Highway-in-the-sky Research Articles

Multicriteria Spatial Decision Analysis for the Development of the Italian Minor Airport System

The infrastructures supporting air transport throughout the world in the civil sector are classified as primary-level (large numbers of passengers and goods on both commercial and charter long- and medium-haul flights) and secondary-level (few passengers and goods on general aviation private, short-haul flights). In parallel with primary-level air traffic general growth all over the world and in Italy, the popularity of “individual” nonscheduled general aviation traffic increased in many countries since 1990s. The latter aviation has proved to be a valid alternative to rail and road transport for short-medium distance journeys (100-500 km) for classes of business and tourist passengers. In keeping with the national and international airport system development scenarios, the paper illustrates the results of in-depth analyses aiming to construct an integrated GIS-based Multicriteria Decision Analysis evaluation methodology. It gears towards formulating strategies for the development and streamlining of some existing (51) Italian minor airports and for the right locations for the new hubs required to construct an efficient second-level air transport network (the “highway in the sky”). Different levels of evaluation verify the suitability of airport services and infrastructure (status quo) and the attractiveness of airport hubs given the territorial facilities found in their catchment areas.

Review of conformal displays: more than a highway in the sky

A head-worn display combined with accurate head-tracking allows one to show synthetically generated symbols in a way that they appear as a part of the real world. Depending on the specific research context, different terms have been used for the ability to show display elements as parts of the outside world. These include contact analog, scene linked, augmented reality, and outside conformal. While the famous highway in the sky was one of the first applications in avionics, over the years more and more conformal counterparts have been devised for aircraft-related instruments. Among them are routing information, navigation aids, specialized landing displays, obstacle warnings, drift indicators, and many more. Conformal displays have been developed for more than 40 years. We present a review of some results, as well as look ahead to research trends for the next years. We suggest that naturalism is not the best choice for the design of conformal displays. Instead, more abstract representations often yield better pilot acceptance.

Head-mounted displays for civil helicopter navigation and obstacle avoidance

Civilian helicopter pilots flew simulated Helicopter Emergency Medical Service (HEMS) scenarios using a head-mounted display (HMD) with guidance and/or obstruction imagery. Obstructions were detected and avoided earlier when shown in the HMD than those shown only out the window, and highway-in-the-sky (HITS) guidance reduced subsequent maneuvering in the terminal phase of arrival. The HMD depictions of power lines (passive representation) reduced wire strikes but did not eliminate them. An active warning presentation (red warning fence) overlaid on the power-line graphic at the point it transected the flight path completely eliminated flights in-to that obstruction. Pilots preferred the active warning representation, indicating that the passive one was ambiguous. Pilots’ preference tended towards the simplified representations of power lines but towards the complex “realistic” representations of broadcast towers. A strong preference was also expressed for integrated cockpit systems (HMD, MFD, PFD) that depicted the same obstruction information and warnings on each display.

Testing and Validation of a Psychophysically Defined Metric of Display Clutter

Combinations of cockpit display features may lead to increased pilot perceptions of clutter. This research sought to capture pilot perceptions of display clutter associated with primary flight display features during a vertical takeoff and landing scenario and to validate a multidimensional measure of clutter previously developed for a fixed-wing environment. Sixteen active fixed-wing pilots were recruited for the study that used a simulator configured as a vertical takeoff and landing aircraft. A factor analysis was used to reduce the number of subdimensions of the clutter measure based on previous ratings data. The simplified measure revealed an increase in the number of active display features to cause an increase in perceived clutter. Displays including synthetic vision system features were perceived as significantly more cluttered than those without. Although a tunnel (highway in the sky) feature also contributed to clutter, pilots achieved higher navigation system failure detection rates when the feature was active. Significant positive correlations were found between perceived clutter and visual display properties but not between perceived clutter and performance. Although pilots rated some displays as being highly cluttered, the increased information aided navigation failure detection. Overall, the clutter measure was found to have validity and sensitivity for application across diverse flight domains.

Interactions Among Target Salience, Eccentricity, Target Expectancy and Workload in an Alert Detection Task

Attentional behavior in complex visual workspaces is driven by the physical and temporal characteristics of the display, the goals and knowledge of the operator, and task demands. Accordingly, to develop effective displays, designers must understand how these factors interact to influence attentional allocation within the display and the detectability of critical alerts. In the current study, participants performed a central highway-in-the-sky (HITS) manual tracking task and a peripheral alert detection task concurrently while alert eccentricity, salience, expectancy, and central task workload were manipulated. Eccentricity and expectancy effects were observed in both hit rates and response times (RTs). RT evinced interactions of salience with both eccentricity and expectancy, indicating that the absence of dynamic distractors allowed for more rapid detection of near alerts and more effective use of top-down attentional guidance in the detection of targets in high expectancy locations. Effects also manife...

Predicting Pilot Performance in Off-Nominal Conditions: A Meta-Analysis and Model Validation

Pilot response to off-nominal (very rare) events represents a critical component to understanding the safety of next generation airspace technology and procedures. We describe a meta-analysis designed to integrate the existing data regarding pilot accuracy of detecting rare, unexpected events such as runway incursions in realistic flight simulations. Thirty-five studies were identified and pilot responses were categorized by expectancy, event location, and whether the pilot was flying with a highway-in-the-sky display. All three dichotomies produced large, significant effects on event miss rate. A model of human attention and noticing, N-SEEV, was then used to predict event noticing performance as a function of event salience and expectancy, and retinal eccentricity. Eccentricity is predicted from steady state scanning by the SEEV model of attention allocation. The model was used to predict miss rates for the expectancy, location and highway-in-the-sky (HITS) effects identified in the meta-analysis. The correlation between model-predicted results and data from the meta-analysis was 0.72.

