Air Rescue Mission Effectiveness - Complexity and Attention

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Effective information acquisition and processing is one of the key requirements to satisfy in safety critical industries. In the context of air rescue missions, and in this first part of a two-part article, SCT’s Mario Pierobon looks at human information processing, the relationship between attention and decision making, as well as strategies to overcome selective attention.

High Workload

Helicopter emergency medical service (HEMS) missions are characterised by high workload for the cockpit crew, affirm Maiwald and Schulte in their 2014 IEEE International Conference on Systems, Man, and Cybernetics paper [i]. "Cognitive assistant systems investigated today to counteract high workload issues are proven beneficial in principle, but may also induce additional load for the pilot, especially if the system intervenes when the human operator has little or no free cognitive resources to adopt the offered support," the researchers say.

Handling Complexity

A transformation of operations is being experienced in modern civilian HEMS missions, affirm Maiwald and Schulte. "The intended operations are characterized by short-term operational readiness which requires the cockpit crew for mission planning in short time and handling incomplete mission orders. Hence the cockpit crew needs to search for persons and objects in unexplored topography and possibly complex obstacles," the researchers say. "Due to the integration into complex information structures, coordination and communication with different locations such as integrated medical centre, air traffic control, firefighters, police as well as other emergency services is necessary."

Responding to Automation Failure

Safety critical systems today are strongly interconnected, indeed in case of interrupted information, the cascading effects can be extensive, according to Vidulich et al in their book ‘Information Processing in Aviation’ [ii]. "For example, on August 26, 2008, one of the two computers that handle all flight plans for the US airspace was given corrupted data and shut down," the researchers say. "Despite the continual development of sophisticated sensing, data processing, and communicating technology applied to the real time control in both commercial and military aviation, human information processing capabilities remains a cornerstone of aviation safety and effectiveness." [iii]

Attention and Decision Making

Attention has to do with the limits of processing information about multiple tasks and their perceptual and cognitive elements, point out Vidulich et al. "Such elements can be objects or events in the environment (e.g. two plane symbols on a traffic display), ideas, thoughts, or plans in cognition and working memory (instructions from ATC and implications of a weather forecast), or tasks and goals (e.g., communicating while loading a flight plan in an FMS)," the researchers say. "Across these different entities (environmental events, cognitive elements, and tasks), it is possible to focus either on constraints imposed by the limits of attention, or techniques for overcoming these limits."

Failure in attention that cause pilots to not notice critical events are ample. This phenomenon is called selective attention. According to Vidulich et al., selective attention can be seen as the vehicle whereby the eyes or the focus of auditory attention select parts of the environment for processing, while filtering others. "Selection is driven both by internal goals and by external events, as the latter is defined by attention capture," the researchers say.

The decisions that pilots make are done with high frequency. Some of these are routine, and indeed are hardly thought of as ‘decisions’ at all, but rather more like following procedures, e.g. lowering the landing gear or initiating a check list, observe Vidulich et al. "Typically the correct option to choose is so obvious, and its consequences so well anticipated that little cognitive effort is involved, once the appropriate time to make the decision has been identified."

Overcoming Selective Attention

Selective attention, however, is serial and there are some strategies whereby these serial limits can be overcome to foster desirable parallel processing in high tempo domains, according to Vidulich et al.

One main strategy is display integration, where two successive fixations are not needed to extract information about pitch and roll from the moving horizon. Another one is automaticity, i.e. practice and familiarity with a visual image can trigger nearly attention-free or ‘automatic’ processing, according to Vidulich et al. "For example, the skilled pilot knows from a rapid glance, whether s/he is on the appropriate glide path for landing from the desired convergence angle or trapezoidal shape of the runway. The pilot also knows that she will be automatically alerted when hearing her call sign spoken over the radio, not needing to continuously devote attention to: 'Listen for’ it. Such automaticity is associated with the concept of very low workload," the researchers say.

Peripheral and Ambient Vision

An additional strategy has to do with peripheral and ambient vision, according to Vidulich et al. "The human visual system is constructed so that peripheral vision can process ambient cues such as motion flow and roll attitude using ambient vision of the outside world, very much in parallel with the focal vision typically used for object detection and reading print," the researchers say. "Often pilots' tasks must be completed (or initiated) in sequence, just as selective attention to inputs is necessarily sequential for widely separated displays. For example, verifying engine health cannot be done in parallel with solving a navigational problem. Thus not only does the eye constrain sequential processing of relevant inputs, but the brain also cannot ‘engage’ in both cognitive tasks at once."

Indeed, the limits of attention constrain pilots’ sampling of the environment and multi-tasking ability, according to Vidulich et al. "But understanding of when and how these constraints can be reduced; by display design and task structure, can go a reasonably long way to improving the pilots multitask information processing capabilities," the researchers say.



Felix Maiwald and Axel Schulte, Workload Prediction and Estimation of Human Mental Resources in Helicopter Emergency Medical Service Missions in proceedings to the 2014 IEEE International Conference on Systems, Man, and Cybernetics.


Michael A. Vidulich, Christopher D. Wickens, Pamela S. Tsang and John M. Flach, ‘Information Processing in Aviation’ (2010) in ‘Human Factors in Aviation’, edited by Eduardo Salas and Dan Maurino.


Vidulich et al.


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