LEDs on NVGs

One important topic of discussion today...the change from incandescent to LED.

Red lights are BRIGHT on NVG's, but as towers (scary) and airplanes change over to LED's we have found that they throw off so very LITTLE NVG compatible light as to be nearly invisible until very close. One example, think of those bright blue taxi lights...look at them the next time you fly on a DARK night. I can't see those until I am hovering above them at around 150 AGL!

Red lights on towers...they become invisible (or nearly so) until a FEW HUNDRED feet away in some cases! Even scarier, the tower people do NOT need to inform the FAA (as far as we can tell) since it still complies with the lighting standards!

Why do I bring this up? If you fly at night in an area with military aircraft and have LED NAV light, just think about this...you don't have UHF (we use it almost exclusively), we DO have NVGs and we DO see and avoid, but remember we can get task saturated too. I just want everybody to be safe. DO a chart study and look for MTR's in your area (look it up if you can't remember what it is).

Also, any LED manufacturers out there...simple, add ONE IR LED to each side, now we will see you!

this is not meant to be a "MIL v GA" argument, I just want to make sure everyone is aware of this as we though it important enough to bring up at work today!

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. To achieve an NVG compatibility most light sources are heavily filtered with optical filters to cut emissions that fall outside of the narrow NVG amplification band. Unwanted light outside the NVG band causes the NVG's to "bloom" and can pretty much wipe out any meaningful image.

In a normal beacon light we have a white incandescent bulb that's covered by a red filter. There's still enough NVG-spectrum light escaping from this unit to allow the beacon light to be visible. Now we install a set of red LEDs which are fairly pure in their output. Sure, they make great red light, but the down-side is they aren't making much in the way of spurious light that might fall within the NVG amplification spectrum. the net effect, as LAMPSguy points out, is that LEDs aren't nearly as visible to NVG wearers as their filtered-incandescent forebears.

Oh, and don't think you're going to safely see towers from any distance while blasting along in a helicopter doing nap-of-the-earth flying. If we can't avoid towers and wires during the day with eagle eye vision then the poor NVG wearers don't stand a chance at night.

Come to think of it, what's likely really required is that obstruction lighting LED modules carry a small emitter that produces light in the NVG spectrum. It wouldn't have to be nearly as powerful as the red LEDs in order to be visible on goggles.

Just a thought . . .

Isn't there an official avenue for filing a incident with FAA regarding the lack of NVG visibility in the FAA standards? The standards must evolve for safety of all technology. If so, you have probably already done this, and the heads up here (VAF) for LED users is appreciated. This is a real eye opener. Thanks,

In the summer often our airpark gets visits from ANG Blackhawks who like to come out here at night lights out to practice hovering. One time three came in trail and one of my bright neighbors (pun intended) decided to click the runway lights on for them thinking they didn't know how to. They quickly peeled off as soon he did that. Several of my neighbors told him not to do that again...

WICKED good advice, never even thought about that, even though I spent this rainy day transcribing multiple 'goggle' hops into my electronic logbook. I will ping my LED vendor right now about incorporating an IR LED. Thanks!

LAMPSguy said:

look for MTR's in your area (look it up if you can't remember what it is).

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I'll save everyone the trouble...MTR = Military Training Route (i.e. low level routes).

We routinely fly night low levels in the C-17 at 500' going well north of 300 knots. Fighter types fly at night as well and at much faster speeds. Lots of new radio towers popping up these days along our routes with the new "invisible" red LEDs on top of them. We now typically have to have an additional crew member upstairs not on the nogs looking out for these things.

Sage advice, thanks Lamps for posting. Definitely agree that LED manufacturers ought to consider adding an IR bulb.

These posts are a little heavy on the acronyms to the point that some may be tuning you out without ever getting your important message.

Nonmilitary folks often don't have much experience with NIGHT VISION GOGGLES

erich weaver said:

These posts are a little heavy on the acronyms to the point that some may be tuning you out without ever getting your important message.