Attentional Tunneling and Task Management in Synthetic Vision Displays

This article discusses attentional tunneling as one cause of breakdowns in task management. The phenomenon is defined, and it is shown how it can be induced by head-up display location, and compelling 3-dimensional perspective displays. The results of 6 experiments using a synthetic vision display, with or without a highway in the sky (HITS) display are then summarized, as these reveal the attention tunneling phenomenon manifest in the failure to detect unexpected air hazards. Two factors that enhance this phenomenon are identified: location away from the center of visual scan and the presence of the HITS.

Integrated Hazard Displays: Individual Differences in Visual Scanning and Pilot Performance

Synthetic vision systems, of which integrated hazard displays may be an integral component, are being developed to allow for safe and efficient navigation through terrain-challenging or low-visibility conditions. In this study, 24 pilots flew a series of approaches while maintaining their position within a highway in the sky and responding to periodic queries regarding traffic location as represented within the integrated hazard display. Eye-movement data were examined to determine the effects of visual scanning behaviors on pilot performance (flight control, traffic awareness, and off-normal event detection). Overall, all pilots treated the flight task of aviating as primary, giving it the attentional resources required to maintain adequate performance. While scanning patterns were relatively equivalent between the offnormal event detection groups, the detectors did not appear to be as attentionally tunneled to the compelling SVS suite as the non-detectors, given that they were able to notice and respond to the non-database tower visible only in the outside world. In fact, pilots who failed to detect the off-normal event spent less time scanning the outside world on the relevant trial, where the ground truth information was represented. The results are interpreted within a task management framework mediated by performance resource functions.

Effects of Advanced Cockpit Displays on General Aviation Pilots' Decisions to Continue Visual Flight Rules Flight into Instrument Meteorological Conditions

Thirty pilots flew a simulated VFR cross country flight into deteriorating weather with one of three levels of display support: a control display with standard instruments, a synthetic vision system (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. Results revealed that nearly all pilots in the control condition avoided penetrating the IMC clouds. Significantly, 60% of pilots across both SVS conditions penetrated the clouds and continued to their destination in zero visibility conditions. 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. 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.

Impact of Aviation Highway-in-the-Sky Displays on Pilot Situation Awareness

Thirty-six pilots (31 men, 5 women) were tested in a flight simulator on their ability to intercept a pathway depicted on a highway-in-the-sky (HITS) display. While intercepting and flying the pathway, pilots were required to watch for traffic outside the cockpit. Additionally, pilots were tested on their awareness of speed, altitude, and heading during the flight. Results indicated that the presence of a flight guidance cue significantly improved flight path awareness while intercepting the pathway, but significant practice effects suggest that a guidance cue might be unnecessary if pilots are given proper training. The amount of time spent looking outside the cockpit while using the HITS display was significantly less than when using conventional aircraft instruments. Additionally, awareness of flight information present on the HITS display was poor. Actual or potential applications of this research include guidance for the development of perspective flight display standards and as a basis for flight training requirements.

A comparison of pilot navigation performance using conventional instrumentation, head-down, and head-up highway-in-the-sky primary flight displays

A study was conducted to compare pilot eye movements and flight performance attainable using highway-in-the-sky (HITS) format displays in both head-up display (HUD) and head-down display (HDD) configurations and conformal (with outside world) and compressed forms within the HUD, with a baseline conventional-instruments condition. Results were mixed, and the HUD was not clearly superior to the equivalent HDD when comparing flight technical error. Workload appeared to be comparable for the HITS formats but slightly elevated for specific tasks in a baseline condition using conventional instrumentation. The need for a conformal HUD for general aviation operations was not supported for most flight operations, and pilots preferred the HUD over the HDD and the compressed HITS format over the conformal HITS or conventional instruments.

Impact of Aviation Highway-in-the-Sky Displays on Pilot Situation Awareness

Thirty-six pilots were tested in a flight simulator on their ability to intercept a pathway depicted on a highway-in-the-sky (HITS) display. While intercepting and flying the pathway, pilots were required to watch for traffic outside the cockpit. Additionally, pilots were tested on their awareness of speed, altitude, and heading during the flight. Results indicated strong practice effects for a pilot's ability to intercept the pathway and that the presence of a flight guidance cue significantly improved performance. The ability to spot traffic was relatively unaffected by, display novelty, and new display concepts are needed for supporting secondary flight information present on the HITS display. Recommendations for training and use of HITS displays are given, along with recommendations for display enhancements to support situation awareness.

Study on Integrated Cockpit Display Using Flight Simulator

The cockpit display systems in the newest aircraft have been integrated and automated using digital and graphics technologies. However, there seems to be much room for improvement from the Pilot-Vehicle Interface point of view. We believe that it is possible to improve the PVI dramatically by pursuing the most desirable way of transferring the information the pilot requires, and throwing away present ideas on existing cockpit hardware. We have generated some prospective display formats such as the highway in the sky, the chaser's view through a series of flight simulation tests based on this idea. We have also found usefulness of the Cockpit Display Research Tool which we developed.

Flight Display Dynamics Revisited

Good old ideas for pictorial flight displays that were once impractical warrant reconsideration in light of current microcomputing and display technology. Among the ideas are the contact analog, highway in the sky, and flight path predictor concepts. Basic pictorial display principles established in the 1950s and 1960s have been supported by additional experimental findings in the 1970s. These include pictorial realism, magnification, integration, compatible motion, frequency separation, pursuit presentation, quickening, and predicting. An extended analysis of dynamic display variables provides a broadened conceptual foundation for future multifactor experimental optimization of forward-looking pictorial flight displays.