In this Issue:

Product Liability Testing

Might You Need a Human Factors Scientist on Your Team?
By Julianne M. Fox, Principal Scientist - Decision Speed, Inc.

This Issue's Toolbox Feature
Human Factors

Product Liability Testing

Product liability litigation arises from allegations that products are somehow defective in design, manufacturing or marketing. Claims of design or manufacturing defects can often be effectively explored, by either the plaintiff or the defendant, through product testing. Addressing a marketing defect claim is trickier business, because such a claim may involve not only the objective behavior of the product but also psychological factors linked to the user’s expectations about how the product should behave.

A design or manufacturing defect may reveal itself as a simple component failure; e.g. a bolt breaks in a structure when the structure experiences a foreseeable dynamic load. On the other hand, defects in complex products are often system failures, in which no individual component experiences a permanent breakdown, but the system fails to perform as intended when components interact in surprising ways; e.g. in a high-speed process operation, the contacts of an electrical switch may unexpectedly bounce apart when closed quickly, not allowing sufficient current to flow through the switch to accomplish a given task before the switch is intentionally re-opened in the on-going process.

Motor vehicles and boats are complex, physically large products which, if they are to be tested as whole systems, are usually more amenable to being tested on the road or in the water than in a laboratory setting. Past issues of this newsletter have described field tests of automobiles, motorcycles, trucks, trailers, buses, railroad locomotives, freight cars, recreational boats and commercial marine vessels that have been conducted by ATA Associates, Inc. as part of its litigation support and forensic engineering services. Typically those tests employed specialized electronic test instrumentation, such as accelerometers, inclinometers or yaw-rate meters, to characterize vehicle starting/stopping performance and maneuverability. More recently, quantification of vehicle performance has increasingly come to rely on global position system (GPS) measurements, made by electronics either already built in to the vehicles or added by ATA specifically for testing purposes.

Over the past 20 years, ATA has also tested a variety of vehicle subsystems as well as industrial components and consumer products in a well-equipped laboratory at ATA’s office and technical center in the Clear Lake area of Houston, Texas. In a recent example of consumer/industrial product component testing by ATA, a series of destructive tests were conducted that compared the strength of standard doorframe components used in the home-building industry with the strength of reinforced components developed by a specialty hardware manufacturer. In other tests, ATA measured the tensile strength and pressure holding capacity of hydraulic fitting and tubing assemblies that are commonly found in a variety of industrial and vehicular systems.


ATA’s laboratory adjoins a shop and high bay facility served by a 10-ton capacity bridge crane which provides exceptional material handling capability within those facilities. ATA’s secure, clean, well-lighted lab, shop and high bay facilities are excellent venues for product assembly, testing, tear-down and inspection.


Might You Need a Human Factors Scientist on Your Team?

By Julianne M. Fox, Principal Scientist - Decision Speed, Inc.

Depending upon the source, human error has been cited as a contributing or causal factor in upwards of 60%-80% of all industrial accidents (Lautman & Gallimore, 1987; Rasmussen et al., 1994). Thus, when an accident occurs, as part of the investigation, Human Factors scientists are called upon to focus their analysis upon the human component.

What is Human Factors?

Human Factors is the scientific study of how human strengths and limitations affect the way that people interact with products, machines, systems, and with other personnel within their environment and how these strengths and limitations can impact human performance in both anticipated and unanticipated ways. Objective data collected over more than 70 years during scientific research, in addition to that which we have collected ourselves, combined with our study of the discipline, forms the basis of our ability to assist you.

Why Might the Human Factors Discipline Be Relevant to You?

We have worked with many clients as consultants during the design process and we have also assisted after an accident has occurred in an effort to assist in determining the root cause. After an accident occurs, if it’s one where a human error component is deemed likely, then we seek to determine “why” the error(s) occurred, “what” caused and contributed to the failure, whether it was foreseeable, and “how” (or whether) it could have been reasonably prevented. So we not only analyze the operation and the operator, but we also assess the role that the relevant organizations may have had in the error chain.

Our consultation, whether it is design-related or investigation-related, focuses on scientific research in the following areas: human perception, cognition, decision-making, memory and learning. In our analysis, we consider the effects of the following on human performance: stress, time pressure, inattention and distraction, workload, situational awareness, training, risk perception, fatigue, and age. As an example, we assess the reasonableness of response types and response times and we understand what may have driven inappropriate, untrained responses and/or lengthened operator response times beyond what would be considered normal. We evaluate unsafe behavioral patterns at both the operator and the organizational level and the adequacy of warnings and safety information. We review incident and accident data to understand whether and/or how a product’s use may exacerbate or help to prevent future occurrences. We participate in the development and evaluation of Functional Hazard Analyses and Failure Modes and Effects Analyses. We conduct usability tests to evaluate whether designs meet their intended function. We are also called upon to design and evaluate displays and instrumentation that are intended to enable an operator to interface effectively and efficiently with a complex system. As a part of our analysis we assess the training content, the recency of personnel having received it, and correspondingly, the likelihood of operator proficiency. When non-compliant behavior has been found to have occurred, we seek to understand whether it was a chronic behavioral pattern or a one-time event.

