Night vision limitations and techniques

Question 1

Effectiveness

Reference:

Answer 1

The effectiveness of unaided night vision is highly dependent upon the level of ambient light. It
can be near impossible to see in dark environments, making it extremely difficult to detect
obstacles.

Reference: TC 3-04.4 Ch. 4

Question 2

The night blind spot (due to a concentration of _____ in the _____ ______) creates a blind spot __-___ degrees wide in the center of the visual field.

Normal central daylight vision _____ due to low illumination or dark viewing condition.

Answer 2

The night blind spot (due to a concentration of cones in the fovea centralis) creates a blind spot 5-10 degrees wide in the center of the visual field.

Normal central daylight vision decreases due
to low illumination or dark viewing condition.

Question 3

Crew members must use proper techniques for night vision:

Answer 3

● Scanning: Objects more readily identified at night when crew members use proper scanning. Looking from left to right at a greater distance and moving inward (stop-turnstop-turn pattern).

● Off-center vision: Requires crew-members to view an object by looking 10 degrees above, below, or to the side rather than directly at the object. Must maintain visual contact with the object via peripheral vision (viewing longer than 2-3 seconds can bleach out image).

● Shapes or silhouettes: Since visual acuity is reduced at night, must identify objects by
shapes or silhouettes. Must be familiar with architectural design of structures in the AO.

Question 4

Reference:

Answer 4

Reference: TC 3-04.93 Ch. 8