Usability of this website
One of our important jobs is the development and evaluation of effective user interfaces for FAA systems—and fair is fair. Here is our evaluation of some of usability characteristics of our website. We're always looking to improve and we hope to eliminate the "not-so-good" stuff soon. Comments and suggestions are always welcome at kenneth.allendoerfer@faa.gov.
Our website also follows the Web-Based Portal Computer-Human Interface Guidelines recently published by the Human Factors Team-Atlantic City.
Some good usability characteristics of our site
1. Links are text-based and graphics contain alternate descriptions.
This is important for visually-impaired users who may be browsing the site using text-to-speech technologies. If a link were a graphic and contained no alternate description, there would be no way for a visually-impaired user to determine the function of the link. In addition, text-based links load faster than graphic-based ones which increases the speed of the site for everyone.
2. Most graphics are small. The large graphics have thumbnails.
A usable site is a fast site. To achieve fast download times, we have reduced the pixel and file size of nearly all our graphics. Large graphics on the site are provided as thumbnails first, which allow the users to decide whether to download the full-size image or not.
3. The site makes extensive use of Cascading Style Sheets (CSS).
This enables users to configure their browsers themselves so the site more usable for them. It also reduces the site download time and makes the site easier to index by search engines. Finally, it corresponds better to the original intent of HTML to markup meaning rather than appearance.
4. Links to frequently accessed items, like the HFDS, are available from all pages.
Dozens of people come to our site each month to access the Human Factors Design Standard. The HFDS files, however, are stored fairly deep in the directory hierarchy. Accessing the HFDS would be significantly more awkward if we had forced them to navigate the hierarchy every time.
5. The site uses meaningful file and directory names.
We have tried to make the names of our files and directories understandable and memorable by a human. This helps users understand where they are in the site and helps them navigate more effectively. It also helps well trying to tell someone about the site or send them the URL.
6. The page layout limits the width of the body text.
This is somewhat controversial. Good arguments can be made that the width of body text should be restricted only by the user by adjusting his or her browser window. Many believe that by restricting the width of body text, we are restricting users' flexibility. However, we believe that people read and comprehend most effectively with medium line lengths, approximately 55 characters. Many users are not aware that column width can affect reading speed and comprehension and will not adjust their column widths accordingly. By using CSS and relative character sizes, we believe that most users can find an acceptable browser configuration.
7. We provide "breadcrumbs."
The first line of each page shows the user where in the site hierarchy they are. This helps users understand the organization of the site, especially when they're browsing in a non-linear pattern.
8. The site does not use frames.
Frames can create numerous usability problems, the most serious of which is that it is very difficult for users to bookmark individual pages in the site. They typically end up bookmarking the navigation frame or the frame they first encountered when visiting the site.
9. The site has sophisticated search functions.
Full-text searching is the primary navigation method for many users. Our site allows users to search the site itself using a sophisticated search tool. Users can also search the text of our technical notes, including PDF files, using a separate tool on our Products pages.
10. The site is designed to prevent horizontal scrolling even at small screen resolutions.
Horizontal scrolling is serious website usability problem. Sites that use columns with a fixed width will require horizontal scrolling at some screen resolutions. Though most of our users will view the site on larger screens, some users will use older technology or smaller displays such as PDAs or cell phones. Though our site does not look its best at small resolutions, horizontal scrolling is not required at any screen resolution 640x480 or better.
And some not-so-good...
1. The site isn't browser neutral.
We intend to accommodate users of as many browsers and platforms as possible. To this end, we use standard character sets and closely follow the HTML and CSS specifications. However, the transition to CSS is not a simple one and browsers vary in CSS support. To preserve consistency across browsers for our users, some pages still contain elements that follow old layout and coding practices. Over time, we will eliminate these.
We have tested the site on Microsoft Internet Explorer 6.0, Netscape Navigator 7.0, and FireFox 1.0 and found it to work acceptably, though there may still be some small problems depending on the configuration. Please let us know when you find a page that doesn't seem to look or behave correctly.
2. Some of our technical note PDF files are not readable by text-to-speech technology.
We hope to make our research available to as wide an audience as possible. However, technical notes written before the early 1990s were not created with word processors and are difficult to convert into PDF files. In most cases, these older technical notes are available only as paper copies or as PDFs based on scanning the printed pages as pictures rather than as text. If there is a technical note that you need but you are unable to read such a PDF, please contact the webmaster and we will try to provide something suitable.
