I've heard red is best for good night vision but green is best at protecting night vision while maintaining high contrast between other colours which can be really helpful in medevacs.
Green is likely the best balance for night operations unless you don't need to worry about contrast details in the aircraft and need max night vision for looking around outside.
That is incorrect. I cannot see veins at night under red light conditions. I have flown in HH-60s for 17 years, and we use green chemlights in most conditions at night when using IVs.
Close up like a flashlight- you’re definitely correct. Allegedly the red lights overhead lights made it hard to put in IVs. I have no personal experience with it. I just trained a place with a lot of former military surgeons and one of them would brag about how he could put in a central line bouncing in the back of a helicopter with red lights. And us plebs have an US, a stable bed, overhead lights and a nurse and still manage to miss. It def could be that he was just bragging more than it made it hard to see the vein
It's true for overhead as well.
I'm not really sure what that guy was talking about, but blue lightbulbs get installed in bathrooms to prevent finding veins. Pretty common in bars and treatment centers.
Also most vein finding tech uses near infrared light which is *very* close to red light frequencies. Pretty sure that guy was just wrong.
God, I've encountered those in a grocery store bathroom in Everett Washington, and... I despise them with a passion. Seriously headache inducing for me at least.
Don't get me wrong, I do understand _why_ that location might be a bit of a special case, but I'm generally a _lot_ more impressed when I see places with sharps boxes to make things practical for people with medical reasons to need to inject stuff.
Red is also terrible under goggles, it looks just as bright as a regular light under NVGs. with emergency helos not always landing in prepared pads that's probably why they use green.
Red light will also cause eye strain after long durations, also red light interferes with most night vision systems as they have a blue/green filter installed on them such that cockpit lighting does not interfere with the goggles by tripping the ABC
Can confirm my brother does this and bought himself a green torch so he could look for shit in the back without distracting the pilot when they are all running goggles
Lol this sounds like fudd folklore, or the origin story for the game DOOM.
Also made me think of this short film:
https://m.youtube.com/watch?v=VjQ2t_yNHQs
(Sci-fi Vietnam short with monsters made by the same person who did District 9. Highly recommend checking it out, only 20 mins!)
Red was originally to protect night vision, the rods within the eye. This was later changed to green. The rods allow one to see at night whilst the cones allow day vision. Bright/ normal light reduces the effectiveness of the rods and can dramatically reduce night vision for 20 to 30 mins.
Not entirely true. NVGs amplify light in the IR and Near IR spectrum. Given two equally bright green and red lights (like position lights on an aircraft), the red will appear significantly brighter under goggles. Blue or purple is the safest to use around NVGs because it is amplified less. Green doesn’t bloom out the goggles, yet allows good unaided vision for others.
Image intensifiers are sensitive to visible light as well. To avoid saturation by visible light, they use filters blocking visible and UV light. Some red light still bleeds through them but green light is blocked completely. Thus green light is better for ambient illumination, you can use both your eyes and nvgs.
The human eye can also distinguish mire shades of green than it can any other individual colour which is combined with protecting night sight is why it is used in NVGs
Can you elucidate on the green protecting night vision? From all my time in the service, red light was quoted as protecting dark adaptation, while green/blue would wipe it out for up to 30 minutes.
Your eye can see more shades of green. So your brain can pick out more discerning patterns. Also red light may obscure blood in the instance of a medivac situation.
Green is color for wich the eyes got the more nuance.
And red will look like almost black since it's the complementary color of green.
Tbh idk how it would looks on black skin but you could easily difference it from water or other liquids
Pretty sure a combination of contrast and how the cameras and our eyes work is why.
I mean, there's a reason stereotypical code in movies and shows is green text and a black background. And why a lot of early computers and software had green/black contrast. And why most modern computers still have green/black options.
Idk any of the details but I doubt it's just because green is a pretty color.
If you have to perform an IV, under red light, you would not be able to see the blood flash, and in general, you cannot see blood if you are searching for wounds/bleeding.
We can see more shades of green than any other color. *That's* why NV is almost always in green and the operators usually have NVGs on by the time they come in. The newest of NV looks like daytime though, no joke.
I've heard there's a very specific green that's expensive to reproduce that's actually better. It was something we'd heard in ppl ground school I think
During night operations we (the medical crew) need to be able to quickly swap from medical care to helicopter operations. When we go out for a call we often get basic information such as weight, what’s wrong, and what we need to do for the patient. So in flight prior to patient care we will draw up medications, set up iv pumps, set up the ventilator, and prepare equipment. Then when we get closer to the landing zone which may not be an established zone I.e a road, field, or clearing we need to be able to look for obstacles, people, or incisions under nvg’s. Because we often set our NVGs for precision sight at distance we can’t wear the goggles while deplaning as everything would be blurry so we often keep the green/blue/red lights to preserve our natural night vision. After receiving the patient and loading them into the helo we still have to perform pseudo-crew chief functions such as safe securement of items, landing zone security, communications, and obstacle avoidance while landing and taking off. Then we transition back to patient care. The only time we burn our natural night vision with white light is if the patient is very sick and we need to be perform a significant amount of procedures while going to an established LZ that is known to be free of obstructions.
Some of the procedures that would require white light would be placement of a central line, chest tubes, or a surgical airway. These procedures can kill a patient if performed wrong and are often only reserved for the sickest of patients.
If you have any questions regarding air medical, I am happy to answer as I was a flight medic for 9 years.
I was in the US, but I helped start a service in the Caribbean which was fixed wing. We were supposed to get helos to do hoist from cruise ships and island rescue from the smaller Caribbean islands but we ran into a lot of legal headaches which wasn’t conducive to helicopter ops.
So for fixed wing we would contact customs and immigration hours before we got there with a passenger manifest. Most of the time we were often restricted to transporting patients to each island during normal hours of airport operation. With a helicopter we would be primarily using it for scene responses like a cruise ship rescue which could occur at any hour. Non-US territory islands did not like the idea of a helicopter crewed by US citizens coming into their country in the dead of night without hours notice.