Nonmilitary folks often don't have much experience with NIGHT VISION GOGGLES

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Good point, however I'm sure he chose to mention it because it is something he deals with routinely while flying at night (seeing/avoiding other airplanes), and with all the buzz of using LEDs for nav lights instead of the old traditional bulbs thought it might be helpful in educating other pilots on the limitations of military equipment (we DON'T have it all...reference the near midair with a C-130 thread in this sub forum).

Pardon all the military jargon; I for one will try to be more careful of that in the future. Just trying to make the skies a safer place, that's all.

I have no idea how much NVG flying goes on anywhere near my home field - we're not far from Offutt. It's good to know about this, though. I'll make sure to include some IR LED strobes on the plane... I've got a few dozen of them laying around anyway. Thanks for posting the info!

Not just the military

Most EMS helicopter operations use NVGs. There are more folks out there wearing googles than you think.

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.

Canadian_JOY said:

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.

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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...?

sahrens said:

Most EMS helicopter operations use NVGs. There are more folks out there wearing googles than you think.

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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.

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.

Canadian_JOY said:

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.

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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.

LAMPSguy said:

I sometimes forget how little breadth is required to earn a day VFR ticket

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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.

Not always

Dean_aeroleds said:

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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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.

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.

paul mosher said:

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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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.

EMS pilot

sahrens said:

Most EMS helicopter operations use NVGs. There are more folks out there wearing googles than you think.

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We use Anvis 9's in our EMS operation. Very nice equipment. I have not found LED lights to not be visible with NVG's just very muted. Many of the hospital helipads are now LED. They are sometimes tough to see only because they don't appear as bright as former lighting. I will usually shift my vision to the side or under the goggles to see the color and get a complete picture of the LZ.

As far as seeing other AC at night, I have found this to not be a problem as well. Strobes seem to be strobes and other lighting is visible too.

few responses.

Dean_aeroleds said:

Personally I think that any military flight with more than one crew member should keep one of them naked eye in civilian airspace

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Great Idea Dean, but we are not allowed...entire crew is aided or none are aided. The newest goggles add enough safety that I think unaided night currency will be gone for all military aviation within a few years!

Additionally, we have other safety rules regarding landing on ships with them and how long between being on them prior to landing.

humptybump said:

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.

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Glen, please re-read my comment and realize it was not a slight against anyone, nor a comment saying that the PPL is not a significant accomplishment. I would never infer that and am sorry if you took it that way. There is quite a difference in the way military aviators are trained to fly and how/when we MUST fly to get paid. Our syllabus begins with basic familiarization flights, a solo within a handful of flights, then immediately you begin working on basic instrument procedures through full blown approaches. You move onto AOA approaches, Aerobatics and formation. All of that is in the first 6 months.

What I was referring to is that it is GOOD that for your PPL you get to focus on the joy, the basics, and not much else...that is all I meant by it. I do not expect ANY GA pilot to know much more than the fact that NVG's exist as it takes a lot to learn how to use them and you end up using them as an instrument...NOT the fun stuff that you SHOULD be focusing on as you earn your PPL (although NVG's can be a lot of fun).


Also, I am not saying they are invisible...but muted lights that blend with city lights until 500 feet away, depending on airspeed, depending on single ship or section...might as well be invisible!

Finally, I just like that we can have great, open lines of communication like this. If it makes even one person a little more safe, SCORE!

LAMPSguy said:

There is quite a difference in the way military aviators are trained to fly and how/when we MUST fly to get paid. Our syllabus begins with basic familiarization flights, a solo within a handful of flights, then immediately you begin working on basic instrument procedures through full blown approaches. You move onto AOA approaches, Aerobatics and formation. All of that is in the first 6 months.

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Interesting training regiment and something I can relate too (on a smaller scale) .. although in 1996, AOA was not something you'd find in the GA fleet. My training took place in south Texas with the PPL + instrument + aerobatics + various aircraft configurations in a little more than 3 months.

Anyway, I will look into IR markers given there's a lot of military activity in this section of rural America.