Text: Serge Van Heertum - Pictures: Serge Van Heertum & Marc Arys - Translation: Marc Arys
İ sbap 2019

We finished the 2018 season with the Belgian Air Force and finally, we are launching the 2019 season from Beauvechain airbase and especially with the 17th and 18th squadron.
January was certainly a cold and rainy month, with some winter tendencies. But even with possible bad weather, crews continue their dayly and nightly trainings.
Our first report of the season is devoted to night flight training and the use of NVG (Night Vision Goggles) equipment.
Two rotations were planned on the evening of January 28th, but the very wet weather, the low and well charged clouds decided otherwise. It was, however, an opportunity to appreciate the crew's know-how in these real conditions, without staging and adding of external lighting. During the action, lighting, car headlights and flashes were banned as not to dazzle the crews in their cockpit.
The training of the crews is essential, whether it be fighters or transports, the qualification for night flying remains paramount, which allows us to say that our Air Force is always present for the preservation of peace, be it day or night.

NVG helmet mounting
(Serge Van Heertumİ)
NVG effect in the cockpit
(DR via web)

How do night vision goggles work?

There are two type of "night vision" that are commonly used: passive and active.

Passive (often called "starlight vision") night vision equipment simply amplifies the available light and will not work in absolute darkness. It is similar in principle to adjusting the contrast (difference between light and dark) of a picture.

Active night vision, like the type found on many new camcorders, actually projects a near-infrared light source out. The optics in the camera are sensitive to this spectrum, but it is just out of the visual range so we can't see it.
Some military equipment uses ultraviolet radiation instead of near-infrared because of the potential interference with common devices like remote controls and ease of detection.
Night vision goggles depend on the photo electric effect. This effect was first discovered experimentally by Heinrich Hertz in 1887 and explained by Albert Einstein in 1905 using quantum theory.
Basically when a polished plate is exposed to electromagnetic radiation, it may emit electrons. These electrons are referred to as photoelectrons. These electrons are only emitted if the frequency of the incident light exceeds a threshold value f>f0. The threshold value f0, depends on the particular metal. The magnitude of the emitted current of electrons depends on the intensity of the light source and the kinetic energy on the frequency of the light source.
In the night vision goggles, the photoelectric effect is used to amplify the presence of individual photons. A lens system sends any collected light to a glass plate coated with a photoelectric material on the back side. The photoelectrons are accelerated through a potential difference of several hundred volts to a "channel plate" containing many fine holes about 10 microns in diameter. These holes have a conducting surface and an additional potential difference from one side of the plate to another. When a photoelectron strikes a hole, it ionizes the atoms at the point of impact. This in turn releases several electrons, which are accelerated further down the hole to produce even more electrons. This part of the device is called a photomultiplier. The result of this device is that tens of thousands of electrons leave the hole. These electrons are further accelerated to strike a fluorescent screen, where the effects can easily be seen by the eyes. 'Noise' keeps this device from being infinitely sensitive. Photons arriving on the photoelectric surface are discreet and hence the numbers fluctuate with time. The smaller the rate of arrival the larger, the fluctuation of any given pixel. This manifests itself as a fluctuating brightness called "photon noise".

Night Flight
H-46 ready for the night flight session (Marc Arysİ)
Waiting to turn off the light
(Serge Van Heertumİ)
H-24 (Demo helicopter) as reserve
(Serge Van Heertumİ)
End of the day, the other machines return to the nest
(Serge Van Heertumİ)
Mirror, mirror, tell me who is the most handsome
(Serge Van Heertumİ)
Start of the preflight turn around
(Serge Van Heertumİ)
Agusta in his coat of light
(Serge Van Heertumİ)
Start up...  (Serge Van Heertumİ)
Ready for taxi
(Serge Van Heertumİ)
Ghost Agusta
(Marc Arysİ)
It's raining man
(Serge Van Heertumİ)
Slow taxi
(Marc Arysİ)
(Serge Van Heertumİ)
NH-90 TTH ready for night mission
(Marc Arysİ)
(Serge Van Heertumİ)
Magic LED effects  (Serge Van Heertumİ)
Take off
(Serge Van Heertumİ)
End of mission for the A109
(Serge Van Heertumİ)

SBAP would like to warmly thank the entire ComOpsAir IPR team for the kind invitation, the perfect organization and the warm welcome (especially at the squadron bar with a hot coffee). Thank you also to the authorities of Beauvechain airbase for making this report possible.


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