What must be considered to adjust basic daytime visual Sweep Width (W) values?

• A. Weather, crew fatigue, speed (aircraft only)
• B. Wind direction
• C. Time of day
• D. Visibility

Answer: (A)

Sweep Width is the width of the area you can effectively observe as you move along a search track. In daytime visual search, how far you can reliably detect targets isn’t fixed; it changes with conditions that affect both visibility and human performance. Weather directly changes visibility and contrast; clear conditions allow a larger sweep width, while fog, rain, or haze shrink how far you can see and identify objects. If the crew is fatigued, vigilance and cue recognition drop, so the observer’s effective detection range decreases and you should reduce Sweep Width accordingly. Speed also matters, especially for aircraft: higher airspeed means less time to look and identify targets, so the effective sweep width decreases to reflect the reduced observation opportunity.

Other factors like wind direction or time of day aren’t standalone determinants for W in the same way, since their impact is encompassed by visibility and lighting conditions. So you adjust basic daytime visual Sweep Width values by considering weather, crew fatigue, and speed (aircraft only).