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Pilots first experimented with NVIS by wearing Gen 2 AN/PVS-5 goggles in helicopters. Intended for low-speed ground applications, the sensitivity and resolution of those goggles proved inadequate for the high speed of aircraft, which leaves no room for hesitation or error, especially at low altitude. Another disadvantage was the AN/PVS-5’s face mask, which restricts peripheral vision. Interference from crewstation lighting also hampered visibility, and pilots at first turned off or taped over any non-essential displays. The problems of Gen 2 NVIS were resolved in three ways:
- Switching to Gen 3 NVIS for sharper, more detailed imaging.
- Adding minus-blue filters to reduce NVIS response to visible light from crewstation displays.
- Redesigning crewstation lighting to make it compatible with the response of the filtered Gen 3 NVIS.
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