Chapter headings include Typeface, Lower-case vs. UPPER-CASE Characters, Font height (type size), Contrast and even Glare – all potentially matters of life and death when it comes to the legibility of in-flight controls and emergency response manuals. In fact, the report is prefaced with terrifying examples of what can go wrong – and has gone wrong – when the text is too small, or the contrast unclear.
This report is, in effect, a style guide, and a strong one at that. It plainly states why its guidance is important, and gives clear instructions on how to comply. It’s also very specific to the context of aeronautics, yet we might do well to consider the broader utility of its lessons. For example:
[i]t is also evident that they [serifs] somewhat aid the horizontal movement of the eye along the printed line—the serifs at the top and bottom of a character create a “railroad track” for the eye to follow along the line of print. Therefore, when using a typeface without serifs, adequate spacing between the lines of print should be used in order to prevent the eye from bridging (slipping) to the adjoining line (Craig, 1980). The designer should safeguard against this factor as it may lead to skipping a line while reading a long list.
In one experiment preformed by Tinker (1965), italic face was read 2.7 per cent slower than roman lower-case (with an equal “x”- height). Further- more, 96% of the 224 subjects who participated in this study judged that italic is less legible than a regular roman font (see Figure 18). Bold face was read at the same reading speed as lower-case text. However, the majority of the subjects (70%) commented about the unpleasingness of the text as compared to plain roman font. Results of another experiment (Antersijn and de Ree, 1989) indicated “that bold and medium face do not differ in readability, even under low illumination” (p. 291); suggesting that there is no apparent advantage in printing long chunks of text in bold face. Nevertheless, bold face can be safely and advantageously used for contrast and emphasis. Although faces can highlight a specific item on a document, over usage of this typographical technique can be inefficient.
All very rational food for thought when we’re faced with the inclination to cram too many lines of text onto a page, or to use bold for every other keyword – whether we’re at 20,000 feet, exiting Earth’s atmosphere or sitting at the editor’s desk with two feet firmly on the ground.