Workload benefits of colour coded head-up flight symbology during high workload flight

The manipulation of colour in display symbology design has been recognised as a method to improve operator experience and performance. An earlier paper by the authors demonstrated that redundantly colour coding head-up flight symbology supported the manual flying performance of both professional and non-professional pilots during low-workload flying scenarios. In this study the workload and performance of 12 professional airline pilots was evaluated in high workload conditions whilst they flew manoeuvres and an instrument landing system (ILS) approach with and without the presence of colour feedback on a head up display (HUD). Workload was manipulated by presenting pilots with a concurrent auditory n-back task. Colour coded flight symbology reduced the subjective workload of the pilots during high workload conditions. In contrast, manual flying performance during high workload was not improved by the presence of colour coded feedback.     

Use of Highways in the Sky and a virtual pad for landing Head Up Display symbology to enable improved helicopter pilots situation awareness and workload in degraded visual conditions

Abstract

Flight within degraded visual conditions is a great challenge to pilots of rotary-wing craft. Environmental cues typically used to guide interpretation of speed, location and approach can become obscured, forcing the pilots to rely on data available from in-cockpit instrumentation. To ease the task of flight during degraded visual conditions, pilots require easy access to flight critical information. The current study examined the effect of ‘Highways in the Sky’ symbology and a conformal virtual pad for landing presented using a Head Up Display (HUD) on pilots’ workload and situation awareness for both clear and degraded conditions across a series of simulated rotary-wing approach and landings. Results suggest that access to the HUD lead to significant improvements to pilots’ situation awareness, especially within degraded visual conditions. Importantly, access to the HUD facilitated pilot awareness in all conditions. Results are discussed in terms of future HUD development.

Practitioner Summary: This paper explores the use of a novel Heads Up Display, to facilitate rotary-wing pilots’ situation awareness and workload for simulated flights in both clear and degraded visual conditions. Results suggest that access to HUD facilitated pilots’ situation awareness, especially when flying in degraded conditions.     

Benefits of color coding weapons symbology for an airborne helmet-mounted display

We assessed the advantages of a color-coded weapons symbology for a helmet-mounted display over monochrome symbology by measuring military pilots' performance while they flew air-to-air combat in a simulator. The pilots fired missiles significantly sooner without sacrificing probability of kill when using the color-coded symbology, demonstrating a substantial practical benefit of color. Actual or potential applications of this work include the design of color codes for helmet-mounted and other displays that use complex symbology to assist performance on cognitively challenging tasks.     

The virtual landing pad: facilitating rotary-wing landing operations in degraded visual environments

The safety of rotary-wing operations is significantly affected by the local weather conditions, especially during key phases of flight including hover and landing. Despite the operational flexibility of rotary-wing craft, such craft accounts for a significantly greater proportion of accidents than their fixed-wing counterparts. A key period of risk when operating rotary-wing aircraft is during operations that occur in degraded visual environments, for example as a result of thick fog. During such conditions, pilots’ workload significantly increases and their situation awareness can be greatly impeded. The current study examines the extent to which providing information to pilots via the use of a head-up display (HUD) influenced perceived workload and situation awareness, when operating in both clear and degraded visual environments. Results suggest that whilst the HUD did not benefit pilots during clear conditions, workload was reduced when operating in degraded visual conditions. Overall results demonstrate that access to the HUD reduces the difficulties associated with flying in degraded visual environments.     

Ocular measures of redundancy gain during visual search of colour symbolic displays

Sixteen observers participated in a visual search experiment in which colour coding, search type, and the amount of pre-search information available to the observers were varied. Observers searched simulated symbolic tactical displays to find the number of target symbols (i.e. exhaustive search) or the quadrant of the display in which a single target symbol was located (i.e. self-terminating search). Displays varied in the way in which the symbology was colour coded: colour was either relevant (i.e. redundant with symbol shape) or irrelevant (orthogonal to symbol shape), or the display was monochrome. Half of the observers were cued with regard to the coding scheme prior to display onset, while the other observers were not. There was no overall difference in search time or accuracy, number of eye fixations, or pupillary response between cued and non-cued observers, but only because cued and non-cued observers used the coding schemes differently. Redundancy gain was only evident for cued observers, who searched colour relevant displays faster and with fewer fixations than colour irrelevant or monochrome displays. Non-cued observers' search pattern did not differ across colour coding schemes, but they searched colour irrelevant and monochrome displays faster than the cued observers. Differences between cued and non-cued observers' search strategy are discussed with regard to their implications for design and evaluation of colour multipurpose displays.     

