Motion is invaluable in drawing the eye’s attention. Yet two aircraft on a collision course will appear virtually motionless to each other. When observed from the cockpit, the conflicting target will look like a small, stationary speck until it is at a distance from which it may be too close to avoid. This is called the “blossom effect.” If a pilot sees an aircraft that remains in the same spot in the windshield (unless it is directly ahead and moving in the same direction), there is a high probability the two aircraft will collide unless one changes their course. Once a threat has been identified, it’s essential to keep the other aircraft in sight until the threat is resolved.
…irritants in the air, fatigue, age, residual alcohol in the bloodstream, and lower oxygen levels can all impact the ability of your eyes to perform at the optimum level.
Haze, flight over open water, or an obscured horizon can make it difficult to see distant objects, impairing the ability to refocus. The same phenomenon can occur when flying over a haze or cloud layer with a high overcast layer above. Focus on the farthest point visible, even the wing tip, to overcome the problem. In poor visibility, repeat refocusing every minute or so.
In addition, be extra vigilant when the sun is low on the horizon. It makes any traffic between the observer and the sun very difficult to see.
Optical illusions can affect what we see in flight. For example, an aircraft at a slightly lower altitude coming toward you may look like it’s above you and appear to descend as it comes closer. At night, a pilot’s ability to judge distance above the ground may be impaired when on visual approach to a runway. It may also be difficult to identify aircraft below you that blend in with lighting on the ground.
In addition to atmospheric conditions and optical illusions, irritants in the air, fatigue, age, residual alcohol in the bloodstream, and lower oxygen levels can all impact the ability of your eyes to perform at the optimum level.
All aircraft have blind spots. High-wing aircraft have reduced visibility of aircraft above them, and can have their view of traffic blocked when making turns in the pattern as the wing is lowered in the direction of the turn. Low-wing aircraft have a large blind spot beneath them that may obscure conflicting traffic when descending into the pattern or while on final approach. Recognize and compensate for visual limitations, whether it’s raising a wing to check for traffic before making a turn in a high-wing airplane, or making shallow S-turns when climbing or descending in any aircraft.
Windshield distortion, placement of window and windshield posts, and other structural elements can also hinder visibility. The brain requires input from both eyes to accurately interpret the visual cues it receives. If a windshield post or other obstruction blocks the vision of one eye, the brain may not perceive the object—even with the other eye providing input. A high glareshield can also block vision, which is especially problematic during climbout.