Story ID: 013
Learning To Fly with Night-vision Goggles
By: Matt Thurber
Caption: Training is essential when learning to fly with NVG at night
Word Count: 1657
A variety of companies offer pilots training to fly with night-vision goggles (NVG), but one is also the pioneer of developing NVG for the civil aviation market and manufactures and maintains these precision optical-electronic devices: Aviation Specialties Unlimited (ASU). AIN visited ASU recently at its Boise, Idaho headquarters to learn more about NVG, including participating in a training class and flying ASU’s Bell 505 at night while wearing NVG. NVG have seen dramatic improvements since military helicopter pilots first began flying with them in the 1960s. Now most medevac operations use NVG during night operations, and they are penetrating the fixed-wing market. ASU offers training in its Bell 505 and a Cessna 206 equipped for NVG operations and says it is the only company offering fixed-wing NVG training. NVG amplify existing light by 6,000 to 10,000 times, a great aid for pilots flying in areas with little natural or artificial lighting. The technology involved has improved greatly, and ASU is now employing the latest version of the image intensifier “tube,” the component that amplifies the light, in its lightest and most compact set of NVG, the E3.  A simple description of a set of NVG would describe it as two lenses surrounding an image intensifier, and there are two of these components, one for each eye. Just because they are binocular, however, doesn’t mean that NVG provide a binocular view, like wearing glasses, for example. The view is monocular, which does affect depth perception, but there are techniques to overcome this, and I didn’t find it difficult. The sight picture through each goggle is limited to a 40-degree field of view, which means the pilot must look around to get a complete view of the outside world. The image intensifier tube, which is only about half an inch long, is where the magnification happens. As light enters the tube, a photocathode converts light energy (photons) into electrical energy (electrons), as ASU describes the process. All of this requires energy, and surprisingly just 3 volts from two AA batteries are sufficient for up to around 50 hours of operation. ASU's NVG training includes a full day of ground school followed by three nights of flight training, either in the Bell 505 or Cessna 206. Our class included me plus two fixed-wing pilots whose company planned to expand its capabilities with NVG, and they would be flying in the 206. ASU chief flight instructor Bradley Brummett led the ground school and also teaches fixed-wing flying. Because it was early summer in Idaho, our night flying would have to wait until official darkness after 10 p.m. During the ground school, we learned some NVG history; the technology of the tube; ASU’s founding in 1995 by Mike Atwood and its growth as a developer of NVG, repair station, engineering center for NVG supplemental type certificates, and training provider; the regulatory framework surrounding NVG use; and instructions on how to mount NVG on a helmet and adjust the lenses. Brummett also delved into eye anatomy, day and night vision and constraints, how NVG can effectively make up for night-vision drawbacks, and NVG myths. One myth, he pointed out, is that visual acuity, the ability to recognize details, is poor with NVG. In fact, while visual acuity at night drops to 20/200 “unaided”—that is, without NVG—most acuity is restored with NVG, bringing it back to 20/25. Another myth says that there is no peripheral vision with NVG, which is true if the user is looking only through the goggles. But new NVG users soon learn that it’s easy to turn the head to look elsewhere and that looking under or beside the goggles with unaided vision is not only possible but necessary for viewing instruments and avionics or looking outside through a helicopter’s chin bubbles. Brummett explained the regulations that cover NVG-compatible installations and operations. Basically, for an aircraft to be NVG-compatible, its internal and external lighting must “not adversely affect the operation of the NVG during any phase of the NVIS [night vision imaging system] operation.” The standard set of NVG since 1998 has been the ANVIS-9 system, which originally had green phosphor imagery. Recent ANVIS-9 and the E3 NVG are equipped with white phosphor tubes, and this has proven to work better because the eyes use day or bright light photoptic vision when viewing imagery in the NVG. A major advantage of the E3 goggles is that they weigh much less than ANVIS-9 and don’t require the addition of balance weights below the battery pack to even out the load on the helmet. This is a huge benefit for pilots who fly with NVG-equipped helmets for hours at a time. We practiced