Superimposition, symbology, visual attention, and the head-up display

In two experiments we examined a number of related factors postulated to influence head-up display (HUD) performance. We addressed the benefit of reduced scanning and the cost of increasing the number of elements in the visual field by comparing a superimposed HUD with an identical display in a head-down position in varying visibility conditions. We explored the extent to which the characteristics of HUD symbology support a division of attention by contrasting conformal symbology (which links elements of the display image to elements of the far domain) with traditional instrument landing system (ILS) symbology. Together the two experiments provide strong evidence that minimizing scanning between flight instruments and the far domain contributes substantially to the observed HUD performance advantage. Experiment 1 provides little evidence for a performance cost attributable to visual clutter. In Experiment 2 the pattern of differences in lateral tracking error between conformal and traditional ILS symbology supports the hypothesis that, to the extent that the symbology forms an object with the far domain, attention may be divided between the superimposed image and its counterpart in the far domain.     

Eye movement behaviour viewing colour-coded and monochrome avionic displays

Abstract

This paper reports on two experiments in which subjects' eye movement behaviour was monitored while they searched for target information in colour coded and monochrome horizontal situation indicator (HSI) displays. The first experiment required subjects to locate and report alphanumeric information associated with the active waypoint on the displayed flightpath. Initial fixations in the display were more accurately directed to the target information when it was redundantly colour coded compared with when it was coded by shape and relative positional codes. Fewer fixations and a shorter time were required to locate the colour coded target and verbally report the relevant information. The time advantage of colour coded displays compared with monochrome displays was greatest for visually cluttered displays. In the second study there was no advantage of a coloured display when the task was to count all the displayed waypoint symbols on the flight path. The lack of any benefit for colour coding was a result of waypoint symbols having strong positional predictability due to their relationship to the displayed flightpath in both the colour and monochrome displays. The implication from these results is that colour coded information confers an advantage over a spatial code for targets at unknown spatial location but less benefit when target location can be predicted by other visual cues.     

Selected graph design variables in four interpretation tasks: a microcomputer-based pilot study

A pilot study was undertaken to assess the efficacy of selected graph types and information coding schemes in producing quick and accurate graph interpretation. Point-plots, line graphs, bar graphs, and three-dimensional bar graphs were constructed and displayed using an IBM-PC microcomputer with colour monitor. The effectiveness of each of these graph types, as well as the coding scheme used within each (colour versus monochrome), was investigated using 32 subjects in four separate experiments involving either point-reading, point-comparison, trend-reading, or trend-comparison tasks. Dependent measures including task completion time, graph interpretation error, subjective mental workload rating, and graph preference rating were obtained. In three of the tasks, colour-coded graphs were associated with lower task completion time, lower rated mental workload, and higher rated preference than monochrome graphs. However, there were no differences in subjects' error scores between colour and monochrome coding for any of the tasks. For the point-reading task, the three-dimensional bar graphs were less effective than the other graph types, though there were no differences among graph types for the other three tasks. Implications for graph design given specific data interpretation tasks are discussed, based on the results of the four experiments and related literature.     

Synthetic vision systems: the effects of guidance symbology, display size, and field of view

Two experiments conducted in a high-fidelity flight simulator examined the effects of guidance symbology, display size, and geometric field of view (GFOV) within a synthetic vision system (SVS). In Experiment 1, 18 pilots flew highlighted and low-lighted tunnel-in-the-sky displays, as well as a less cluttered follow-me aircraft (FMA), through a series of curved approaches over rugged terrain. The results revealed that both tunnels supported better flight path tracking and lower workload levels than did the FMA because of the availability of more preview information. Increasing tunnel intensity had no benefit on tracking and, in fact, degraded traffic awareness because of clutter and attentional tunneling. In Experiment 2, 24 pilots flew a lowlighted tunnel configured according to different display sizes (small or large) and GFOVs (30 degrees or 60 degrees). Measures of flight path tracking and terrain awareness generally favored the 60 degrees GFOV; however, there were no effects of display size. Actual or potential applications of this research include understanding the impact of SVS properties on flight path tracking, traffic and terrain awareness, workload, and the allocation of attention.     