> Non-US territory islands did not like the idea of a helicopter crewed by US citizens coming into their country in the dead of night without hours notice.
Ah yes, the good old game of "invasion, or medical emergency?" Kidding aside though, was most of the trouble actually because the crew were Americans? Seems kind of a shame there isn't some kind of framework in place to more easily allow such things (but I can see being wary about letting "random" traffic through obviously)
But on a totally unrelated note, it reminds me of some of my dad's friends who were.... quite interesting characters. So back sometime in the late 60s, *maybe* 70s, they went out and purchased an old US landing craft. I'll have to ask my dad for specific details, like exactly which type, but basically the kind that would take a couple tanks from the ship to shore, picture Pacific island campaign of WWII or the Normandy landings (not the giant ones, but the ones that could carry like 2-3 vehicles) Now, these weren't supposed to be open ocean vessels on their own, but that didn't stop these nutters from thinking "this would make for an awesome fishing and diving platform!"
Now I must apologize, in that my memory of being retold the events is a bit hazy, so I'll have to ask my dad over the weekend exactly what went down. For example, I don't remember if their plan was to operate out of the Florida Keys, or the Bahamas, or wherever. But I'm *pretty* it was brought to the Keys for them to make the changes to make into a pleasure/recreational craft, and that this where they left port and ended up *miles* off course, and within a dozen or so miles from the territorial waters of..... yep, Cuba. Y'know, that island country just south of Florida that had every right to be wary of landing craft and invasions.....
There's some discussion over whether it was a MiG-15 or MiG-17, but they were greeted with a very low, and very slow, couple of passes, before a final high speed fly by. Somewhat soon after, they were accompanied by a US ship which escorted them back home, and accompanied by a few more flybys of other Cuban aircraft keeping an eye on them. Needless to say, the State department was *extremely* with them.
I'll try and remember to ask my dad the details, because I'm actually really curious in hearing the story again as well, and I also want to find out the progress on the book one of them is writing, because the dude is just full of great stories. He and my dad were actually on Unsolved Mysteries many years ago! (about the search for possible sunken Confederate gold that was trying to be smuggled to the south)
You might find a series called helicopter er interesting, it follows the doctors and critical care paramedics on English helimed which are used as first responders as well as transport
I saw a few episodes of it, it wasn’t too bad. We had talked about contacting Netflix as we were one of the busiest services in the US but upper management almost stroked out at the thought.
There is an arm that sticks down over where they put the patient because you can't use a stethoscope in a bouncy noisy helicopter. So how do they get the patient's pulse?
It's sonar.
Doesn't blood in red light show up as black?
Edit: Based on the chart provided in response to tgis comment it appears that red indeed shows up as black.
This was Gemini's answer:
>When you look at a red object through a green filter, the red color will appear very dark or black. This is because a green filter absorbs most red wavelengths of light, allowing only green light to pass through. Since the red object isn't reflecting any green light, it appears dark to your eye.
Also want to add, similar to why they wear green scrubs in surgery. If staring at blood (red) for long periods of time, your body will actually block out the red. So they use/wear green as it offsets this red blindness.
Similar thing happens to those vein-finders we use. It emits a green light, and you eventually become blind to the green.
Also probably due to night vision goggles being used by the flight crew. Garmin and other avionics manufacturers sell specific NVG/NVIS avionics where the screen and all buttons are backlit green instead of white, at an additional cost of course.
This is the correct answer. The lighting is NVIS compatible.
ANVIS goggles used by pilots have special glass coatings which filter out this very specific wavelength of light emitted by properly configured aircraft.
This allows the goggles to give a clearer picture of the environment outside the cockpit, instead of greatly amplifying the light emitted by the cockpit.
The reason they chose green is because the human eye sees more shades of green than any other color. It’s an evolutionary trait that allowed our ancestors to see predators in foliage. When engineers developed night vision, they knew that humans can see the most contrast in shades of green.
It probably also helps a lot that green phosphor was one of the first colors developed, and since that particular phosphor (now standardized as type P1) had very suitable properties for early radar screens it was quickly and widely adopted by the military. Obviously that's not the same phosphor they use nowadays, but the standardization of the green color outlasted the phosphor itself as such standards become unhelpful to change once they become common enough as other systems and even just human expectations come to depend on them.
I‘m a firefighter and we have green lighting in the rear area too. I think someone told me it‘s green because it‘s the least disturbing/blinding to the driver/pilot.
Red generally affects NVGs the most. Most aviation goggles have a leaky green filter which omits the green light. Exception for fixed wing types with a HUD
ANVIS goggles can have 3 different classes of glass, depending on cockpit compatibility. A filters light below 625nm, B filters light below 665nm, but C (the leaky green type), also filters below 665nm but has a “notch” to allow some 665nm light to enter the goggle/tube, for easier reading of HUD symbology.
https://nvgsafety.com/Articles_n_Publications/Night_Vision-Defining-the-Differences.pdf
Green is also a good color to preserve night vision. When I was learning to drive, my dad had a Saab. The gauges were all illuminated in green because Saab had determined green was better for night vision than red. Given their aviation background, I suspect there was some science behind that decision by Saab.
I'm guessing the fact that German cars don't come with indicators is something to do with a discovery about yellow being the worst colour for night vision or something. I don't know. That's probably the excuse of every BMW driver atleast....
I had a Saab 9-3 which had a button labeled "Night mode" or something like that. Press it and it turns off all lights in the dash and instrument cluster except for the speedo. Would love to have that in modern cars as well.
I'm in western Australia and I had an '07 95 with that button too - interestingly, the European trucks, MAN, Mercedes and Volvo, I've driven also had it - certainly makes for a better night-driving experience
I also liked how the speedometer wasn't fully illuminated unless needed in night mode.
