allocation decisions. Although there are many algorithms for automatically solving resource allocation problems, it is often the case that human judgment is also required. Also, while there are software user interfaces to support decision-making for specific resource allocation problems, most of them serve more as organizational charts than as decision-support systems, and most of them become increasingly difficult to use as the size of the resource allocation problem increases. This paper discusses the design and rationale for RAPS and gives an example of how RAPS can be adapted to a specific resource allocation problem.

The simulator sickness syndrome is receiving increased attention in the simulation community. NASA-Ames Research Center has initiated a program to facilitate the exchange of information on this topic among the tri-services and other interested government organizations. The program objectives are to identify priority research issues, promote efficient research strategies, serve as a repository of information, and disseminate information to simulator users.

Deep space missions such as Voyager rely upon a large team of expert analysts who monitor activity in the various engineering subsystems of the spacecraft and plan operations. Senior teammembers generally come from the spacecraft designers, and new analysts receive on-the-job training. Neither of these methods will suffice for the creation of a new team in the middle of a mission, which may be the situation during the Magellan mission. New approaches are recommended, including electronic documentation, explicit cognitive modeling, and coached practice with archived data.

Space Station Freedom will be a permanently manned multipurpose facility in low Earth orbit by the late 1990's. Integral to Space Station Freedom will be Data Management System workstations. These workstations will provide the human-machine interface for controlling such systems as Guidance, Navigation and Control, Propulsion, and Environmental Control and Life Support. In addition, they will be used by crewmembers in the space station's pressurized shirt-sleeve environment to control remote manipulator systems and free-flyer devices. This paper presents an overview of proposed workstations and current task-analytic evaluations being used to assess their adequacy in supporting Space Station Freedom operations. Particular emphasis is placed on the results and conclusions of the analysis.

The use of aptitude tests and questionnaries to evaluate an individuals aptitude for teleoperation is studied. The Raven Progressive Matrices Test and Differential Aptitude Tests, and a 16-item questionnaire for assessing the subject's interests, academic background, and previous experience are described. The Proto-Flight Manipulator Arm, cameras, console, hand controller, and task board utilized by the 17 engineers are examined. The correlation between aptitude scores and questionnaire responses, and operator performance is investigated. Multiple regression data reveal that the eight predictor variables are not individually significant for evaluating operator performance; however, the complete test battery is applicable for predicting 49 percent of subject variance on the criterion task.

Overall latency remains an impediment to perceived image stability and consequently to human performance in virtual environment (VE) systems. Predictive compensators have been proposed as a means to mitigate these shortcomings, but they introduce rendering errors because of induced motion overshoot and heightened noise. Discriminability of these compensator artifacts was investigated by a protocol in which head tracked image stability for 35 ms baseline VE system latency was compared against artificially added (16.7 to 100 ms) latency compensated by a previously studied Kalman Filter (K-F) predictor. A control study in which uncompensated 16.7 to 100 ms latencies were compared against the baseline was also performed. Results from 10 subjects in the main study and 8 in the control group indicate that predictive compensation artifacts are less discernible than the disruptions of uncompensated time delay for the shorter but not the longer added latencies. We propose that noise magnification and overshoot are contributory cues to the presence of predictive compensation.

Two studies were conducted evaluating methods of controlling a telerobot; bilateral force reflecting master controllers and proportional rate six degrees of freedom (DOF) hand controllers. The first study compared the controllers on performance of single manipulator arm tasks, a peg-in-the-hole task, and simulated satellite orbital replacement unit changeout. The second study, a Space Station truss assembly task, required simultaneous operation of both manipulator arms (all 12 DOFs) and complex multiaxis slave arm movements. Task times were significantly longer and fewer errors were committed with the hand controllers. The hand controllers were also rated significantly higher in cognitive and manual control workload on the two-arm task. The master controllers were rated significantly higher in physical workload. There were no significant differences in ratings of manipulator control quality.

The Airborne Science Office (ASO) of the Ames Research Center has for 10 years operated an airborne scientific research program in infrared astronomy and other disciplines. The Lear Jet, CV-990, and C-141 flying laboratories are flown by ASO crews, while the major responsibility for defining, developing, and operating the experimental equipment is placed on individual researchers, who have included scientists from many countries. The ASSESS (Airborne Science/Shuttle Experiment Systems Simulation) program consists of two phases: Phase A documents the present management and operational practices of the ASO, and Phase B consists of airborne research missions constrained (for example, by crew confinement) to simulate certain aspects of experimental operations on Shuttle/Spacelab missions. Various parallels between the Airborne Science Program and Spacelab are pointed out and their applications to Spacelab planning are discussed.

The Subjective Workload Assessment Technique (SWAT) and the NASA weighted-bipolar method used for evaluating subjective workload assessment are compared. The application of these methods to the rating of single- and dual-task trials of tracking and spatial transformation is described. The methods used to collect the ratings for the SWAT and bipolar technique are examined. Analysis of the transformation-tracking data reveal that the two assessment techniques produce similar results and both measure the differences in task difficulty. The positive and negative characteristics of each technique are analyzed.