During a night flight, a remote pilot notices that objects viewed directly are harder to see than objects viewed slightly off-center. What explains this, and how should the pilot adjust their scanning?

Question

Accepted Answer

The center of the retina is dominated by cone cells that function poorly in low light; looking slightly off-center uses rod cells, which are more sensitive in darkness, a technique called averted vision. The fovea, at the center of the retina, is packed with cone cells that require relatively bright light to function. Rod cells surround the fovea and are far more sensitive in low-light conditions. By looking approximately 10 degrees off-center from a target, the image falls on the rod-rich area of the retina, making dim objects more detectable. PHAK Chapter 17 describes this technique as averted vision.

Answer

This is caused by eye fatigue; the pilot should rest their eyes by closing them periodically

Answer

Direct viewing is less effective at night because the pupil constricts when focused on a specific point