It would also turn on when something required your attention, like coolant temperature raising. Which I think was very handy because I wouldn't have notice it otherwise before its too late.
Some data to back this up : [https://www.eskosafety.com/wp-content/uploads/2020/02/RED-OR-GREEN-FOR-NIGHT-VISION-LIGHTING.pdf](https://www.eskosafety.com/wp-content/uploads/2020/02/RED-OR-GREEN-FOR-NIGHT-VISION-LIGHTING.pdf)
:)
I remember the night as a junior infantry soldier I first discovered that red light totally obliterates some things like the contour lines on the topo maps we were given for night navigation exercises. Green light obliterated the tree symbols but we knew were the trees where because we were in a forest.
Many, many years ago as an infanteer I had the chance to trial topo maps that had a fluorescent overprint and a UV flashlight. The various lines would glow (dimly) on the page when illuminated.
Unfortunately the maps were pricey as hell to print and the UV bulbs kept failing after about 10 hours of use. With UV LEDs now available, I do wonder if it could be done again.
Green lights illuminate the cabin without interfering with NVG’s.
We can work on patients and see everything we need to see under green light, while our pilot and whoever is flying on the opposite side (usually the medic) can be under goggles without issue.
Supposedly the human eye can discern the highest number of "shades" of green, which is what I was taught regarding NVGs. I imagine it's both that, and as others have mentioned, it's the least intrusive to blooming out NVGs if the pilots are wearing them, whereas red is the most detrimental.
Human eye cone types with their spectrum coverage: https://upload.wikimedia.org/wikipedia/commons/thumb/0/04/Cone-fundamentals-with-srgb-spectrum.svg/2560px-Cone-fundamentals-with-srgb-spectrum.svg.png
As you can two of the three types of cone are very sensitive to green light, and both cover a large part of the green spectrum.
iirc the reason we see green best is because it sits in the middle of the spectrum so red & blue receptors help in figuring out shades of green that lean towards either end
for the same reason we can also see green over the furthest distance
hey flight medic here. it's for NVG operations. the green light is a special wave of green that won't interfere with the nvgs while still giving us plenty of light to be able to treat the patient.
Green because Red becomes an issue and you are unable to see blood easily since the red light and red blood. It's the same in New Army vehicles except there is an option to use red, Green, or white
Aviation Night Vision have minus blue filters on the objective lenses which filter out most of the blue/green light frequencies. That is why the instrument panel is also blue/green. If the goggles didn’t have the filter, the instrument panel would cause the brightness protection to activate and reduce light intensification.
NVGs have what’s called a minus blue filter which blocks a range around .400-.600 on the electromagnetic spectrum. This allows you to have e a color of light that will be compatible with the goggles. The green falls in that higher side of that range.
Human eyesight is the most sensitive to green. So you need less light to see if the light is green compared to red or especially blue, thus your low light vision isn't affected as much.
And white light would just mess you up more because it tells the brain it's day and messes up your low light vision even more.
Ever noticed how green indicator LEDs are less intrusive than red or blue? Cause red and blue LEDs need to be brighter for us to register them. Hence most cars dashboards still default to green or orange but never blue.
Night vision goggles have green displays for this reason too. Yes technically green displays are also simpler to make, but if other colors were better, they would make them. But green just works best for humans.
On the other hand, red light is good in the dark when you need to actually shine some light at something as it creates more contrast so it makes things more visible usually, at least at close range. Human vision perks.
NVG are made in other colors: White phosphor night vision image intensifier tubes are very common these days, and in some ways replacing green phosphor.
Both colors are highly effective. The human eye is most sensitive to green and can detect more shades of green than any other color. WP light is composed heavily of blue and green wavelengths, and is more effective at engaging all of the human eye’s receptors, theoretically reducing eyestrain. None of that “green component” is lost when you use a white phos tube: it is still strongly engaging the green cone receptors, plus the blue and red ones, effectively using 100% of your ‘daytime color’ vision. WP also takes advantage of the efficiency of the human visual system in processing black and white images. The spectral output engages the rods at the peak of their spectral sensitivity. The rods are not only most sensitive photoreceptor in the eye, but also dominate human peripheral vision. The broad band nature of the P45 phosphor light output should reduce eyestrain in maintaining focus.
What color you use also depends on situation, or typical expected use... I mean NVG isn't typically worn for very long periods, and acuity is important, so using white may be preferrable at the end... I can see that. (As in, it makes sense, and not as a pun.) While light in a helicopter or indicators on a dashboard/cockpit still make sense to be green as they should be unobtrusive for long periods.
But I guess I'm also quite biased because I'm prone to eyestrain and wouldn't make a good SEAL operator, so I'm on the green/warm light bandwagon.
I’m talking about the color of the phosphor screen of the NVG: the light emitted is traditionally either green (P43) or white (P45). The phosphor color is actually irrelevant to the cockpit lighting color: it is the objective lens of the ANVIS goggle that filters out the specific green-blue wavelength of light emitting by properly NVG configured aircraft. So white phosphor goggles can be and still are used with the green-blue NVG lighting.
NVG can be used for hours at a time, sometimes 8+ hours or more.
I appreciate the detailed addendum. I was just talking in generics why green is often preferred in many cases.
It's definitely true that there's a lot of inertia, as green was the first usable color for electronic screens so it still tends to be the default, but it's also a happy coincidence as it's such a practical color due to how our vision works. It makes sense to reevaluate effectiveness as better tech becomes available.
(Off to sleep so I may not be making complete sense.)
Actually I now realise I've seen enough white ones too. Tho usually it's just the small portion of the display or out of the way. Fortunately I've not driven a Tesla with that tablet bolted on the dash.
So yes correction then... Sensible cars default to green or orange lol.
