STUDIES OF HUMAN FACTOR IN PANEL DESIGN 



163 



techniques, the investigator observed the 

 subjects directly during the operation of the 

 equipment and tallied the frequency of use 

 of each control and display. The results 

 on frequency of use obtained with these two 

 techniques agreed reasonably well, and to- 

 gether with the data on importance, pro- 

 vided a basis for some fairly clear cut dis- 

 tinctions among the different controls and 

 displays. In another study, the method of 

 micromotion analysis was apphed success- 

 fully to the more compHcated operations 

 involved in flying multi-engine mihtary air- 

 craft (7). The problem in this case was 

 infinitely more complex, for different con- 

 trols and displays ranked higher in frequency 

 of use in different types of operations such 

 as takeoff, cruising, landing, etc. Never- 

 theless, a clear basis was provided for dis- 

 tinguishing among the various controls of 

 the cockpit. 



In view of the need for greater simplicity 

 in the panels of most current mihtary equip- 

 ment, the less important and rarely used 

 controls and displays may be located off 

 the main surface of the panel or at least on 

 its periphery. Several novel suggestions 

 have been made in connection with these 

 minor controls and displays and are worth 

 mentioning here. For one thing, infrequent- 

 ly used controls, especially switches and 

 small knobs, may be recessed into the face 

 of the panel so that they will be out of the 

 way, even though perhaps somewhat harder 

 to operate. For displays used only rarely 

 or in special operations, it has been suggested 

 that they be of the plug-in variety so that 

 they can be stowed away when not in use, 

 but plugged into optimal positions when 

 needed (15). Both of these recommenda- 

 tions are good, but should be subjected to 

 experimental test. 



Patterning of Controls 

 and Displays 



Under certain conditions of panel design, 

 it may be possible to shorten the layout 

 procedure by first determining the key con- 



trols and displays and placing these in posi- 

 tions for optimal use. Then the remainder 

 of the items needed in the panel can be 

 placed according to their relationship to the 

 key items, by following the logic of arrange- 

 ment of controls and displays in patterns 

 most suited to human use. The use of the 

 first step in this type of procedure is illus- 

 trated by an actual example of the redesign 

 of one type of Navy aircraft instrument 

 panel (15). In this case, it was considered 

 that the basic instruments used in the "at- 

 titude" system of instrument flying, the ar- 

 tificial horizon and the directional gyro, 

 should be given the central positions on the 



^lockj 



Tr/c) (r/c 



Fig. 7. Naval aircraft instrument panel de- 

 signed according to the principle of functional 

 grouping of displays. (From Foley, 15) 



panel. Once these important and frequent- 

 ly used displays were placed, displays of 

 secondary importance and use associated 

 with them were placed conveniently around 

 them (Fig. 7). The rate of climb indicator 

 was placed to the right of the artificial hori- 

 zon because these two instruments are often 

 used together. The air speed indicator, sen- 

 sitive altimeter, and turn and bank indicator 

 were placed close to these basic instruments 

 in the central area because these were con- 

 sidered rather important adjuncts to the 

 attitude flying instruments. Then, on the 

 periphery of this central region, instruments 

 were arranged near the basic displays with 

 which they were functionally associated. 

 The radio altimeter was placed to the left 

 of the sensitive altimeter, and the radio 

 compass indicator and remote compass in- 

 dicator were placed below the directional 

 gyro since both of these instruments are 

 direction indicators. 



