Aviation Visual Perception by Scharff Lauren Dr Gray Rob Dr Gibb Randy Colonel & Rob Gray & Lauren Scharff

Author:Scharff, Lauren, Dr, Gray, Rob, Dr, Gibb, Randy, Colonel & Rob Gray & Lauren Scharff
Language: eng
Format: epub
Publisher: Ashgate Publishing Ltd
Published: 2010-08-14T16:00:00+00:00

Chapter 6

Spatial Disorientation—Cues, Illusions and Misperceptions

Human beings are not designed for aerial operations, either by day or by night. We can only achieve this by the use of technology and training. Our physiological limitations become very evident under certain flight conditions, and the night environment is perhaps the most significant. (Ostinga, Wolff, Newman, and White, 1999, p. 25)

Actions and behavior in visual space require accurate estimation of the depth and distance of objects. A rich viewing environment is filled with redundant cues providing depth and distance information. This redundancy makes it difficult to determine the dominant visual cues that are used for the control of different types of actions (Warren and Owen, 1982), which in turn makes it difficult to predict the influence of the reduction of available cues. While rich viewing conditions reduce (but do not eliminate) visual illusions and misperceptions, impoverished viewing conditions such as at night and/or in the weather, increase the likelihood that a pilot will experience visual illusions and misperceptions, and pilots often do. Wickens and Hollands (2000), explain the impact of cue reduction in that “there are occasions when the hypotheses we assume do not correspond with reality because the cues are few in number, the assumptions we make about the world are incorrect, or the cues are ambiguous” (p. 143). Previc (2004a) reminded readers that only bats have successfully found a way to fly without the aid of vision.

Both Gillingham (1992) and Previc (2004a) concluded that in assessing mishap statistics one may safely assume that roughly half of all spatial disorientation mishaps have some form of visual misperception as a contributing factor. Following an analysis of controlled flight into terrain (CFIT) data between the years of 1980–1996, Khatwa and Helmreich (1998) reported that the incidence of an approach-and-landing accident at night was three times higher than such an accident during daylight hours. More specifically, they found that disorientation or some sort of visual illusion was cited 21.1 percent of the time as the causal factor across 76 approach-and-landing accidents.

Before continuing with the discussion on spatial disorientation, it must be emphasized that pilots are generally aware that during impoverished visual conditions they are more prone to misperceptions. The paradox of this scenario is that pilots continue to confidently control their aircraft on the basis of visual information and fail to utilize the instruments right under their noses. For example, during a night approach to landing pilots often overconfidently attempt to fly “visual” knowing full and well that they are susceptible to misinterpretation of the runway size, shape and distance. Thus, while visual perception underlies many misperceptions, the cognitive aspect of overconfidence also plays a large role in aviation mishaps; understanding this influence of cognition may help reduce the hazards via education and training. Active training may potentially be the best tool because education alone has not been able to significantly impress upon pilots their susceptibility. By having pilots experience their misperceptions first hand in a training simulator, their perceptual limitations can be demonstrated (Gibb, Schvaneveldt, and Gray, 2008; Gibb, 2007).

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