NVG Flashcards
What are the three types of vision? When is each used?
- Photopic - full daylight
- Mesopic - dawn/dusk
- Scotopic - night
What type of vision is used when wearing NVGs?
Photopic
What is off-center viewing/vision?
Looking 10 degrees above, below, or to the side of an object to compensate for night blind spot
Monocular cues are used for ___ and remembered with the acronym ___?
Depth perception and distance estimation
“GRAM”
(Geometric, retinal image, aerial, motion parallax)
Describe the geometric monocular cues; and are remembered with what acronym?
An object appears to have a different shape when crew members view it at varying distances and from different angles
“LAV”
- Linear perspective
- Apparent foreshadowing
- Vertical Position
Describe the retinal image size monocular cues; and are remembered with what acronym?
An image focused on the retina is perceived by the brain to be of a given size
“KITO”
- Known size
- Increasing size
- Terrestrial association
- Overlapping contours
Describe the aerial perspective monocular cues; and are remembered with what acronym?
The clarity of an object and the shadow cast by it are perceived by the brain and are cues for estimating distance
“FLP”
- Fading color/shades
- Loss of detail
- Position of light, shadows
Describe motion parallax.
“Most important” monocular cue for stationary objects when moving left/right
- close stationary objects appear to move in fast and in opposite direction of travel
- far stationary objects appear to move slowly in same direction of travel
The moon angle changes at what rate per hour?
13.2 degrees, approximately equal to it’s apparent size
What is the field of vision of the ANVIS-6?
40 degrees
Normal night visual acuity is approximately ___. NVGs enhance this to about ___. The best possible visual acuity at night is ___.
- 20/200
- 20/70
- 20/25 (if 100% illum, clear weather, low humidity)
What is the focal range of the ANVIS-6?
11” to 50m (“optical infinity”)
The ANVIS-6 amplifies light by ___.
2000-3000x
The battery low voltage indicator flashes ___ when the batteries fall below ___?
- red
- 2.4V
Why should rechargeable (NiCd) batteries not be used?
Combined voltage of 2 AA batteries is only 2.4V, and would trigger the low-voltage indicator with new batteries
What are the 4 operational defects? What acronym is used to remember them?
“FEES”
- Flickering
- Emission point
- Edge glow
- Shading
- Laser Damage (not a conventional defect but should not use if seen)
What is the magnification of the ANVIS-6?
1x - NVGs amplify light, do not magnify
If needed, how are the electrical contacts cleaned?
Pencil eraser
When the low voltage indicator starts flashing, you have approx how much battery life remaining?
30 minutes
What acronym is used to remember the visual illusions?
FFF CRASH CSAR
What visual illusions are represented by FFF?
- Flicker Vertigo
- Fixation
- False Horizon
What visual illusions are represented by CRASH?
- Confusing Ground Lights
- Relative Motion
- Altered Plane of Reference
- Structural Illusions
- Height/Depth Perception
What visual illusions are represented by CSAR?
- Crater Illusion
- Size-Distance Illusion
- Autokinesis
- Reversible Perspective
What are the three types of spatial disorientation?
- Unrecognized (Type 1) – Aviator is disoriented but does not believe anything is wrong. Most dangerous type.
- Recognized (Type 2) – Aviator perceives a problem but may not recognized it as spatial disorientation.
- Incapacitating (Type 3) – Aviator cannot orient to visual cues or instruments due to severity of disorientation. Co-pilot/CE should recognize, announce, and/or take control of aircraft.
What exterior lights must be operational before an NVG flight?
Cargo hook well area electroluminescent lighting, IR formation and position lights
What are the 7 most common cosmetic blemishes?
Bright spots, black spots, chicken wire, fixed-pattern noise, image disparity, output brightness variation, distortion
How should the battery pack be oriented on the flight helmet? Where is the primary and alternate battery when oriented properly?
- Oriented with switch/cable up.
- Primary battery on right, alternate battery on left.
What is the ABC, what part of the NVG does it effect, and what does it do?