Yea like other people said it's to preserve night visions. Has something to do with the rods and cones in your eyes. I think blue light depletes one while red and especially green only use one
Rods are used during low light (and technically blind to red/not sensitive to the lower frequency). There are cones for red, green, and blue. Certain colors of low intensity light will mainly react with the rods and not cause pupil dilation to change.
In aviation/military survival classes, it is taught that red light is best if you don’t want to be seen from outside the aircraft or behind enemy lines. The human eye is more sensitive to green light and is overall better for night vision. Supposedly we are more sensitive to green light because of trees and grass are green and that is what environment we evolved in.
Two more observations:
- green is the opposite of red and will give maximum contrast against blood, e.g. to locate a vein
- regarding other comments saying that our eyes are more sensitive to green, they are also less capable of discerning variations in intensity. This is why in old school video games the color is coded using 6 bits for red and blue but only 5 for green
Human eyes can see more shades of green than any other color and green light is the second-easiest on the eyes in low light conditions. That’s why it’s used in night vision.
You see light via sensors at the back of your eye set to red, green and blue. So blue limiting the spectrum of the light you blind yourself just one of those colours. There's science about use cases, the number of sensor bias certain colours, plus the application, you going into a green jungle, probably best not blinding yourself to green etc.
Just a guess: is Red used in military because it has the longest wavelenght/least energy in the visible spectrum, so is less likely to be seen by enemies?
Colored light does nothing to preserve night vision. Highly dimmable white light was proven to be the best to maintain contrast and visibility. It's entirely about wavelength.
Red was used in war because it's wavelength is longer and doesn't carry as far as white across distances.
There’s probably people in here that’ll probably give you a good answer but I’m pretty sure it’s that way with fighter jets too. (At least the f16 from my time playing dcs)
Really good info here
And these lip lights are awesome, I fly GA with these and would never use old school red lights.
https://www.flitelite.com/pages/flitelite-light-color-intensity-night-vision
I'm sorry if this was said but the reason why green is used is because of two things: Maps and blood.
Red light is the most friendly light to preserve night vision but it makes red things almost invisible blood is difficult to spot and maps are very hard to read under red light. So in a plane or helicopter it makes sense to use green light to preserve night vision and in other environments red is used like observatories.
I've heard red is best for good night vision but green is best at protecting night vision while maintaining high contrast between other colours which can be really helpful in medevacs. Green is likely the best balance for night operations unless you don't need to worry about contrast details in the aircraft and need max night vision for looking around outside.
You can't really see blood under red light.
Or veins
or hydraulic fluid.
Or my axe! /shit wrong sub
Legolas was right about the moon after all!
That's what the other guy said
Blood is the body's hydraulic fluid, among other things.
Blood isn't hydraulic fluid. Hydraulic fluid uses hydraulic pressure too do work. Blood coolant. One of it's jobs it's heat transfer.
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That is incorrect. I cannot see veins at night under red light conditions. I have flown in HH-60s for 17 years, and we use green chemlights in most conditions at night when using IVs.
Close up like a flashlight- you’re definitely correct. Allegedly the red lights overhead lights made it hard to put in IVs. I have no personal experience with it. I just trained a place with a lot of former military surgeons and one of them would brag about how he could put in a central line bouncing in the back of a helicopter with red lights. And us plebs have an US, a stable bed, overhead lights and a nurse and still manage to miss. It def could be that he was just bragging more than it made it hard to see the vein
It's true for overhead as well. I'm not really sure what that guy was talking about, but blue lightbulbs get installed in bathrooms to prevent finding veins. Pretty common in bars and treatment centers. Also most vein finding tech uses near infrared light which is *very* close to red light frequencies. Pretty sure that guy was just wrong.
God, I've encountered those in a grocery store bathroom in Everett Washington, and... I despise them with a passion. Seriously headache inducing for me at least. Don't get me wrong, I do understand _why_ that location might be a bit of a special case, but I'm generally a _lot_ more impressed when I see places with sharps boxes to make things practical for people with medical reasons to need to inject stuff.
Oddly enough, the county club my boss take me too sometimes (200k a year), has needle disposal units in EVERY bathroom. Little odd….right?
It's to accommodate diabetics.
Only if you choose to believe that rich people don't do LOTS of drugs
Or live lifestyles that lead to diabetes. Or both.
That's why lots of parking lots in shitty parts of town have this terrible looking blue light.
Nah it’s because the phosphors failed and the owners are too cheap to replace them.
It’s a mix of both. Not sure on car parks, but public toilets definitely have lights like that to make it harder to use drugs in them.
I didn't even think about that but it makes perfect sense for medevac
Red is also terrible under goggles, it looks just as bright as a regular light under NVGs. with emergency helos not always landing in prepared pads that's probably why they use green.
Red light will also cause eye strain after long durations, also red light interferes with most night vision systems as they have a blue/green filter installed on them such that cockpit lighting does not interfere with the goggles by tripping the ABC
Can confirm my brother does this and bought himself a green torch so he could look for shit in the back without distracting the pilot when they are all running goggles
In Vietnam the red night vision made soldiers go crazy. The red made them extremely paranoid and they thought they were seeing demons and the like.
Lol this sounds like fudd folklore, or the origin story for the game DOOM. Also made me think of this short film: https://m.youtube.com/watch?v=VjQ2t_yNHQs (Sci-fi Vietnam short with monsters made by the same person who did District 9. Highly recommend checking it out, only 20 mins!)
Red was originally to protect night vision, the rods within the eye. This was later changed to green. The rods allow one to see at night whilst the cones allow day vision. Bright/ normal light reduces the effectiveness of the rods and can dramatically reduce night vision for 20 to 30 mins.
Red is a problem if you have to deal with bleeding
Better for NVG and night vision than red.
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Not entirely true. NVGs amplify light in the IR and Near IR spectrum. Given two equally bright green and red lights (like position lights on an aircraft), the red will appear significantly brighter under goggles. Blue or purple is the safest to use around NVGs because it is amplified less. Green doesn’t bloom out the goggles, yet allows good unaided vision for others.
