Author Archives: Beth Lyall, Ph.D.


A lot of airplane and avionics manufacturing companies are starting to prepare their teams to address the newly released FAA regulation covering human factors issues: 14 CFR 25.1302.  There is a lot to learn, but here are the top five things you should know. In a nutshell, 14 CFR 25.1302… 1. Applies to everything in the flight deck meant to be used by the flight crew It is a general applicability regulation that applies to all systems and equipment that will be used by the flight crew in any way during their flight duties. 2. Applies to system individually as well as possible impact on other systems Showing compliance to the regulation must include human factors considerations on the design and performance of the system or equipment in isolation, as well as how it will be used with other flight deck systems or equipment.  The potential impact on the use … Continue reading

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Pilot manually flying aircraft.

Recently we have been involved in providing evaluations and coaching addressing the safety impact of policies and procedures related to pilot use of automated systems in a large international airline.  One of the first questions typically raised in this type of project is: How can we reduce the possibility of pilots losing their manual flying skills when they routinely use automated systems to fly the airplane? In other words, we are often asked for strategies an airline can use to address the complex web of trade-offs associated with the consistent, economical, and safe routine operation of transporting passengers and the potential for unexpected situations in which pilot expertise, judgment, and skills are necessary for a safe outcome. This is a balancing act that must be performed by each airline within their own unique blend of national, corporate, and safety cultures.  Unfortunately, one solution does not work for all companies. But, … Continue reading

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Last week (Oct 2-3), I attended a meeting addressing the challenges and issues related to the interoperability of medical devices hosted jointly by the Association for the Advancement of Medical Instrumentation (AAMI) and the Food and Drug Administration (FDA) Center for Devices and Radiological Health (CDRH).  The purpose of the meeting was to discuss challenges, share best practices, and develop ideas for moving forward to address the issues raised. Human factors and usability issues were raised throughout the meeting, as you would expect when discussing the design and development of a complex system made up of many other systems, and all the systems have many and varied users.  There are several factors that increase system design challenges, and they all arise when addressing medical device interoperability as the design of a large system made up of all inter-related and interfacing systems.  Examples include: defining and documenting the functions and attributes of … Continue reading

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Collection of small display devices

When creating a display on a small device, how large or small should your characters be?  The size of alphanumeric characters affects the readability of information on the display. The size of an alphanumeric character is determined by three features: stroke width: distance across a stroke line used to form an individual character character width: distance across an individual character from one side to another character height: full vertical distance between the top and bottom elements of a character Stroke width Stroke width should be equal for all characters of equal height on a display.  Stroke width-to-height ratio is the ratio of the thickness of the stroke used to form an individual character and the measured height of the character.  It is recommended that stroke width-to-height ratio be 1:6 to 1:8 for black text on a white background under adequate lighting and 1:8 to 1:10 for white text on a … Continue reading

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Collection of small display devices

When designing small device displays, factors such as the size, contrast, and brightness of the display are frequently addressed. However, one factor that is often not given enough consideration is the impact of glare and reflections on visibility. What creates glare and reflection? The potential for glare and reflections is impacted by the viewing distances, viewing angles, luminance, reflectance, direct lighting, ambient lighting, and indirect lighting expected during use. In controlled environments like an airplane flight deck, glare and reflection problems can be addressed by eliminating the source of the glare through adjusting or filtering the lighting conditions because they are part of the overall design (this is described in detail in areas of the Design CoPilot application). However, when addressing devices used in the home, lighting conditions are not under the control of the designer. So, what can be done to reduce the likelihood of glare and reflections for … Continue reading

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Collection of small display devices

Recently, while conducting an evaluation of medical devices to be used at home by patients, I was reminded of the importance and challenge of designing usable displays, in particular, usable displays for small devices. The small displays on these hand-held medical devices must allow the user to accomplish tasks like setting doses, monitoring settings, or reading test results. Having a well-designed display under these circumstances is not just convenient, it’s critical. Whether you are designing a small display on a hand-held home medical device, like I am discussing here, or a complex display in an airplane cockpit, which we address in the Design CoPilot application, two of the primary human factors issues that should be considered are: Can the information be seen? Can the information be read and used appropriately? Although the primary issues, whether the information can be seen and then can be read and used appropriately, seem fairly straightforward, each involves a … Continue reading

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