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Acronyms
Sorry about the jargon. I sometimes forget how little breadth is required to earn a day VFR ticket (and I think that is a good thing). As mentors, CFI's, etc it is surely in our best interest to share this with as many people as we can.
NVG's = Night Vision Goggles (sometimes referred to as Night Vision Devices). Contrary to popular Hollywood lore, they DO not turn night into day and they do not bathe your entire face in enough green light to make sure the audience can recognize your face. They make a small amount of received light turn into a bunch of electrons, which then hit a plate that throws off photons of the greenish frequency. This large increase in electrons is how they amplify light. Also, if you were 20/20 BEFORE you put them on, you will probably be no better than 20/40 after you put them on...but fear not, if you fly at night WITHOUT them, you are seeing 20/200! LEDs and MTRs have been explained (I usually do not because I find people often learn more by looking it up and will probably spend extra time reading the respective publication if forced to search for it). Even if you do not have an active/reserve/guard base near you, and there are no outlying fields, and you have never seen any military aircraft, they MIGHT still be around. If you are in Jacksonville, get a hold of me, maybe I can set up a demo of the NVGs for a group of people. |
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How does adding an IR LED help, as IR is closer to Red on the spectrum than Blue...? |
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They have just finished a new, and very short, runway at the East end of the complex for tactical practice. This has become the main training facility for this on the West Coast and soon large aircraft from all the other bases will be flying in here at night to practice NVG landing in total blackout conditions. Point being they asked that we pass around the word that, even though they can see your transponder and the area above 2600' is only an alert area, it would be beneficial to all if the airspace was avoided at night. |
Red LEDs visibility will vary depending on the type of NVG goggles you are using.
NVIS-A goggles will pick up the red LEDs quite well because they have a fairly high sensitivity in the 600-660nm range. NVIS-B goggles will be less sensitive to red LEDs due to a lower sensitivity in the red spectrum area. NVIS-C goggles are the least sensitive to red LEDs. ![]() So the best type of goggle to use in civilian airspace is the NVIS-A if you want to be able to see LEDs. |
To build on Dean's comments as well as addressing previous comments about acronyms, the various versions of NVIS specify performance parameters for the several currently-available versions of Night Vision Instrument Systems equipment. Each generation, A through C, produces a different light amplification device with different performance characteristics.
As Dean has pointed out, some NVIS devices (which include NVG night vision goggles, night vision rifle scopes, etc) amplify different light frequencies. The different versions also vary in other attributes such as the effective viewing angle of the device. The original NVIS-A devices often featured a very narrow field of view which, in aviation applications, easily led to spatial disorientation. Many years ago I flew in a Blackhawk with NVIS-A goggles and felt at least somewhat disoriented all the time and near tossing my cookies frequently. Since then the newer design specs have opened up the viewing angle, making them much easier to use in flight. I have the utmost respect for aircrews flying under goggles - it ain't anything like an easy task, despite what Hollywood might portray. |
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On the original purpose of the post, I was not aware that LED position lights had such a different visibility to the eye vs to goggles. It would seem the industry in general has the same level of understanding as me. When I google "aircraft position lights with IR" the results are not good. It takes quite a bit of digging. Further, it is not well advertised or documented. The question then is if this is a significant general issue or one with specific implications. As a point of reference I did find a product that was LED position lights with "visible" and "IR" but that the IR capability was not TSO'd. This suggests the problem is still not general enough for safety products to be focused on it across the board. All in all, an interesting topic. |
Not always
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Now I fly EMS helicopters. One of the medical staff has goggles on, but when a patient is on board they are both busy inside of the aircraft. That leaves me to see and avoid, under goggles. Once at altitude I can, and sometimes do, flip the goggles up. That depends on weather, terrain and ambient light. Normally I can see your lights from many, many miles away. I know IR glows white "hot" in the dark, but I can not say how the IR LEDs will show up. Many emergency vehicles are switching to LEDs for the flashing lights. I have not had any problem seeing those lights with NVGs. |
look out window with bare eyeballs
Don't military helicopters have more than one crew member?
I think it would be more logical for the military to spec a goggle system to detect LEDs than for every tower to install ir LEDs. I'm assuming the tower lights meet FAA specs otherwise they wouldn't even be installed. And please, stop with the acronyms. It's bad enough without tossing in military ones. |
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In the Army, ALL crewmembers wear night vision goggles or NO ONE has goggles on. That was the Army's rule, it had to do with crew coordination, crew resource management and safety. Up until recent years, say more than 10 years or so ago, the training was done at military reservations. That is no longer the case. If you look at the printed notams you can see areas where the military trains on a regular basis. Look in section 2 Special Military Operations. Those are not the only areas, others may/will pop up as usual notams. Emergency Management Services (EMS) helicopters, civilian medivac if you prefer, are civilian operators flown single pilot with a medical crew in back. Those single pilot aircraft may have a crew member in back wearing NVGs, but as I wrote earlier, a critical patient is taking priority. It is up to the pilot to see and avoid. Many pilots I know "flip the goggles up" or get them out of the way when they have climbed to altitude. But that is not a rule and it depends on a lot of different factors. For example, some folks do not fly night VFR in their airplane due to limited ability to see potential emergency landing sites. I do not have the option. We are flying over rugged terrain, with limited ground lights in a single engine helicopter. If the engine quits, or have some other emergency, I want to see where I am going to land so my goggles stay down until I get to a more urban area. Hope that helps folks understand the NVG world a little. I will say I have had alot more close calls at non-towered airports in day VFR than at night wearing NVGs. |
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