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”
Describe the geometric monocular cues; and are remembered with what acronym?
“LAV”
- Linear perspective (converging lines - railroad tracks)
- Apparent foreshadowing (objects appear elliptical when viewed at distance, and appear normal when approaching)
- Vertical Position (objects at distance appear higher on the horizon)
Describe the retinal image size monocular cues; and are remembered with what acronym?
“KITO”
- Known size (closer objects appear larger)
- Increasing size (object increase in size as they get closer)
- Terrestrial association (objects associated with each other are judged to be at the same distance)
- Overlapping contours (when objects overlap, the hidden object is farther away)
Describe the aerial perspective monocular cues; and are remembered with what acronym?
“FLP”
- Fading color/shades (objects appear farther than actual when viewed through fog/haze, and closer than actual when viewed through clear sky)
- Loss of detail (as objects get farther away, detail is reduced)
- Position of light, shadows (shadows are cast away from a light source)
Describe motion parallax.
“Most important” monocular cue for objects on 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 – rotors interrupting sunlight, strobe lights (especially in clouds); creates flashing effect, generally annoying but may induce seizures between 4-20 Hz. Turn off light source if possible
- Fixation – Task or target; do not focus on an object/task for too long and forget to scan effectively
- False Horizon – Confusing clouds/snowbanks with horizon, causes false sense of orientation
What visual illusions are represented by CRASH?
- Confusing Ground Lights – mistaking ground lights for stars, causing false sense of orientation. Maintain proper scan.
- Relative Motion – Perceive self in motion due to movement of another object. Maintain scan, be aware of problem.
- 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.
- Structural Illusions – 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.
- Height/Depth Perception – Loss of depth perception due to insufficient visual cues. Trust instruments and scan horizon.
What visual illusions are represented by CSAR?
- 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.
- 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.
- 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.
- 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)
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 under high-light conditions to reduce image brightness, so that night vision is not affected
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 under high light conditions (tracers, explosions) to prevent 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
