NVG MET

Question 1

Which astronomical factors have an effect on the night illumination?

Answer 1

• Sun elevation
• Moon elevation, moon phase
• Other sources of natural light

Question 2

Which meteorological factors have an effect on the night illumination?

Answer 2

• Clouds
• Precipitation
• Ground conditions

Question 3

Define the term “civil twilight”

Answer 3

Time after SS and before SR when the sun is up to 6 degrees below the horizon

Question 4

Define the term “nautical twilight”

Answer 4

Time after SS and before SR when the sun is > 6 up to 12 degrees below the horizon

Question 5

When do you expect “dark night” conditions after sunset?

Answer 5

Time after SS and before SR when the sun is more than 16 degrees below the horizon

Question 6

Explain the term “moon brightness”

Answer 6

Brightness of the horizontal ground caused by the moonlight, not the brightness of the moon itself!

Question 7

Define the term “meteorological optical range”

Answer 7

The MOR is defined as the horizontal distance, on which an attenuation of white light by 95% takes place

Question 8

Write down the limiting value for the NVG range for flights with night vision goggles

Answer 8

1,5 km NVG-Range and
0,5 mlx Illumination
(4600 m)

Question 9

The forecast for the NVG-Range for a planned night flight with NVG is:
P: ≥ 1,8 km, LOC M: < 1,5km
According to valid regulations, is it allowed to perform this mission?

Answer 9

Yes, but the person assigning the flight missions will descide

Question 10

Explain the “Chlorophyll - effect”

Answer 10

Chlorophyll in leaves creates a higher degree of reflectivity in near-IR-wavelenghts, which is the range of the NVG.
Be aware of the differance between leaves on the tree and leaves on the ground.

Question 11

The weather forecaster expects upcoming snowfall during the planned night flight period. Astronomical illumination values will not change significantly. What is the effect for flying with NVG?

Answer 11

NVG image deteriorates strongly

Question 12

The weather forecaster expects dense mist forming during the planned night flight period. Astronomical illumination values will not change significantly. What is the effect for flying with NVG?

Answer 12

NVG image deteriorates strongly

Question 13

Determine the night illumination by means of the attached diagram at
- 1900
- 2100
- 2300

Answer 13

19 mlx
70 mlx
200 mlx