Static Visual Displays: Flight Deck Documentation

Transcription

1 Static Visual Displays: Flight Deck Documentation Source: Degani, A. (1992). On the Typography of Flight-Deck Documentation, NASA Contractor Report # Moffett Field, CA: NASA Ames Research Center, 1

2 Background: Flight Deck Documentation Types of documentation manuals charts flight plans Quick Reference Handbooks (QRHs) checklists Checklist use to check that things were done as to-do lists 2

3 Significance of Checklists Aircraft complexity Human memory limits Multiple tasks, interruptions Recent accidents 3

4 B-747 Checklist Starting Engines (1). CKPIT / SMK BARR DR CLSD / LCKD E (2). GALLEY POWER OFF E (3). PACK VALVES CLSD E (4). FUEL BOOST PUMPS ON E 5. HYDS CLRD / PRESSZD C, E 6. PRKNG BRK / PRESS SET / NORM C 7. NAV / ANTI-COLL LTS ON C 8. START PRESS PSI E 9. PUSHBK CLRNCE REC D C 10. STRTING ENGS CHK COMPLETE E 4

5 Typography (1) Definition: arrangement, style, appearance of type Print legibility quality of print allowing reader to quickly and positivley identify characters depends on stroke width character form illumination on page contrast 5

6 Typography (2) Print readability quality of print allowing rapid recognition of words, word groups, etc. depends on character spacing word spacing line spacing character area/background area ratio Flight deck characteristics non-optimal viewing conditions changes in accommodation (near/far) interruptions & distractions several age groups 6

7 Typography (3) serifs ascenders counters baseline Alphabet descender x-height upper-case letter lower-case letters 7

8 Typefaces (Fonts) Major font groups roman fonts (with serifs) sans-serif fonts (without serifs) Serif pros & cons - serifs aid horizontal movements of eyes + serifs disrupt character discrimination 8

9 Font Examples Arial ABCDEFGHIJ abcdefghij Antique Olive ABCDEFGHIJ abcdefghij Helve-WP ABCDEFGHIJ abcdefghij Impact ABCDEFGHIJ abcdefghij Rockwell ABCDEFGHIJ abcdefghij Times New Roman ABCDEFGHIJ abcdefghij 9

10 Font Recommendations Use sans-serif fonts (usually). Avoid fonts having similar characters. Avoid dot matrix fonts. 10

11 Lower-Case vs UPPER-CASE Characters Research findings: lower-case headings located faster lower-case read faster, ranked higher Factors Most printed material in lower-case. Total word form is more obvious in lower-case. 11

12 Word Form START PAUSE start pause 12

13 Case Recommendations Long chunks of text should be set in lower-case. If upper-case is required, make first letter larger. START PAUSE 13

14 Font Height (Typesize) Size measurement 1 point = 1/100 in. (when part of character) 1 point - 1/72 in. (when between lines, words, etc.) Font height vs. viewing condition 14

15 Character Height Recommendations (1) H (in.) = D + K1 + K 2 K1 : correction factor for illumination & viewing conditions K1 = 0.06 in. for good illumination (> 1.0 fc), favorable reading conditions K1 = 0.26 in. for poor illumination (< 1.0 fc), unfavorable reading conditions K2 : correction factor for importance K2 = 0 in. for non-important markings K2 = in. for important markings 15

16 Character Height Recommendations (2) Viewing Nonimportant markings, Important markings, distance, D K2 =.0 K2 =.075 in value K1 =.06 K1=.26 K1 =.06 K1 = Derived from formula H (in) = D + K1 + K2 16

17 Character Height Recommendations (3) Low luminance (to 0.03 ft-l) High luminance (> 1.0 ft-l) Critical markings, position variable (e.g., numerals on counters) Critical markings, position fixed (e.g., numerals on fixed scales) Non-critical markings (e.g., instrument labels) Assumes viewing distance of 28 inches. Heights in inches. 17

18 Other Height Recommendations Distinguish between x-height and overall height when designing for lower-case. x-height should generally be > 0.10 in. (under good viewing conditions). 18

19 Stroke Width Measured as stroke width : character height character height F Recommendations stroke width 1 : 6-1 : 8 (black on white, viewed straight-on) 19

20 Height-to-Width Ratio Measured as character height : character width character height F character width Recommendations 5 : 4 (to compensate for variable angles) 20

21 Horizontal and Vertical Spacing Affect legibility and readability Clarity can be enhanced by increasing vertical separation between lines Recommendations Vertical spacing between lines > 25-33% overall font size Horizontal spacing 25% overall size (between words) > 1 stroke width (between characters) 21

22 Line Length Long lines make difficult transition from end of one line to beginning of next. Recommendations single-column text: 4 in double-column text: 3 in 22

23 Face and Underline Very, very long sentences that run on and on like this one can be quite difficult for most people to read, when set entirely in italics, though difficulty may vary with the specific font used. Using too many faces -- italic, bold, shaded -- and too many forms of underline for EMPHASIS can also make text difficult to read. Recommendations avoid long strings of italics use primarily one or two typefaces for emphasis 23

24 Contrast Recommendation use dark characters over a light background If white on black is desired use minimum amount of text use large font use sans-serif font 24

25 Color Coding For short viewing distances, large luminance differences are more effective than chromatic (color) differences. Recommendations (dark characters over colored background) reflectance of background > 70% luminance ratio, character:background 1:8 typesize > 0.10 in Caution 25

26 Color Coding (2) General Recommendations Use black characters over white or yellow background for most applications. Avoid using black over dark red, dark green, or dark blue. satisfactory satisfactory unsatisfactory unsatisfactory unsatisfactory 26

27 Cumulative Effects of Improper Typography Combination of two or more non-optimal characteristics has a greater effect on legibility and readability. e.g., roman font, small typesize, italics, dark characters over dark background: It is very, very likely that most of you will have trouble reading this. 27

28 Wording Recommendations Use familiar words. Use short words, when possible. Avoid jargon. Use only standard abbreviations. 28

29 Sentences Recommendations Use clear syntax, usually subject-verb-object. Use correct grammar. Use short sentences. Use positive rather than negative construction (tell what to do rather than what not to do). Use active rather than passive voice: Push the button. not The button should be pushed. 29

30 Glare Definition: presence of an area of very high relative luminance in the field of view. Recommendation Use anti-glare plastic to laminate documents 30

31 Slope and Angular Alignment Optimal conditions: document perpendicular to sight When document if tilted about an axis vertical to line of sight, changes in accommodation have to be made as the text is scanned. Recommendation Orient document perpendicular to line of sight. 31

32 Quality of Paper and Print Recommendations Print on thick, opaque paper Print should be clear: boundaries between strokes and spaces should be distinguishable Quality of paper and print should be well above normal 32

33 Effects of Age on Reading 50% reduction in retinal illumination at age 50 compared to age 20. Lens thickens and yellows with age. Recommendation Assess age groups of users and take conservative approach in document design. 33