NVG Flashcards
Size constancy illusion
Depending on your relative location and the size of the runway, a narrower runway can make you seem higher, and a wider runway can make you feel lower.
NVG operational considerations
CALMWWADSOS
Color- black and white with minus blue filter
Airspeed/groundspeed limitations- dont outfly what you can see
Lights- Halos, you need illum to see
Magnification- 0X
Weather- can see through some weather
Weapons- activates ABC/
Aircraft lighting- (tend to drift towards red light, blue/green in cockpit)
Depth perception and distance estimation
Scanning techniques
Obstruction detection
Spatial Disorientation
ANVIS limitations
Requires ambient light (Illum)
Visual acuity is reduced (20/25-20/75)
Smoke,dust, haze reduces acuity
Low contrast environments degrades acuity
Loss of performance in temps >100degF
40 deg FOV
LED lights are difficult to see
Spatial disorientation can be induced/aggravated under NVG’s by
Bank angles >30deg
Significant/abrupt manuevers
Three axis head movements
Lack of NVG experience
Degraded visual acuity
Fatigue
High task loads
Day blind spot
5.5 deg - 7.5deg
15deg from the fovea
Where the optic nerve attaches to the retina
No cones or rods
Compensated for by having binocular vision
Monocular cues
GRAM
Geometric Perspective
Retinal Image Size
Aerial Perspective
Motion Parallax
Geometric Perspective
An object appears to have a different shape based on the distance and angle it is viewed
Linear perspective- Parallel lines tend to converge at distance(railroad tracks)
Apparent foreshortening- Circles appears elliptical at a distance
Vertical position in field- objects at further distances appear higher above the horizon
Retinal Image size
How the eye/brain perceives the image
Known size of objects
Increasing/decreasing size
Terrain association
Oerlapping contours/interposition of objects
Aerial perspective
Based on clarity and shadows
Fading colors/shades
Loss of detail/texture
Position of light source
What are the visual illusions you might ecperience flying with and without NVG’s?
ICCHAAFFSS
Induced motion (vection)
Crater Illusion]
Confusion with ground lights
Height/depth perception
Aerial perspective
Autokenesis
False Horizon
Fascination/fixation
Size Distance
Structural
What is the crater illusion?
When flying under night vision it gives you the sensation that you are landing in a crater because of the position of the IR searchlight, causing you to contact the ground earlier than expected.
What are the scanning techinques when flying under NVG’s?
Off-center viewing
Shapes/Sillouhettes
Stop-turn-stop-turn
How long does it take for your eyes to dark adapt?
30-45 mins
What are the types of vision?
Photopic- daylight/artificial illum- primarily uses cones
Mesopic- dawn/dusk/artificial illum- uses rods and cones, most dangerous
Scotopic- low light levels- primarily uses rods
Parts of the ANVIS
OPMPFE
Objective lense
Photocathode
Microchannel plate
Phosphor screen
Fiber optic inverter
Eye piece lense
ABC- protects the user
BSP- protects the goggles
What are the cosmetic blemishes?
Image disparity
Fixed pattern noise
Image distortion
Chicken wire
Bright spots
Black spots
Output brightness variation
What is the night blind spot?
It is when the fovea because inactive because of the lack of rods
5-10 deg wide
Corrected with scanning techniques and off-center vision
What are the ANVIS operational defects?
SEEF
Shading
Edge glow
Emission points
Flashing, flickering, intermittent operation
What are the ANVIS characteristics?
Definition
Acuity- 20/25 best 20/75 worst
Limited FOV- 40deg
Low battery- 30 mins
Breakaway- 10-15 g’s
Counterweight- 0-22oz
What is height-depth perception illusion?
When a pilot has absent or insufficient visual cues causing you to misjudge altititude. (desert, snow, water)
What is the shape constancy illusion?
Illusions that have to do with a runway or landing surface being sloped. If it is up-sloped you will feel as if you are too high, and if it is down-sloped you will feel too low.
What helps with distance estimation and depth perception?
Binocular cues
Monocular cues
GRAM
What is the aerial perspective illusion?
When something is a different size than expected, a pilot can mistake small items for a large one like trees, misjudging altitude.
