TD 66

Question 1

. Describe the factor that aids in determining distance using the retinal image: Known size of objects

Answer 1

A structure projects a specific angle on the retina based on its distance from the observer. If the angle is small, the observer judges the structure to be a great distance away, while a larger angle indicates the structure is close

Question 2

2. Describe the factor that aids in determining distance using the retinal image: Increasing or decreasing size of objects

Answer 2

Increasing or Decreasing Size of Objects 8-62. If the retinal image of an object increases in size, the object is moving closer to the observer. If the retinal image decreases, the object is moving further away. If the retinal image is constant, the object is at a fixed distance.

Question 3

3. Describe the factor that aids in determining distance using the retinal image: Terrestrial Association

Answer 3

Terrestrial Association 8-63. Comparison of one object such as an airfield with another object of known size such as a helicopter helps in determining the relative size and apparent distance of the object from the observer.

Question 4

4. Describe the factor that aids in determining distance using the retinal image: Overlapping Contours or Interposition of Objects

Answer 4

8-64. When objects overlap, the overlapped object is further away. For example, an object partially concealed by another object is behind the object concealing it. Crewmembers must be especially conscious of this cue when making an approach for landing at night. Lights disappearing or flickering in the landing area should be treated as barriers and the flight path adjusted accordingly. (TC 3-04.93, Para., 8-64)

Question 5

5. Describe the factor that aids in determining distance using the aerial perspective: Fading of Colors or Shades

Answer 5

8-66. An object viewed through haze, fog, or smoke appears less distinct and at a greater distance than it actually is. Conversely, if atmospheric transmission of light is unrestricted, the object appears more distinct and closer than it actually is.

Question 6

Describe the factor that aids in determining distance using the aerial perspective: Loss of detail or texture

Answer 6

8-67. The further an observer is from an object, the less apparent discrete details become. For example, at a distance a cornfield appears to be a solid color, tree leaves and branches appear to be a solid mass, and objects appear to be at a great distance

Question 7

7. Describe the factor that aids in determining distance using the aerial perspective: Position of Light Source and Direction of Shadow

Answer 7

Position of Light Source and Direction of Shadow 8-68. Every object casts a shadow in the presence of a light source. The direction in which the shadow is cast depends on the position of the light source. If an object’s shadow is cast toward an observer, the object is closer to the observer than the light source.

Question 8

8. Describe the monocular cue: Motion parallax.

Answer 8

Motion Parallax 8-69. Motion parallax is often considered the most important depth perception cue. Motion parallax refers to the apparent relative motion of stationary objects as viewed by an observer moving across the landscape. Near objects appear to move past or opposite the path of motion; far objects appear to move in the direction of motion or remain fixed. The rate of apparent movement depends on the distance the observer is from the object. Objects near an aircraft appear to move rapidly, while distant objects appear to be almost stationary.

Question 9

9. What is an operational defect? Operational defects include

Answer 9

Operational Defects

These defects relate to the reliability of the image intensifier and are an indication of instability. If identified, they are an immediate cause for rejecting the ANVIS.

They include
 Shading, 
Edge Glow, 
Flashing, 
Flickering, 
Intermittent Operation 
and Emission Points.