Table 1
Visual Factors in Approach-and-Landing Events
Visual Illusions Awareness
Page 1
AIRBUS INDUSTRIE
Flight Operations Support
Visual Illusions – Factors and Conditions
The following factors and conditions affect the flight crew ability to accurately perceive the environment, resulting in visual illusions.
Airport environment:
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Ground texture and features;
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Off-airport light patterns such as brightly lighted parking lots or streets;
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“Black hole” along the final approach flight path; and/or,
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Uphill or downhill sloping terrain before the runway threshold or in the approach path environment.
Runway environment:
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Runway dimensions (aspect ratio);
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Runway uphill or downhill slope;
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Terrain drop-off at the approach end of the runway;
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Approach and runway lighting; and/or,
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Runway condition (e.g., wet runway).
Weather conditions:
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Ceiling;
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Visibility (i.e., vertical visibility, slant visibility and horizontal visibility); and/or,
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Cloudiness (e.g., rain, fog or fog patches, haze, mist, smoke, snow, whiteout effect).
How do Visual Illusions Affect the Pilot’s Perception ?
Visual illusions result from the absence of or the alteration of visual references that modifies the pilot perception of his / her position relative to the runway threshold.
Getting to Grips with Approach-and-Landing Accidents Reduction
Visual illusions affect perception of heights, distances and/or intercept angles.
Visual illusions are most critical when transitioning from IMC and instrument references to VMC and visual references.
Visual illusions (such as the black-hole effect) affect the flight crew vertical and horizontal situational awareness, particularly during the base leg and when turning final (as applicable) and during the final approach.
Visual illusions usually induce crew inputs (corrections) that cause the aircraft to deviate from the original and intended vertical or lateral flight path.
Visual illusions can affect the decision about when and how fast to descend from the MDA(H).
The following paragraph provides an expanded overview of all the factors and conditions creating visual illusions to discuss how each factor or condition may affect the pilot perception of:
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The airport and runway environment;
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The terrain separation; and,
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The aircraft vertical or lateral deviation from the intended flight-path.
Usually, more than one factor is involved in a given approach, compounding the individual effects.
Airport environment:
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