Automatic Brightness Control - reduces voltage to microchannel plate (abC mCp). Under high-light conditions reduces image brightness so that night vision is not affected
‘ABC is for me’
What is the BSP, what part of the NVG does it effect, and what does it do?
Bright-source Protection - reduces voltage to the photocathode (bsP mcP). Under high light conditions (tracers, explosions) prevents damage to the MCP
What part of the ANVIS-6 filters blue light?
A coating on the objective lens - filters blue light so that blue interior/instrument lights do not cause glare
Night vision adaptation takes approximately how long in optimal conditions?
30-45 minutes
What are the 5 deadly self-imposed stressors
“DEATH”
Drugs, Exhaustion, Alcohol, Tobacco, Hypoglycemia
What are the 4 types of hypoxia?
Hypoxic, Hypemic, Histotoxic, Stagnant
What are the major components of the ANVIS-6? What does each do? What mnemonic is used to remember them?
“Other people’s money pays for everything” - Objective - inverts image, filters blue light - Photocathode - converts photons to electrons (1:1) - Microchannel Plate - multiplies number of electrons - Phosphorescent Screen - creates visible (green) image from electrons - Fiberoptic Inverter - inverts image to proper orientation - Eyepiece - view image, artificial focal depth of 6 feet
What is scintillation? When is it seen?
- Snowy/static pattern (like an old tv)
- Seen in low illumination (<25%); can be a sign of worsening weather
Describe Linear Perspective
Parallel lines, such as runway lights, tend to converge as distance from the observer increases
Describe apparent foreshortening
The true shape of an object or a terrain feature appears elliptical when viewed from a distance
Describe Vertical position in the field
Objects or terrain features farther away from the observer appear higher on the horizon than those closer to the observer
Describe Known size of objects
The nearer an object is to the observer, the larger its retinal image
Describe increasing/decreasing size of objects
If the size of an object increases in size, the object is moving closer to the observer. If the size decreases, the object is moving farther away.
Describe 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 of the object from the observer
Describe overlapping contour
When objects overlap, the overlapped object is farther away
Describe fading colors/shades
Objects viewed through haze, fog, or smoke are seen less distinctly and appear to be at a greater distance than they actually are
Describe loss of detail
The farther from an object that an observer is, the less apparent discrete details become. For example, a cornfield at a distance becomes a solid colour
Describe position of light/shadows
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
What is scotopic vision
What is mesopic vision
What is photopic vision
Explain false horizon
Confusing clouds/snowbanks with horizon, causes false sense of orientation
Explain flicker vertigo
rotors interrupting sunlight or strobe lights (especially in clouds) creates flashing effect, generally annoying but may induce seizures between 4-20 Hz.
Turn off light source if possible
Explain fixation
Focusing too long on a task or target
Explain Confusing Ground Lights
mistaking ground lights for stars, causing false sense of orientation. Maintain proper scan.
Explain relative motion
Perceive self in motion due to movement of another object. Maintain scan, be aware of problem.
Explain Altered Plane of Reference
Inaccurate sense of altitude, attitude, or flight path due to very large object (mountain), will maneuver to avoid object though not required. Perform map recon and search for true horizon.
Explain Structural Illusion
Caused by heat, rain, or snow; straight lines appeared curved when viewed through heat isotherms, ice or rain on windshield. Be aware of conditions and problem.
Explain Height/Depth Perception
Loss of depth perception due to insufficient visual cues. Trust instruments and scan horizon.
Explain Crater Illusion
When landing under NVGs with searchlight, shadow may cause illusion of landing surrounded by upslopeing terrain. Use search/landing light appropriately, be aware of problem.
Explain Size-Distance Illusion
False perception of distance from an object of unfamiliar size (smaller or larger runway/trees/buildings/aircraft than used to). Be aware of problem, use experience.
Explain autokinesis
Occurs when few visual cues are available - an object appears to move when fixated on for more than 5-6 seconds. Avoid fixation and maintain proper scan
Explain Reversible Perspective
Silhouette of an object appears same from front or back, unable to tell if object is moving toward or away from viewer. Maintain proper scan, remember 3 Rs (Red on Right is Returning)
