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04-07-2014, 03:28 PM
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Join Date: Feb 2008
Location: Pensacola, FL
Posts: 374
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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!
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RV-? in planning stages.
RV-14 #140050 SOLD
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Atlanta based.
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04-07-2014, 03:43 PM
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Join Date: Aug 2007
Location: Ontario, Canada
Posts: 2,291
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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.
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04-07-2014, 04:26 PM
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Join Date: Sep 2007
Location: Central IL
Posts: 5,516
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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,
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Bill
RV-7
Lord Kelvin:
“I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.”
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04-07-2014, 05:32 PM
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Join Date: Jun 2006
Location: 8I3
Posts: 3,564
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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...
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Not a thing I own is stock.
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04-07-2014, 07:16 PM
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Join Date: Dec 2005
Posts: 917
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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!
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Mike C.
Sierra Nevada
RV-6A bought flying
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04-07-2014, 07:48 PM
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Join Date: Dec 2013
Location: Tacoma, WA
Posts: 29
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Quote:
Originally Posted by LAMPSguy
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.
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Doug
Dreaming of an RV-8!
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04-07-2014, 08:10 PM
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Join Date: Aug 2006
Location: santa barbara, CA
Posts: 1,682
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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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04-07-2014, 09:54 PM
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Join Date: Dec 2013
Location: Tacoma, WA
Posts: 29
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Quote:
Originally Posted by erich weaver
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. 
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Doug
Dreaming of an RV-8!
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04-07-2014, 10:59 PM
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Join Date: Sep 2012
Location: Omaha, NE (KMLE)
Posts: 2,247
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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!
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Dale
Omaha, NE
RV-12 # 222 N980KM "Screamin' Canary" (bought flying)
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Previous RV-7 project (sold)
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04-08-2014, 01:38 AM
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Join Date: Jan 2007
Location: Battle Ground
Posts: 480
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Not just the military
Most EMS helicopter operations use NVGs. There are more folks out there wearing googles than you think.
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Scott
RV-7 N818BG (flying)
Bearhawk Patrol (building)
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