Colin G. Drury

Feedback strategies for visual search in airframe structural inspection

Feedback of information has consistently shown positive results in human inspection, provided it is given in a timely and appropriate manner. Feedback serves as the basis of most training schemes; traditionally this has been performance feedback. Other forms of feedback which provide strategy information rather than performance information may have a role in improving inspection. This study compared performance feedback and cognitive feedback in a realistic simulation of an aircraft structural inspection task. Performance (time, errors) feedback showed the greatest improvements in performance measures. Cognitive feedback enhanced efficiency measures of search strategy. When cognitive feedback consisted of visual representations of the path and the coverage of the search sequence, subjects also were able to use this task information to improve their search performance.

Medical Error and Human Factors Engineering: Where Are We Now?

The goal of human factors engineering is to optimize the relationship between humans and systems by studyinghuman behavior, abilities, and limitations and using this knowledge to design systems for safe and effective human use. With the assumption that the human component of any system will inevitably produce errors, human factors engineers design systems and human/machine interfaces that are robust enough to reduce error rates and the effect of the inevitable error within the system. In this article, we review the extent and nature of medical error and then discuss human factors engineering tools that have potential applicability. These tools include taxonomies of human and system error and error data collection and analysis methods. Finally, we describe studies that have examined medical error, and on the basis of these studies, present conclusions about how human factors engineering can significantly reduce medical errors and their effects.

Design and evaluation of an inspection training programme

As a follow-up to a study of human and machine inspection of precision metal components, a training programme was designed to improve the performance of the inspectors. The methodology for task description, task analysis (including experiments), training programme design and final evaluation are presented as a case study. Improvements due to training were measured both on an individual basis and from plant-wide statistics to show the success of the programme.

Service, quality and human factors

As pressures on the service economy from globalisation increase, new techniques may be appropriate for designing service systems. This paper examines the tradition of service quality and argues that its unique characteristics, such as the joint production of offerings by operators and customers, could benefit from the techniques of human factors. The interaction between human factors and quality is reviewed and four issues are extracted that should be directly applicable to service encounters. These are interface design, the understanding of error causation, a design for operator well-being and human/automation function allocation. A framework is proposed for considering technology explicitly in the design of service systems.

Information processing in assembly tasks - a case study

In a surface wiring task the terminals of electrical components are connected by wires according to a wiring list. This series of experiments examined one such task in a batch assembly environment where production runs are short. The findings show that information theory is a good predictor of performance, that different sources of information within the task are processed in different ways, and that considerable symmetric transfer can be expected between different batches.

On mathematical modelling in ergonomics

This paper is the combination of three separate discussion documents, presented amongst others at a parallel session at the Ergonomics Society Annual Conference, 1979, at Oxford. The discussion documents were general in tone and followed logically after one another, and the authors were asked to provide a joint paper for wider dissemination. This is the product, and represents a more-or-less common viewpoint between the authors (and others - it will no doubt be obvious that much of what is said has already been said by Chapanis (1961, 1967) in particular, in his usual elegant prose).

Outsourcing Aviation Maintenance: Human Factors Implications, Specifically for Communications

As part of the Federal Aviation Administrations response to the 1997 crash of ValuJet Flight 592, the potential for human errors unique to the aviation third-party repair station environment was investigated. Data collected at 5 U.S. and 1 foreign repair stations disclosed a number of opportunities for errors arising from the more complex interactions among the repair station, the airline customers, and the regulatory authority. Two quantitative studies gathered data to test for 1 expected problem: that of using multiple formats of procedure document. First, a repair station error database was analyzed and concluded that “information” (e.g., documentation) was a significant causal factor associated with specific error types. Second, although repair stations must switch frequently between the documentation systems of different airlines, a task card comprehension study did not find increased error rates from changing document formats. With 54 licensed mechanics, well-designed procedure documentation greatly reduced comprehension errors. Improved documentation by following human factors good practice is recommended as a strategy to mitigate error potential for the repair stations where work is outsourced.

Predictive models of safety based on audit findings: Part 1: Model development and reliability.

This consecutive study was aimed at the quantitative validation of safety audit tools as predictors of safety performance, as we were unable to find prior studies that tested audit validity against safety outcomes. An aviation maintenance domain was chosen for this work as both audits and safety outcomes are currently prescribed and regulated. In Part 1, we developed a Human Factors/Ergonomics classification framework based on HFACS model (Shappell and Wiegmann, 2001a,b), for the human errors detected by audits, because merely counting audit findings did not predict future safety. The framework was tested for measurement reliability using four participants, two of whom classified errors on 1238 audit reports. Kappa values leveled out after about 200 audits at between 0.5 and 0.8 for different tiers of errors categories. This showed sufficient reliability to proceed with prediction validity testing in Part 2.

Patterns in Mining Haul Truck Accidents

To help develop ergonomics audit programs for mining, one source of data on both work tasks and their failures is accident reports. These are available in most industries and are often used in human factors engineering, but typically to justify and evaluate interventions rather than to provide task details and failure mechanisms. Because fatal accidents in particular contain considerable detail resulting from thorough follow-up investigations, they are thus a useful starting point for analysis. A set of 40 detailed fatal accident reports for mining haul truck accidents were analyzed to develop repeating patterns of accidents. This paper examines the accident patterns found from the initial sample, the refined pattern analysis developed from a subsequent larger sample, and the task analyses used later to help develop valid audit programs.

A Quantitative Methodology for Assessment of Wheelchair Controllability

Changes in wheeled mobility user demographics and technologies over the past 30 years show the need for design guidelines for accessibility to persons with disabilities, including those who use wheelchairs. A key component is wheelchair maneuverability, which determines the clear space needed for travel in the environment. Previous studies have applied rating scales to assess the difficulty when wheelchair users maneuver in a built environment. These need to be complemented by direct maneuverability measurements. Having wheelchair users perform self-paced control tasks, for both lateral and longitudinal tasks is a potential method to meet the requirement. This study validated a methodology of measuring the steering controllability and start/stop controllability of wheelchairs so that further studies can apply this methodology to evaluate either environmental or wheelchair designs. The same speed/accuracy relationships were found for wheelchair users as had been found earlier for a variety of vehicles.