TD 67 Flashcards
- Describe how exposure to bright sunlight can have a cumulative and adverse effect on dark adaptation.
Exposure to bright sunlight also has a cumulative and adverse effect on dark adaptation. Reflective surfaces such as sand, snow, water, and manmade structures intensify this condition. Exposure to intense sunlight for 2 to 5 hours decreases visual sensitivity for up to 5 hours and also decreases the rate of dark adaptation and degree of night visual acuity. These cumulative effects can persist for several days. (TC 3-04.93, Para., 8-36)
Describe the protective measures that can be taken to preserve an aviator’s night vision
COCKPIT LIGHT ADJUSTMENT (TC 3-04.93) 8-43. Instrument, cockpit, and rear cargo area overhead lights should be adjusted to the lowest readable level that allows instruments, charts, and maps to be interpreted without prolonged staring or exposure. EXTERIOR LIGHT ADJUSTMENT 8-44. If possible, exterior lights should be dimmed or turned off, mission permitting. Aviators should consult command policy for local procedures. LIGHT FLASH COMPENSATION 8-45. The pilot should turn the aircraft away from a light source if a high-intensity flash is expected from a specific direction.
Explain binocular cues and their value to crewmembers?
- Binocular cues depend on the slightly different view each eye has of an object. Thus, binocular perception is of value only when the object is close enough to make a perceptible difference in the viewing angle of both eyes. However, since most distances outside the cockpit are so great, binocular cues are of little to no value to crewmembers. (TC 3-04.93, Para., 8-54)
- What are the monocular cues that can assist crewmembers with distance estimation and depth perception?
-55. Several monocular cues assist crewmembers with distance estimation and depth perception. These cues are geometric perspective, retinal image size, aerial perspective, and motion parallax and can be remembered by the mnemonic acronym GRAM. (TC 3-04.93, Para., 8-55)
- Describe the type of geometric perspective: Linear perspective
Linear Perspective 8-57. Parallel lines such as railroad tracks tend to converge as distance from the observer increases.
- Describe the type of geometric perspective: Apparent foreshortening
-58. The shape of an object or terrain feature appears elliptical (oval and narrow) when viewed from a distance 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.
- Why is terrain interpretation more difficult when the moon is low on the horizon?
Low Angle 4-36. Terrain interpretation is more difficult when the moon is low on the horizon. This is due to the lower light level and the shadows caused by the low angle. If low-level flight is conducted toward the moon, with the moon at a low angle, glare may bother the aircrew causing distorted vision and a loss of dark adaptation. During aided flight, glare may also degrade NVD capability. However when the moon is low on the horizon, terrain features or objects on the skyline are more recognizable.
. What factors affect the quality of depth perception and distance estimation while using NVGs?
Depth Perception and Distance Estimation Factors include available light, type and quality of NVGs, degree of contrast in the FOV, and user experience. The aircrew must often rely on the monocular cues. (FM 3-04.203, Para., 4-75)
How can crewmembers compensate for the loss of peripheral vision while wearing NVGs?
An NVG’s FOV significantly reduces peripheral vision as compared with unaided flight. Crewmembers must use a continual scanning pattern to compensate for the loss. When scanning to the right, crewmembers should move their eyes slowly from the left limit of vision inside the device to the right limit while moving their head to the right. This enables a crewmember to cover a 70- to 80-degree FOV with only 30 to 40 degrees of head movement, minimizing head rotation. The crewmember should scan back to the left in reverse order avoiding rapid head movements.
How is spatial disorientation affected by wearing NVGs
Maneuvers requiring large bank angles or rapid attitude changes tend to induce spatial disorientation. An aviator should avoid making drastic changes in attitude/bank angles and use proper scanning and viewing techniques.
- 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?
These are usually the result of manufacturing imperfections that do not affect image intensifier reliability and are not normally a cause for rejecting an ANVIS. However, some types of blemishes can get worse over time and interfere with the ability to perform the mission. If you believe a blemish is cause for rejection, record the specific nature of the problem on the maintenance forms and identify the position of the blemish by using the clock method and approximate distance from the center (e.g., 5 o’clock toward the outside, 2:30 near the center, or 1:00 midway).
