Dancing in the Dark- page 2 | How Things Work | Air & Space Magazine
Pointers and illuminators that project infrared light, invisible to the human eye, enable ground commanders and combat controllers in Iraq and Afghanistan to identify targets and designate them for pilots with NVGs. (USAF/Tech. SGT. Scott Reed)

Dancing in the Dark

Night vision goggles can save a pilot's life or, if he hasn't had adequate training, take it.

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Education is the tool of choice to counter the Superman syndrome, both in the armed forces and at Bell. The company's week-long NVG course, created by Baxter and C. "Mac" McMillian, Bell's chief flight instructor, demonstrates to students in the civilian sector both the advantages and the limitations of NVGs. Pilots can take the $8,500 package, which includes six lectures in the classroom and at least 7.5 hours in the air at night in the school's three NVG-equipped helicopters, before they take jobs with police or emergency medical services (EMS) operations. Baxter briefed me on the schoolwork before we flew, describing classroom modules on everything from cockpit lighting to mission planning.

Information in Bell's course is largely drawn from the harsh lessons that the military, particularly the Army, learned when it first put NVGs into aircraft in the 1970s. "They gave them to us and said, ‘Go fly,' " says Roger Anderson, a former Army helicopter pilot who is now a marketing manager with NVG maker ITT Industries.

While archaic by today's standards, the first aviation goggles, called PVS-5s, were quite advanced compared to the IC-16 infrared night scopes, known as Gen 0 (generation zero) technology, that appeared in the field in the 1950s in order to gain the tactical advantages of being able to see an enemy who couldn't see you. Since that time, night vision systems took two paths: Infrared sensors like the IC-16 evolved into forward-looking infrared (FLIR) systems, which include a bulky sensor pod outside the aircraft and an electronics box and display unit inside, while goggles evolved into image intensifiers. FLIRs, while well suited to view details of a target area from a head-up or panel-mounted display, are not good candidates for piloting, partly because the view doesn't follow the pilot's line of sight.

In Vietnam in the 1960s, ground forces used unwieldy Gen 1 image intensifiers called starlight scopes, in which three image intensifier tubes were stacked end to end, like flashlight batteries. Gen 2 came out in the 1970s with the introduction of the microchannel plate, which eliminated the need to stack multiple intensifiers and paved the way for compact helmet-mounted goggles like the PVS-5.

While the technology had improved, inexperience with human factors issues in night vision systems for aviation proved troublesome and often disastrous. Unlike today's NVGs, the PVS-5 clamped onto the pilot's face like a weighty scuba mask. In order to see the instrument panel, crews had to either focus one side of the goggle outside and the other on the instrument panel, or have one pilot focus outside and one inside.

Dutch Fridd, an EMS pilot and the first civilian appointed as an NVG instructor by the Federal Aviation Administration in 1999, began using the full-face PVS-5 in 1978 in Army helicopters. Fridd says crews went out with no guidance on the use of the goggles and no information about their performance in various weather conditions. Some pilots were refusing to fly and others who tried had trouble controlling their helicopters or became ill from spatial disorientation. "During formation takeoffs, you had people flying backwards, sideways," Fridd says. "Others were hitting wires or trees." During his first 40 or 50 hours of PVS-5 flight time, he "absolutely detested it," he says.

But the pilots felt that they had to make it work: "The only way we'd survive [in hostile airspace] would be down in the trees, and we needed goggles to do that," Fridd says. A major threat for helicopters then, as now, was shoulder-launched missiles. Anderson says the PVS-5, though not designed for aviation, gave the Army a real edge. "It didn't take long for the strategists to figure out that we'd have a huge advantage working at night," he says.

Both Fridd and ITT's Anderson say pilots eventually discovered that cutting away some of the casing below the PVS-5 eyepiece would give them a much more comfortable view both outside and inside the cockpit, a finding that was later built into Gen 3 units, which sit an inch or so away from the eye. Also problematic at the time were instrument panel lights that swamped the NVGs with photons, making it hard to see the outside scene. Pilots dealt with the problem by turning off the instrument lights and illuminating the panel with chemical light sticks—"chemsticks," which emitted light in a narrow part of the spectrum. Today's NVG-compatible aircraft emit light in the blue end of the visible spectrum or have glass filters to cancel out the white lighting of older cockpits.

In 1980, Operation Eagle Claw, the attempt to rescue 53 U.S. hostages in Iran, proved disastrous when an RH-53 helicopter collided with an EC-130 refueling aircraft, killing eight soldiers. The mission had been planned as a night operation, but pilots had received only 15 hours of NVG training, and instrument panels had to be taped over to prevent interference with the PVS-5s. As is often the case, disaster spawned research.

Gen 3 NVGs, which introduced image-enhancing gallium arsenide photocathodes, longer life (10,000 hours, up from 2,000), and other enhancements, came into service in the early 1980s and, when combined with experience gained in training and in designing compatible lighting, proved themselves in night operations in the 1991 and current Iraq conflicts. Almost every U.S. military aircraft is now equipped with compatible lighting, and crews are training to use NVGs for every night flight. Goggles continue to improve, though the technology is still called Gen 3.

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