Pilot maneuver choice and workload in free flight

Two experiments examined pilots' maneuver choice and visual workload in a free-flight simulation. In Experiment 1, 12 pilots flew a high-fidelity flight simulator with a cockpit display of traffic information and maneuvered to avoid traffic in a simulated free-flight environment. Pilots' choices reflected a preference to make vertical rather than lateral avoidance maneuvers and to climb rather than descend. Pilots avoided both complex maneuvers and airspeed maneuvers. The data were modeled in terms of how pilots traded off factors related to safety, efficiency, mental effort, and prior habits. In Experiment 2, 10 pilots flew the same maneuvers as the pilots in Experiment 1 but followed ATC instructions rather than using the CDTI. The CDTI in Experiment 1 occupied 25% of the pilots' visual attention. A comparison of scanning with Experiment 2 suggested that the CDTI pulled visual attention away from the outside world, but this attention diversion did not leave pilots vulnerable to missing traffic not annunciated on the CDTI. Actual or potential applications of the results include understanding the safety implications of presenting traffic displays in the cockpit, and the impact of pilot maneuver preferences on airspace procedures.     

Pilots' monitoring strategies and performance on automated flight decks: an empirical study combining behavioral and eye-tracking data

OBJECTIVE: The objective of the study was to examine pilots' automation monitoring strategies and performance on highly automated commercial flight decks. BACKGROUND: A considerable body of research and operational experience has documented breakdowns in pilot-automation coordination on modern flight decks. These breakdowns are often considered symptoms of monitoring failures even though, to date, only limited and mostly anecdotal data exist concerning pilots' monitoring strategies and performance. METHOD: Twenty experienced B-747-400 airline pilots flew a 1-hr scenario involving challenging automation-related events on a full-mission simulator. Behavioral, mental model, and eye-tracking data were collected. RESULTS: The findings from this study confirm that pilots monitor basic flight parameters to a much greater extent than visual indications of the automation configuration. More specifically, they frequently fail to verify manual mode selections or notice automatic mode changes. In other cases, they do not process mode annunciations in sufficient depth to understand their implications for aircraft behavior. Low system observability and gaps in pilots' understanding of complex automation modes were shown to contribute to these problems. CONCLUSION: Our findings describe and explain shortcomings in pilot's automation monitoring strategies and performance based on converging behavioral, eye-tracking, and mental model data. They confirm that monitoring failures are one major contributor to breakdowns in pilot-automation interaction. APPLICATION: The findings from this research can inform the design of improved training programs and automation interfaces that support more effective system monitoring.     

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.     

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.     

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.     

Flight deck disturbance management: a simulator study of diagnosis and recovery from breakdowns in pilot-automation coordination

OBJECTIVE: To examine operator strategies for diagnosing and recovering from errors and disturbances as well as the impact of automation design and time pressure on these processes. BACKGROUND: Considerable efforts have been directed at error prevention through training and design. However, because errors cannot be eliminated completely, their detection, diagnosis, and recovery must also be supported. Research has focused almost exclusively on error detection. Little is known about error diagnosis and recovery, especially in the context of event-driven tasks and domains. METHOD: With a confederate pilot, 12 airline pilots flew a 1-hr simulator scenario that involved three challenging automation-related tasks and events that were likely to produce erroneous actions or assessments. Behavioral data were compared with a canonical path to examine pilots' error and disturbance management strategies. Debriefings were conducted to probe pilots' system knowledge. RESULTS: Pilots seldom followed the canonical path to cope with the scenario events. Detection of a disturbance was often delayed. Diagnostic episodes were rare because of pilots' knowledge gaps and time criticality. In many cases, generic inefficient recovery strategies were observed, and pilots relied on high levels of automation to manage the consequences of an error. CONCLUSION: Our findings describe and explain the nature and shortcomings of pilots' error management activities. They highlight the need for improved automation training and design to achieve more timely detection, accurate explanation, and effective recovery from errors and disturbances. APPLICATION: Our findings can inform the design of tools and techniques that support disturbance management in various complex, event-driven environments.     

Visual misperception in aviation: glide path performance in a black hole environment

OBJECTIVE: We sought to improve understanding of visual perception in aviation to mitigate mishaps in approaches to landing. BACKGROUND: Research has attempted to identify the most salient visual cues for glide path performance in impoverished visual conditions. Numerous aviation accidents caused by glide path overestimation (GPO) have occurred when a low glide path was induced by a black hole illusion (BHI) in featureless terrain during night approaches. METHOD: Twenty pilots flew simulated approaches under various visual cues of random terrain objects and approach lighting system (ALS) configurations. Performance was assessed relative to the desired 3 degrees glide path in terms of precision, bias, and stability. RESULTS: With the high-ratio (long, narrow) runway, the overall performance between 8.3 and 0.9 km from the runway depicted a concave approach shape found in BHI mishaps. The addition of random terrain objects failed to improve glide path performance, and an ALS commonly used at airports induced GPO and the resulting low glide path. The worst performance, however, resulted from a combination ALS consisting of both side and approach lights. Surprisingly, novice pilots flew more stable approaches than did experienced pilots. CONCLUSIONS: Low, unsafe approaches occur frequently in conditions with limited global and local visual cues. Approach lights lateral of the runway may counter the bias of the BHI. The variability suggested a proactive, cue-seeking behavior among experienced pilots as compared with novice pilots. APPLICATION: Visual spatial disorientation training in flight simulators should be used to demonstrate visual misperceptions in black hole environments and reduce pilots' confidence in their limited visual capabilities.     

