Visual Spatial Disorientation: Re-Visiting the Black Hole Illusion

Abstract

The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewirg instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of informstion, including suggestions for reducing the burden, experienced by pilots. A BHI environment refers not to the landing runway but the environment surrounding the runway and the lack of ecological cues for a pilot to proceed visually. The problem is that pilots, despite the lack of visual cues, confidently proceed with a visual approach.The featureless landing environment may induce a pilot into feeling steep (above the correct glide path) and over-estimate their perceived angle of descent (PAD) to the runway.Consequently, a pilot may initiate an unnecessary and aggressive descent resulting in an approach angle far too shallow (below the correct glide path to landing) to guarantee obstacle clearance. This review addresses two questions. One, why do pilots over-estimate their PAD?And two, if visual SD is such a well-researched and documented phenomenon, why does visual SD still continue to contribute to aviation accidents today? Based on previous research, eight reasons are hypothesized as why a pilot over-estimates PAD. Also, a historical review of the BHI is presented as well as a discussion of past research and accident investigations that demonstrate inconsistencies regarding the state of the BHI.

Pilot gaze and glideslope control

“…Our findings in day lighting conditions were generally consistent with those of an earlier study by Lintern and Koonce [1991], which found that pilots were poor at converging on the ideal glideslope and often drifted through it. During night lighting conditions, we found that when pilots started either too high or on the ideal approach, they tended to adopt too steep a glideslope initially, only curbing this trajectory very late in the approach (consistent with the "black hole illusion"; see Gibb [2007]). However, very little change in glideslope was observed for night approaches that started too low, where pilots maintained a very shallow approach throughout the entire glideslope phase of landing.…”

The “Black Hole” Night Visual Approach: Calculated Approach Paths Resulting From Flying a Constant Visual Vertical Angle to Level and Upslope Runways

“…One wonders if novice or low time general aviation pilots would fare as well as these professionals, or would be more prone to be affected by the CVA issue. In addition various other known visual illusions may contribute to the difficulties of a black hole approach (Gibb, 2007). SUMMARY 1.…”

“…Approach strategies for light aircraft to avoid this psychological phenomenon are indicated. A template for accident investigation use is illustrated.Night visual approaches in clear weather over dark territory to lighted airfields with no glideslope indicator have resulted in a high number of accidents characterized as controlled flight into terrain (Gibb, 2007;Kraft, 1978). Remarkably, many of these accident impact sites have been several miles away from the runway threshold.…”

“…For an excellent review of the magnitude of the problem and the possible causes of black hole illusions (excessively low approaches) see Gibb (2007).…”

Assessing the Impact of a Dynamic Intervention within a Perceptual Discrimination Training Module

“…When flying approach scenarios, pilots use out-the-window visual references for accurate and safe landing. However, the abundance of visual stimuli during approach creates visual illusions (e.g., black hole, visibility, form ratio, terrain) that can alter the perception of runways and thus lead to accidents (Galanis, Jennings, & Beckett, 2001;Lintern & Walker, 1991;Mertens, 1981;Mertens & Lewis, 1982;Gibb, 2007;Previc, 2004). Previous research has found that perceptual discrimination training aids on the development of perceptual strategies (Doane, Alderton, Sohn, & Pellegrinom, 1996) and decreases dependence on utilizing visual illusions as a means of distance estimation on visual approach scenarios (Curtis, Schuster, Jentsch, Harper-Sciarini, & Swanson, 2008;Rivera, et al, 2011).…”