HAI Convention News

Operators are seeing the benefits of night vision

 - February 25, 2008, 8:42 AM

Growing interest from helicopter operators wanting to use night-vision goggles (NVGs) is spurring demand for better training as well. Feedback from long-time NVG users demonstrated that they improve safety, but lessons from the field also highlight the need to use the technology with caution.

Aviation Specialties Unlimited (ASU) of Boise, Idaho, was the first company to train civil EMS pilots in the U.S. to use NVGs, training 830 pilots and 2,200 medical crewmembers in the last three years. ASU president Mike Atwood said he expects an increasing number of EMS operators to adopt NVG technology. He also believes that the market is growing at a healthy annual rate of 15 percent per year. “More and more of those operators are going to night-vision goggles,” he said, estimating that operators of 800 EMS helicopters in domestic service could benefit from their use.

American Eurocopter offers a five-day initial training course on NVG operations that attracted 40 pilots in 2006, but enrollment could increase dramatically if Eurocopter assumes NVG training for U.S. Army National Guard pilots flying UH-72A Lakotas, the military variant of the EC 145.

“Initial, recurrent and standardized training is critical,” Atwood noted. “Just because people flew [with NVGs] in the military doesn’t qualify them for civil operations. The operational profile is totally different. In the military you are trained to fly no-light, nap-of-the-earth missions. On the civil side you often fly in high-traffic environments and you need to be able to use lighting systems to properly operate everything within the aircraft.”

In Europe, two major rescue operators–Sécurité Civile and Rega–have built significant NVG operational experience over the years.

Guy Roger, an EC 145 pilot for France’s Sécurité Civile, the nation’s rescue arm, described the positive experiences his agency has had with NVGs, but he also discussed some disadvantages to them, pointing out that training is key.

NVGs enable operators to complete more missions, regardless of the preciseness of the weather forecast (which can be vague), Roger said. They are reliable, require a minimum of maintenance and are cost effective and ergonomic, he added. They offer a huge advantage over a head-up display because they move along with the pilot’s head, whereas HUDs can be used only in the forward field of vision. Finally, in addition to being easy to use, they provide an excellent “perception of weather conditions,” Roger said.

Sécurité Civile helicopters are crewed with a pilot and a flight engineer. The latter handles navigation and hoist operations. For the most part, both crewmembers wear NVGs simultaneously. However, when the second crewmember operates the hoist with a conventional searchlight, only the pilot wears them.

During training, crews need to be warned about some unexpected potential pitfalls of NVG use. For example, “The way trees appear is not exactly intuitive. Some are white and some are black,” Roger explained. In addition, “You do not see green and blue colors very well through NVGs, whereas infrared, which you would not normally see, appears clearly,” he added.

The way this device modifies sight has to be taught carefully, experts say. First, the field of vision is restricted to 40 degrees. According to Roger, 120 degrees is usually recommended for flying purposes. In addition, the pilot has to direct his attention under the goggles to see the instrument panel.

Another major drawback is poor separation performance. “You cannot see a power line until it is as close as 650 feet,” Roger said. If a bright light illuminates in the NVG field of view, the system protects itself. The pilot cannot see anything as long as the light overwhelms the system’s ability to see.

Another consideration for pilots is that NVGs affect the mental process. “There is a lot of brain activity to estimate distances,” Roger said. In fact, the absence of 3-D references (NVGs provide 2-D vision) means the brain has to work hard to make estimates based on the data that’s available. As a result, it is impossible for NVG users to sleep immediately after an NVG mission, and this quirk of NVG use has to be taken into account when operators design a roster with duty and rest periods.

Not all operators adopt the same philosophies about NVG use. In Switzerland, the Rega air rescue organization uses NVGs to enhance safety during operations that would otherwise be conducted with the naked eye. Rega pilots do not fly with NVGs if conditions prevent a VFR mission, and weather minimums remain unchanged.

“We do not do anything more, but we do it more safely,” pilot and instructor Walter Schneibel, who is also responsible for night flights and NVG operations, told HAI Convention News. All 43 Rega pilots are trained to use the devices. Schneibel deemed their use extremely cost effective even given the price of training because one pair of NVGs costs “three times less than a big searchlight.”

Under Rega’s principles, only one crewmember wears NVGs. This way, at least one of them has a full field of vision. For example, during a final approach, the second crewmember looks for visual cues without the aid of NVGs. He communicates with the pilot as soon as he sees something. The pilot then flips up his goggles. Rega pilots do not use NVGs when the helicopter is near the ground.

In addition, always having one pair of unaided eyes in the cockpit eliminates the risk of developing a false sense of security, Schneibel said. “One can tell the other visibility is too bad, we must fly back home,” he said.