The development of a scenario-based human-machine-environment-procedure (HMEP) classification scheme for the root cause analysis of helicopter accidents.

The current study analyzed the root causes of 22 helicopter accidents/incidents that took place between 1998 and 2019. Each root cause was coded using three commonly used classification models in aviation HFACS, ATSB, and IATA to identify recurring factors for better targeting of future prevention strategies. The frequency analysis revealed that not following procedure (22 observations), training inadequate or unavailable (17), inadequate regulatory oversight (17), inadequate procedure guidance (16), company management absent or deficient (10) and incorrect manuals/charts/checklists (9) were the most frequent contributing factors. Since none of the existing models could summarize the root causes of 22 occurrences effectively, a scenario-based human-machine-environment-procedure (HMEP) classification scheme was proposed to use organizational influences, people management, technical failure, procedure and document, and environment as the first-layer subcategories. The HMEP scheme was additionally applied to the analysis and coding of 4 helicopter accidents in the USA published by the NTSB. The HMEP scheme revealed that NTSB had identified a significantly greater number of root causes in the manufacturer design, manufacturing & documentation. Overall, HMEP can be used to guide the data collection during accident investigation and subsequently to aggregate aviation accidents to derive recurring factors and compare accident patterns in an efficient manner.

Models of the effect of teleoperation transmission delay on robot movement time.

Recent research of [Scholcover and Gillan ( 2018 )] has shown experimentally that system transmission delay has a linear effect on the time taken to perform a complex tracking task with a simple teleoperated robot. This note shows that, for the case of moving a robot through a straight path, this relationship is predicted. The result is a simple modification of Drury's law to take into account the system delay. This work extends the model for performance under intermittent illumination of Drury to the effects of fixed delays in task performance, occurring with teleoperated robots. In all cases, there was empirical evidence for the predicted linear relationship. Practitioner summary: When there is a delay in system response for robotic teleoperation between a control input and system output, movement time (MT) is increased and the increased times are linearly related to the system delay. This is true for zero and first-order control and for delays occurring before and after the control action.

Development of ergonomics audits for bagging, haul truck and maintenance and repair operations in mining.

The development and testing of ergonomics and safety audits for small and bulk bag filling, haul truck and maintenance and repair operations in coal preparation and mineral processing plants found at surface mine sites is described. The content for the audits was derived from diverse sources of information on ergonomics and safety deficiencies including: analysis of injury, illness and fatality data and reports; task analysis; empirical laboratory studies of particular tasks; field studies and observations at mine sites; and maintenance records. These diverse sources of information were utilised to establish construct validity of the modular audits that were developed for use by mine safety personnel. User and interrater reliability testing was carried out prior to finalising the audits. The audits can be implemented using downloadable paper versions or with a free mobile NIOSH-developed Android application called ErgoMine. Practitioner Summary: The methodology used to develop ergonomics audits for three types of mining operations is described. Various sources of audit content are compared and contrasted to serve as a guide for developing ergonomics audits for other occupational contexts.

Human factors/ergonomics implications of big data analytics: Chartered Institute of Ergonomics and Human Factors annual lecture.

In recent years, advances in sensor technology, connectedness and computational power have come together to produce huge data-sets. The treatment and analysis of these data-sets is known as big data analytics (BDA), and the somewhat related term data mining. Fields allied to human factors/ergonomics (HFE), e.g. statistics, have developed computational methods to derive meaningful, actionable conclusions from these data bases. This paper examines BDA, often characterised by volume, velocity and variety, giving examples of successful BDA use. This examination provides context by considering examples of using BDA on human data, using BDA in HFE studies, and studies of how people perform BDA. Significant issues for HFE are the reliance of BDA on correlation rather than hypotheses and theory, the ethics of BDA and the use of HFE in data visualisation.

Verification of models for ballistic movement time and endpoint variability.

A hand control movement is composed of several ballistic movements. The time required in performing a ballistic movement and its endpoint variability are two important properties in developing movement models. The purpose of this study was to test potential models for predicting these two properties. Twelve participants conducted ballistic movements of specific amplitudes using a drawing tablet. The measured data of movement time and endpoint variability were then used to verify the models. This study was successful with Hoffmann and Gan's movement time model (Hoffmann, 1981; Gan and Hoffmann 1988) predicting more than 90.7% data variance for 84 individual measurements. A new theoretically developed ballistic movement variability model, proved to be better than Howarth, Beggs, and Bowden's (1971) model, predicting on average 84.8% of stopping-variable error and 88.3% of aiming-variable errors. These two validated models will help build solid theoretical movement models and evaluate input devices. PRACTITIONER SUMMARY: This article provides better models for predicting end accuracy and movement time of ballistic movements that are desirable in rapid aiming tasks, such as keying in numbers on a smart phone. The models allow better design of aiming tasks, for example button sizes on mobile phones for different user populations.

