Testing airline web sites for accessibility compliance: use of colour

AccessibilityOz worked with a number of airlines to address their requirements by the deadline. Each airline came to us with the same problem: their booking engine was not accessible.

This article focuses on the use of color in a booking engine. The inaccessible use of color can severely affect a user’s ability to understand information,or to interact with features such as a seat selector or route map. A large percentage of the population is color-blind, so the accessible use of color should be considered a high priority issue.

Use of color in the booking engine

A booking engine is the feature that customers use to book a flight online. It is a complex process and includes interactive features such as the ability to review and choose a desired flight or select a specific seat on the aircraft, perhaps with particular requirements such as additional legroom.

The booking process also requires that important information such as terms and conditions and baggage policy information is clearly available and accepted by the person making a booking prior to payment.

Use of color

WCAG2 Level A Success Criterion 1.4.1 (Use of Color) says:

The intent of this Success Criterion is to ensure that all users can access information that is conveyed by color differences, that is, by the use of color where each color has a meaning assigned to it. If the information is conveyed through color differences in an image (or other non-text format), the color may not be seen by users with color deficiencies. In this case, providing the information conveyed with color through another visual means ensures users who cannot see color can still perceive the information.

Color is an important asset in design of Web content, enhancing its aesthetic appeal, its usability, and its accessibility. However, some users have difficulty perceiving color. People with partial sight often experience limited color vision, and many older users do not see color well. In addition, people using text-only, limited-color or monochrome displays and browsers will be unable to access information that is presented only in color.

Understanding Success Criterion 1.4.1

Complex interactive features often make use of color to highlight items such as flight paths on an airline route map, the availability of a certain flight or type of fare, or seat types in a seat selector. People who are color-blind may not be able to differentiate between items (e.g. an available or unavailable seat) where the only difference between them is the color.

On many systems we also found that links within the content are not underlined by default and differ from standard text by color alone. Being able to identify and follow links to important information such as terms and conditions, help information, baggage policy etc. is essential to any user (not just people with disabilities) prior to finalising a flight booking. It is vital that this information is clearly presented and can be accessed by all users.

The color issue is also compounded if items relying on color alone also do not meet color contrast requirements.

Color contrast

WCAG2 Level AA Success Criterion 1.4.3 (Contrast – Minimum) says:

The intent of this Success Criterion is to provide enough contrast between text and its background so that it can be read by people with moderately low vision (who do not use contrast-enhancing assistive technology). For people without color deficiencies, hue and saturation have minimal or no effect on legibility as assessed by reading performance (Knoblauch et al., 1991). Color deficiencies can affect luminance contrast somewhat. Therefore, in the recommendation, the contrast is calculated in such a way that color is not a key factor so that people who have a color vision deficit will also have adequate contrast between the text and the background.

Understanding Success Criterion 1.4.3

We encountered the use of low contrast shading (or greying out) in most airline systems reviewed. This was evident within the booking system when highlighting flight unavailability, within date pickers and when showing the navigation stages through the booking process.

All information presented as text in a data table, link, promotional images, and form validation error messages for example should comply with color contrast requirements to ensure visual readability by the greatest number of users.

Please also see our original article on U.S. Department of Transport Rule for Web Accessibility in Air Travel. Feel free to contact us if you need assistance meeting these requirements.

By Alison Ennis

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