The influence of training level on manual flight in connection to performance,scan pattern,and task load

This work focuses on the analysis of pilots’ performance during manual flight operations in different stages of training and their influence on gaze strategy. The secure and safe operation of air traffic is highly dependent on the individual performances of the pilots. Before becoming a pilot, he/she has to acquire a broad set of skills by training to pass all the necessary qualification and licensing standards. A basic skill for every pilot is manual control operations, which is a closed-loop control process with several cross-coupled variables. Even with increased automation in the cockpit, the manual control operations are essential for every pilot as a last resort in the event of automation failure. A key element in the analysis of manual flight operations is the development over time in relation to performance and visual perception. An experiment with 28 participants (including 11 certified pilots) was conducted in a Boeing 737 simulator. For defined flight phases, the dynamic time warping method was applied to evaluate the performance for selected criteria, and eye-tracking methodology was utilized to analyze the gaze-pattern development. The manipulation of workload and individual experience influences the performance and the gaze pattern at the same time. Findings suggest that the increase of workload has an increased influence on pilots depending on the flight phase. Gaze patterns from experienced pilots provide insights into the training requirements of both novices and experts. The connection between workload, performance and gaze pattern is complex and needs to be analyzed under as many differing conditions. The results imply the necessity to evaluate manual flight operations with respect to more flight phases and a detailed selection of performance indications.

     

Examining the Effects of Conformal Terrain Features in Advanced Head‐Up Displays on Flight Performance and Pilot Situation Awareness

Synthetic vision systems (SVS) render terrain features for pilots through cockpit displays using a GPS database and three‐dimensional graphical models. Enhanced vision systems (EVS) present infrared imagery of terrain using a forward‐looking sensor in the nose of an aircraft. The ultimate goal of SVS and EVS technologies is to support pilots in achieving safety under low‐visibility and night conditions comparable to clear, day conditions. This study assessed pilot performance and situation awareness (SA) effects of SVS and EVS imagery in an advanced head‐up display (HUD) during a simulated landing approach under instrument meteorological conditions. Videos of the landing with various HUD configurations were presented to eight pilots with a superimposed tracking task. The independent variables included four HUD feature configurations (baseline [no terrain imagery], SVS, EVS, and a combination of SVS and EVS), two visibility conditions, and four legs of the flight. Results indicated that SVS increased overall SA but degraded flight path control performance because of visual confusion with other display features. EVS increased flight path control accuracy but decreased system (aircraft) awareness because of visual distractions. The combination of SVS and EVS generated offsetting effects. Display configurations did not affect pilot spatial awareness. Flight performance was not different among phases of the approach, but levels and types of pilot SA did vary from leg to leg. These results are applicable to development of adaptive HUD features to support pilot performance. They support the use of multidimensional measures of SA for insight on pilot information processing with advanced aviation displays. © 2012 Wiley Periodicals, Inc.     

Effects of modes of cockpit automation on pilot performance and workload in a next generation flight concept of operation

The objective of this study was to compare the effects of various forms of advanced cockpit automation for flight planning on pilot performance and workload under a futuristic concept of operation. A lab experiment was conducted in which airline pilots flew simulated tailored arrivals to an airport using three modes of automation (MOAs), including a control‐display unit (CDU) to the aircraft flight management system, an enhanced CDU (CDU+), and a continuous descent approach (CDA) tool. The arrival scenario required replanning to avoid convective activity and was constrained by a minimum fuel requirement at the initial approach fix. The CDU and CDU+ modes allowed for point‐by‐point path planning or selection among multiple standard arrivals, respectively. The CDA mode completely automated the route replanning for pilots. It was expected that the higher‐level automation would significantly reduce pilot workload and improve overall flight performance. In general, results indicated that the MOAs influenced pilot performance and workload responses according to hypotheses. This study provides new knowledge about the relationship of cockpit automation and interface features with pilot performance and workload in a novel next generation–style flight concept of operation. © 2012 Wiley Periodicals, Inc.     