Comment on "Visual layout modulates Fitts's law: the importance of first and last positions".

Pratt, Adam, and Fischer (2007) investigated the effect of surrounding targets on the time it took to move to an individual target and found that the movement time to a central target was above the Fitts's law line related to the first and last targets. They explained their results in terms of a "visuomotor hypothesis." Here, an alternative explanation is given in terms of a previously validated model of the "available target width" that is determined by the size of the target and the width of the finger pad that is being used to hit the target.

Performance in one-, two- and three-dimensional terminal aiming tasks.

Arm movement times were measured to targets with independent constraints (target sizes) in one, two or three directions (width, height and depth). In each case, modified forms of Fitts' law give a good fit to the data, with the best form being dependent on all constraints in the 'Weighted Euclidean' model of Accot, J. and Zhai, S., 2003. (Refining Fitts' law models for bivariate pointing. Proceedings of the SIGCHI conference on Human factors in computing systems CHI '03, 5-10 April 2003, Ft. Lauderdale, FL. New York: ACM Press, 193-200). The best predictor includes all the individual ratios of amplitude of movement to target dimension related to the various constraints, with the maximum portion of variance accounted for by the index of difficulty (ID) in the direction of motion. The suggestion by various authors that the maximum of the ID associated with the different constraints will determine the movement times is only partially successful. An explanation for the results is given in terms of control strategy and the form of target. STATEMENT OF RELEVANCE: In many tasks, workers move objects into limited spaces that allow only a single entry area. Termination of the movement may have constraints in one, two or three dimensions. Movement times for such tasks are important to predict industrial performance, and guide task designers in reducing physical constraints on performance.

Change of search time and non-search time in X-ray baggage screening due to training.

As found in studies of aircraft structural inspection, the time used for judging if a part of an aircraft shows tiny cracks is composed of search time, used for actively scanning, and non-search time, used for matching and decision while fixating a region of interest (Drury et al. 1997). These findings can be applied to detection of threats by X-ray screening of passenger bags at airports. To investigate whether search time and non-search time change when an experienced screener is given additional training in recognising threat objects in passenger bags, data from a European airport were analysed. A comparison of detection performance and reaction time between two large groups of screeners, one trained for 6 months, shows a large impact of training on overall performance and on both search and non-search components of the task. There was also a small but consistent decline in performance measures with screener age. This study shows a way to localise the effect of training on threat detection performance for aviation security screening. Analysis of the time needed for screening each passenger bag showed that training had a significant effect, particularly on the non-search part of the searching process (i.e. identification, recognition, decision, response execution, etc.).

The impact of joint responses of devices in an airport security system.

In this article, we consider a model for an airport security system in which the declaration of a threat is based on the joint responses of inspection devices. This is in contrast to the typical system in which each check station independently declares a passenger as having a threat or not having a threat. In our framework the declaration of threat/no-threat is based upon the passenger scores at the check stations he/she goes through. To do this we use concepts from classification theory in the field of multivariate statistics analysis and focus on the main objective of minimizing the expected cost of misclassification. The corresponding correct classification and misclassification probabilities can be obtained by using a simulation-based method. After computing the overall false alarm and false clear probabilities, we compare our joint response system with two other independently operated systems. A model that groups passengers in a manner that minimizes the false alarm probability while maintaining the false clear probability within specifications set by a security authority is considered. We also analyze the staffing needs at each check station for such an inspection scheme. An illustrative example is provided along with sensitivity analysis on key model parameters. A discussion is provided on some implementation issues, on the various assumptions made in the analysis, and on potential drawbacks of the approach.

Human factors in industrial systems: 40 years on.

OBJECTIVE: I evaluate the contribution of a pioneering Human Factors special issue on human factors in industrial systems. BACKGROUND: Papers on the content of the journal's first 10 years showed that industrial human factors/ergonomics (HF/E) in 1969 was quite a rarity in the journal and the society. METHOD: The 12 papers in the special issue are reviewed briefly and show a wide range of topics, including traditional industrial engineering, physical HF/E, and more mainstream applications of HF/E in this domain similar to those in military and aerospace domains. The evaluation is through citations, later journal content, society technical group membership, and specific influences of Harris's own paper in the issue. RESULTS: The expected direct citation influence of this special issue was not found: Citation counts were in line with all papers in Human Factors. However, other journals have been founded in North America that serve industrial HF/E and provide an outlet for more papers per year than Human Factors. In addition, the industrial domain is well represented in the Human Factors and Ergonomics Society. Finally, Harris's paper has been influential in the specific area of HF/E in inspection. CONCLUSIONS: Industrial HF/E is now more accepted within the HF/E community, although largely in the physical ergonomics subspecialty. APPLICATION: There is now evidence of use of HF/E techniques more broadly in industry, including service as well manufacturing enterprises.

