NVGs Operations and limitations

Question 1

NVGs Defined

Answer 1

ANVIS is a passive, binocular, helmet-mounted, light intensification device that allows aircrews to conduct operations at terrain flight altitudes during low ambient light levels to include overcast conditions.

Question 2

NVGs Characteristics:

Answer 2

● 40-degree FOV
● Enhanced visual acuity from 20/200 (normal unaided acuity) to 20/25 under optimal conditions
● Amplifies light 2,000-3,000 times (depending on illumination)
● Powered by dual battery pack (flashes at 2.4 V or less, 30 min remaining)
● 10-15 G Breakaway feature
● Counterweight: Recommended 12 oz. (22 ox. max)

Question 3

How it works:

Answer 3

Question 4

Operational Considerations: CALMWWADSOS

Answer 4

● Color Discrimination: picture viewed is monochromatic (green hue)
● Aircraft Lighting: NVG designed to be operated with blue-green cockpit (sources of lighting not compatible with NVG, like red, may degrade the ability to see)
● Lights and Lighting: Performance of NVG directly related to ambient light (lights too bright can adversely affect NVG)
● Magnification vs. Enhancement: NVG systems do not magnify an image, just enhance illumination of an object
● Weapons: Bright flash of weapons may cause temporary inoperability of NVG (recovery more rapid than being unaided)
● Weather: When using NVG, aviators may fail to detect entry into or presence of IMC
(can see through obscurations such as fog, rain, haze)
● Airspeed and Ground Speed Limitations: Don’t overfly capability to see
● Depth Perception and Distance Estimation: NVG distort depth perception and distance estimation (see below)
● Scanning Techniques: Crew members must use a continual scanning pattern to compensate for loss of FOV
● Obstruction Detection: Obstructions having poor reflective surfaces, such as wires and small tree limbs, are difficult to detect (look for support structures)
● Spatial Disorientation: Maneuvers requiring large bank angles or rapid attitude changes
tend to induce spatial disorientation

Question 5

Reference:

Answer 5

Reference: TC 3-04.4 Ch. 4

Question 6

Automatic Brightness Control (ABC):

Answer 6

Automatic Brightness Control (ABC): Automatically adjusts MCP voltage to maintain NVG image
brightness within set limits

Question 7

Bright Source Protection (BSP):

Answer 7

Bright Source Protection (BSP): When exposed to bright light sources, BSP limits electrons leaving the photocathode by limiting the voltage from photocathode to MCP to protect against damage to the photocathode, MCP, or eye

Question 8

Controls

Answer 8

Question 9

Optimal Sight Adjustment Point (OSAP) Procedure:

Answer 9

Optimal Sight Adjustment Point (OSAP) Procedure: Occurs when the optical axes of the ANVIS is aligned with your visual line-of-gith and eyepieces are at a maximum distance from your eyes that still allow the full FOV

Question 10

Operational Defects:

Answer 10

● Shading
● Edge Glow
● Emission Points
● Flashing, Flickering, Intermittent Operation

Question 11

Cosmetic Blemishes:

Answer 11

● Image Distortion
● Fixed Pattern Noise
● Image Disparity
● Chicken Wire (dark thin lines)
● Bright Spots (if it goes away with lens covered)
● Output Brightness Variation
● Black Spots

Question 12

Limitations:

Answer 12

● Requires some ambient light to operate
● Visual acuity is reduced using ANVIS (20/25 at best and 20/70 at worst, scintillation present at low ambient light levels ~30% illumination and below)
● Air clarity has an impact on acuity
● Low contrast environments negatively affect visibility
● May experience a measurable loss of performance at temperatures above 100 deg F
● 40 deg FOV
● Important for crewmembers to periodically look under goggles to ensure they don’t miss LED lit towers, etc. (Goggles see in the visible spectrum and near-IR range, and incandescent lights release much more heat)

Question 13

Reference:

Answer 13

Reference: TM 11-5855-313-10 Operator’s Manual for Aviator’s Night Vision Imaging System
ANVIS Ch. 1-2