Case Studies & Examples of Human Factors Consultation Services

An operator decided to ride within the bucket of an articulating boom crane while controlling it remotely (from within the bucket). The arm of the crane swung into a tree and the hydraulic override became jammed causing the jaws of the bucket to close while negating the remote control from being operational. We assessed the operator’s decision-making, his response type and response time. We assessed the design of the remote control for the crane. We considered whether training had been received and we evaluated the warnings and safety information related to this cranes operation.

A company was seeking to manufacture and sell GPS and autopilot systems for agricultural tractors --with the United States being a new targeted territory. Their outside counsel suggested that their client (the manufacturer) retain us to assess their product design prior to entry into service. Since the system would inherently be more autonomous and require less operator involvement in the tractor’s operation, we assessed whether the historic causal and contributing factors in tractor accident and incidents (obtained from the Bureau of Labor Statistics data) would likely be mitigated, unaffected, or exacerbated by this new system. Based upon our findings, we assisted the manufacturer in developing warnings and safety information for their manuals, on-product placards, and suggested designs for visual and auditory warnings to be integrated into this onboard system. We also suggested changes to their marketing materials.

A chemical release occurred which was visible across a major metropolitan area. A root cause analysis was conducted. Through evaluating the plant and assessing the operations (including conducting interviews with all involved personnel), we determined that many process gaps existed. For example, the methodology for temperature information retrieval from the interface was insufficient. Gauge standardization did not exist. A process step for ascertaining whether or not heating of the chemical was required also did not exist. Additionally, we assessed whether fatigue due to circadian misalignment, an extended wake time, and an existing sleep debt for the operator who misinterpreted the temperature information contributed to the cause of this accident.

An electric arc flash electrocution occurred at the time a licensed electrician connected a “hobbyist” voltmeter to 480 volts of incoming power at a switch gear. The operational regulations related to this activity were identified and compliance assessed. The training provided to personnel in place at the time of the accident was reviewed and operator decision-making analyzed. Additionally, we conducted a state of art assessment of voltmeters appropriate for use in this situation versus those for use by a hobbyist where far less current would be present. Assessment revealed that “industrial” voltmeters meant for use by electricians had a distinctly different look and feel than their counterparts and at quick glance, a licensed electrician should have been equipped to decide whether a particular voltmeter was appropriate for the job at hand.

UPS Flight# 1354 crashed as the result of Controlled Flight Into Terrain (CFIT). We investigated an Airbus 300-600 commercial air transport cargo airplane accident that occurred during FAR Part 121 operations. Human factors analysis focused upon human perception and performance, attention, situational awareness, decisionmaking, judgement, reaction types and reaction times, and the effects of stress and perceived time pressure on this flight crew’s performance. We conducted a fatigue assessment which analyzed this flight crew’s schedule during both operations and personal time during the days leading up to this accident and focused upon assessing whether circadian misalignment, sleep restriction, extended wakefulness, and/or sleep debt was likely to have culminated in a fatigued crew. Additionally, we assessed the underpinnings of the automation error made and the non-compliant crew behavior that was exhibited. The impact of interruptions, distractions, and the potential for prospective memory error was assessed. The analysis included a review of the flight crews training history and performance, the recency by which certain types of procedures had been flown, and assessed whether an absence of proficiency may have existed. Additionally, we evaluated the organizational behavior and identified decision-making errors which contributed to this outcome. Lastly, as a part of this investigation, we conducted a state of art assessment for the industries adoption of the 500’ callout and identified the difference in time which would have been available to react had the automated 500’ callout been adopted.

As you can see from the project examples cited above, the work of a Human Factors expert is not domain limited. The human operator’s performance, regardless of the domain, benefits from the same inherent strengths and is limited by the same deficiencies. A human is a human. It doesn’t matter whether the operator is operating a crane, a power plant, mining or agricultural equipment, driving a semi tractor-trailer or flying an airplane, a Human Factors specialist is poised to help assist you to analyze the human component of your project.


This issue’s featured topic for ATA’s Toolbox is Human Factors. This is one of the most critical disciplines in the field of forensic engineering. There are Human Factors componrents involved in nearly every incident that ATA investigates. The study of human factors involves topics such as expectancy, human body motion, judgement of speed and distance, perception reaction, visibility problems and anthropometrics.

For more information on this critical topic, visit the ATA Toolbox/Human Factors drawer.