The following table provides a summary of the various factors and conditions together with their effects on the pilot’s perception and actions:
Result
Narrow or long runway Being too high Push Land short / land hard
Runway or terrain uphill slope
Wide or short runway Being too low Pull Land long / overrun
Runway or terrain downhill slope
Pitch down or Duck under - - Land short / land hard / CFIT
Bright runway lighting Being too close (too steep) Push Land short / land hard
Low intensity lighting Being farther away (too shallow) Pull Land long / overrun
Light rain, fog, haze, mist smoke, dust Being too high Push Land short / land hard
Entering fog (shallow layer) Being pitch up Push over Steep glide path / ( CFIT )
Flying in haze Being farther away (too shallow) Pull Land long / overrun
Wet Runway Being farther away (too high) Late flare Hard landing
Crosswind Being angled with runway Cancel drift correction Drifting off track / off runway centerline
Visual Illusions Awareness
Page 5
How to Lessen the Effects of Visual Illusions ?
To lessen the effects of visual illusions, prevention strategies and lines-of-defense should be developed and implemented based on the following recommendations.
Hazard Awareness
Operators should assess their exposure to visual illusions in their operating environment (i.e., over the entire route network).
Flight crews should be educated and trained on the factors and conditions creating visual illusions and their effects on the perception of the environment and aircraft position:
.
Perception of heights / depth, distances, and angles;
.
Assessment of aircraft lateral position and glide path.
The awareness of visual illusions can be supported by an identification of all hazard-airports and/or hazard-runways (in the operator’s network) as a function of the available navaids, visual aids and prevailing hazards.
Hazard Assessment
Approach hazards should be assessed for each individual approach, during the approach and go-around briefing, by reviewing the following elements:
.
Ceiling and visibility conditions;
.
Weather:
. wind, turbulence;
. rain showers; and/or,
. fog or smoke patches;
. Crew experience with airport and airport environment:
. surrounding terrain; and/or,
. specific airport and runway hazards (obstructions, black-hole, off-airport light patterns, …);
. Runway approach and visual aids:
. Type of approach (let-down aid restriction, such as glide slope unusable beyond a specific point or below a specific altitude);
. Type of approach lighting system; and,
. VASI or PAPI availability.
Terrain awareness
When requesting or accepting a visual approach, flight crew should be aware of the surrounding terrain features and man-made obstacles.
At night, an unlighted hillside between a lighted area and the runway threshold may prevent the flight crew from correctly perceiving the rising terrain.
Flying techniques
Type of approach
At night, when an instrument approach is available, prefer this approach to a visual approach to reduce the risk of accident caused by visual illusions:
.
ILS approach, with use of VASI / PAPI (as available) for the visual segment; or,
.
Non-precision approach, supported by a VASI / PAPI (as available).
On a non-precision approach, do not descend below the MDA(H) before reaching the visual descent/decision point (VDP), even if adequate visual references have been acquired before reaching the VDP.
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