Change blindness in pilot perception of METAR symbology

ObjectiveTo assess General Aviation (GA) pilots' perception of changes in aviation routine weather report (METAR) symbols.MethodSixty instrument-rated GA pilots were randomly assigned to one of three METAR symbology groups. We assessed pilots' ability to detect changes to the METAR symbols during a simulated flight, and examined the relationship between detection performance and pilots' flight behavior, cognitive engagement, and decision making.ResultsDepending on the symbology, pilots varied considerably in their overall detection of METAR symbol change during flight. Pilots who detected the METAR-symbol changes differed in their cognitive engagement compared to pilots who did not detect the changes.ConclusionWeather presentation symbology affects pilots' perception of symbol change and cognitive engagement.Relevance to industryThe simulation outcome provides important data on the perception of weather-presentation symbology important to the design and optimization of cockpit weather displays.     

Pilots’ gaze strategies and manual control performance using occlusion as a measurement technique during a simulated manual flight task

The aim of this study was to analyze pilots’ visual scanning under conditions visually restricted by the occlusion paradigm. During manual flight, pilots experienced interruptions in their panel scan due to concurring tasks and monitoring of distant displays. Eleven volunteer airline pilots performed several manual instrument landing system approaches in a fixed-base flight simulator. Some of these approaches were performed using the paradigm of occlusion with shutter glasses. Under occlusion, the gaze pattern analysis revealed that pilots demonstrated reduced mean glance durations, but did not reduce their attention to lesser information displays. The results also indicated that the attitude indicator (artificial horizon) as a preview instrument was less affected by occlusion compared to other areas of interest. A subsequent scanpath analysis revealed that vertical tracking was the predominant information acquisition strategy and corresponded to larger deviations on the glideslope. These results imply the need to optimize information even for short glances, and to be very cautious with adaptive layouts of free programmable or dynamic displays, and not to overburden the pilot flying with parallel tasks.     

The ergonomic evaluation of eye movement and mental workload in aircraft pilots

This paper presents an experiment which examines characteristics of pilots' scanning behaviour when using integrated CRT displays, and the changes in characteristics when pilots face abnormal situations. The subjects were five experienced pilots. They performed two modes of flight tasks, under normal and abnormal situations, in flight simulators with standard settings. The flight simulators were for a Boeing 747-300 (B747), which made use of electromechanical displays, and for a Boeing 767 (B767), equipped with integrated CRT displays. The results showed that the B767 pilots tended to gaze at the attitude director indicator which was displayed in the integrated CRT display. It was assumed that 'gaze-type scanning' might be one of the characteristics of pilots' scanning behaviour in cockpits which use the integrated display. By employing subjective ratings and heart rate variability to measure mental workload, no differences in mental workload between the B767 pilots and the B747 pilots were observed. However, in abnormal situations, the changes in scanning pattern for B767 pilots were found to be smaller than those of the B747 pilots. It is concluded that the application of integrated displays helps pilots to obtain sufficient information more easily than electromechanical displays do, even under abnormal situations.     

基于负荷均衡的飞机驾驶舱动态功能分配

为了提高动态复杂环境下飞机驾驶舱人机系统的安全性,提出一种基于负荷均衡的动态功能分配方法。结合飞行任务和飞行员生理特征预测飞行员的工作负荷,将预测结果作为动态功能分配的触发条件,基于模糊推理调整驾驶舱自动化等级,实现飞行任务在飞行员和自动化系统之间的协调分配。基于Simulink建立飞行任务需求、飞行员生理特征、飞行员工作负荷预测、模糊推理、任务分析与再分配模块,通过仿真测试对提出的方法进行分析和验证,结果表明该方法能够及时有效地调整任务分配,避免飞行员工作负荷过高或过低。     