mounting, flip-up, and flip-down procedures using the lock release with the NVG on our helmets and how to switch between the primary and backup AA batteries. Adjustments included eye span so each monocular is properly aligned with each eye, fore-aft, and tilt. These helped ensure each monocular was providing the full 40-degree field of view, which should look like a complete circle with a crisp, distinct edge. I showed up for the Bell 505 flight at 9 p.m., and it was still light out. Once it was darker, Bell 505 instructor and ASU director of operations Tony Tsantles showed me how to adjust each monocular’s lenses for optimal viewing. While the E3 uses the same tube as the ANVIS-9, a big difference, other than the lighter weight, is that the E3 NVG doesn’t have a metal ring around the eyepiece lens. This results in a better view through the lenses but also a cleaner unaided view because it opens up some space around the eyepiece and makes it easier to look around, not through, the lens. After official night, which is an hour after sunset, I climbed into the right seat of the 505 with Tsantles flying left seat. We flipped our goggles into position and started the engine, and then he did the liftoff from the ASU ramp at Boise Air Terminal. Once airborne, Tsantles handed over control, and I flew the 505 over to the assault strip, an unlit runway used for military training for the Idaho Air National Guard wing. I flew a normal approach then landed on the strip, and even with the goggles on, I didn’t feel like depth perception was compromised. There was plenty of ambient light, but I looked through the goggles almost exclusively and felt like I could easily judge the helicopter’s height near the ground. We did use the 505’s searchlight and landing light to illuminate the ground, and this proved helpful, especially when peeking under the goggles to look through the chin bubbles. After taking off from the assault strip, Tsantles had me fly south to a low set of hills. Here he asked me to land in a small area at the top of one of the hills next to some old railroad tracks. I was able to touch down fairly precisely, not too bad given that I didn’t have much time in 505s before this, and had never flown one at night. After landing, he asked me to flip my goggles up, and it was almost completely pitch black, with one dim light visible on a hill in the distance. With the goggles on, I could see every divot in the dirt and each blade of grass dancing in the wind from the rotors. {{NOTE TO MARTHA: USE PICTURE 1 AND 2 SIDE BY SIDE HERE}} After taking off, I followed a draw to the north and over Lucky Peak Reservoir to a Forest Service helipad, where again I landed in what was pitch-black conditions without the goggles. There was no moonlight that night.  After taking off from the pad, Tsantles took the controls briefly so I could see what a dying campfire looked like with goggles on and off. Without the goggles, I couldn’t see anything but with the goggles on, the small fire bloomed into view, only blocked when some trees obscured it as we flew circles over the spot. The amount of light amplification with the goggles is stunning. We swapped our goggles so I could feel the lighter-weight E3 setup, and it does indeed add less pressure on the neck. I was fairly comfortable with the view through the ANVIS-9 goggles by then, but the E3 monoculars are easier to look around for unaided views. Tsantles did the next landing near Little Grouse Creek, where we were surrounded by high terrain with no apparent ambient light but plenty of illumination in the NVG. I then flew us over the hills and downtown Boise and the capitol and back to the airport for a landing on the ASU ramp. The plan wasn’t for me to go through the full flight training portion of the ASU program, but flying the 505 with NVG gave me an excellent feel for what it’s like. I did return the following night to sit in the back seat of the 206 while one of my ground school classmates flew his second lesson. For this operation, I chose not to wear a helmet but just held the monoculars to my eyes when I wanted to get a view through the NVG so I could more easily compare the NVG versus non-NVG views and take photos and videos through the goggles. Flying with NVG was an amazing experience; so little ambient light was needed to provide a clear view through the goggles. Looking up into the night sky with the goggles reminded me of visiting a planetarium as a school kid; every scrap of the sky was filled with bright stars. However, the main takeaway from this experience is that night operations of any kind can be flown much more safely with NVG. I can’t imagine flying medevac missions to unlit areas without goggles, and the high takeup rate of aeromedical operators using NVG underscores that sentiment. 
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