Definition
The ability of the eye to see in low-light conditions, relying primarily on the rod cells of the retina rather than the cones used in daylight. Night vision develops gradually as the eyes adapt to darkness, is centered on the peripheral (off-center) field of view rather than directly ahead, and is degraded by exposure to bright light, low oxygen levels at altitude, fatigue, and certain substances such as tobacco and alcohol.
Plain English
How well a pilot can see at night. It works differently from daytime vision -- it takes time to develop, things are seen more clearly out of the corner of the eye than dead ahead, and it's easily ruined by bright lights or being tired.
Context Anchor
Used in night flying, especially during preflight, taxi, takeoff, landing, traffic scanning, and looking for terrain or lights outside the airplane.
Why Pilots Care
Effective night vision prevents spatial disorientation and maintains situational awareness during night operations.
Grounding Statement
After sitting in a dark cockpit for a while, your eyes become more useful outside, but one bright white light can set that adjustment back.
Intuition Check
Night vision does not mean your eyes see at night the same way they see in daylight. It means your eyes have adapted to darkness and must be protected from bright light to stay effective.
Example Sentence 1
The pilot avoided looking at the bright apron lights before departure to preserve night vision for the flight ahead.
Example Sentence 2
Using a red flashlight during preflight helped preserve the pilot’s night vision.