All displays, including alarm indicators, should be within the upper limit of the visual field (75 degrees above the horizontal line of sight) of the 5th percentile female (see Table 11.1), and should be mounted so that the interior angle between the line of sight and the display face is 45 degrees or greater (see Figure 11.4).
Additional Information:
The 5th percentile female determines the upper limit. Practically, there is no lower limit for a plausible sit-down console design. The principal factors affecting the readability of displays, including alarm indicators, are: (1) display height and orientation relative to the user's LOS when standing directly in front of the display; (2) display distance and orientation relative to the user's straight-ahead LOS when the user must read the display from an off-side position; and (3) the size of display markings relative to the distance at which the display must be read. Character size is addressed in Section 1.3.1, Alphanumeric Characters, and is not considered here. Except as specifically noted, measurements of angles should be made with the eye point in line with the leading edge of the benchboard.
Table 11.2 Relative legibility of color combinations.
Figure 11.4 Display height and orientation relative to a seated user's line of sight.