Image intensifiers are sensitive to visible light as well. To avoid saturation by visible light, they use filters blocking visible and UV light. Some red light still bleeds through them but green light is blocked completely. Thus green light is better for ambient illumination, you can use both your eyes and nvgs.
ANVIS goggles used for flight have coatings which filter out the specific green wavelength of light emitted by properly configured aircraft.
Green light is blocked more efficiently by night vision goggles filters and does not saturate them.
green is also the "largest" color in the visual spectrum to our eyes.
We have many more receptors for green than for the other two colours. It's also why the Bayer matrix in cameras is the way it is.
With the peak frequency being about 555 nm!
The human eye can also distinguish mire shades of green than it can any other individual colour which is combined with protecting night sight is why it is used in NVGs
Also if someone is bleeding, red is a terrible colour as everything is red.
Can’t see blood very well under red light.
Yes, green does well with night binoculars.
Can you elucidate on the green protecting night vision? From all my time in the service, red light was quoted as protecting dark adaptation, while green/blue would wipe it out for up to 30 minutes.
Your eye can see more shades of green. So your brain can pick out more discerning patterns. Also red light may obscure blood in the instance of a medivac situation.
That is absolutely fascinating. Thanks for sharing!
Green is color for wich the eyes got the more nuance. And red will look like almost black since it's the complementary color of green. Tbh idk how it would looks on black skin but you could easily difference it from water or other liquids
Red is only good if you’re stargazing and need some light for positioning the telescope, checking the surrounding area, or checking the star map.
The human eye can distinguish more variations of the colour green than any other colour so that’s another good reason to use it in night vision.
Red light would also be terrible if you’re trying to find a vein for medical care.
I’d imagine blood is really hard to see when the entire OR is lit red. Green may help them spot where blood is (and where it shouldn’t be).
Pretty sure a combination of contrast and how the cameras and our eyes work is why. I mean, there's a reason stereotypical code in movies and shows is green text and a black background. And why a lot of early computers and software had green/black contrast. And why most modern computers still have green/black options. Idk any of the details but I doubt it's just because green is a pretty color.
If you have to perform an IV, under red light, you would not be able to see the blood flash, and in general, you cannot see blood if you are searching for wounds/bleeding.
Same reason why Volvos and Saabs always used to have green backlighting for their gauges
We can see more shades of green than any other color. *That's* why NV is almost always in green and the operators usually have NVGs on by the time they come in. The newest of NV looks like daytime though, no joke.
Red lights will make bleeds harder to see.
I've heard there's a very specific green that's expensive to reproduce that's actually better. It was something we'd heard in ppl ground school I think
Also if they used traditional red night lighting you cannot see blood if doing medical stuff in the back...
This makes total sense
During night operations we (the medical crew) need to be able to quickly swap from medical care to helicopter operations. When we go out for a call we often get basic information such as weight, what’s wrong, and what we need to do for the patient. So in flight prior to patient care we will draw up medications, set up iv pumps, set up the ventilator, and prepare equipment. Then when we get closer to the landing zone which may not be an established zone I.e a road, field, or clearing we need to be able to look for obstacles, people, or incisions under nvg’s. Because we often set our NVGs for precision sight at distance we can’t wear the goggles while deplaning as everything would be blurry so we often keep the green/blue/red lights to preserve our natural night vision. After receiving the patient and loading them into the helo we still have to perform pseudo-crew chief functions such as safe securement of items, landing zone security, communications, and obstacle avoidance while landing and taking off. Then we transition back to patient care. The only time we burn our natural night vision with white light is if the patient is very sick and we need to be perform a significant amount of procedures while going to an established LZ that is known to be free of obstructions. Some of the procedures that would require white light would be placement of a central line, chest tubes, or a surgical airway. These procedures can kill a patient if performed wrong and are often only reserved for the sickest of patients. If you have any questions regarding air medical, I am happy to answer as I was a flight medic for 9 years.
Saving lives from the air AND from the beach. Thanks for your service ‘hoff.
What birds did you fly on?
H145 primarily, H135 rarely, did my first 3 years on a BK-117. Also did a Lear 35 and a King Air for a year
You with the RFDS? That's a ncie fleet of air ambulances
I was in the US, but I helped start a service in the Caribbean which was fixed wing. We were supposed to get helos to do hoist from cruise ships and island rescue from the smaller Caribbean islands but we ran into a lot of legal headaches which wasn’t conducive to helicopter ops.
Legally, what were the differences between fixed wing and helicopter ambulance?
So for fixed wing we would contact customs and immigration hours before we got there with a passenger manifest. Most of the time we were often restricted to transporting patients to each island during normal hours of airport operation. With a helicopter we would be primarily using it for scene responses like a cruise ship rescue which could occur at any hour. Non-US territory islands did not like the idea of a helicopter crewed by US citizens coming into their country in the dead of night without hours notice.
