NVG's

Question 1

Night/IMC Descent Over Water

Answer 1

The following SHALL be performed for all night/IMC descents over water at 1,000 feet AGL and below:

Descent:

1. The PAC reports “ON INSTRUMENTS” and states the leaving altitude, intended altitude, and variable RAWS/LAWS index position.
2. The PNAC acknowledges descent commencement, intended altitude, and RAWS/LAWS index position..
3. The aircrewman acknowledges the intended altitude (monitors altitude via the NAV PARAMETERS table or altitude display to the max extent practicable.)

Level-off:

1. As the helicopter nears the intended altitude, the PNAC reports 200 feet and 100 feet prior.
2. When level, the PAC reports “LEVEL” and “ALTITUDE HOLD ENGAGED.”

Question 2

Night/ IMC Descent Over Water Warning and Notes

Answer 2

W-BAR-W

Warning: Failure to follow night/IMC descent procedures over water may lead to a loss of situational awareness and result in water impact.

Note: Prior to commencing night/IMC descent over water, bar alts should be synced

Note: Altitude hold shall be used in level flight at 500 feet AGL and below

Note: RAWS/LAWS tones shall be verbally acknowledged by pilot and copilot

Note: Descents should be commenced and conducted in a wings-level attitude when circumstances allow

Question 3

NVD Nomenclature

Answer 3

AN/AVS-9

Question 4

Alignment order

Answer 4

Vertical, tilt, fore and aft, IPD adjustment

Question 5

NVG FOV reduction

Answer 5

You normally have 180, with NVG’s you have 40 degrees

Question 6

IIMC indications

Answer 6

Increased halo around light sources
Obscuration of moon and stars
Increased graininess or video noise
Loss of ground lights
Reflection of exterior aircraft lights off moisture in the air

Question 7

Gain definition

Answer 7

The amount that the input photons are amplified, which governs the image brightness for low light level inputs.

Question 8

Automatic brightness control (ABC)

Answer 8

A circuit that automatically adjusts MCP voltage to maintain NVG image brightness at a preset output for a wide range of illumination levels by controlling the number of electrons that exit the MCP. The NVG’s gain up or gain down according to the light level. The ABC holds the image brightness constant.

Question 9

Bright Source Protection (BSP)

Answer 9

The BSP circuit limits the number of electrons leaving the photocathode by reducing voltage between the photocathode and the input side of the MCP. Effects are noticed when a bright light source enters FOV and the I2 Tube significantly degains leading to reduced NVG image contrast and detail.

Question 10

Civil twilight, nautical twilight, astronomical twilight

Answer 10

civil: sun is 0-6 degrees below horizon
nautical: sun is 7-12 degrees below horizon
astronomical: sun is 13-18 degrees below horizon

Aircrew should plan for NVG’s to be most effective after nautical twilight (45-60 minutes after sunset, depending on latitude)

Question 11

NVG’s electromagnetic spectrum

Answer 11

They operate in the visible and near IR frequency ranges of the EM spectrum. Energy less than 665nm is rejected by the objective lens (minus blue), and the photocathode converts incoming visible and near IR energy in the .6-.9 micron range into electrons.

Question 12

Objective lens focal range

Answer 12

41 cm to beyond optical infinity (150 ft)

Question 13

What causes scintillation

Answer 13

As light level decreases, NVG’s gain level increases and creates a higher level of electronic noise.

Question 14

LLL definition

Answer 14

.0022 LUX

Question 15

Dark adaptation after removal of NVG’s

Answer 15

It takes 10 minutes to maximize unaided adaptation after removal of NVG’s.

Question 16

Three primary components of the I2 tubes

Answer 16

photocathode, microchannel plate (MCP), and phosphor screen

Question 17

What does the photocathode do?

Answer 17

The photocathode is responsible for converting the incoming visible and near-infrared energy into electrical energy in the form of electrons.

Question 18

What is the MCP and what does it do?

Answer 18

The MCP is a very thin (1 mm) wafer comprised of more than six million tiny glass tubes or channels. The MCP is located between the photocathode and the phosphor screen. The inside passages of the MCP channels are coated with a material that causes secondary electron emissions when a passing electron strikes them.

Question 19

What does the phosphor screen do?

Answer 19

The phosphor screen is comprised of a very thin layer of phosphor deposited on the inside of the rear window of a fiber optic bundle. The basic function of the phosphor screen is to convert the electrons into photons so the user can view the image.