Comparison of colour and black-and-white visual displays as indicated by bombing performance in the 2B35 TA-4J flight simulator

Ten highly qualified and experienced instructor pilots were tested with respect to bombing performance in the General Electric 2B35 full colour wide screen flight simulator. Half the pilots flew with colour first and then black-and-white and the other half with the reverse order. Repeated bombing runs were made and circular bombing errors obtained. Under the conditions of the study, no statistically significant differences were shown between performances in colour and those in black-and white.     

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.

     

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.     

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.     

Pilot performance, strategy, and workload while executing approaches at steep angles and with lower landing minima

OBJECTIVE: We examined the willingness and ability of general aviation pilots to execute steep approaches in low-visibility conditions into nontowered airports. BACKGROUND: Executing steep approaches in poor weather is required for a proposed Small Aircraft Transportation System (SATS) that consists of small aircraft flying direct routes to a network of regional airports. METHOD: Across two experiments, 17 pilots rated for Instrument Flight Rules at George Mason University or Virginia Tech flew a Cessna 172R simulator into Blacksburg, Virginia. Pilots were familiarized with the simulator and asked to fly approaches with either a 200- or 400-foot ceiling (at approach angles of 3 degrees, 5 degrees, and 7 degrees in the first experiment, 3 degrees and 6 degrees in the second). Pilots rated subjective workload and the simulator recorded flight parameters for each set of approaches. RESULTS: Approaches with a 5 degree approach angle produced safe landings with minimal deviations from normal descent control configurations and were rated as having a moderate level of workload. Approaches with 6 degree and 7 degree approach angles produced safe landings but high workload ratings. Pilots reduced power to control the speed of descent and flew the aircraft slightly above the glide path to gain time to control the landing. CONCLUSION: Although the 6 degree and 7 degree approaches may not be practical for routine approaches, they may be achievable in the event of an emergency. APPLICATION: Further work using other aircraft flying under a wider variety of conditions is needed before implementing SATS-type flights into airports intended to supplant or complement commercial operations in larger airports.     

Investigating pilot performance using mixed-modality simulated data link

OBJECTIVE: General aviation (GA) pilot performance utilizing a mixed-modality simulated data link was objectively evaluated based on the time required in accessing, understanding, and executing data link commands. Additional subjective data were gathered on workload, situation awareness (SA), and preference. BACKGROUND: Research exploring mixed-modality data link integration to the single-pilot GA cockpit is lacking, especially with respect to potential effects on safety. METHODS: Sixteen visual flight rules (VFR)-rated pilots participated in an experiment using a flight simulator equipped with a mixed-modality data link. Data link modalities were text display, synthesized speech, digitized speech, and synthesized speech/text combination. Flight conditions included VFR (unlimited ceiling and visibility) or marginal VFR flight conditions (clouds 2,800 ft above ground level, 3-mile visibility). RESULTS: Statistically significant differences were found in pilot performance, mental workload, and SA across the data link modalities. Textual data link resulted in increased time and workload as compared with the three speech-type data link conditions, which did not differ. SA measures indicated higher performance with textual and digitized speech data link conditions. CONCLUSION: Textual data link can be significantly enhanced for single-pilot GA operations by the addition of a speech component. APPLICATION: Potential applications include operational safety in future GA systems that incorporate data link for use by a single pilot and guidance in the development of flight performance objectives for these systems.     

The VNAV Tutor: addressing a mode awareness difficulty for pilotsof glass cockpit aircraft

One of the major tasks of pilots of modern aircraft is monitoring and understanding the status and behavior of the auto-flight system, i.e., mode awareness. In order to maintain mode awareness in the dynamic environment, pilots must be continuously vigilant of indications from several locations within the cockpit. Lacking accurate and complete system knowledge and interfaces that clearly present the system state and constraints, pilots may misunderstand the control modes, pilots often cite vertical path navigation (VNAV) as a flight management system function that “surprises” them. The VNAV Tutor, a computer-based training system, was developed to address this issue. The VNAV Tutor attempts to improve pilots' understanding of VNAV control modes and the interaction of the mode control panel functions with the flight management system during VNAV usage. An evaluation showed that the VNAV Tutor enhanced both the conceptual understanding and the operational use of the vertical navigation function by pilots transitioning to aircraft with sophisticated auto-flight systems     

Remembrance of cases past: who remembers what, when confronting critical flight events?