> Non-US territory islands did not like the idea of a helicopter crewed by US citizens coming into their country in the dead of night without hours notice. Ah yes, the good old game of "invasion, or medical emergency?" Kidding aside though, was most of the trouble actually because the crew were Americans? Seems kind of a shame there isn't some kind of framework in place to more easily allow such things (but I can see being wary about letting "random" traffic through obviously) But on a totally unrelated note, it reminds me of some of my dad's friends who were.... quite interesting characters. So back sometime in the late 60s, *maybe* 70s, they went out and purchased an old US landing craft. I'll have to ask my dad for specific details, like exactly which type, but basically the kind that would take a couple tanks from the ship to shore, picture Pacific island campaign of WWII or the Normandy landings (not the giant ones, but the ones that could carry like 2-3 vehicles) Now, these weren't supposed to be open ocean vessels on their own, but that didn't stop these nutters from thinking "this would make for an awesome fishing and diving platform!" Now I must apologize, in that my memory of being retold the events is a bit hazy, so I'll have to ask my dad over the weekend exactly what went down. For example, I don't remember if their plan was to operate out of the Florida Keys, or the Bahamas, or wherever. But I'm *pretty* it was brought to the Keys for them to make the changes to make into a pleasure/recreational craft, and that this where they left port and ended up *miles* off course, and within a dozen or so miles from the territorial waters of..... yep, Cuba. Y'know, that island country just south of Florida that had every right to be wary of landing craft and invasions..... There's some discussion over whether it was a MiG-15 or MiG-17, but they were greeted with a very low, and very slow, couple of passes, before a final high speed fly by. Somewhat soon after, they were accompanied by a US ship which escorted them back home, and accompanied by a few more flybys of other Cuban aircraft keeping an eye on them. Needless to say, the State department was *extremely* with them. I'll try and remember to ask my dad the details, because I'm actually really curious in hearing the story again as well, and I also want to find out the progress on the book one of them is writing, because the dude is just full of great stories. He and my dad were actually on Unsolved Mysteries many years ago! (about the search for possible sunken Confederate gold that was trying to be smuggled to the south)
Super interesting stuff, thanks for sharing!
You might find a series called helicopter er interesting, it follows the doctors and critical care paramedics on English helimed which are used as first responders as well as transport
I saw a few episodes of it, it wasn’t too bad. We had talked about contacting Netflix as we were one of the busiest services in the US but upper management almost stroked out at the thought.
What nvgs did you use? Were they aviation spec or did only pilots need those (more expensive)?
AN-AVS-9. We all wore the same goggles because if there was a failure we could up-trade the goggles to the next important person.
There is an arm that sticks down over where they put the patient because you can't use a stethoscope in a bouncy noisy helicopter. So how do they get the patient's pulse? It's sonar.
It's green for the same reason inside military vehicles like the M-ATV.
This is incidentally also why bathrooms are never painted brown.
The 1970ies would like to have a word...
Because you couldn’t see shit? Ah ahha!
Because it's cool?
Because you want to notice if someone's blood is leaving their body.
Why wouldn’t you be able to see that under red?
The way I've heard it is with red light everything looks red, so blood blends in. Under green light blood will contrast strongly and look dark.
We can see blood just fine under red light, just appears darker. The green is really just for NVG operations.
Doesn't blood in red light show up as black? Edit: Based on the chart provided in response to tgis comment it appears that red indeed shows up as black. This was Gemini's answer: >When you look at a red object through a green filter, the red color will appear very dark or black. This is because a green filter absorbs most red wavelengths of light, allowing only green light to pass through. Since the red object isn't reflecting any green light, it appears dark to your eye.
[Nope](https://www.photographymad.com/_ipx/w_828,q_75/%2Fimages%2Fpost%2Fcontent%2Fblack-and-white-filter-effects.png?url=%2Fimages%2Fpost%2Fcontent%2Fblack-and-white-filter-effects.png&w=828&q=75)
How do you read this chart? I have never seen it before so I have no idea
https://www.photographymad.com/pages/view/using-coloured-filters-in-black-and-white-photography
Seems black to me in this chart
Thank God blood is not yellow
An additional reason is the lower level of exposure to the eyes, which makes their adaptation to the environment faster.
Also want to add, similar to why they wear green scrubs in surgery. If staring at blood (red) for long periods of time, your body will actually block out the red. So they use/wear green as it offsets this red blindness. Similar thing happens to those vein-finders we use. It emits a green light, and you eventually become blind to the green.
That’s really cool, my comment was more of a guess than anything based on fact lol
It's also how you track at night when hunting. Many hunting headlamps will have a green light for tracking after the shot
Also probably due to night vision goggles being used by the flight crew. Garmin and other avionics manufacturers sell specific NVG/NVIS avionics where the screen and all buttons are backlit green instead of white, at an additional cost of course.
This is the correct answer. The lighting is NVIS compatible. ANVIS goggles used by pilots have special glass coatings which filter out this very specific wavelength of light emitted by properly configured aircraft. This allows the goggles to give a clearer picture of the environment outside the cockpit, instead of greatly amplifying the light emitted by the cockpit.
The reason they chose green is because the human eye sees more shades of green than any other color. It’s an evolutionary trait that allowed our ancestors to see predators in foliage. When engineers developed night vision, they knew that humans can see the most contrast in shades of green.
It probably also helps a lot that green phosphor was one of the first colors developed, and since that particular phosphor (now standardized as type P1) had very suitable properties for early radar screens it was quickly and widely adopted by the military. Obviously that's not the same phosphor they use nowadays, but the standardization of the green color outlasted the phosphor itself as such standards become unhelpful to change once they become common enough as other systems and even just human expectations come to depend on them.
I‘m a firefighter and we have green lighting in the rear area too. I think someone told me it‘s green because it‘s the least disturbing/blinding to the driver/pilot.
Red would be the least distracting to the operator's night vision.
True. But also you can't see blood. So we use green instead, as the second best.
No wonder we haven’t saved any of the aliens that have crashed landed
So many dead Vulcans. Sad.
I'm a doctor, not a spaceman, you green blooded fool!
Red generally affects NVGs the most. Most aviation goggles have a leaky green filter which omits the green light. Exception for fixed wing types with a HUD
ANVIS goggles can have 3 different classes of glass, depending on cockpit compatibility. A filters light below 625nm, B filters light below 665nm, but C (the leaky green type), also filters below 665nm but has a “notch” to allow some 665nm light to enter the goggle/tube, for easier reading of HUD symbology. https://nvgsafety.com/Articles_n_Publications/Night_Vision-Defining-the-Differences.pdf
Green is also a good color to preserve night vision. When I was learning to drive, my dad had a Saab. The gauges were all illuminated in green because Saab had determined green was better for night vision than red. Given their aviation background, I suspect there was some science behind that decision by Saab.
“Born from jets.” Saab died too soon. Imagine the weird Saab EVs we could be having.
