How long should each scanned area be observed for effective detection of other aircraft?

The most effective observation time for each scanned area during a visual scan for other aircraft is at least one second. This duration allows pilots enough time to register visual stimuli, making it possible to detect aircraft in different positions and orientations relative to their own. One second is generally considered the minimum time to permit an adequate assessment of airspace for potential conflicts.

Longer observation times may provide additional safety, but the key is that one second is sufficient for quick visual checks while maintaining efficiency in scanning the surrounding airspace. By scanning each area for this amount of time, pilots can achieve an appropriate balance between vigilance and task management, ensuring they cover as much airspace as possible within their vigilance cycle.

While observing for longer durations may seem beneficial, excessive time spent on each section can lead to gaps in scanning other critical areas around the aircraft, potentially increasing the risk of missing an approaching aircraft.