Hate to interrupt you,but… analyzing turn-arounds from a cockpit perspective

This study aimed to analyze aircraft ground operation processes from a human factors perspective with special emphases on the occurrence and influence of interruptions on pilots’ workload. Interruptions have been shown to increase workload and error probability as well as to contribute to fatal accidents in various fields. Countermeasures have been initiated especially in high-risk environments such as those involving medical issues. In aviation, more explicitly during turn-around processes, interruptions might occur frequently and impair flight safety. One hundred and sixty fully certified pilots working for a European airline were observed during their turn-around while performing real operations. Pilots’ interruptions were documented and classified in order to predict subjectively perceived workload by use of multiple linear regression analysis. External factors such as weather conditions, technical problems, and time pressure were considered as covariates. On average, a pilot experienced about eight interruptions during a turn-around. Overall workload estimates showed a level comparable to that of manual flying in a simulator. Interruptions from colleagues or from outside the cockpit were found to predict pilots’ workload; however, further external factors such as poor weather conditions impacted workload even more strongly. We suggest two approaches based on our results to handling the high rate of interruptions. We first recommend procedural changes to diminish the interruption rate; second, we recommend comprehensive, line-oriented flight training for airline and ground staff to raise awareness about the negative influence of interruptions.     

The influence of different electronic maps and displays on performance and operator state in a geographic orientation task

Mobile electronic displays for geographic orientation and navigation are used increasingly in various civil and military domains. But it is still unclear which displays and kinds of map presentation suit best for specific purposes. In the present experiment, a head-mounted display (HMD) and a display from a personal digital assistant (PDA) were compared in a simulated geographic orientation task in an urban environment. Furthermore, the effect of three kinds of map presentation (egocentric, geocentric and geocentric with colour cues) was analysed. The simulated orientation task was projected on a screen and participants controlled their locomotion within the urban area by means of a joystick. Task completion time, peripheral attention, workload, fatigue and simulator sickness were registered as dependent variables. In comparison to the geocentric map the egocentric map showed a significant shorter task completion time and the geocentric map with colour cues a significant higher peripheral attention. Task completion time of the HMD and the PDA did not differ significantly. However, peripheral attention and most indices of workload, fatigue and simulator sickness were significantly better for the PDA. Therefore, the results recommend to apply PDAs and egocentric maps for comparable orientation tasks.     

Pilots strategically compensate for display enlargements in surveillance and flight control tasks

OBJECTIVE: Experiments were conducted to assess the impact of display size on flight control, airspace surveillance, and goal-directed target search. BACKGROUND: Research of 3-D displays has shown that display scale compression influences the perception of flight path deviation, though less is known about the causes that drive this effect. In addition, research on attention-based tasks has shown that information displaced to significant eccentricities can amplify effort, but it is unclear whether the effect generates a performance difference in complex displays. METHOD: In Experiment 1, 16 pilots completed a low-fidelity flight control task under single- and dual-axis control. In Experiment 2, the control task from Experiment 1 was scaled up to a more realistic flight environment, and pilots performed hazard surveillance and target search tasks. RESULTS: For flight control, pilots exhibited less path error and greater stick activity with a large display, which was attributed both to greater enhanced resolution and to the fact that larger depictions of error lead to greater urgency in correcting deviations. Size did not affect hazard surveillance or search, as pilots were adaptive in altering scanning patterns in response to the enlargement of the displays. CONCLUSION: Although pilots were adaptive to display changes in search and surveillance, display size reduction diminished estimates of flight path deviation and control performance because of lowered resolution and control urgency. APPLICATION: Care should be taken when manipulating display size, as size reduction can diminish control performance.     

Color coding of control room displays: the psychocartography of visual layering effects

OBJECTIVE: To evaluate which of three color coding methods (monochrome, maximally discriminable, and visual layering) used to code four types of control room display format (bars, tables, trend, mimic) was superior in two classes of task (search, compare). BACKGROUND: It has recently been shown that color coding of visual layers, as used in cartography, may be used to color code any type of information display, but this has yet to be fully evaluated. METHOD: Twenty-four people took part in a 2 (task) x 3 (coding method) x 4 (format) wholly repeated measures design. The dependent variables assessed were target location reaction time, error rates, workload, and subjective feedback. RESULTS: Overall, the visual layers coding method produced significantly faster reaction times than did the maximally discriminable and the monochrome methods for both the search and compare tasks. No significant difference in errors was observed between conditions for either task type. Significantly less perceived workload was experienced with the visual layers coding method, which was also rated more highly than the other coding methods on a 14-item visual display quality questionnaire. CONCLUSION: The visual layers coding method is superior to other color coding methods for control room displays when the method supports the user's task. APPLICATION: The visual layers color coding method has wide applicability to the design of all complex information displays utilizing color coding, from the most maplike (e.g., air traffic control) to the most abstract (e.g., abstracted ecological display).