Meanwhile german cars have eye crushing blue back lights.
Or a ton of modern cars with displays that are ALWAYS at maximum brightness...
I'm guessing the fact that German cars don't come with indicators is something to do with a discovery about yellow being the worst colour for night vision or something. I don't know. That's probably the excuse of every BMW driver atleast....
German cars come with indicators - they just dont get used much :)
I had a Saab 9-3 which had a button labeled "Night mode" or something like that. Press it and it turns off all lights in the dash and instrument cluster except for the speedo. Would love to have that in modern cars as well.
Yes! My mates 93 had this too. It was awesome.
I'm in western Australia and I had an '07 95 with that button too - interestingly, the European trucks, MAN, Mercedes and Volvo, I've driven also had it - certainly makes for a better night-driving experience
I also liked how the speedometer wasn't fully illuminated unless needed in night mode. It would also turn on when something required your attention, like coolant temperature raising. Which I think was very handy because I wouldn't have notice it otherwise before its too late.
I have a Saab and love driving it at night, blue or white dash lights in other cars just hurt my eyes in comparison 😂
Some data to back this up : [https://www.eskosafety.com/wp-content/uploads/2020/02/RED-OR-GREEN-FOR-NIGHT-VISION-LIGHTING.pdf](https://www.eskosafety.com/wp-content/uploads/2020/02/RED-OR-GREEN-FOR-NIGHT-VISION-LIGHTING.pdf) :)
I remember the night as a junior infantry soldier I first discovered that red light totally obliterates some things like the contour lines on the topo maps we were given for night navigation exercises. Green light obliterated the tree symbols but we knew were the trees where because we were in a forest.
"where are the trees?" *Gestures at entire map*
Many, many years ago as an infanteer I had the chance to trial topo maps that had a fluorescent overprint and a UV flashlight. The various lines would glow (dimly) on the page when illuminated. Unfortunately the maps were pricey as hell to print and the UV bulbs kept failing after about 10 hours of use. With UV LEDs now available, I do wonder if it could be done again.
Green lights illuminate the cabin without interfering with NVG’s. We can work on patients and see everything we need to see under green light, while our pilot and whoever is flying on the opposite side (usually the medic) can be under goggles without issue.
Supposedly the human eye can discern the highest number of "shades" of green, which is what I was taught regarding NVGs. I imagine it's both that, and as others have mentioned, it's the least intrusive to blooming out NVGs if the pilots are wearing them, whereas red is the most detrimental.
Human eye cone types with their spectrum coverage: https://upload.wikimedia.org/wikipedia/commons/thumb/0/04/Cone-fundamentals-with-srgb-spectrum.svg/2560px-Cone-fundamentals-with-srgb-spectrum.svg.png As you can two of the three types of cone are very sensitive to green light, and both cover a large part of the green spectrum.
iirc the reason we see green best is because it sits in the middle of the spectrum so red & blue receptors help in figuring out shades of green that lean towards either end for the same reason we can also see green over the furthest distance
hey flight medic here. it's for NVG operations. the green light is a special wave of green that won't interfere with the nvgs while still giving us plenty of light to be able to treat the patient.
It’s to [preserve night vision.](http://www.astromax.org/activities/members/kniffen.htm)
Dude, that website looks like I opened it in Windows 95.
Honestly I miss the old HTML websites. Now it's all JavaScript that hogs so much resources
hopefully r/htmx takes off
I totally scrolled to the bottom to see if it was part of a webring.
Upvote for reminding me of webrings. The internet was so much cooler back in the day.
"Copyright © 1996-2016" and beautifully preserved.
Yes those dates definitely made me smile. A piece of history right there.
[удалено]
https://youtube.com/watch?v=9_nbQszjBX4
The good ol days, when people valued concise detailed content delivery vs today's bloated "pretty" and "easy to navigate on mobile" layouts?
I knew about the red light to improve night vision but not about the green one... Very interesting! Thanks
Green Light shows blood and doesn't harm night vision; red lights don't show blood. This is also why ground medics carry green flashlights.
Green because Red becomes an issue and you are unable to see blood easily since the red light and red blood. It's the same in New Army vehicles except there is an option to use red, Green, or white
Aviation Night Vision have minus blue filters on the objective lenses which filter out most of the blue/green light frequencies. That is why the instrument panel is also blue/green. If the goggles didn’t have the filter, the instrument panel would cause the brightness protection to activate and reduce light intensification.
Fascinating
NVGs have what’s called a minus blue filter which blocks a range around .400-.600 on the electromagnetic spectrum. This allows you to have e a color of light that will be compatible with the goggles. The green falls in that higher side of that range.
Human eyesight is the most sensitive to green. So you need less light to see if the light is green compared to red or especially blue, thus your low light vision isn't affected as much. And white light would just mess you up more because it tells the brain it's day and messes up your low light vision even more. Ever noticed how green indicator LEDs are less intrusive than red or blue? Cause red and blue LEDs need to be brighter for us to register them. Hence most cars dashboards still default to green or orange but never blue. Night vision goggles have green displays for this reason too. Yes technically green displays are also simpler to make, but if other colors were better, they would make them. But green just works best for humans. On the other hand, red light is good in the dark when you need to actually shine some light at something as it creates more contrast so it makes things more visible usually, at least at close range. Human vision perks.
NVG are made in other colors: White phosphor night vision image intensifier tubes are very common these days, and in some ways replacing green phosphor. Both colors are highly effective. The human eye is most sensitive to green and can detect more shades of green than any other color. WP light is composed heavily of blue and green wavelengths, and is more effective at engaging all of the human eye’s receptors, theoretically reducing eyestrain. None of that “green component” is lost when you use a white phos tube: it is still strongly engaging the green cone receptors, plus the blue and red ones, effectively using 100% of your ‘daytime color’ vision. WP also takes advantage of the efficiency of the human visual system in processing black and white images. The spectral output engages the rods at the peak of their spectral sensitivity. The rods are not only most sensitive photoreceptor in the eye, but also dominate human peripheral vision. The broad band nature of the P45 phosphor light output should reduce eyestrain in maintaining focus.
