Are modern night vision goggles still green?

I see, I see what you don't see and that is green

December 2015

Seen through night vision goggles, many things look very different than in daylight. The emergency doctor helicopters of the ÖAMTC are now also ready for primary operations at night.

It is getting dark at the Christophorus Air Rescue Center Wr. Neustadt. 5:20 p.m .: Time for a night flight to the training area on the Hohe Wand. Max Weiermayer unpacks two Night Vision Goggles (NVG), each costing 12,000 euros. "Do not drop and do not hit the lens" - the instructions of the pilot of the intensive care transport helicopter of the Christophorus air ambulance do not tolerate contradiction. Weiermayer mounts one of the 700 gram night vision devices on his helmet and gives one to me. Get in the helicopter, buckle up and off you go. After two minutes, the yellow helicopter takes off into the night sky for a training flight.

Before my eyes the black void turns into a bright green-tinted world. About Wr. Neustadt reflect the illuminated houses and the cars of the Südautobahn. The view of the starry sky is almost dazzling, so bright are the countless flashing points of light. The stars provide good background lighting and account for around 30% of the lighting at night. They emit their light for the most part in the infrared range. Of the around 200 billion stars in our galaxy, the Milky Way, only a maximum of 3,000 are visible to the naked eye from a fixed position on earth, but 8,000 with the NVG.

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Image 1: © Heinz Henninger Image 2: © Heinz Henninger

We let the sea of ​​lights from Wr. Neustadt behind us and approaching the Hohe Wand. The city lights are fading, it's getting darker and darker. Nevertheless, with the night vision device I can discover the secrets of the night like a cat. Many details that are completely in the dark with the naked eye can be seen. However, there is a problem with the assignment. Something is missing. "The third dimension," explains Max. "In addition to the narrow field of view of only 40 degrees (normally 220 degrees), that is the greatest challenge - to fly in a three-dimensional world with a two-dimensional image." The view through the NVG is like the view of the environment through two short pieces of pipe. Everything is clearly visible directly in front of it, but the things on the periphery require a conscious readjustment of the head. "I look through the instruments under the eyepieces."

The landing area for the night flight training on the Hohe Wand is hardly illuminated. I can still see everything through the night vision goggles.

The use of the residual light intensifiers opens up a completely new dimension in night flight.

Max Weiermayer, ÖAMTC pilot

The power line between two houses and the silhouette of an animal with two rapidly moving flashing points - presumably a fleeing deer - are clearly recognizable. But we don't land, we make a 180-degree turn and fly back to Wr. Neustadt. I'm surprised by the heavy air traffic over Vienna and Bratislava. The planes appear like small comets. With the night vision device, the Slovak capital looks very close, as if it weren't 50 km away as the crow flies. Just before landing, I open my glasses. Thanks to sufficient lighting, the landing site can be seen even without a night vision amplifier. I've had enough of seeing green and I'm looking forward to the night. Fortunately, I don't have to see everything.
© Heinz Henninger
Landing approach Air Rescue Center Wr. Neustadt - view with goggles.
© Heinz Henninger
Landing approach Heliport Wr.Neustadt - view without goggles.
© Heinz Henninger

ÖAMTC ready for 24-hour operation

The ÖAMTC helicopters can and may fly at night. This happens very often, especially in winter - you go to the scene of the accident at dusk and back to the base in the dark. All technical requirements are met, all pilots have a night flight authorization. However, there are aviation law and labor law regulations. In aviation law in particular, the pilot flies on visual flight even at night, which means that he needs a free field of vision of around five kilometers. In order for the pilot to land safely at night, there must be an unobstructed, illuminated landing field of around 20 by 20 meters.

The intensive care transport helicopter has been used to fly patient transfer flights from one hospital to another at night for years. Illuminated landing areas known to the pilots are available in the hospitals. Political decisions and financing are still missing for primary operations, i.e. emergency operations directly on site.


1 NVG and autopilot control are standard on the intensive care transport helicopter. © Heinz Henninger

2 Almost all intensive care procedures are in place during the flight
and monitoring equipment available. © Heinz Henninger

3 The pilots know the Vienna Lorenz Böhler Accident Hospital even during the day. © Weiermayer

The ÖAMTC air rescue already uses night vision goggles to increase flight safety in the dark. The devices enable the crew to recognize obstacles such as power lines, masts or wind turbines even in complete darkness. Changes in weather, such as the approaching fog or bad weather fronts, can also be detected and flown around at an early stage.

The use of Night Vision Goggles (NVG) opens up completely new possibilities in air rescue. When serious traffic accidents occur or people become seriously ill, you should be particularly quick - even in the dark. Because in order to ensure optimal patient care, the patient should receive first aid within 60 minutes (the so-called golden hour) and be treated in a suitable clinic.

Using goggles requires intensive training for the entire crew. The pilots first have to get used to the restricted field of vision and two-dimensional vision. This two-dimensional image with the NVG makes it very difficult to estimate height and distance and the crew coordination (pilot and flight rescuer) is trained particularly intensively. Due to the artificial image and the additional weight of the goggles on the helmet, the strain on the human eye is 2.5 times greater than with conventional night flights.

The training at the ÖAMTC air rescue consists of three parts. In the theoretical part, the pilots are taught knowledge, for example, of aviation medicine, flight weather for NVGs, the technical structure of night vision devices and emergency procedures in connection with the new aid. The practical flight training for the night flight with the night vision goggles consists of two parts: In the so-called "Basic Flight Training", the pilots are taught how to use the Night Vision goggles, regardless of mission-specific issues. In the "Advanced Flight Training" that follows, they are prepared for practical application.

We have done our homework and are also ready for 24-hour work if clients want this and the financial framework is in place.

Reinhard Kraxner, ÖAMTC head of air ambulance

Interior lighting also has to be adapted

The night flight with night vision goggles is tied to certain requirements that the ÖAMTC helicopters already meet.

- The helicopters have a specially designed cockpit (NVG compatible) and NVG-friendly exterior lighting. The correspondingly equipped helicopters have individual approvals from the European aviation authority EASA.

- A satellite navigation system with digital map and autopilot control at the ITH are a matter of course.

- For night missions, high-performance night vision goggles according to modern standards are used.

- The machines are currently being converted to a "Moving Maps System". In this way, the helicopters quickly encounter dangerous new obstacles such as material or cable cars.

- The crews are specially trained and usually know the area of ​​operation even in daylight.

© Heinz Henninger
Cockpit suitable for night flight.
© Heinz Henninger
© Heinz Henninger

What does Wikipedia say?

In 1887 Heinrich Hertz discovered the principle of photo emission, which is the basis of residual light amplifier technology. However, because the technology was not yet fully developed, it was not until the Korean War that so-called 1st generation glasses were finally used. These glasses were still called image converters because they converted darkness into a visible image. However, they still had many shortcomings, such as being heavy and unreliable.

The Night Vision Goggles (NVG) have been in production since 1974 and are much lighter and more compact than their predecessors. These glasses were first used extensively in the Falklands War. In the Gulf War, 21% of all night missions were flown with NVG.

© Heinz Henninger