[Seahawk]

Another cross post: (You do anyone can do this, right, J?)

Originally Posted by Indescikov

There is no peripheral vision with standard aviation goggles. The field view is limited to about 90 degrees, I believe less. Why the need to be constantly rotating ones head to expand your enterpretation of what is around you. In addition, AGC (automatic gain control) will lower the amplification / intensity of the screens to brightest light in the field of view perhaps reducing lower lit detail to be undetectable.
In a NVIS cockpit, you look at the flight instruments unaided with your normal vision (by looking under the goggle tubes). NVG's are like a camera, adjusted to a single focal length (usually infinity) for viewing at a distance. You can not view close in objects without refocusing, thus why you view the flight deck instrumentation unaided.
Additionally because the screens on the NVGs are so bright while you looking into them, you have NO night vision until your pupils redialate. Very difficult to switch back and forth between aid vs. unaided. The flight deck instruments are set brighter then they would be for normal night flight.
A NVIS cockpit must be certified for NVIS flight but having compatiable lighting for NVGs. Aviation NVGs have specific wavelenghts that NOT amplified for this very reason, to avoid interferencd from the cockpit.
Really bright lights can completely bloom the entire FOV to unusability. Something as simple as a vehicle setting next to the touchdown point on a runway/LZ with its brake lights illuminated. Many PAPIs/VASI /visual glide path indicators are still incandescent bulbs, absolutely blocking ones view beyond that source. Some LED light sources can be an entirely different problem, virtually invisible to NVG amplication (blue led taxi way edge markings). Initially when LEDs came into use for obstacle/tower identification, they were incredibly bright to unaided vision but almost undetectable to NVGs. I have noticed that has changed.
Point is there are many pros and cons to NVIS flight. Requires training to enterpret how the goggles are depicting the view. Requires more recurrent training/ currency beyond any other flight currency requirement (6 approaches/6 months for IFR), with NVIS flight its is TWO calendar months to carry pax. The FARs were changed several years ago to reflect the constant currency requirements versus proficiency. Too many EMT helicopters were utilizing NVG with hazardous results. Obviously this has drastically improved but still very hazardous in a uncontrolled environment.

Originally Posted by Seahawk

Excellent post. I will add that I flew ANVIS 6 with an ELBIT HUD displayed on the NVG tube...airspeed, altitude and some attitude information.