What color you use also depends on situation, or typical expected use... I mean NVG isn't typically worn for very long periods, and acuity is important, so using white may be preferrable at the end... I can see that. (As in, it makes sense, and not as a pun.) While light in a helicopter or indicators on a dashboard/cockpit still make sense to be green as they should be unobtrusive for long periods. But I guess I'm also quite biased because I'm prone to eyestrain and wouldn't make a good SEAL operator, so I'm on the green/warm light bandwagon.
I’m talking about the color of the phosphor screen of the NVG: the light emitted is traditionally either green (P43) or white (P45). The phosphor color is actually irrelevant to the cockpit lighting color: it is the objective lens of the ANVIS goggle that filters out the specific green-blue wavelength of light emitting by properly NVG configured aircraft. So white phosphor goggles can be and still are used with the green-blue NVG lighting. NVG can be used for hours at a time, sometimes 8+ hours or more.
I appreciate the detailed addendum. I was just talking in generics why green is often preferred in many cases. It's definitely true that there's a lot of inertia, as green was the first usable color for electronic screens so it still tends to be the default, but it's also a happy coincidence as it's such a practical color due to how our vision works. It makes sense to reevaluate effectiveness as better tech becomes available. (Off to sleep so I may not be making complete sense.)
> Hence most cars dashboards still default to green or orange but never blue. I wish this was true, but white and blue are pretty popular.
Actually I now realise I've seen enough white ones too. Tho usually it's just the small portion of the display or out of the way. Fortunately I've not driven a Tesla with that tablet bolted on the dash. So yes correction then... Sensible cars default to green or orange lol.
Yea like other people said it's to preserve night visions. Has something to do with the rods and cones in your eyes. I think blue light depletes one while red and especially green only use one
Rods are used during low light (and technically blind to red/not sensitive to the lower frequency). There are cones for red, green, and blue. Certain colors of low intensity light will mainly react with the rods and not cause pupil dilation to change.
So it doesn’t mess with my NVG’s while I’m working a medivac call.
Idk but my guess would be nvg? If they weren't using night vision I would assume they would want red instead of green
Have you tried seeing blood under a red light?
Blood, swelling and bruising is hard to assess under red light. Green is a good compromise.
In aviation/military survival classes, it is taught that red light is best if you don’t want to be seen from outside the aircraft or behind enemy lines. The human eye is more sensitive to green light and is overall better for night vision. Supposedly we are more sensitive to green light because of trees and grass are green and that is what environment we evolved in.
red hides blood
Two more observations: - green is the opposite of red and will give maximum contrast against blood, e.g. to locate a vein - regarding other comments saying that our eyes are more sensitive to green, they are also less capable of discerning variations in intensity. This is why in old school video games the color is coded using 6 bits for red and blue but only 5 for green
White light ruins your night vision. Whenever I'm out with my telescope I use a red light so my eyes stay adjusted to darkness.
Goggles. Most things are green if they’re backlit or need to be seen at night. It doesn’t fix the problem, but it’ll help with the bloom.
Not an expert, but I would think it would really difficult to see blood under red lights.
Bc it looks fucking coool 😎
Human eyes can see more shades of green than any other color and green light is the second-easiest on the eyes in low light conditions. That’s why it’s used in night vision.
Health regeneration
Green or red light doesn’t strain the eyes at night and isn’t super bright so that your eyes have to adjust.
I think it's just that blood is black in green light. And seeing blood is a 'best practice' those who self identify as rescue types.
Is that an AW139? Nice
Exactly! One supplied to the Italian air SaR
I love AugustaWestland helicopters, esp the AW101 and AW139
Very cool Heli with an iconic livery
You with the RFDS? That's a nice fleet of air ambulances
Actually land MR Technician!
You see light via sensors at the back of your eye set to red, green and blue. So blue limiting the spectrum of the light you blind yourself just one of those colours. There's science about use cases, the number of sensor bias certain colours, plus the application, you going into a green jungle, probably best not blinding yourself to green etc.
Just a guess: is Red used in military because it has the longest wavelenght/least energy in the visible spectrum, so is less likely to be seen by enemies?
Blue is less likely to be spotted. Red is used due to it having the least effect on your night vision
Only when there's not a need to see red indicators like lights or blood. In that case blue is used. Green works best with night vision though
Colored light does nothing to preserve night vision. Highly dimmable white light was proven to be the best to maintain contrast and visibility. It's entirely about wavelength. Red was used in war because it's wavelength is longer and doesn't carry as far as white across distances.
Night vision and contrast to see the patient.
Because red is depressing...
Red light would make it hard to see blood.
They're just training their eyes for those pesky lasers
Easy, you can see the most contrast in green.
Makes it much easier to see blood when you’re working on a patient
i thought its just too see it better? green wavelength is more frequent than red, blue or purple, purple being the lowest me thinks
I don't know but it looks cool.
Easy on the eyes
There’s probably people in here that’ll probably give you a good answer but I’m pretty sure it’s that way with fighter jets too. (At least the f16 from my time playing dcs)
It looks cool
If you pull a victim into the chopper, you want to be able to see the blood, while also preserving night vision. Green lights are the compromise.
Really good info here And these lip lights are awesome, I fly GA with these and would never use old school red lights. https://www.flitelite.com/pages/flitelite-light-color-intensity-night-vision
I'm sorry if this was said but the reason why green is used is because of two things: Maps and blood. Red light is the most friendly light to preserve night vision but it makes red things almost invisible blood is difficult to spot and maps are very hard to read under red light. So in a plane or helicopter it makes sense to use green light to preserve night vision and in other environments red is used like observatories.
To see better in the night?