TD-202 Martin ✔

Question 1

1. Describe how exposure to bright sunlight can have a cumulative and adverse effect on dark adaptation.

Answer 1

Exposure to intense sunlight for two to five hours decreases visual sensitivity for up to five hours. In addition, the rate of dark adaptation and the degree of night visual acuity decrease. These cumulative effects may persist for several days.

FM 3.04.301 para 8-32

Question 2

2. Describe the protective measures that can be taken to preserve an aviator’s night vision.

Answer 2

When exposed to bright sunlight for prolonged periods, aircrew members should wear military-issued, neutral-density sunglasses (ND-15) or equivalent filter lenses when anticipating a night flight. This precaution minimizes the negative effects of sunlight (solar glare) on rhodopsin production, which maximizes the rate of dark adaptation and improves night vision sensitivity and acuity.

FM 3.04.301 para 8-36

Question 3

3. Explain binocular cues and their value to crewmembers?

Answer 3

Binocular cues depend on the slightly different viewing angle each eye has of an object to estimate its distance. Since most of the distances outside the cockpit are so great, binocular cues are of little to no value to crewmembers. (TC 3-04.93 pg 8-14 para 8-54)

Question 4

4. What are the monocular cues that can assist crewmembers with distance estimation and depth perception?

Answer 4

**GRAM** 
_Geometric Perspective (LAV):_
An object appears to have a different shape when crew members view it at varying distances and from different angles. The types of **geometric perspective** include;
**Linear perspective, Apparent foreshortening, and Vertical position in the field.**

Retinal Image Size (KITO):
Distance Estimation. An image focused on the retina is perceived by the brain to be of a given size. The factors that aid in determining distance using the retinal image are known size of objects, increasing and decreasing size of objects, terrestrial association, and overlapping contours or interposition of objects. These factors can be remembered by the acronym KITO.
Known Size of Objects. The nearer an object is to the observer, the larger its retinal image.
Increasing or Decreasing Size of Objects.
Terrestrial Association. Comparison of one object, such as an airfield, with another object of known size, such as a helicopter, will help to determine the relative size and apparent distance.
Overlapping Contours or Interposition of Objects. When objects overlap, the overlapped object is farther away.

Aerial Perspective (FLP):
The clarity of an object and the shadow cast by it are perceived by the brain and are cues for estimating distance.
Fading of Colors or Shades. Objects viewed through haze, fog, or smoke are seen less distinctly and appear to be at a greater distance than they actually are.
Loss of Detail or Texture. The farther from an object that an observer is, the less apparent discrete details become.
Position of Light Source and Direction of Shadow. Every object will cast a shadow if there is a source of light. The direction in which the shadow is cast depends on the position of the light source.

Motion Parallax:
This is often considered the most important cue to depth perception. Motion parallax refers to the apparent, relative motion of stationary objects as viewed by an observer who is moving across the landscape.

Question 5

5. Describe the type of geometric perspective: Linear perspective

Answer 5

Linear Perspective. Parallel lines, such as railroad tracks, tend to converge as distance from the observer increases.

Question 6

6. Describe the type of geometric perspective: Apparent foreshortening

Answer 6

Apparent Foreshortening. The true shape of an object or terrain feature appears elliptical (oval and narrowed appearance) when viewed from a distance when aircrew members are flying at both higher and lower altitudes.
As the distance to the object or terrain feature decreases, the apparent perspective changes to its true shape or form. When flying at lower altitudes and viewing at greater distances, aircrew members may not view objects clearly. If the mission permits, pilots should gain altitude and decrease distance from the viewing area to compensate for this perspective.

Question 7

7. Why is terrain interpretation more difficult when the moon is low on the horizon?

Answer 7

More difficult shadowing to judge and determine distance, shape and/or size, and lower illumination level.

Question 8

8. What factors affect the quality of depth perception and distance estimation while using NVGs?

Answer 8

Illumination level, environmental conditions, focus and adjustments, scanning technique, type topography/ terrain.

Question 9

9. How can crewmembers compensate for the loss of peripheral vision while wearing NVGs?

Answer 9

By utilizing propper scanning technique

Question 10

10. How is spatial disorientation affected by wearing NVGs?

Answer 10

Because of limited FOV and increased level of fatigue, the pilot is more likely to experience SD during night missions.
Increasing the change of getting SD - Common errors:

• Distance estimation
• Terrain contour misperception
• Relative motion illution
• “extreme” AC manouvering
• too “violent” head movement

Question 11

11. Explain the term cosmetic blemish. If you believe a cosmetic blemish is cause for rejection how should you record the problem on the maintenance form?

Answer 11

Usually result from a manufacturing imperfection that does not cause for a rejection (red X), and that does not affect image intensifier reliability.

I - Image distortion
F - Fixed pattern noise

I - Image disparity (=difference)

C - Chicken wire

B - Bright spots
O - Output brightness variation
B - Black spots