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  #11  
Old 04-08-2014, 03:46 AM
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LAMPSguy LAMPSguy is offline
 
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Default 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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  #12  
Old 04-08-2014, 07:31 AM
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Quote:
Originally Posted by Canadian_JOY View Post
Having worked for a while making NVG-compatible cockpit displays, it might help if folks understood that NVG's work by amplifying a very narrow spectrum of light in the blue-green wavelengths.
Forgive a question that is based firmly in a lack of understanding of how NVGs work...

How does adding an IR LED help, as IR is closer to Red on the spectrum than Blue...?
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  #13  
Old 04-08-2014, 07:56 AM
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Quote:
Originally Posted by sahrens View Post
Most EMS helicopter operations use NVGs. There are more folks out there wearing googles than you think.
Speaking of NVG use near Petaluma, went on a tour of Travis a couple months ago. Something they will hopefully do a couple times a year where they gave us the full tour of facilities, TRACON and a C-5 and C-17.

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.

Last edited by flyingriki : 04-08-2014 at 07:58 AM.
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  #14  
Old 04-08-2014, 08:04 AM
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Dean_aeroleds Dean_aeroleds is offline
 
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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.
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  #15  
Old 04-08-2014, 09:49 AM
Canadian_JOY Canadian_JOY is offline
 
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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.

Last edited by Canadian_JOY : 04-08-2014 at 09:51 AM. Reason: fixed grammar
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  #16  
Old 04-08-2014, 09:52 AM
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Dean_aeroleds Dean_aeroleds is offline
 
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Quote:
Originally Posted by Canadian_JOY View Post
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 features 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. I flew in a Blackhawk with NVIS-A goggles and felt at least somewhat disoriented all the time. 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.
Personally I think that any military flight with more than one crew member should keep one of them naked eye in civilian airspace both for seeing visible lights and for the wider field of view that comes from NOT using NVG's. There are also civilian helicopter operators that fly with one eye under NVG and the other eye naked.
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  #17  
Old 04-08-2014, 10:47 AM
humptybump humptybump is offline
 
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Quote:
Originally Posted by LAMPSguy View Post
I sometimes forget how little breadth is required to earn a day VFR ticket
I am feeling a bit thin skinned. I worked hard for my PPL, My Instrument rating, my continued training, etc. and in none of that has "NVG" every come up. Thankfully Google and some intelligent filtering translated NVG = "night vision goggles"

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.
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  #18  
Old 04-08-2014, 11:13 AM
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sahrens sahrens is offline
 
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Quote:
Originally Posted by Dean_aeroleds View Post
Personally I think that any military flight with more than one crew member should keep one of them naked eye in civilian airspace both for seeing visible lights and for the wider field of view that comes from NOT using NVG's. There are also civilian helicopter operators that fly with one eye under NVG and the other eye naked.
When I flew in the military every crewmember was goggled at the same time or no one was goggled.

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.
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Last edited by sahrens : 04-08-2014 at 11:15 AM. Reason: Spelling
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  #19  
Old 04-08-2014, 11:47 AM
paul mosher
 
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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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  #20  
Old 04-08-2014, 12:41 PM
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sahrens sahrens is offline
 
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Quote:
Originally Posted by paul mosher View Post
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.
Yes all military helicopters normally have more than one crewmember, although a few can be flown single pilot. I could be wrong, but I do not believe the military is flying single pilot while using night vision goggles. I retired a little over a year ago and that was the rules then, but things may have changed.

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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Last edited by sahrens : 04-08-2014 at 12:42 PM. Reason: clarity
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