Biomechanical, physiological and psychophysical evaluations of clean room boots.

The purpose of this study was to evaluate the significance of boot sole properties on reducing fatigue, to evaluate the effects of load carrying and walking (over a 1 h period) on biomechanical, physiological and psychophysical responses, and to investigate the correlations between the measurements. The results indicated that elasticity and shock absorption of the boot had significant effects on outcome variables. Significant load effects were seen in most measurements. All of the significant time period effects gave strong regressions, with no R2 value less than 0.983. The findings of this study provide useful information for the selection and design of clean room boots as well as for job design for load carrying tasks in the clean room environment.

Task demands and human capabilities in door use.

Doors are ubiquitous in the built environment, bur despite their frequent use by people and their involvement in over 300,000 injuries per year (USA), they are little studied from a human factors perspective. This paper provides a classification scheme for doors based on human/door interaction and a prototypical task analysis of door use. Two observational studies were performed on a particular type of door. The first observed 1600 human/door interactions and found that people's use of force-enhancing strategies increased for larger doors, particularly for people of smaller stature. The second observed 800 interactions with push doors and found that the pont where force is exerted is higher for taller individuals and closer to the center of the door than is typically assumed for placing handles. Th second study was partly corroborated by measuring the position of wear patterns on doors. As is expected in human factors, the was people used doors was a function of both task demands and human capabilities. These results suggests that those specifying doors for building s use a restoring torque below 30 Nm and site the handle or push plate 250-350 mm from the door edge and 1000-1500 mm above the floor.

Vicarious perception of postural discomfort and exertion.

Perceived exertion and discomfort have been used extensively in ergonomics practice. Job incumbents typically rate their exertion on scales such as Borg's rated perceived effort (RPE) and their discomfort on scales such as Corlett and Bishop's body part discomfort scales (BPD). This study asks whether exertion and discomfort can be perceived by an external observer, i.e. is vicarious perception possible? Four participants (targets) performed 20 postural holding tasks selected from Ovako Working Posture Analysing System postures and gave RPE and BPD scores for each posture. Video clips of each target in each posture were shown to four expert ergonomists and 23 novices, who also gave RPE and BPD scores. Correlations between targets and observers scores were high, with significance exceeding p = 0.01. Observers were generally conservative, rating easy postures too high and difficult postures too low. All observers rated female targets higher than male targets. Female observers rated all targets higher then male observers. Vicarious perception of discomfort and exertion was possible, but there was not a one-to-one correspondence to ratings given by those experiencing the posture.

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 studying human 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.

Using simulated investigations for accident investigation studies.

Regardless of the actual causes of particular accidents, it is the causes identified by the analyst that determine what responses are made, and how safety is managed in industry. Past authors have suggested that investigation might be biased, but studies were limited by the lack of similarity to real-world investigation tasks in which investigators must decide what information to acquire as well as analyse and interpret it. A technique was developed to use simulated investigations rather than attribution judgements about causation. Three studies are described, using simulated investigation to compare elicited knowledge and hypotheses among safety specialists, to compare investigations using job aids with unaided investigations, and to teach students about investigation bias and comprehensiveness. The method was well accepted by participants and shows flexibility for a range of uses, although it may have limitations.

The effects of probe length on Fitts' law.

Experiments were aimed at determining the effect of a human using an extended probe when making movements that required accuracy at the completion of the movement. Ten subjects performed 64 conditions of varying amplitude of movement, final accuracy and probe length. Movement time increased with probe lengths from 100 to 400mm for all conditions of amplitude and required accuracy. The effect of probe length was included in a mathematical description of the data through a multiplicative term on Fitts' index of difficulty (ID), possibly arising from tremor of the hand probe system in controlling approach to the target. Probe length had the greatest effect at high ID, where a probe of 400 mm length increased movement time by about 25% over that for a 100mm probe. The model developed has application for accurate movements with long tools such as screwdrivers or crowbars, head-mounted devices for the disabled, or other tasks where the work interface is at the end of an extended probe.