Recent "naturalistic" theories of decision making emphasize the role of stored prior experiences or cases as a guide to current action. However, there is little empirical evidence on the role that case-based remindings play in real-life decision making. The present study utilized a Web-based survey to collect data about the role of prior cases in pilot decision making about critical flight events. Results showed that more than half of the 1081 pilots who responded could provide details about utilizing a previous case in responding to a critical flight event. These events were most likely to involve weather or equipment failure. The cases were found to be useful in situational assessment rather than option evaluation. The use of cases increased with age and experience. Data obtained from a concurrent conventional survey showed broadly similar results. The implications of these results are that case-based remindings play an important role in expert pilot decision making and that a training system that incorporates case-based learning would be a potentially useful means of improving pilot decision making. Actual or potential applications of this research include the development of case-based training systems to enhance flight training.     

Flight decks and free flight: where are the system boundaries?

The change from managed to free flight is expected to have large effects, over and above the intended efficiency gains. Human factor concerns have understandably focused on how free flight may affect the pilots in the cockpit. Yet it is necessary to see the change from managed to free flight as more than just an increment to the pilots' work. Despite the best intentions the transition will not be a case of a smooth, carefully planned and therefore uneventful introduction of a new technology. It is more likely to be a substantial change to an already challenging working environment, in the air as well as on the ground. The significant effects will therefore not just happen within the existing structure or distribution of work and responsibilities, but affect the structure of work itself. This paper takes a look at free flight from a cognitive systems engineering perspective and identifies two major concerns: first what effects free flight has on the boundaries of the joint cognitive systems, and second how this affects demands to control. The conclusion is that both will change considerably and that we need to understand the nature of these changes before focusing on the possible effects of free flight on pilots' performance.     

Weather display symbology affects pilot behavior and decision-making

ObjectiveTo examine the basic discriminability of weather display symbols and to assess the effects of weather display symbology on pilot behavior and decision-making.MethodDuring a cockpit simulation, 24 instrument-rated general aviation (GA) pilots were randomly allocated to one of three simulation groups. Pilots flew a Cessna 172 single-engine GA aircraft under Visual Meteorological Conditions (VMC) and Instrument Meteorological Conditions (IMC) while avoiding hazardous weather. We manipulated the weather display so that each pilot group used a different weather symbology (i.e., symbols and colors). We measured dependent variables for weather avoidance, communication, weather display usage, and cognitive engagement (i.e., oxygenation from Functional Near-Infrared [fNIR] measures). During a change-detection experiment, 20 naïve participants performed a detection task of changes in Aviation Routine Weather Reports (METARs), precipitation, Significant Meteorological Information (SIGMET), lightning, and time-stamp images.ResultsThe simulation outcome showed credible pilot group differences in weather deviations, cognitive engagement, and weather display usage. The change-detection experiment revealed credible differences in discriminability of METAR, SIGMET, and lightning symbols.ConclusionSymbol and color variations in weather displays contribute to perceptual asymmetries which affect pilot behavior and decision-making. We recommend the development of cockpit applications that use weather data to automatically track hazardous conditions and alert the pilot of potential weather conflicts or weather changes.     

Factors affecting task management in aviation

OBJECTIVE: We investigated the influence of ongoing task display "compellingness" on attention allocation patterns and assessed its interaction with interrupting task salience and importance. BACKGROUND: There are some concerns that the compellingness of flight deck tunnel displays renders the task they support more resistant to interruptions, thus preventing the pilot from noticing cues signaling the need to divert attention to other tasks. METHODS: Forty pilots flew three curved approaches in a high-fidelity simulation using a synthetic vision system (SVS) display. In addition to the primary task of flying, during the last approach they were required to select the approach path on the basis of environmental information concerning weather. The display layout supporting the primary flight task (tunnel vs. baseline display), the nature of the cue signaling the need to divert attention to the path selection task (visual vs. auditory-visual cue), and the cost of not performing the secondary task were manipulated to investigate their influence on task prioritization. RESULTS: The modality and priority of the cue affected the frequency of the switch to the secondary task. Furthermore, pilots flying with a tunnel display were more likely to detect the change in the weather and were easily interrupted by the secondary task when priority was high. CONCLUSION: Our results suggest that some of the concerns regarding the negative consequences of the compelling nature of the tunnel display may not be as pronounced as thought. APPLICATIONS: This study highlights the utility of the tunnel display in improving flight safety.     

Incorporating data link messaging into a multi-function display to support the Small Aircraft Transportation System (SATS) and the self-separation of general aviation aircraft

One objective of the Small Aircraft Transportation System (SATS) Project is to increase the capacity and utilization of small non-towered, non-radar equipped airports by transferring traffic management activities to an automated system and separation responsibilities to general aviation (GA) pilots. This paper describes the development of a research multi-function display (MFD) to support the interaction between pilots and an automated Airport Management Module (AMM). Preliminary results of simulation and flight tests indicate that adding the responsibility of monitoring other traffic for self-separation does not increase pilots' subjective workload levels. Pilots preferred using the enhanced MFD to execute flight procedures, reporting improved situation awareness (SA) over conventional instrument flight rules (IFR) procedures.     

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.