What barrier significantly affects effective visual scanning?

Aircraft physical blind spots significantly affect effective visual scanning because these blind spots create areas around the aircraft where the pilot's line of sight is obstructed or limited. Blind spots can arise from the aircraft's structure, such as the wings or fuselage, which can block the view of other aircraft or obstacles. As a result, pilots must actively compensate for these blind spots through techniques such as head movement and using visual references outside the aircraft to ensure comprehensive situational awareness.

While weather conditions, aircraft speed, and proper scoring techniques can influence a pilot's overall performance or situational awareness, they do not specifically relate to the barriers of visual scanning in the way that physical blind spots do. Addressing blind spots is crucial for maintaining safety in flight by ensuring that the pilot is aware of their surroundings, especially in busy airspace or during maneuvering.