Human Performance on the Flight Deck by Don Harris

Author:Don Harris
Language: eng
Format: epub
Publisher: Ashgate
Published: 2011-03-14T16:00:00+00:00

Figure 12.2 Circular dial and tape formats of fixed-index, moving-pointer displays arranged to optimise a check reading (Harris, 2004a)

If the purpose of the display is to make a comparative check reading between several systems, circular dials are superior. Dials can all be arranged so that their nominal position is, for example, at 12 o’clock. This allows a fast scan of the instruments enabling an emergent feature of the group of displays as a whole to reveal itself, which is not apparent when each display component is considered in isolation. An abnormal value is easily and quickly spotted as the emergent feature of the vertical line formed by all the pointers when in their nominal position is broken. Tape-type instruments have a slight disadvantage in this respect. It is easy to make a swift check reading across a row of tapes but not down a column of tapes. Their emergent features are not as strong as dials and they do not have an implicit nominal position (see also Figure 12.5). Check readings can also be aided by the selective use of colour on the displays around the nominal position. When information from several sources needs to be mentally integrated in some way, there is a benefit in arranging the display elements in close proximity to one another and in such a way so that they form an emergent whole (the proximity compatibility principle – see Barnett and Wickens, 1988).

‘Open window’ displays of a moving-index, fixed-pointer design have all the disadvantages of both traditional dials and counters, with none of their benefits. It is impossible to make a check reading from these displays, as the pilot has no idea where in the range of potential values the current value lies without actually reading the value. Additionally, they do not possess the accuracy of a counter. They do, however, transmit some trend information, although not as efficiently as a fixed-index, moving-pointer displays.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.